The 2015 COMLEX Level 1 exam is upon us and if you’re a second-year osteopathic medical student, you’re probably in extreme cram mode right now. We’ve searched through COMBANK’s SmartBank of over 2,000 COMLEX Level 1 practice questions and found three of the hardest questions based on actual user performance.
Take the practice questions to see how you fare.
COMLEX Level 1 Practice Questions
Q: A 3-year-old male is presented to the pediatrician for an annual well-child examination. Physical examination reveals a mild mid-systolic murmur on the mid-precordium. The parents deny a history of cyanosis or respiratory distress. The most likely cause of this murmur is:
A) Atrial septal defect
B) Patent ductus arteriosus
C) Tricuspid atresia
D) Tetralogy of Fallot
E) Still’s murmur
Q: A 20-year-old college football player is seen at the Emergency Department having been taken from the playing field during a game. He had received a blow to theinferomedial side of his left knee while struggling to break a tackle. A plain film radiograph is obtained and reveals a fracture of the head and neck of the fibula. In this situation, the most likely associated muscle strength deficit would be in the:
A) Extensor hallucis longus
B) Flexor digitorum longus
E) Tibialis posterior
Q: A 29-year-old female is brought to the emergency department by her mother after exhibiting unusual behavior. According to her mother, she has not slept in eight days, appears extremely agitated, and is unable to concentrate. Her mother says she has seen her like this in the past and it is usually followed by an episode of severe depression. She is admitted for psychiatric evaluation and treatment is initiated. Three weeks after she is discharged from the hospital she begins complaining of polyuria and intense thirst. Urinalysis reveals a specific gravity of 1.001 and osmolality of 188 mOsm/kg. After one hour of water restriction, urine osmolality is 204 mOsm/kg. Which of the following psychiatric drugs would likely cause tardive dyskinesia?
Question Answers & Explanations
Correct Answer: E
Systolic murmurs are present in approximately 60 percent of the population; 90 percent will have normal echocardiograms. Still’s murmur is a benign pediatric murmur that commonly presents in healthy children, two to eight years old. It is typically heard as a mid-systolic murmur of musical quality between the apex of the heart and left sternal border. There is no congenital heart defect associated with this murmur. The cause of the murmur is thought to be due to either aortic blood flow or vibrations from pulmonic valve leaflets. The murmur may be more pronounced in children with a fever, anemia, or who are lying supine.
Answer A: Atrial septal defects present with a loud S1 and wide, fixed split S2 heart sounds. This heart defect is not as common as a Still’s murmur.
Answer B: Patent ductus arteriosus presents as a continuous “machine-like” murmur. The ductus arteriosus is a fetal shunt connecting the pulmonary artery and aortic arch. Upon closure at birth, it becomes the ligamentum arteriosum. Failure to close can lead to late cyanosis in the lower extremities. Indomethacin is the drug of choice to treat this condition by blocking prostaglandin synthesis.
Answer C: Tricuspid atresia is a defect of early cyanosis. Tricuspid atresia is usually detected in infancy because of presenting cyanosis, congestive heart failure, and growth retardation. Parents provide a history of poor skin coloration (ranging from pallor to frank cyanosis), inability to complete a feeding session, frequent pauses during feeding and/or anorexia. As a result, the infant demonstrates poor growth patterns. Respiratory difficulties are often reported as nasal flaring or muscle retractions.
Answer D: A child with Tetralogy of Fallot will present earlier than age three with cyanosis, although diagnosis may be as late as adolescence. Tetralogy of Fallot consists of pulmonary stenosis, right ventricular hypertrophy, overriding aorta, and ventricular septal defect. A murmur may be appreciated along the left mid/upper sternal border as an early systolic click due to flow in the dilated aorta (due primarily to right ventricular outflow obstruction). It is typically of crescendo-decrescendo quality with a harsh systolic ejection. This congenital heart defect requires surgery for a good outcome.
Bottom Line: Not all childhood heart murmurs are associated with congenital heart defects. Still’s murmur is a common, benign heart murmur heard in healthy children between the ages of two and eight.
Correct Answer: A
The common peroneal nerve branches off into the deep and superficial peroneal nerve. The superficial peroneal nerve innervates the lateral compartment of the leg, which includes the peroneal longus and peroneal brevis. The deep peroneal nerve innervates the anterior compartment of the lower leg. The extensor hallucis longus is part of the anterior compartment, and thus is innervated by the deep peroneal nerve. All other muscles listed are innervated by the posterior tibial nerve.
Answer B: The flexor digitorum longus is part of the posterior compartment of the lower leg. Thus, it is innervated by the posterior tibial nerve.
Answer C: The gastrocnemius is part of the posterior compartment of the lower leg. Thus, it is innervated by the posterior tibial nerve.
Answer D: The popliteus is part of the posterior compartment of the lower leg. Thus, it is innervated by the posterior tibial nerve.
Answer E: The tibialis posterior is part of the posterior compartment of the lower leg. Thus, it is innervated by the posterior tibial nerve.
Bottom Line: The anterior compartment of the lower leg is innervated by the deep peroneal nerve. The lateral compartment is innervated by the superficial peroneal nerve, and the posterior compartment of the lower leg is innervated by the posterior tibial nerve. Injury to common peroneal nerve can create a “foot drop” in which the patient cannot actively dorsiflex the foot. For more information, see: Anatomy of Compartment Syndrome on Medscape
Correct Answer: B
Tardive dyskinesia is a complication of long-term treatment with older antipsychotic agents (more common with typical antipsychotics, such as haloperidol, fluphenazine, thioridazine, chlorpromazine). It is thought to result from increased dopamine receptor synthesis in response to long-term receptor blockade. This leads to increased sensitivity of dopamine at its receptors in the basal ganglia, altering the balance between cholinergic and dopamine input responsible for voluntary movement. Patients commonly present with stereotyped involuntary oral-facial movements such as lateral deviations of the jaw, grimacing, chewing, or protrusion of the tongue. These symptoms are often irreversible. Of the drugs listed, fluphenazine, a typical neuroleptic agent, would be the most likely agent to cause tardive dyskinesia.
Answer A: Clozapine is an atypical antipsychotic agent that blocks both serotonin 5HT2 and dopaminergic receptors. Atypical antipsychotic agents have a much lower risk of tardive dyskinesia than typical antipsychotic agents. They also have fewer extrapyramidal and anticholinergic side effects. A significant side effect of clozapine is agranulocytosis, which can be fatal if untreated. Therefore, patients treated with clozapine require weekly WBC monitoring.
Answer C: Lithium is a mood stabilizer that is primarily used to treat episodes of mania in patients with bipolar disease. Significant side effects include nephrogenic diabetes insipidus, hypothyroidism, heart block, and fetal cardiac defects in women who are pregnant. It does not cause tardive dyskinesia.
Answer D: Risperidone is an atypical antipsychotic and, like clozapine, has a lower incidence of tardive dyskinesia than typical antipsychotics. A significant side effect of risperidone is hyperprolactinemia. Dopamine release from the hypothalamus is responsible for tonically inhibiting prolactin release from the anterior pituitary. Therefore, inhibition of dopamine D2 receptors by antipsychotic agents leads to unregulated release of prolactin. This can cause amenorrhea and galactorrhea in women or gynecomastia and impotence in men. Hyperprolactinemia is more common with typical antipsychotics(haloperidol, chlorpromazine, thioridazine), however there is increased incidence in patients taking risperidone compared to other atypical antipsychotic agents.
Answer E: Selegiline is a monoamine oxidase B inhibitor used to treat Parkinson’s disease. Monoamine oxidase B is an enzyme that preferentially metabolizes dopamine over norepinephrine and serotonin. Therefore, inhibition of MAO-B leads to increased circulating dopamine. Selegiline does not cause tardive dyskinesia directly. However, it can cause an increase in dyskinesia when added to a levodopa regimen in patients who already developed dyskinesia. More common side effects include GI upset, insomnia, dry mouth, and heartburn.
Bottom Line: Long-term treatment with typical antipsychotics, such as haloperidol, trifluoperazine, fluphenazine, thioridazine, and chlorpromazine, can cause tardive dyskinesia. This commonly presents with irreversible, involuntary movement of facial and oral muscles.