What is the most appropriate treatment for a 15-month-old boy with repeated episodes of powerful contractions of trunk and limb muscles?

Correct Answer: B

Rationale: The correct answer is B: Ethosuximide. In a 15-month-old with episodes of powerful muscle contractions, the most likely diagnosis is childhood absence epilepsy, which is characterized by brief, subtle seizures involving staring and muscle contractions. Ethosuximide is the first-line treatment for childhood absence epilepsy due to its efficacy and favorable side effect profile in young children. Carbamazepine (A) is not typically used for absence seizures. Phenytoin (C) and Phenobarbital (D) are not recommended for childhood absence epilepsy and may have more side effects in this age group.

Correct Answer: B

Rationale: The correct answer is B because inhibiting the abnormally high cholinergic tone in the striatum can help reduce tremors. The striatum plays a key role in motor control, and an imbalance between cholinergic and dopaminergic signaling can lead to tremors. By inhibiting the excessive cholinergic activity, the balance is restored, resulting in reduced tremor. A: Inhibition of levodopa metabolism in the striatum wouldn't directly affect tremors as levodopa is a precursor to dopamine. C: Activation of dopaminergic receptors in the striatum may help with motor control but wouldn't specifically address the cholinergic imbalance causing tremors. D: Blockade of β adrenoceptors in skeletal muscle is unrelated to the striatum and cholinergic signaling involved in tremors.

Correct Answer: D

Rationale: The correct answer is D: Omeprazole. Omeprazole is a proton pump inhibitor used to reduce stomach acid production, which can cause nausea as a side effect. Carbidopa is used to treat Parkinson's disease, Benztropine is an anticholinergic used to treat Parkinson's symptoms, and Pramipexole is a dopamine agonist also used in Parkinson's disease. None of these drugs are known to commonly cause nausea as a side effect.

Correct Answer: A

Rationale: The correct answer is A: Haloperidol and clonazepam. Haloperidol is an antipsychotic medication used to treat acute psychotic states, while clonazepam is a benzodiazepine commonly used to manage seizures. The combination is appropriate as it addresses both the acute psychotic symptoms and the history of seizures in the patient. Explanation for incorrect choices: B: Chlorpromazine and lamotrigine - Chlorpromazine is an antipsychotic, but lamotrigine is primarily used for mood disorders, not seizures. C: Clozapine and ethosuximide - Clozapine is an antipsychotic, but ethosuximide is used to treat absence seizures, not generalized seizures. D: Thioridazine and ethosuximide - Thioridazine is an antipsychotic, but ethosuximide is not commonly used for seizures in adults.

Correct Answer: B

Rationale: The correct answer is B: Risperidone. Risperidone is an atypical antipsychotic known to cause side effects such as abnormal breast growth (gynecomastia) due to its effects on hormone levels. Haloperidol (A) is a typical antipsychotic with a lower likelihood of causing gynecomastia. Amitriptyline (C) is a tricyclic antidepressant that does not typically cause gynecomastia. Buspirone (D) is an anxiolytic medication that is not associated with gynecomastia. Therefore, based on the patient's symptoms, the most likely culprit is Risperidone due to its known side effect profile.