ABEM Neurological & Psychiatric Disorders 4 — Questions and Answers
Question 1: A 50-year-old presents with acute onset severe headache after intercourse. CT and LP are negative for subarachnoid hemorrhage. What is the most likely diagnosis?
- Cluster headache
- Primary thunderclap headache / coital cephalgia (Correct answer)
- Basilar migraine
- Cerebral venous sinus thrombosis
Correct answer: Primary thunderclap headache / coital cephalgia
Primary thunderclap headache (coital or exertional cephalgia) can mimic SAH and must be a diagnosis of exclusion after negative workup.
Question 2: A 65-year-old diabetic presents with painful ophthalmoplegia, ptosis, and normal pupillary response. What is the most likely etiology?
- Posterior communicating artery aneurysm
- Cavernous sinus thrombosis
- Microvascular ischemic CN III palsy (Correct answer)
- Myasthenia gravis
Correct answer: Microvascular ischemic CN III palsy
Diabetic microvascular ischemia causes pupil-sparing CN III palsy because the pupillomotor fibers travel on the outside of the nerve and are spared by ischemia that affects the inner fibers.
Question 3: A patient with known myasthenia gravis presents with worsening dyspnea and inability to swallow after starting ciprofloxacin for a UTI. What is the most likely explanation?
- Cholinergic crisis from pyridostigmine overdose
- Fluoroquinolone-induced myasthenic crisis (Correct answer)
- Aspiration pneumonia
- Autonomic neuropathy
Correct answer: Fluoroquinolone-induced myasthenic crisis
Fluoroquinolones, aminoglycosides, and other antibiotics can worsen neuromuscular junction blockade and precipitate myasthenic crisis.
Question 4: A 32-year-old presents with visual disturbances, bilateral internuclear ophthalmoplegia, and an episode of transverse myelitis 6 months ago. MRI shows periventricular white matter lesions. What is the most likely diagnosis?
- Neurosarcoidosis
- Multiple sclerosis (Correct answer)
- CNS vasculitis
- Anti-NMDA receptor encephalitis
Correct answer: Multiple sclerosis
Multiple sclerosis presents with relapsing-remitting neurological episodes, periventricular demyelinating lesions, and internuclear ophthalmoplegia due to MLF involvement.
Question 5: A comatose patient has pinpoint pupils, bradycardia, and respiratory depression after being found with empty prescription bottles. What is the antidote?
- Flumazenil 0.2 mg IV
- Naloxone 0.4–2 mg IV (Correct answer)
- Physostigmine 1–2 mg IV slow push
- N-acetylcysteine IV
Correct answer: Naloxone 0.4–2 mg IV
The opioid toxidrome (CNS depression, miosis, respiratory depression) is reversed with naloxone, an opioid receptor antagonist.
Question 6: A 22-year-old college student presents with fever, severe headache, photophobia, and a non-blanching petechial rash. Which action is most critical and time-sensitive?
- Obtain blood cultures before any treatment
- Administer IV ceftriaxone immediately without waiting for LP (Correct answer)
- Perform LP to identify organism before antibiotics
- Give dexamethasone and await CT results
Correct answer: Administer IV ceftriaxone immediately without waiting for LP
Bacterial meningitis with petechial rash (suggesting meningococcemia) requires immediate IV antibiotics; any delay for cultures or CT is unacceptable given mortality risk.
Question 7: A patient with a known seizure disorder is brought in seizing. He received 4 mg of lorazepam IV and continues to seize at 10 minutes. What is the next intervention?
- Administer a second dose of lorazepam 4 mg IV
- Load with fosphenytoin or levetiracetam IV (Correct answer)
- Proceed directly to intubation and propofol
- Administer phenobarbital 20 mg/kg IV
Correct answer: Load with fosphenytoin or levetiracetam IV
After benzodiazepine failure, the next step in status epilepticus management per guidelines is a second-line antiepileptic such as fosphenytoin, valproate, or levetiracetam.
ABEM Neurological & Psychiatric Disorders 4
A 50-year-old presents with acute onset severe headache after intercourse.
CT and LP are negative for subarachnoid hemorrhage.
What is the most likely diagnosis?