Question: A 14-year-old boy is brought to the pediatrician for behavioral issues. At school, he interrupts class by making barking noises. His mother notes that he has been making throat-clearing noises daily for the past 2 years. He has no medical problems and takes no medications. He gets along with his 2 brothers, plays turn-taking games with his friends, and completes his chores. His temperature is 98.4°F (36.9°C), blood pressure is 118/72 mmHg, pulse is 72/min, and respirations are 16/min. On exam, he grimaces several times and blinks his eyes rapidly. He does not appear to be reacting to internal stimuli. His mood and affect are normal. Which of the following is the most appropriate treatment for this patient?

Answer: Haloperidol

Explanation:
This patient presents with multiple motor tics (grimacing, eye blinking) and phonic tics (barking, throat-clearing) on a daily basis for more than 1 year, which are consistent with Tourette syndrome. Tourette syndrome can be medically treated with antipsychotic agents such as haloperidol.

Tourette syndrome presents with multiple motor tics (e.g., grimacing, sniffing) and 1 or more phonic tics (e.g., throat-clearing, barking) that occur for at least 1 year. Tics must begin before the age of 18 years, and their location, frequency, type, complexity, or severity must change over time. Attention-deficit hyperactivity disorder (ADHD) and obsessive compulsive disorder (OCD) are often co-morbid conditions. Common first-line treatments for Tourette syndrome-related tics include habit reversal training and alpha-2 agonists such as guanfacine or clonidine. However, the only pharmacologic treatments approved for Tourette syndrome in the United States are the antipsychotics haloperidol, pimozide, and aripiprazole. Risperidone is also used due to its favorable side effect profile.

Seideman and Seideman review the current treatments for Tourette syndrome. They note it is a hyperkinetic movement disorder that often occurs in children and presents with motor and phonic tics. They recommend treating with both non-pharmacological and pharmacological treatments for optimal care.

Incorrect Answers:
Answer A: Clozapine is an atypical antipsychotic that blocks dopamine D2 receptors but is not approved for treatment of Tourette syndrome. It is typically avoided due to the risk for agranulocytosis and is mainly used for treatment-resistant schizophrenia as a last-line agent. Weight gain is another significant side-effect.

Answer B: Dextroamphetamine is a stimulant commonly used for the treatment of ADHD. ADHD can be comorbid with Tourette syndrome but presents with hyperactivity (e.g., fidgeting, difficulty taking turns, blurting out answers) and/or inattentive symptoms (e.g., daydreaming, difficulty completing tasks) in at least 2 settings. While this patient’s phonic tics are disruptive, he has no difficulty waiting his turn and completing his chores, making Tourette syndrome more likely.

Answer C: Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) that may be used for the treatment of OCD. OCD is often co-morbid with Tourette syndrome but compulsions are present, which manifest as repetitive counting, hoarding, tapping, or error checking. This patient’s behavior is better attributed to his tics rather than compulsions.

Answer E: Methylphenidate is a stimulant used for the treatment of ADHD. ADHD would present with hyperactivity and/or inattentive symptoms. The patient's vocal interruptions are better attributed to his phonic tics.

Bullet Summary:
Tourette syndrome is treated with habit reversal training, alpha-2 agonists (e.g., guanfacine, clonidine), and/or antipsychotics (e.g., haloperidol, risperidone).


Question: A 38-year-old man presents to the emergency department with nasal congestion, blurry vision, and diplopia. His nasal congestion started about 1 week ago and he noticed the blurry vision this morning when he struggled to read the words on his television screen. His medical history is significant for IV drug use, HIV (CD4: 47/mm^3), hypertension, hyperlipidemia, diabetes mellitus, and seasonal allergies. His home medications include hydrochlorothiazide, atorvastatin, metformin, cetirizine, darunavir, tenofovir, and emtricitabine. He denies recent IV drug use. His temperature is 100.8°F (38.2°C), blood pressure is 127/85 mmHg, pulse is 78/min, and respirations are 12/min. He has injected conjunctiva and rhinorrhea. His cranial nerves are intact, and his motor and sensory neurologic exam is normal. A MRI of the brain is performed and can be seen in Figure A. Which of the following is the most appropriate next step in management?

Empiric treatment with pyrimethamine-sulfadiazine

Serology for anti-John Cunningham (JC) virus antibodies

Answer: Empiric treatment with pyrimethamine-sulfadiazine

Explanation:
This patient with a past medical history of immunosuppression due to HIV (CD4 < 100/mm^3), new focal neurologic findings, and ring-enhancing lesions on head MRI should be treated empirically with pyrimethamine-sulfadiazine for 10-14 days.

The differential diagnosis for ring-enhancing lesions in patients with HIV is determined by the degree of immunosuppression. For patients with CD4 counts > 200/mm^3, the most likely diagnoses include primary brain tumors and metastases. In patients with CD4 counts < 200/mm^3, the differential includes toxoplasma encephalitis, primary CNS lymphoma, progressive multifocal leukoencephalopathy (PML), and other infections. Patients with CD4 counts < 100/mm^3 should have empiric treatment for toxoplasma encephalitis with pyrimethamine-sulfadiazine with follow-up head imaging after 10-14 days. If the patient fails to improve clinically or the size of the lesion does not change, the next step would be a biopsy of the lesion.

Robert-Gangneux and Darde present a review of toxoplasmosis diagnosis and treatment. They discuss how the incidence of these infections has increased dramatically since the advent of organ transplantation and HIV. They recommend increasing vigilance and prophylaxis for this disease.

Figure/Illustration A is an MRI of the brain that demonstrates a ring-enhancing lesion (red circle) in the right occipital lobe. This lesion is likely causing the patient's visual complaints and is consistent with toxoplasmosis.

Incorrect Answers:
Answer A: Brain biopsy should be performed if the patient has no response clinically or on follow-up head imaging to empiric treatment with pyrimethamine-sulfadiazine for 10-14 days. Biopsy in these cases may reveal a CNS lymphoma or other neoplastic process.

Answer C: Empiric treatment with dexamethasone is indicated for patients with substantial mass effect on imaging and severely depressed mental status, neither of which is present in this patient.

Answer D: Lumbar puncture is contraindicated in patients with focal neurologic findings due to the risk of transtentorial herniation. Lumbar puncture would be indicated in the diagnosis of meningitis which presents with fever, headache, photophobies, and meningeal signs.

Answer E: There is no role for serology for anti-John Cunningham (JC) virus antibodies in the workup of ring-enhancing lesions. If it were safe to perform a lumbar puncture (if the patient had no focal findings and no evidence of mass effect on head imaging), it would be reasonable to perform PCR of the CSF for JC virus.

Bullet Summary:
For patients with a past medical history of HIV with CD4 <100 cells/µL, focal neurologic findings, and ring-enhancing lesions on head imaging, the next step in management is empiric treatment for toxoplasma encephalitis with pyrimethamine-sulfadiazine for 10-14 days.


Question: A 2-week-old boy is evaluated by his pediatrician for abnormal feet. The patient was born at 39 weeks via vaginal delivery to a G1P1 29-year-old woman. The patient has been breastfeeding and producing 5 stools/day. He is otherwise healthy. His temperature is 99.5°F (37.5°C), blood pressure is 60/38 mmHg, pulse is 150/min, respirations are 24/min, and oxygen saturation is 98% on room air. A cardiopulmonary exam is notable for a benign flow murmur. A musculoskeletal exam reveals the findings shown in Figure A. Which of the following is the most appropriate next step in management?

Answer: Serial casting

Explanation:
This patient is presenting with talipes equinovarus (congenital clubfoot) for which the most appropriate initial step in management is serial casting using the Ponseti method.

Talipes equinovarus is described clinically as a foot that is cavus, adductus, varus, and equinus. Cavus occurs when the forefoot is pronated relative to the hindfoot. Adductus occurs when the forefoot is medially deviated compared to the hindfoot. Varus occurs when the heel is medially deviated compared to the ankle. Finally, equinus occurs when the ankle rests in a plantarflexed position. The most appropriate initial step in management for this condition is serial casting using the Ponseti method. Cases that are refractory to this intervention are treated with surgical interventions such as split tibialis anterior transfer.

Cady et al. review the evidence regarding the treatment of clubfeet. They discuss how the Ponseti method is now the standard of care in the treatment of this disorder. They recommend early diagnosis and treatment of these patients.

Figure/Illustration A is a clinical photograph that demonstrates cavus, adductus, equinus, and varus positioning of the foot (red circles). This appearance is classically seen in congenital talipes equinovarus.

Incorrect Answers:
Answer A: Botulinum toxin injections are often used to treat spasticity and tension headaches; however, they are not indicated for the treatment of talipes equinovarus.

Answer B: Reassurance and reassessment in 1 month would be inappropriate management and could lead to permanent sequelae. Patients require immediate treatment with serial casting in order to correct the deformity.

Answers 4 & 5: Surgical interventions are reserved for cases of clubfoot that are refractory to stretching and serial casting. A percutaneous Achilles tenotomy is part of the Ponseti method but tendon transfers and releases are reserved for recurrent cases.

Bullet Summary:
The most appropriate initial step in management for congenital clubfoot (talipes equinovarus) is serial casting using the Ponseti method.


Question: A 56-year-old woman presents to the emergency department with muscle weakness. Her symptoms have progressively worsened over the course of 2 weeks and are most significant in her lower extremities. She also notices increased urinary frequency. Approximately 1 month ago, she was diagnosed with calcium phosphate nephrolithiasis. Medical history is significant for rheumatoid arthritis diagnosed approximately 10 years ago and treated with methotrexate as well as type 2 diabetes mellitus treated with metformin. Her temperature is 98.6°F (37°C), blood pressure is 138/92 mmHg, pulse is 92/min, and respirations are 17/min. On physical exam, there is mild tenderness to palpation of the metacarpophalangeal and proximal interphalangeal joints. There is 4/5 power throughout the lower extremity. Laboratory testing is shown. Serum: Na+: 137 mEq/L Cl-: 106 mEq/L K+: 2.9 mEq/L HCO3-: 18 mEq/L Glucose: 115 mg/dL Creatinine: 1.0 mg/dL Urine pH: 5.6 Which of the following is the most appropriate next step in management?

Administer intravenous sodium bicarbonate

Begin potassium replacement therapy with dextrose

Answer: Administer intravenous sodium bicarbonate

Explanation:
This patient's non-anion gap metabolic acidosis, hypokalemia, alkaline urine, and history of a calcium phosphate kidney stone and rheumatoid arthritis are suggestive of type 1 (distal) renal tubular acidosis. The treatment of choice is alkali replacement (sodium bicarbonate).

Type 1 (distal) renal tubular acidosis results from impaired acid (H+) secretion in the distal nephron. Impaired acid secretion decreases the kidney's ability to acidify the urine, thus increasing the urine pH. Impaired acid secretion also results in potassium wasting resulting in hypokalemia. Acidemia causes the bone to release calcium phosphate which buffers the acid. The alkaline urine along with decreased citrate excretion (caused by acidemia) leads to a favorable environment to form calcium phosphate stones. Therefore, correction of metabolic acidosis is essential in managing this condition.

Palmer et al. review the evidence regarding the treatment of renal tubular acidosis. They discuss how this disease can be divided into types based on the location of the deficit. They recommend using alkali therapy in patients with distal renal tubular acidosis.

Incorrect Answers:
Answer A: Administering hydrochlorothiazide would be a treatment option for type 2 (proximal) renal tubular acidosis. Patients with this condition can have associated hypokalemia but would be expected to have an acidic urine pH (less than 5.5) after significant bicarbonate excretion.

Answer B: Administering intravenous insulin would further decrease the serum potassium and place the patient at risk of developing cardiac arrhythmia. This patient's most important concern is her renal tubular acidosis that is resulting in muscle weakness from hypokalemia. Her polyuria is caused by hypokalemia, as it decreases the kidney's responsiveness to antidiuretic hormone. Her serum glucose is also not significantly elevated to cause osmotic diuresis.

Answer D: The dextrose (in the replacement therapy with potassium) would trigger the pancreas to secrete insulin and would lead to an intracellular shift of potassium. This would not particularly improve extracellular potassium levels. Treatment should be aimed at addressing the root of the patient's symptoms. Potassium citrate can be administered in cases of severe hypokalemia and hypokalemia that persists after correcting the serum bicarbonate level.

Answer E: Increasing the methotrexate dose is not appropriate in this case. The patient's muscle weakness is more suggestive of hypokalemia secondary to type 1 renal tubular acidosis. She does not report symptoms of inflammatory arthritis (joint pain/stiffness that is worse in the morning and improves with use).

Bullet Summary:
Type 1 (distal) renal tubular acidosis is treated with alkali replacement (sodium bicarbonate or sodium citrate).


Question: A 3-month-old boy presents to the pediatrician with his mother for a well-child visit. The patient drinks 4 ounces of cow’s milk formula every 3 hours. He usually stools 1 time per day and urinates up to 6 times per day. He regurgitates a moderate amount of formula through his nose and mouth after most feeds. He does not seem interested in additional feeding after these episodes of regurgitation and he has become progressively more irritable around meal times. The patient is starting to refuse some feeds. His mother denies seeing blood or streaks of red in his stool and she denies any family history of food allergies or dermatological problems. The patient’s weight was in the 62nd percentile 4 weeks ago and he is now in the 48th percentile. His height and head circumference have followed similar trends. His temperature is 98.2°F (36.8°C), blood pressure is 72/47 mmHg, pulse is 125/min, and respirations are 27/min. On physical exam, the patient smiles reciprocally and can lift his head and chest when in the prone position. His abdomen is soft, non-tender, and non-distended. Which of the following is the most appropriate next step in management?

Counsel on positioning and thickening feeds

Answer: Counsel on positioning and thickening feeds

Explanation:
This patient presents with frequent regurgitation after feeding, worsening irritability, feeding aversion, and poor weight gain, which is concerning for gastroesophageal reflux disease (GERD). The most appropriate next step in management is counseling on proper positioning and thickening feeds.

Infants with GERD may present with regurgitation or vomiting after feeding, significant irritability, feeding aversion, and poor weight gain or failure to thrive. Symptoms can usually be managed with lifestyle changes including more frequent, thicker, and lower volume feeds and positioning the patient upright during and after feeding. If symptoms continue, patients should undergo a trial of a dairy-free diet to address possible underlying food protein intolerance. Pharmacotherapy with proton pump inhibitors (PPI) is appropriate for patients with persistent symptoms despite these changes, although PPIs can increase the risk of pneumonia and infection with C. difficile.

Chabra and Peeples review the evidence regarding the treatment of neonatal GERD. They discuss how alterations in the infant's environment and feeding pattern are effective in most cases. They recommend proton pump inhibitors if conservative treatments are not effective.

Incorrect Answers:
Answer B: Initiating medical therapy with a proton pump inhibitor is appropriate for patients who have already failed lifestyle changes, including positioning therapy, adjusting feeding patterns, and eliminating cow’s milk and soy from the diet.

Answer C: Obtaining an abdominal ultrasound would help diagnose pyloric stenosis. Patients with pyloric stenosis typically present at a younger age (between 3 and 6 weeks of life) with non-bilious, projectile vomiting and a palpable “olive-shaped” mass in the epigastrium. Treatment is with a pyloromyotomy.

Answer D: Providing reassurance would not be appropriate due to this patient’s poor weight gain. Although most cases of gastroesophageal reflux are uncomplicated and self-resolve by 1 year of age, this patient’s symptoms should be addressed to ensure he is meeting his nutritional requirements.

Answer E: Switching to a hydrolyzed formula to eliminate cow’s milk and soy protein from the patient’s diet would be appropriate if the patient’s symptoms did not improve with changing position and thickening feeds.

Bullet Summary:
The most appropriate initial step in managing gastroesophageal reflux disease in infants is counseling on proper positioning and thickening feeds.


Question: A 1-month-old girl presents to her pediatrician with her mother. The patient was born at 38 weeks gestation via Caesarean section for cervical incompetence. The patient’s mother has no complaints. The child had a runny nose and cough for a few days last week. The patient’s mother endorses decreased appetite during the aforementioned illness which has now returned to baseline. The patient’s family history is significant for an older brother with glucose-6-phosphate dehydrogenase (G6PD) deficiency and a maternal uncle with cirrhosis secondary to chronic hepatitis B. On physical exam, the patient has scleral icterus and dark urine staining her diaper. Laboratory testing reveals the following: Serum: Na+: 137 mEq/L Cl-: 102 mEq/L K+: 4.2 mEq/L HCO3-: 24 mEq/L Urea nitrogen: 12 mg/dL Glucose: 96 mg/dL Creatinine: 0.36 mg/dL Alkaline phosphatase: 146 U/L Aspartate aminotransferase (AST): 86 U/L Alanine aminotransferase (ALT): 76 U/L Total bilirubin: 4.6 mg/dL Direct bilirubin: 3.8 mg/dL Which of the following is the most likely diagnosis?

Increased enterohepatic circulation of bilirubin

Obstruction of the extrahepatic biliary tree

Answer: Obstruction of the extrahepatic biliary tree

Explanation:
This 2-month-old patient presents with jaundice, dark urine, mild transaminitis, and conjugated hyperbilirubinemia, which suggests the diagnosis of biliary atresia. Biliary atresia is characterized by obstruction of the extrahepatic biliary tree.

Biliary atresia is a progressive, obliterative disease of the extrahepatic biliary tree. It presents in the first 8 weeks of life with jaundice, acholic stools, dark urine, hepatomegaly, mild transaminitis, and conjugated hyperbilirubinemia. The definitive diagnosis is made by a cholangiogram that will demonstrate the obliteration of these ducts. Patients who are untreated experience fatal neurological defects due to kernicterus and accumulation of bilirubin in the brain. Treatment usually involves hepatoportoenterostomy (Kasai procedure), in which the duodenum is directly anastomosed to the liver. Most patients also eventually require a liver transplant.

Hartley et al. review the evidence regarding the diagnosis and treatment of patients with biliary atresia. They discuss how researchers are trying to reverse the liver fibrosis associated with this disease. They recommend early referral for a Kasai procedure or liver transplant as needed.

Incorrect Answers:
Answer A: Decreased metabolism of bilirubin occurs with enzymatic deficiencies such as those seen in Crigler-Najjar or Gilbert syndrome. Both Crigler-Najjar and Gilbert syndromes lead to unconjugated hyperbilirubinemia (much more severe in Crigler-Najjar syndrome) rather than the conjugated hyperbilirubinemia seen in this patient.

Answer B: Increased enterohepatic circulation describes the pathophysiology underlying breast milk jaundice. Breast milk jaundice classically peaks in the first 2 weeks of life and leads to unconjugated rather than conjugated hyperbilirubinemia. Treatment is usually supportive and patients can typically continue to breastfeed.

Answer C: Increased production of bilirubin can occur in hemolytic diseases such as G6PD deficiency or hereditary spherocytosis. These conditions would similarly lead to an unconjugated hyperbilirubinemia. Treatment is with addressing the underlying anemia with possible transfusion or splenectomy.

Answer E: Obstruction of the intrahepatic biliary tree describes Alagille syndrome, in which patients have a paucity of interlobular bile ducts. Alagille syndrome is less common than biliary atresia and usually presents with other associated features, such as short stature, dysmorphic facies, ocular findings, and cardiac or renal anomalies. Treatment is with ursodiol.

Bullet Summary:
Biliary atresia presents in the first 8 weeks of life with jaundice and conjugated hyperbilirubinemia.


Question: A 59-year-old man presents to his primary care physician for abdominal pain and foul-smelling diarrhea that has persisted for the past 2 years. The patient has a medical history of alcoholism and has been admitted to the hospital multiple times for withdrawal, abdominal pain, and traumatic injuries from his drinking. The patient states that his last drink was more than 1 year ago. His temperature is 99.3°F (37.4°C), blood pressure is 115/78 mmHg, pulse is 78/min, respirations are 15/min, and oxygen saturation is 99% on room air. Physical exam reveals a non-tender, non-distended abdomen. Laboratory studies are notable for a serum calcium of 7.0 mg/dL. A computed tomography (CT) scan of the abdomen is performed as seen in Figure A. A Sudan Black stain of the patient’s stool is positive. Which of the following is the most appropriate treatment for the underlying cause of this patient’s diarrhea?

Answer: Pantoprazole

Explanation:
This patient with a history of alcoholism is presenting with steatorrhea (foul-smelling diarrhea that stains with Sudan Black, a stain that detects fat in the stool), hypocalcemia, and findings suggestive of chronic pancreatitis on CT scan (inflammatory changes and calcification). His steatorrhea can be improved with the administration of proton pump inhibitors such as pantoprazole.

Chronic pancreatitis is a sequela that occurs after repeated bouts of acute pancreatitis. It can occur secondary to alcoholism or gallstones, and it may present with chronic abdominal pain, hypocalcemia, and signs of malnutrition and weight loss. Malnutrition and weight loss occur secondary to the pancreas’ inability to produce pancreatic enzymes which leads to poor nutrient absorption. Lack of lipase can lead to fat wasting in the stool, steatorrhea, and fat-soluble vitamin deficiency (A, D, E, and K). The management of chronic pancreatitis is the cessation of the underlying cause, pancreatic enzyme replacement, and the administration of proton pump inhibitors. Proton pump inhibitors help with steatorrhea by increasing the pH as low pH inactivates pancreatic enzymes.

Singh et al. review the diagnosis and management of chronic pancreatitis. The authors find that the diagnosis can be secured by typical findings on CT or magnetic resonance imaging (MRI) including pancreatic calcifications, ductal dilatation, and pancreatic atrophy. The authors recommend the use of endoscopic ultrasound in securing the diagnosis in patients with equivocal imaging findings and a high index of suspicion, such as patients with repeated episodes of acute pancreatitis.

Figure/Illustration A is a CT scan of the abdomen demonstrating calcifications and chronic inflammatory injury (red arrows) suggesting a diagnosis of chronic pancreatitis.

Incorrect Answers:
Answer A: Ciprofloxacin or ceftriaxone is the appropriate management of infectious diarrhea from a bacterial organism. This usually presents with fever, as well as bloody or purulent diarrhea. In general, young and healthy patients who are able to hydrate themselves should not be given antibiotics, even for infectious diarrhea. Elderly patients, immunosuppressed patients, or patients with symptoms that do not improve spontaneously should be managed with a stool culture and antibiotics.

Answer B: Loperamide is an anti-diarrheal agent that could be used for irritable bowel syndrome to decrease bowel motility and improve symptoms of diarrhea. Loperamide and other antidiarrheals should never be used for infectious causes of diarrhea as they will delay the fecal shedding of the organism or virus and could prolong symptoms.

Answer C: Oral rehydration is recommended for any patient with diarrhea and signs of volume depletion and is preferred to IV fluids as the integrity of the gut is protected. This patient’s diarrhea is likely caused by his chronic pancreatitis; thus, oral rehydration may be indicated but does not address the underlying cause of this patient’s diarrhea.

Answer E: Rifaximin is an antibiotic that targets gut flora and can decrease enteric flora and treat conditions such as small bowel bacterial overgrowth. Small bowel bacterial overgrowth presents in patients with conditions such as diabetic gastroparesis or scleroderma secondary to decreased bowel motility causing bacterial overgrowth and profuse diarrhea. Treating the underlying cause in addition to rifaximin will eliminate the excess bacteria.

Bullet Summary:
Proton pump inhibitors should be given in patients with persistent diarrhea in the setting of chronic pancreatitis to prevent the inactivation of pancreatic enzymes.


Question: A newborn boy is evaluated in the hospital nursery 2 hours after birth. The patient was born at 39 weeks of gestation to a 30-year-old primigravid via vaginal delivery. The patient’s mother received routine prenatal care and the pregnancy was uncomplicated. The patient’s anatomy ultrasound at 20 weeks of gestation was unremarkable. The patient’s mother denies any family history of genetic diseases. The patient’s APGAR scores were notable for poor muscle tone at both 1 and 5 minutes of life. The patient’s birth weight is 2.6 kg (5 lb 11 oz), which is at the 5th percentile. His height and head circumference are in the 15th and 3rd percentile, respectively. His temperature is 97.1°F (36.2°C), blood pressure is 57/42 mmHg, pulse is 140/min, and respirations are 38/min. On physical exam, the patient has a wide nasal bridge, down slanting palpebral fissures, and widely spaced eyes. He has good respiratory effort with a high-pitched cry. This patient is most likely to have experienced a deletion on which of the following chromosomes?

Answer: 5p

Explanation:
This patient presents with a characteristic mew, microcephaly, hypertelorism, wide nasal bridge, and hypotonia, which suggests a diagnosis of cri-du-chat syndrome. Cri-du-chat syndrome is caused by a deletion on chromosome 5p.

Cri-du-chat syndrome is most commonly caused by a de novo partial deletion of chromosome 5p. Other cases may be caused by a parental translocation involving the relevant section of chromosome 5p. Patients present with a mew-like cry, microcephaly, hypertelorism, down slanting palpebral fissures, a broad nasal bridge, low-set ears, low birth weight, hypotonia, and intellectual disability. The cat-like cry usually resolves by 2 years of age. Treatment is supportive though some patients may have cardiac abnormalities that require surgical intervention.

Cerruti Mainardi reviews the evidence regarding the etiology and diagnosis of patients with Cri-du-chat syndrome. She discusses how the diagnosis is mostly made clinically at this time. She recommends karyotype and FISH studies for those with ambiguous features.

Incorrect Answers:
Answer A: A deletion on chromosome 4p causes Wolf-Hirshhorn syndrome, which presents with growth restriction, microcephaly, congenital heart disease, severe intellectual disability and dysmorphic "Greek warrior helmet" facies of a high forehead, prominent glabella, arched eyebrows, hypertelorism, and epicanthal folds. Treatment is supportive though some patients may require surgical intervention for heart defects.

Answer C: A deletion on chromosome 5q results in Sotos syndrome, a pediatric overgrowth disorder characterized by an increase in head circumference, hypotonia, delayed acquisition of motor skills, and mild intellectual disability.

Answer D: A deletion on chromosome 7q may results in Williams syndrome, which presents with dysmorphic, “elfin” facies, global developmental delay with a hypersocial personality, and supravalvular aortic stenosis. Treatment is supportive though some patients will require surgical intervention for aortic stenosis.

Answer E: A deletion on chromosome 15q may cause either Prader-Willi syndrome or Angelman syndrome, depending on whether the deletion affects the maternal or paternal chromosome. Prader-Willi syndrome classically presents with dysmorphic facies, hyperphagia, and hypogonadism. Angelman syndrome classically presents with intellectual disability, frequent smiling or laughing, and gait ataxia. Treatment is supportive with seizure control for those who develop seizures.

Bullet Summary:
Cri-du-chat syndrome (presents with a characteristic mew, microcephaly, hypertelorism, wide nasal bridge, and hypotonia) is most commonly caused by a deletion on chromosome 5p.


Question: A 55-year-old woman presents to a primary care physician with persistent nausea and abdominal discomfort. She has experienced these symptoms daily for the past 3 months. She feels bloated and has episodic loose and watery stools. She has a history of hypertension and hyperlipidemia for which she takes amlodipine and atorvastatin. She immigrated from Vietnam 6 months ago. Her temperature is 98.6°F (37.0°C), blood pressure is 110/60 mmHg, pulse is 70/min, and respirations are 18/min. Physical exam reveals a thin-appearing woman in no acute distress. Her mucous membranes are moist. Cardiac and lung examinations are unremarkable. Laboratory results are as follows: Leukocyte count: 13,000/mm^3 Segmented neutrophils: 54% Bands: 2% Eosinophils: 6% Basophils: 0.4% Lymphocytes: 30% Monocytes: 5% A vitamin D level is 26 ng/mL (reference: >= 30 ng/mL). Which of the following is the most appropriate test in making the diagnosis?

Answer: Stool ova and parasite assay

Explanation:
This patient who presents with persistent abdominal discomfort, nausea, bloating, diarrhea, eosinophilia, and signs of malabsorption (thin-appearing, vitamin D deficiency) in the setting of immigration from a resource-limited country most likely has a gastrointestinal parasite infection (Ascaris lumbricoides). The most appropriate next step in management is to obtain a stool ova and parasite assay.

Ascaris lumbricoides is a roundworm that is transmitted via the fecal-oral route (egg ingestion). While most patients are asymptomatic, there can be pulmonary and intestinal manifestations in the early and late phases, respectively. Pulmonary signs include dry cough, dyspnea, fever, and wheezing. Intestinal signs include abdominal discomfort, diarrhea, nausea, vomiting, malabsorption, and/or anorexia. The diagnosis should be suspected in patients with vague abdominal symptoms with travel history to an endemic area. The diagnosis is secured with stool microscopy for eggs or worms. Complications of this condition include intestinal obstruction or hepatobiliary/pancreatic involvement, presenting as biliary colic, obstructive jaundice, and/or ascending cholangitis. Treatment in patients with uncomplicated infection is with anti-helminth therapy (albendazole or mebendazole).

Parija et al. review the epidemiology of helminth infections globally. The authors note that many cases are caused by Ascaris species. They recommend prompt identification of these infections as they can cause lack of school attendance, anemia, and cognitive deficits if left untreated.

Incorrect Answers:
Answer A: Bowel wall biopsy is used in the diagnostic work-up of suspected Whipple disease, which presents with chronic diarrhea, malabsorption, weight loss, and joint symptoms (arthralgias). This disease is progressive over years and would be less likely in this patient with disease onset of 3 months.

Answer B: CT scan of the abdomen is used in the diagnostic work-up of small bowel obstruction, which presents as crampy abdominal pain, constipation, obstipation, and/or vomiting. Bowel obstruction is an acute process that would be unlikely in this patient with chronic symptoms. Although bowel obstruction is a complication of Ascaris infection, this patient has no signs of obstruction. Diarrhea may occur secondary to infection of the colon as well including colitis or diverticulitis; however, these conditions typically cause pain and low grade fever.

Answer C: Lower endoscopy (colonoscopy) is used in the diagnosis of inflammatory bowel disease, consisting of Crohn disease and ulcerative colitis. Ulcerative colitis presents with bloody diarrhea, abdominal pain, weight loss, and fatigue. Eosinophilia would be unexpected, and this patient does not have bloody diarrhea.

Answer E: Stool toxin assay is used to diagnose Clostridioides difficile infection. This presents after recent antibiotic use with watery diarrhea, dehydration, fever, and nausea. It presents acutely and generally without eosinophilia.

Bullet Summary:
Parasitic gastrointestinal infections present with chronic diarrhea, abdominal discomfort, malabsorption, and eosinophilia, and are diagnosed using stool ova and parasite assays.


Question: A 55-year-old male bodybuilder presents to the emergency department with weakness of his right arm. The patient states he has experienced these symptoms for a few weeks; however, today his hand felt so weak he dropped his cup of tea. The patient has a medical history of diabetes. He drinks 2-7 alcoholic drinks per day and has smoked 2 packs of cigarettes per day since he was 25. The patient uses anabolic steroids. He has lost 17 pounds since he last came to the emergency department 1 month ago. His temperature is 99.5°F (37.5°C), blood pressure is 177/108 mmHg, pulse is 90/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam reveals decreased sensation in the right arm and 2/5 strength in the right arm and 5/5 strength in in the left arm. The patient states that he is experiencing a dull aching and burning pain in his right arm during the exam. Symptoms are not changed with changes in head and neck position. Which of the following is the most likely diagnosis?

Answer: Apical lung tumor

Explanation:
This patient is presenting with unilateral upper extremity paresthesia and weakness suggestive of compression of the neurovascular structures of the upper extremity secondary to an apical lung tumor.

An apical lung tumor can compress the neurovascular structures in its proximity and cause pain, numbness, and weakness of the ipsilateral arm. A Horner syndrome can also be observed with compression of the sympathetic chain leading to ipsilateral miosis, ptosis, and anhidrosis in some cases. These malignancies typically occur in older male smokers and can be associated with symptoms such as fatigue, cough, and weight loss. Chest radiography will demonstrate an apical opacity and CT scan can confirm the size and location of the mass. Treatment is with chemotherapy and surgical excision of the tumor.

Davis and Knight review the evidence regarding the diagnosis and treatment of patients with apical lung tumors. They discuss how these tumors can be associated with brachial plexus injuries. They recommend surgical excision of these tumors if they are resectable.

Incorrect Answers:
Answer B: Brachial plexopathy could present with weakness and numbness of the ipsilateral arm but is a less likely diagnosis (and a diagnosis of exclusion). Treatment is with identification and surgical release of any underlying anatomic defects (such as compressive bands) and supportive therapy if none are found.

Answer C: Cerebral infarction (stroke) would present with sudden onset of acute neurological deficits. These would typically only affect one side of the body and would not necessarily be associated with a dull pain or numbness that is chronic. Treatment is with thrombolytics if patients meet criteria for acute therapy.

Answer D: Scalenus anticus syndrome occurs in bodybuilders or athletes with hypertrophied neck muscles that compress the brachial plexus. Symptoms are typically worsened by certain positions. Treatment is with physical therapy and surgical decompression in refractory cases.

Answer E: Subclavian steal syndrome presents with numbness, tingling, weakness in a limb, and CNS symptoms (vertigo, slurred speech, or stroke-like symptoms) that are worsened with activity and relieved with rest. Treatment is with vascular intervention to restore blood flow.

Bullet Summary:
Apical lung tumors can compress neurovascular structures in the upper extremity and cause pain, numbness, and tingling in the ipsilateral arm.


Question:
A 27-year-old nurse presents to the emergency department with a 30-minute history of palpitations and chest pain. She has been experiencing nausea, vomiting, and diarrhea after eating leftovers 2 days ago. Her husband tells the physician that he is concerned that the patient has been increasingly obsessed about her weight recently. She has a history of major depressive disorder for which she takes escitalopram. Her temperature is 98.6°F (37.0°C), blood pressure is 110/72 mmHg, pulse is 110/min, and respirations are 11/min. Physical examination is notable for dry mucous membranes and tachycardia with regular rhythm. Laboratory testing shows the following results:

Serum:
Na+: 135 mEq/L
Cl-: 96 mEq/L
K+: 2.9 mEq/L
HCO3-: 36 mEq/L

Venous blood gas shows a pH of 7.52. Which of the following tests is most appropriate in differentiating between different etiologies of this patient's lab abnormalities?

Answer: Urine chloride

Explanation:
This patient who presents with hypokalemia and metabolic alkalosis may either be vomiting or engaging in diuretic abuse. A urine chloride test can be used to distinguish between these possibilities because urine chloride will be high in diuretic abuse and will be low/normal in surreptitious vomiting.

Metabolic alkalosis is an acid-base disorder that is due to an increased level of serum bicarbonate. This increase can be secondary to increased bicarbonate intake or loss of hydrogen ions. Etiologies consistent with increased intake include antacid use or milk-alkali syndrome. Etiologies consistent with hydrogen ion loss include gastrointestinal losses such as vomiting or renal losses such as hyperaldosteronism, Bartter syndrome, or diuretic abuse. Urine chloride can distinguish between gastrointestinal and renal losses because urine chloride levels will be high in patients with renal tubule dysfunction or diuretic abuse. This is due to increased urinary excretion of ammonium chloride in cases of diarrhea. On the other hand, urine chloride will generally be low in hyperaldosteronism due to loss of chloride with vomiting.

Wu et al. studied the causes of chronic hypokalemia as well as laboratory findings that can be used to distinguish between different etiologies. They show how urine sodium and chloride can be helpful for identifying the surreptitious use of diuretics. The authors recommend the use of the sodium-to-chloride excretion ratio to help diagnose patients with chronic normotensive hypokalemia.

Incorrect Answers:
Answer A: Arterial blood gas is useful for determining the acid-base state of a patient because it simultaneously measures carbon dioxide and bicarbonate levels. This test is not as useful in determining different causes of metabolic alkalosis because all of these etiologies will have similar findings (high bicarbonate and compensatory high carbon dioxide), especially in patient who has already received a venous blood gas.

Answer B: Complete blood count is useful for determining whether a patient is anemic resulting in decreased oxygen delivery to end organs due to decreased carrying capacity for oxygen. In cases of severe anemia and hypoperfusion, peripheral tissues produce lactic acid which will result in an anion gap metabolic acidosis rather than metabolic alkalosis.

Answer C: Serum glucose elevation can result in increased diuresis as well as pseudohyponatremia (decreased measured sodium due to increased glucose). Alternatively, acidosis may also be caused by insulin deficiency in diabetic ketoacidosis. Neither of these findings is consistent with the lab results seen in this patient.

Answer E: Urine toxicology can be used to determine whether the patient is taking any substances of abuse. There is no pathognomonic acid-base finding that can aid in diagnosing overdose and/or substance abuse. However, most standard urine toxicology screens do not detect the use of diuretics.

Bullet Summary:
Urine chloride can distinguish between gastrointestinal and renal causes of metabolic alkalosis.


Question: A 2-year-old boy is brought to the emergency room by his mother, who states that her son has been coughing uncontrollably for 3 hours. The child has a medical history of obesity and atopic dermatitis and uses topical steroid cream. His birth history is unremarkable. His family history is notable for asthma in his older sister and irritable bowel syndrome in his father. His temperature is 98.5°F (36.9°C), pulse is 120/min, blood pressure is 90/52 mmHg, and respirations are 32/min. On exam, he appears uncomfortable, is coughing continuously, and is drooling. Cardiopulmonary and abdominal exams are unremarkable. A chest radiograph is performed and the results are shown in Figures A and B. Which of the following is the most appropriate next step in management?

Answer: Endoscopic removal

Explanation:
This child presents with foreign body ingestion with a button battery seen in the esophagus on radiography. The most appropriate next step in management is urgent endoscopic removal of the battery.

Button batteries are commonly used in watches and small electronic devices. If these objects are ingested (usually by children), they can become lodged in the esophagus. Coughing, drooling, and chest discomfort are classic symptoms but a lack of symptoms does not negate the need for evaluation if suspicion is high. The location of the battery can be confirmed by radiograph and orthogonal views can localize the object in the esophagus versus the trachea. Endoscopy is the preferred method of removal as direct visualization of any associated esophageal injury is possible. The battery can cause ulceration or perforation if left in the esophagus due to chemical extravasation.

Baharudin et al. review a number of cases of pediatric ingestions resulting in esophageal lodging. They discuss how a stack of coins can mimic the appearance of a battery. They recommend urgent intervention in cases of suspected battery ingestion.

Figure/Illustration A is a chest radiograph depicting a round object lodged in the esophagus, with a “double halo” sign (red circle). This sign is an indication that this object is a battery rather than a coin. Figure/Illustration B is a lateral chest radiograph demonstrating that the battery is posterior to the trachea (red circle). This view confirms that the location of the battery is in the esophagus.

Incorrect Answers:
Answer A: Balloon catheter removal can be attempted for ingested button batteries but is typically used only if endoscopy is not available. There is more potential for tissue damage without direct visualization, so ingestion time greater than 2 hours is generally a contraindication for this method.

Answer B: Ipecac administration can induce emesis and is rarely used for toxic ingestions. Vomiting can cause further lodging in the esophagus and even more tissue damage. Ipecac is therefore not recommended in the modern management of toxic ingestions.

Answer D: Observation would be appropriate if there is an ingested object that has already traveled further into the gastrointestinal tract (if they are small and smooth), as these objects would likely pass on their own. A classic example would be a coin ingestion that would appear as a single round object rather than a double ring appearance. A button battery in the esophagus is an emergency and should be removed urgently.

Answer E: Surgical extraction of a battery with associated repair may be required if there is suspicion of an esophageal-vascular fistula, mediastinitis, or other such complications. It may also be necessary if a magnet was simultaneously ingested. In the absence of these complications, endoscopic removal should be attempted first.

Bullet Summary:
Button batteries lodged in the esophagus require urgent endoscopic removal.


Question: A 45-year-old man presents to a physician due to difficulty swallowing and slurred speech. For the past 3 months, the patient has been coughing when he drinks liquids. His speech also sounds different according to his wife. The patient has no significant medical history. His temperature is 98.6°F (37.0°C), blood pressure is 110/80 mmHg, pulse is 60/min, and respirations are 12/min. On physical exam, he is unable to fully extend his tongue, and there are fasciculations on his tongue. When tapping the mandible at the chin while the mouth is held open, there is pronounced upward movement of the lower jaw. Sensory exam reveals no deficits. Which of the following therapies is most likely to improve survival for this patient's disease process?

Answer: Riluzole

Explanation:
This patient with dysphagia (difficulty swallowing water), dysarthria (altered and slurred speech), lower motor neuron deficits (tongue fasciculations and weakness), upper motor neuron deficits (exaggerated jaw jerk reflex), and preserved sensory function most likely has amyotrophic lateral sclerosis (ALS). Riluzole, a glutamate inhibitor, is currently the only Food and Drug Administration (FDA) approved medication that improves survival in patients with ALS.

ALS is a neurodegenerative disease that affects both upper and lower motor neurons. Upper motor neuron signs include spasticity and hyperreflexia, while lower motor neuron signs include muscle atrophy and fasciculations (spontaneous, involuntary muscle contraction and relaxation). In patients with bulbar-onset ALS, the initial clinical presentation is dysarthria, dysphagia, tongue atrophy, and abnormal jaw jerk reflex. Riluzole decreases the rate of glutamate release from presynaptic neurons, which is thought to decrease excitatory neurotoxicity. Riluzole improves survival by 2-6 months in patients with ALS and may have a greater survival benefit in patients with bulbar-onset ALS.

Masori and Van Damme review the genetics, pathophysiology, classic clinical presentation, extra-motor manifestations, diagnostic workup, and treatment for ALS. They discuss how riluzole provides a survival benefit in patients with this disease. They recommend treating patients with ALS using riluzole as tolerated.

Incorrect Answers:
Answer A: Baclofen is a gamma-aminobutyric acid (GABA) agonist that reduces the release of excitatory neurotransmitters to decrease spasticity in ALS. Along with tizanidine, baclofen is a first-line symptomatic treatment for spasticity in ALS. Baclofen does not improve survival in ALS.

Answer B: Dextromethorphan and quinidine is a combination of a sigma opioid receptor agonist and a sodium channel blocker used to control pseudobulbar affect in patients with ALS. Pseudobulbar affect is a sudden uncontrollable outburst of laughter or tearfulness that affects almost half of patients with ALS. Dextromethorphan and quinidine has not been shown to improve survival in ALS.

Answer C: Edaravone is an intravenous antioxidant that may decrease the progression of early ALS. Although it is now FDA approved, studies have not yet shown that edaravone improves survival in patients with ALS. Further studies will be needed in order to determine the risks and benefits of using this drug.

Answer E: Tizanidine is a central alpha-2-adrenergic receptor agonist that decreases spasticity in ALS by increasing presynaptic inhibition of motor neurons. Excess spasticity in ALS can negatively impact coordination, ambulation, and other activities of daily living. Tizanidine and other antispastic medications do not improve survival in patients with ALS.

Bullet Summary:
Riluzole is a glutamate inhibitor that improves survival in patients with amyotrophic lateral sclerosis.


Question: A 55-year-old male bodybuilder presents to the emergency department with weakness of his right arm. The patient states he has experienced these symptoms for a few weeks; however, today his hand felt so weak he dropped his cup of tea. The patient has a medical history of diabetes. He drinks 2-7 alcoholic drinks per day and has smoked 2 packs of cigarettes per day since he was 25. The patient uses anabolic steroids. He has lost 17 pounds since he last came to the emergency department 1 month ago. His temperature is 99.5°F (37.5°C), blood pressure is 177/108 mmHg, pulse is 90/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam reveals decreased sensation in the right arm and 2/5 strength in the right arm and 5/5 strength in in the left arm. The patient states that he is experiencing a dull aching and burning pain in his right arm during the exam. Symptoms are not changed with changes in head and neck position. Which of the following is the most likely diagnosis?

Answer: Apical lung tumor


Question: A 41-year-old man presents to his primary care provider after seeing bright red blood in the toilet bowl after his last 2 bowel movements. He reports that he also noticed some blood mixed with his stool. The patient denies abdominal pain or any changes in his stool habits. He notes a weight loss of 8 pounds in the last 2 months with no changes in his diet or exercise habits. His medical history is significant for an episode of pancreatitis 2 years ago for which he was hospitalized for several days. He drinks 2-3 beers on the weekend and he has never smoked. He has no family history of colon cancer. His temperature is 97.6°F (36.4°C), blood pressure is 135/78 mmHg, pulse is 88/min, and respirations are 14/min. On physical exam, his abdomen is soft and non-tender to palpation. Bowel sounds are present, and there is no hepatomegaly. Which of the following is the most appropriate next step in management?

Answer: Colonoscopy

Explanation:
This patient presents with hematochezia and weight loss, which raises concern for colorectal cancer. The most appropriate next step in management is performing a colonoscopy.

The differential diagnosis of hematochezia includes colorectal cancer, inflammatory bowel disease, diverticulosis, and hemorrhoids. The evaluation depends in large part on the age of the patient and whether the patient presents with alarm symptoms such as weight loss, abdominal pain, change in bowel habits, or iron-deficiency anemia. If the patient is over the age of 50, has alarm symptoms, or has a family history of colorectal cancer, the evaluation should begin with a colonoscopy to rule out malignancy. If the patient is between the ages of 40 and 50 and without other red flags, the patient can elect to undergo sigmoidoscopy as a less invasive procedure than colonoscopy. If the patient is under the age of 40 and without alarm symptoms, the workup may begin with an anoscopy to first evaluate for hemorrhoids. Once cancer has been ruled out, additional evaluation for chronic inflammatory diseases such as ulcerative colitis can be conducted.

Church presents evidence regarding the current use of colonoscopy. He discusses how the detection of neoplasia during colonoscopy is suboptimal despite its use as the current screening tool of choice. He recommends understanding which patients are missed and how to better detect neoplasias in these patients.

Incorrect Answers:
Answer A: Abdominal CT might be used to evaluate for metastases if the diagnosis of colorectal cancer is confirmed but it would not be used to diagnose the primary malignancy. A CT scan would be the most appropriate initial step in diagnosis if diffuse metastasis were already suspected such as a presentation of severe weight loss and an enlarged, palpable, and nodular liver.

Answer B: Anoscopy is used for the evaluation of hemorrhoids in a patient < 40 years of age who presents with bright red blood per rectum in the absence of alarm symptoms. It would not be the most appropriate next step for a patient who presents with unexplained weight loss as it cannot be used to diagnose colorectal cancer.

Answer C: Barium enema is sometimes used to screen for colorectal cancer in conjunction with other tests in asymptomatic patients, but it would not be used to diagnose malignancy in a patient with alarm symptoms such as hematochezia and unexpected weight loss.

Answer E: Ultrasound of the abdomen would be effective in diagnosing conditions such as intraperitoneal bleeding and cholecystitis. There is no evidence of abdominal trauma that would suggest intraperitoneal bleeding in this patient. A positive ultrasound with free fluid would be treated with diagnostic laparoscopy.

Bullet Summary:
If a patient is over the age of 50 or has alarm symptoms of weight loss, abdominal pain, change in bowel habits, or iron-deficiency anemia, the patient should undergo a colonoscopy to rule out colorectal cancer.


Question: A 57-year-old man presents to the emergency department for shortness of breath. He was riding the train home from a business conference when his symptoms began. The patient has a medical history of obesity, diabetes, diabetic nephropathy, hypertension, and a 40-pack-year smoking history. His current medications include atorvastatin, lisinopril, insulin, metformin, and nicotine gum. His temperature is 99.5°F (37.5°C), blood pressure is 130/87 mmHg, pulse is 120/min, respirations are 15/min, and oxygen saturation is 93% on room air. An ECG is ordered as seen in Figure A. A chest radiograph is ordered as seen in Figure B. Laboratory values are ordered as seen below: Serum: Na+: 137 mEq/L Cl-: 105 mEq/L K+: 4.1 mEq/L HCO3-: 24 mEq/L BUN: 22 mg/dL Glucose: 129 mg/dL Creatinine: 1.2 mg/dL Ca2+: 10.1 mg/dL AST: 11 U/L ALT: 12 U/L On physical exam, the patient appears to be in distress. His cardiac exam is notable for tachycardia. Pulmonary exam reveals bilateral air movement without any wheezes or crackles. The patient's right lower extremity appears mildly inflamed, and palpation of the calf elicits pain. Which of the following is the most appropriate next step in management?

Answer: Heparin

Explanation:
This patient is presenting with a score of 7.5 on Wells criteria suggesting a diagnosis of pulmonary embolism. The most appropriate initial step in management is heparin administration.

Patients with suspected pulmonary embolism (PE) can be evaluated with Wells criteria which consists of: clinical signs and symptoms of DVT (3 points), PE is the most likely diagnosis (3 points), pulse > 100 (1.5 points), immobilization for 3 days, or surgery within 4 weeks (1.5 points), history of DVT or PE (1.5 points), hemoptysis (1 point), and malignancy (1 point). Scores higher than 3 suggest a high probability of PE. Patients will often present with shortness of breath, with ECG findings of sinus tachycardia, and a chest radiograph that is typically normal. With a high pre-test probability, the most important initial step in management is anticoagulation with heparin versus further diagnostic workup.

Doherty reviews the evidence regarding the diagnosis and treatment of pulmonary embolism. He discusses how clinical criteria such as Wells criteria can be helpful in assessing the likelihood of a PE. He recommends immediate treatment in patients who have a PE.

Figure/Illustration A is an ECG demonstrating sinus tachycardia with a P wave, a QRS complex, and a T wave during every beat (red circle). This is the most common ECG presentation in PE, though right heart strain can also be seen.

Figure B is a chest radiograph that is within normal limits without evidence of fluid in the dependent portions of the lung (red circles). This is the most common radiological presentation in PE.

Incorrect Answers:
Answer A: Aspirin would be the most appropriate initial step in the management of MI and can reduce mortality by up to 25% if administered promptly. PE is a more likely diagnosis in this patient given the ECG that only demonstrates sinus tachycardia.

Answer B: Cardiac troponins could be used to confirm the diagnosis of myocardial infarction (MI). In the presence of this patient's ECG (which does not demonstrate ST elevation), MI is a less likely diagnosis. Treatment would be with aspirin in patients who had an MI followed by emergent revascularization.

Answer C: A CT scan of the chest without contrast would not confirm the diagnosis in this patient; however, a CT angiogram would be the most accurate test. It is more important to begin treatment with heparin when there is a very high clinical suspicion of PE.

Answer E: A ventilation perfusion scan is the most accurate test for PE in a patient who cannot tolerate contrast. This test has a low specificity.

Bullet Summary:
The most appropriate initial step in the management of a pulmonary embolism in patients with a high pre-test probability is anticoagulation with heparin.


Question:
An 18-year-old man presents to his primary care provider with his parents for a sports physical. He was last seen in the clinic several months ago when he was diagnosed with attention deficit hyperactivity disorder (ADHD). He was started on methylphenidate at that time and the patient now reports improvement in his ability to concentrate in school and at home. He hopes to play baseball in college and has begun lifting weights daily in preparation for baseball season. The patient has a healthy diet to fuel his exercise regimen. His parents have no concerns and are pleased with the recent improvement in his grades. His temperature is 98.6°F (37°C), blood pressure is 115/71 mmHg, pulse is 72/min, and respirations are 12/min. On physical exam, the patient has tall stature with average muscle mass for his age. He has no dysmorphic features. His chest has a normal appearance other than mild gynecomastia. The patient has sparse facial hair and a moderate amount of coarse pubic hair that extends across the pubis and spares the medial thighs. His testes are small and firm. Laboratory testing is performed and reveals the following:

Follicle-stimulating hormone (FSH): 42 mIU/mL
Luteinizing hormone (LH): 38 mIU/mL

Which of the following is the most likely etiology of this patient’s presentation?

Answer: Meiotic nondisjunction

Explanation:
This patient presents with tall stature, gynecomastia, and small testes with elevated FSH and LH, which suggests a diagnosis of Klinefelter syndrome. Klinefelter syndrome is usually caused by meiotic nondisjunction that results in a 47,XXY genotype.

Klinefelter syndrome is the most common cause of primary hypogonadism. Patients with Klinefelter syndrome present with tall stature, neurocognitive difficulties (ADHD), and features of hypogonadism including gynecomastia, small testes, small phallus, hypospadias, underdeveloped secondary sex characteristics, and cryptorchidism. Patients without hypospadias or cryptorchidism are often not diagnosed until after puberty when the symptoms of gynecomastia and small testes become more prominent. Because the hypogonadism in Klinefelter syndrome is caused by testicular fibrosis, laboratory results demonstrate low testosterone and elevated FSH and LH levels. Treatment for this condition includes androgen replacement therapy.

Lanfranco et al. review the evidence regarding the treatment of Klinefelter syndrome. They discuss how modern fertility augmentation therapy has allowed some of these patients to produce viable offspring. They recommend having a detailed discussion with these patients and their partners regarding possible outcomes.

Incorrect Answers:
Answer A: Anabolic steroid use causes decreased levels of FSH and LH due to the suppression of GnRH release by the hypothalamus. This results in decreased FSH and LH release by the pituitary gland. Anabolic steroid use would not present with signs of hypogonadism.

Answer B: The CGG trinucleotide repeat disorder characterizes fragile X syndrome. Fragile X presents with macroorchidism rather than hypogonadism and patients typically have dysmorphic features of a long, narrow face with large ears, a prominent forehead, and a prominent chin. Fragile X is the most common cause of inherited intellectual disability.

Answer C: The CTG trinucleotide repeat disorder characterizes myotonic dystrophy. Although myotonic dystrophy presents with hypogonadism, patients would also present with symptoms of progressive weakness, such as facial weakness, dysphagia, or hand grip weakness. Treatment is with cardiac pacemakers and ventilatory support.

Answer D: Failure of neuronal migration characterizes Kallmann syndrome. Kallmann syndrome presents with the classic symptoms of anosmia and hypogonadism, but patients with Kallmann syndrome have a low FSH and LH. Treatment is with hormone replacement therapy.

Bullet Summary:
Klinefelter syndrome results in primary hypogonadism and presents with tall stature, gynecomastia, small testes, a small phallus, hypospadias, and cryptorchidism.


Question:
A 57-year-old immigrant from Nigeria presents to the emergency department for sudden, severe pain and swelling in her lower extremity. She was at a rehabilitation hospital when her symptoms started. The patient has a medical history of obesity, diabetes, bipolar disorder, and tonic-clonic seizures. Her current medications include metformin, insulin, lisinopril, and valproic acid. The patient has IV drug and alcohol use disorder and has presented to the ED many times for intoxication. Her temperature is 98.6°F (37°C), blood pressure is 115/71 mmHg, pulse is 72/min, and respirations are 12/min. Physical exam reveals anasarca and asymmetric lower extremity swelling. Based on the results of a doppler ultrasound of her swollen lower extremity, heparin is started. The patient is then transferred to the general medicine floor for continued management. Laboratory studies are shown below.

Serum:
Na+: 137 mEq/L
K+: 5.5 mEq/L
Cl-: 100 mEq/L
HCO3-: 24 mEq/L
Urea nitrogen: 22 mg/dL
Ca2+: 5.7 mg/dL
Creatinine: 1.7 mg/dL
Glucose: 70 mg/dL

Which of the following is the most likely diagnosis?

Answer: Nephrotic syndrome

Explanation:
This patient who presents with a deep venous thrombosis (lower extremity swelling, ultrasound followed by treatment with heparin), anasarca, and asymptomatic hypocalcemia most likely has a diagnosis of nephrotic syndrome.

Nephrotic syndrome occurs when large amounts of protein are lost in the urine. This can lead to hyperlipidemia (due to loss of lipoproteins), hypercoagulable state (due to loss of antithrombin III and protein C/S), and hypoalbuminemia. Most serum calcium is bound to albumin, so when albumin is lost in the urine, it can lead to profound hypocalcemia. The ionized or free portion of calcium remains the same; therefore, these patients do not exhibit symptoms of hypocalcemia. Furthermore, the loss of albumin will reduce the oncotic pressure in the vessels resulting in massive extravasation of fluid and anasarca.

Ambler et al. report a case of a patient who presented with a DVT and was found to have nephrotic syndrome. They discuss how the patient had asymptomatic changes in lab values including calcium. They recommend performing a urine dipstick for protein in cases of suspected nephrotic syndrome.

Incorrect Answers:
Answer A: Antithrombin III deficiency is a common cause of a hypercoagulable state because antithrombin III normally helps to neutralize coagulation factors. This disease is a possible explanation for this patient's DVT as it predisposes patients to thrombotic events; however, it does not explain her profound hypocalcemia. Asymptomatic antithrombin III deficiency does not need to be treated; however, patients should have anticoagulation if they undergo surgery.

Answer B: Factor V Leiden is the most common cause of a hypercoagulable state because this mutation renders factor V unable to be inactivated by proteins C and S. This is a possible explanation for this patient's DVT; however, it does not explain her hypocalcemia. Asymptomatic factor V Leiden mutation does not need to be treated; however, patients should have anticoagulation if they undergo surgery.

Answer D: Liver dysfunction is possible given this patient's history of alcohol use and IV drug abuse, placing her at risk for chronic hepatitis C infection. Despite the anasarca, this patient has no other stigmata of liver failure such as jaundice or ascites, making nephrotic syndrome more likely.

Answer E: Prothrombin gene mutation could explain this patient's hypercoagulable state because high levels of this gene can result in unprovoked thrombotic events. This disease would not explain why the patient has anasarca or hypocalcemia. Asymptomatic patients with this mutation do not require treatment.

Bullet Summary:
Nephrotic syndrome can present with a hypercoagulable state due to loss of antithrombin III and protein C/S and hypocalcemia from loss of albumin in the urine.


Question: A 57-year-old woman presents to the emergency department for a headache. She was at home when a sudden headache began with greater severity than she had experienced in the past. She presented within 30 minutes of symptom onset. The patient has a medical history of sinusitis, constipation, diabetes, and pelvic inflammatory disease. Her current medications include fexofenadine, oral contraceptive pills, and metformin. She is currently taking amoxicillin for a sinus infection. She smokes 1 pack of cigarettes per day and drinks 2-3 alcoholic beverages daily. Her temperature is 99.5°F (37.5°C), blood pressure is 187/118 mmHg, pulse is 120/min, respirations are 17/min, and oxygen saturation is 98% on room air. On physical exam, the patient is noted to be uncomfortable with the appearance shown in Figure A. Neurological exam reveals a confused woman who is now complaining of "seeing double." Cardiopulmonary exam reveals mild bibasilar crackles and tachycardia. Abdominal exam is within normal limits. Which of the following is the most appropriate initial step in management?

Answer: Piperacillin-tazobactam

Explanation:
This patient is presenting with symptoms suggestive of septic cavernous sinus thrombosis (CST). The most appropriate initial step in management is urgent broad-spectrum antibiotics and surgical drainage.

Cavernous sinus thrombosis is an emergency that requires immediate intervention. It typically occurs in a patient with a history of sinusitis, oral contraceptive pill usage, smoking, or other risk factors that could cause a hypercoagulable state. These patients will often present with severe pain, a sudden headache, and diplopia. A distinct appearance is typically noted with periorbital edema. These patients should be immediately treated with broad-spectrum antibiotics and undergo surgical drainage of the inciting source of infection. In some cases, thrombolytics can be used as well.

Caranfa and Yoon review the evidence regarding the diagnosis and treatment of septic cavernous sinus thrombosis. They discuss how this diagnosis was almost universally fatal in the pre-antibiotic era. They recommend using broad-spectrum antibiotics and debridement to address this disease.

Figure/Illustration A is a clinical photograph demonstrating a face with swelling and periorbital edema (red circles). This appearance is classically seen in patients with CST.

Incorrect Answers:
Answer A: Amoxicillin-clavulanic acid would be appropriate management of acute otitis media or sinusitis; however, it is insufficient coverage for CST. Broad-spectrum antibiotics and surgical intervention are needed to prevent loss of vision.

Answer B: A CT scan of the head could be indicated potentially for surgical planning in a more stable patient; however, in this situation, immediate intervention is more dire. After antibiotics and stabilization, CNS imaging will be needed.

Answer C: Dexamethasone would be appropriate treatment of a relapse of multiple sclerosis, which can also present with visual changes; however, it would not present with sudden headache and periorbital edema.

Answer D: An MRI of the brain would be appropriate for further characterizing neurologic deficits of unclear etiology. In this case, the patient's acute presentation with neurologic changes secondary to CST requires immediate treatment rather than additional imaging.

Bullet Summary:
Cavernous sinus thrombosis should be immediately managed with broad-spectrum antibiotics and neurosurgery.


Question:
A 43-year-old man presents to the emergency department with bright red blood in his stool this morning. He noticed this yesterday as well, but it was much scanter. The patient is otherwise healthy. He was celebrating his birthday last night and admits having "too much to drink" and vomited profusely overnight. He currently feels well and is not nauseous. He has no other significant medical history and does not take any medications. His temperature is 99.2°F (37.3°C), blood pressure is 110/75 mmHg, pulse is 82/min, respirations are 16/min, and oxygen saturation is 100% on room air. Physical exam reveals a nontender abdomen with normal bowel sounds. Rectal exam reveals grossly bloody stool. Laboratory studies are ordered as shown below.

Hemoglobin: 12 g/dL
Hematocrit: 36%
Leukocyte count: 5,500/mm^3 with normal differential
Platelet count: 179,000/mm^3

Which of the following is the most likely cause of this patient's symptoms?

Answer: Vascular malformation

Explanation:
This patient is presenting with bright red blood per rectum with a non-tender abdomen. Of the answer choices given, angiodysplasia is the most likely to cause such profuse and sudden bleeding.

Angiodysplasia is a vascular malformation found in the gastrointestinal (GI) tract, most commonly in the colon. The exposed vessels can bleed, leading to bright red blood per rectum. The diagnosis can be confirmed with colonoscopy. Ablation can be performed to stop the bleeding. Any patient who is unstable or anemic with a hemoglobin < 7.0 g/dL requires a transfusion with blood products. Angiodysplasia is a common cause of bright red blood per rectum but is not more common than diverticulosis.

Garcia-Compeon et al. review the presentation and treatment of gastrointestinal angiodysplasia. The authors note that angiodysplasias are the cause of many "occult" GI bleeds not visualized on upper endoscopy or colonoscopy. The authors recommend the use of capsule endoscopy in occult GI bleeds to identify angiodysplasias as a potential source.

Incorrect Answers:
Answer A: Erosion into a gastric vessel is the pathophysiology of a bleeding gastric vessel secondary to peptic ulcer disease. This usually presents with melena (black tarry stools) rather than bright red blood per rectum. Only in cases of extremely brisk upper GI bleeding would patients present with bright red blood per rectum. Treatment involves treating Helicobacter pylori infection if present, proton pump inhibitors, and sucralfate. Endoscopy is needed to confirm and treat the bleeding vessel.

Answer B: Inflammation and infection of colonic outpouching is the pathophysiology of diverticulitis which presents with a history of constipation with a fever and left lower quadrant abdominal pain. Management involves a computed tomography (CT) scan of the abdomen/pelvis and administration of antibiotics (such as ciprofloxacin and metronidazole or ceftriaxone and metronidazole). Diverticulosis presents with bright red blood and is possible in this patient, but it does not involve inflammation or infection, which defines diverticulitis.

Answer C: Malignancy or colon cancer can present with bright red blood per rectum, malaise, weight loss, and microcytic anemia. While it is possible in this patient, his age, lack of risk factors for colon cancer, and the sudden onset of his symptoms make this diagnosis less likely.

Answer D: Submucosal esophageal (Mallory-Weiss) tear presents after profuse vomiting (as in this patient) with bloody vomitus. Treatment is supportive and involves antiemetics.

Bullet Summary:
Angiodysplasia is a vascular malformation that presents with bright red blood per rectum.


Question: A 5-year-old girl presents to the emergency room due to difficulty walking. She has been complaining of pain in her right leg for the last few days. Her neighbor’s cat bit her last week and her parents attributed the pain to her healing bite. At the time of the bite, they cleaned the wound and irrigated it with sterile saline water from a first aid kit. She has no medical history and has never been hospitalized. Her temperature is 102.2°F (39°C), blood pressure is 118/78 mmHg, pulse is 90/min, respirations are 21/min, and pulse oximetry is 99% on room air. The open wound remains present on the thigh with surrounding erythema and edema. MRI is consistent with osteomyelitis. Which of the following is the most appropriate next step in management?

Answer: Ampicillin and sulbactam

Explanation:
This young girl with a recent history of a cat bite and difficulty walking most likely has likely Pasteurella multocida osteomyelitis. Empiric IV antibiotic therapy with ampicillin-sulbactam is the most appropriate initial management.

Pasteurella multocida is a gram-negative rod that is associated with cat and dog bites. Infection can lead to cellulitis and osteomyelitis. Treatment of minor infection is with amoxicillin-clavulanate; however, patients suspected of having osteomyelitis should be treated empirically with IV antibiotics (e.g., ampicillin and sulbactam) and taken for biopsy/culture to identify the pathogen. Antibiotics can then be narrowed down accordingly. Patients will often require between 4-8 weeks of antibiotic treatment. MRSA coverage may initially be started and tapered later once cultures result.

Mollitt reviews the evidence regarding the microbiology of various injuries. He discusses how Pasteurella multocida is a common complication of animal bites. He recommends early effective antibiotic treatment.

Incorrect Answer:
Answer A: Amoxicillin and clavulanate can be used to treat Pasteurella infection. Patients with osteomyelitis should not be treated with oral antibiotics initially, in particular, when there are systemic manifestations as is present in this patient. IV antibiotics such as ampicillin and sulbactam are the mainstay for empiric osteomyelitis treatment after an animal bite in a patient with systemic manifestations.

Answer C: Doxycycline is used to treat uncomplicated chlamydia infections. Gonococcal osteomyelitis may present in sexually active individuals and may be associated with septic arthritis. Sexually active patients may be suspected of having this disease.

Answer D: Fluconazole is an antifungal that is used to treat Candida osteomyelitis. Candida osteomyelitis would be highly unusual in patients with no other risk factors. Instead, this disease is more common in immunodeficient patients or those who use IV drugs.

Answer E: Vancomycin is used for MRSA infections. Although S. aureus is the most common overall cause of osteomyelitis, this patient with a recent animal bite most likely has Pasteurella infection and this organism should be covered accordingly.

Bullet Summary:
Patients with suspicion of Pasteurella osteomyelitis infection after an animal bite should be treated with empiric IV antibiotics such as ampicillin and sulbactam.


Question: A 14-year-old boy presents to his pediatrician with a 2-month history of intermittent arm and leg spasms. He says that the spasms usually occur after he wakes up as he is getting ready for school, and consist of disorganized jerking motions that stop after a few minutes. He has also noticed that they occur when he stays up late to cram last minute for exams. He has not noticed any other symptoms. He has no medical history and takes no medications. He recently started experimenting with alcohol and marijuana that one of his friends has been stealing from their parents. His temperature is 98.6°F (37.0°C), blood pressure is 115/70 mmHg, pulse is 70/min, and respirations are 12/min. Physical exam reveals a healthy child. Which of the following is the most likely cause of this patient's symptoms?

Answer: Juvenile myoclonic epilepsy

Explanation:
This patient who presents with intermittent jerking of his extremities that occur primarily after waking up or when sleep-deprived most likely has juvenile myoclonic epilepsy.

Juvenile myoclonic epilepsy (JME) is a poorly understood condition that presents with intermittent myoclonic jerks of the extremities. These myoclonic jerks usually have an onset occurring in early adolescence in otherwise healthy children. Myoclonic jerks are most frequently seen right after waking from sleep, but they may also be triggered by lack of sleep, stress, or alcohol consumption. Patients with this disease rarely have associated symptoms but may occasionally also experience absence seizures or generalized tonic-clonic seizures. The diagnosis can be secured with a history of seizures alongside an interictal electroencephalogram (EEG) that shows 4 to 6 Hz bilateral polyspikes. Valproate is the first-line treatment.

Johannessen et al. discuss the treatment of juvenile myoclonic epilepsy. They find that standard antiepileptic treatment with agents such as valproate leads to only 33% of patients remaining seizure-free. They recommend trials of alternative antiepileptic medications such as levetiracetam, lamotrigine, and topiramate in patients that do not respond to valproate.

Incorrect Answers:
Answer A: Absence seizures commonly present during childhood in otherwise healthy children; however, these seizures are typically characterized by short episodes of loss of awareness known as "staring spells" without physical manifestations.

Answer B: Alcohol intoxication is a risk factor for precipitating juvenile myoclonic epilepsy, but alcohol use does not cause this condition. Seizure activity may also occur during alcohol withdrawal, but the timing of this patient's symptoms is more suggestive of seizure symptoms. Alcohol withdrawal requires chronic drinking of large amounts leading to an increase in central nervous system N-methyl-D-aspartate receptors and a decrease in CNS gamma-aminobutyric acid type A receptors. When alcohol cessation occurs, seizures ensue.

Answer C: Cannabinoid use is not associated with seizure activity either during intoxication or withdrawal. Patients may have altered mental status, but this does not manifest as myoclonic jerks.

Answer E: West syndrome is an infantile seizure disorder that usually presents between 3 months and 12 months of age. These patients will present with recurrent flexion spasms of the extremities.

Bullet Summary:
Juvenile myoclonic epilepsy presents in adolescents with recurrent spasms after waking from sleep or when sleep-deprived.


Question: A 4-week-old boy presents to the pediatrician for vomiting. The patient is breastfed and typically feeds for 20-30 minutes every 2 hours. One week ago, he began vomiting and regurgitating breastmilk through his nose after most feedings. His stools over the past week have also become blood-streaked. The patient does not seem to be in any distress when he passes these bloody stools. The patient surpassed his birth weight by 2 weeks of age but has fallen 1 standard deviation on the growth curve since then. His temperature is 98.6°F (37°C), blood pressure is 78/47 mmHg, pulse is 115/min, and respirations are 28/min. On physical exam, the patient is well-appearing. His face and back have the physical exam finding seen in Figure A. The patient’s abdomen is soft, non-tender, and non-distended. A digital rectal exam reveals a small amount of blood in the rectal vault. Which of the following is the most appropriate next step in management?

Answer: Modify mother's diet

Explanation:
This infant presents with vomiting, bloody stools, and poor weight gain, which suggests a diagnosis of milk-protein allergy. The most appropriate next step in management is the modification of the mother’s diet to eliminate cow’s milk and soy.

Infant food protein-induced proctocolitis is caused by distal colon inflammation secondary to an immune reaction to certain food proteins. Milk-protein allergy is the most common food allergy in children and presents with vomiting, bloody stools, and poor weight gain or failure to thrive. In an infant that is breastfed, the most appropriate next step in management is the elimination of cow’s milk and soy from the mother’s diet. In an infant who is formula fed, the most appropriate next step would be switching to either an extensively hydrolyzed or amino acid-based infant formula.

Giannetti et al. review the evidence regarding the diagnosis and treatment of milk protein allergy in infants. They discuss how the selective elimination of certain proteins from the diet is usually effective. They recommend considering oral immunotherapy as an adjuvant in the treatment of this disease.

Figure/Illustration A is a clinical photograph that demonstrates the finding of eczema (red circle). This finding is commonly found in patients with milk-protein allergy.

Incorrect Answers:
Answer A: Initiating a proton pump inhibitor would be appropriate in patients with refractory gastroesophageal reflux disease, which presents with regurgitation or vomiting and symptoms of feeding aversion or failure to thrive. Because this patient presents with bloody stools, he is more likely to have a milk protein allergy.

Answer B: Obtaining an abdominal ultrasound would help evaluate for pyloric stenosis, which presents in infants between 3-6 months of age with non-bilious, projectile vomiting. Pyloric stenosis does not cause bloody stools. Treatment is with surgical pyloromyotomy.

Answer C: Providing reassurance would not be appropriate for an infant presenting with bloody stools and evidence of poor weight gain. The cause of his blood-streaked stools should be investigated to ensure this patient is getting the nutrition he needs.

Answer E: Switching to a hydrolyzed formula would be appropriate if this patient were formula fed, but it is not necessary to discontinue breastfeeding if the mother is willing to modify her diet to exclude cow’s milk and soy.

Bullet Summary:
A milk-protein allergy in a breastfed infant should be treated with modification of the mother’s diet to eliminate cow’s milk and soy.


Question: A 4-year-old boy comes to the pediatrician with his mother with a 3-day history of cough and runny nose with decreased oral intake over the past 24 hours. His activity level has been normal and he has been attending school until this morning. He has no medical history or known allergies, but he has not received any of the recommended vaccines due to parental refusal. His temperature is 100.3°F (37.9°C), blood pressure is 98/62 mmHg, pulse is 85/min, respirations are 22/min, and oxygen saturation is 98% on room air. On examination, the child is fussy. Bilateral conjunctivae are injected, and there is redness on and around the tonsils. There is no lymphadenopathy. Faint rhonchi are heard at the lung bases bilaterally. Which of the following is the most appropriate next step in management?

Obtain chest radiography and respiratory virus panel

Answer: Supportive care with return precautions

Explanation:
This boy presenting with 3 days of progressive fever, rhinorrhea, cough, conjunctivitis, and tonsilar erythema most likely has viral pharyngitis. The appropriate treatment for this is supportive care with return precautions (instructing the mother to bring the child back to a physician if he becomes short of breath).

Viral pharyngitis in children is most often caused by adenovirus, though other viruses can cause the condition as well. The diagnosis is clinical, with a presentation of fever, rhinorrhea, conjunctivitis, sore throat, and cough. Features that can help distinguish viral pharyngitis from pneumonia include a lack of tachypnea, increased work of breathing, hypoxemia, or adventitial lung sounds. No additional testing or intervention is necessary. The illness is typically self-limited and resolves with supportive care.

Shapiro et al. study features predictive of group A streptococcal (GAS) pharyngitis in children. The authors found that among patients with features of viral illness, patients older than 11 years of age who did not have a fever, cervical lymphadenopathy, or tonsillar exudates were at the lowest risk for GAS. The authors recommend against testing low-risk children for GAS to avoid antibiotic treatment in patients merely colonized with GAS.

Incorrect Answers:
Answer A: Administering antitoxin and toxoid vaccine is the treatment for Corynebacterium diphtheriae infection. Although this child has not received his age-appropriate vaccinations, his presentation is not concerning for infection with diphtheria. C. diphtheriae infection presents with cervical lymphadenopathy and gray pseudomembranes on pharyngeal exam, neither of which this child has.

Answer B: Amoxicillin should be given in cases of group A streptococcal (GAS) pharyngitis. Before amoxicillin is prescribed, testing with Streptococcal rapid antigen detection testing should be performed. Additionally, rapid antigen detection testing is not indicated in this patient as she has a cough and does not have cervical lymphadenopathy, tonsillar exudates, or palatal petechiae. All of these findings are not typical of GAS pharyngitis.

Answer C: Influenza testing and oseltamivir are indicated if the child had myalgias or high fevers that would make influenza more likely and if he presented within 2 days of symptom onset. Oseltamivir is only approved for treating influenza in uncomplicated cases if started within this 2-day window from symptom onset. Exceptions to this 2-day guideline include adults greater than 65 years of age, pregnant women, residents of long-term care facilities, American Indians, persons with BMI greater than 40 kg/m^2, and those receiving immunosuppressive medications.

Answer D: Obtaining a chest radiograph and respiratory virus panel can be done when a lower respiratory infection such as bacterial pneumonia is expected. However, viral infections are much more common than bacterial pneumonia in this age group. Additionally, this patient is not tachypneic, does not have evidence of increased work of breathing, and is not hypoxemic, all of which make bacterial pneumonia less likely.

Bullet Summary:
Viral pharyngitis in children is a clinical diagnosis consisting of fever, rhinorrhea, conjunctivitis, cough, sore throat, and pharyngeal erythema, and is treated with supportive care.


Question: A 37-year-old woman presents to the emergency department in cardiac arrest. She was found to have altered mental status at home, and during transport to the hospital, she became pulseless. Cardiopulmonary resuscitation is ongoing and 2 intravenous lines are placed. The patient is obese, and her only medication is an oral contraceptive pill. She recently underwent Achilles tendon repair. She otherwise is known to smoke cigarettes on occasion. Physical exam is notable for a critically ill patient with chest compressions ongoing. The monitor shows pulseless electrical activity. Her right lower extremity is in a post-operative splint. The patient regains her pulse after several rounds of CPR and epinephrine. A bedside echocardiograph is notable for a dilated and hypokinetic right ventricle with septal bowing into a hyperkinetic left ventricle. Which of the following is the most likely diagnosis?

Answer: Obstructive shock

Explanation:
This obese patient on oral contraceptive pills with recent orthopedic surgery (Achilles tendon repair) is presenting in cardiac arrest. Given the bedside echocardiograph that is notable for a dilated and hypokinetic right ventricle with septal bowing into a hyperkinetic left ventricle, the most likely diagnosis is a pulmonary embolism that is causing obstructive shock.

Pulmonary embolism is most commonly caused by a deep vein thrombosis in the veins of the lower extremity that travels to the pulmonary circulation. Patients will present with pleuritic chest pain, hypoxia, sinus tachycardia, and hemoptysis. Massive pulmonary emboli can cause hemodynamic instability. Patients may become hypotensive, tachycardic, and ultimately pulseless. The pulmonary embolism can obstruct blood flow from the right ventricle to the pulmonary artery, leading to a dilated and hypokinetic right ventricle with septal bowing and a hyperdynamic left ventricle. This is a type of obstructive shock. Treatment of a massive pulmonary embolism causing hemodynamic instability may involve thrombolytics or thrombectomy.

Standl et al. review obstructive shock. They note that obstructive shock is caused by an obstruction of blood flow out of (or in the case of tamponade, into) the heart. They recommend that treating the underlying cause is the only effective management option.

Incorrect Answers:
Answer A: Cardiogenic shock is caused by cardiac dysfunction in conditions such as myocardial infarction or heart failure. Cardiac dysfunction then leads to impaired systemic perfusion. Initial management includes treating the underlying cause (e.g., cardiac catheterization for an ST-elevation myocardial infarction) and vasopressors (e.g., norepinephrine) to maintain the patient’s blood pressure.

Answer B: Hemorrhagic shock is a common cause of shock in trauma and presents with hypotension and tachycardia secondary to blood loss. A narrowed pulse pressure may be the first sign of hemorrhagic shock. The mainstay of management is blood transfusion and an intervention to stop the bleeding.

Answer C: Neurogenic shock occurs when there is central nervous system trauma (often to the cervical spine) leading to decreased sympathetic tone systemically. Patients will present with hypotension and bradycardia (contrast with tachycardia in hemorrhagic shock), and management is centered on vasopressors to maintain blood pressure and neurosurgical intervention for the underlying etiology. IV fluids can also be given to maintain blood pressure.

Answer E: Septic shock occurs when a systemic infection leads to vasodilation and endothelial dysfunction with hypotension refractory to fluid resuscitation. The mainstay of management includes fluids, blood cultures, vasopressors, and broad-spectrum antibiotics. Early administration of antibiotics improves outcomes.

Bullet Summary:
Pulmonary embolism is a common cause of obstructive shock.


Question: A 23-year-old woman presents to the emergency room for a self-inflicted laceration of her distal volar forearm. The patient states she knew her boyfriend was having sexual thoughts about the woman from the grocery store, prompting her decision to cut her own wrist. In the emergency department, the bleeding has stopped and the patient is currently medically stable. When interviewing the patient, she is teary and apologizes for her behavior. She is grateful to you for her care and regrets her actions. Of note, the patient has presented to the emergency department before for a similar reason when she was struggling with online dating. The patient states that she struggles with her romantic relationships though she deeply desires them. Her temperature is 98.6°F (37°C), blood pressure is 112/71 mmHg, pulse is 73/min, and respirations are 14/min. On physical exam, you note a frightened young woman who is wearing a revealing dress that prominently displays her breasts. You tell the patient that she will have to stay in the psychiatric emergency department for the night which makes her furious. Which of the following personality disorders is the most likely diagnosis?

Answer: Borderline

Explanation:
This patient is presenting with a suicide attempt, unstable relationships, and emotional lability suggesting a diagnosis of borderline personality disorder.

Borderline personality disorder classically presents with emotional lability, and intense, unstable relationships. These patients fear abandonment and will often engage in self-harming behavior like cutting and suicide attempts. The main defense mechanism these patients employ is splitting, in which patients divide the world into dichotomous categories where people are either all good or all bad. This personality disorder is associated with mood disorders and substance use. The treatment of choice for these patients is long-term dialectical behavioral therapy and mood stabilizers.

Leichsenring et al. review the evidence regarding the treatment of patients with borderline personality disorder. They discuss no specific form of psychotherapy is superior to others. They recommend starting any form of psychotherapy for these patients to improve outcomes.

Incorrect Answers:
Answer A: Antisocial personality disorder presents with aggressive, criminal behavior. These individuals do not conform to social norms or rules and violate the rights of others. Patients often are not amenable to behavioral modification and therefore incarceration may be necessary in order to protect the rights of others.

Answer B: Avoidant personality disorder presents with excessive shyness and hypersensitivity to rejection. These patients fear social interaction though they strongly desire relationships. Cognitive behavioral therapy can be used in order to encourage these patients to be more open to seeking out relationships.

Answer D: Dependent personality disorder presents with submissive and clingy behavior. They often have a need to be cared for and will be very agreeable and dependent on others. This can be harmful as patients may stay in abusive or degrading relationships due to a fear of being alone. Treatment is with cognitive behavioral therapy.

Answer E: Histrionic personality disorder presents with colorful and exaggerated attention-seeking behavior. These patients will often employ sexuality to draw attention to themselves. Though this patient is displaying her breasts and wearing seductive clothing, her history of self-harm behavior and unstable relationships suggests a diagnosis of borderline personality disorder.

Bullet Summary:
Borderline personality disorder presents with emotional instability, unstable relationships, and self-harming behavior.