Neurology Medicine 10 Single Best Answer (SBA)

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Neurology SBA Quiz

1. A 35-year-old man presents with fever, seizures, and confusion. MRI shows temporal lobe involvement. What is the most likely causative organism?

  • Streptococcus pneumoniae
  • Herpes simplex virus (HSV)
  • Mycobacterium tuberculosis
  • Neisseria meningitidis

Answer: Herpes simplex virus (HSV)

HSV encephalitis is the most common sporadic encephalitis in adults. It frequently affects the temporal lobes, leading to seizures, confusion, and fever.

2. A 50-year-old man with a history of sinusitis presents with fever, headache, and right-sided weakness. CT scan reveals a ring-enhancing lesion in the left frontal lobe. What is the next best step in management?

  • Start high-dose IV antibiotics and corticosteroids
  • Perform stereotactic aspiration for microbiological diagnosis
  • Schedule urgent craniotomy for excision of the abscess
  • Begin oral antibiotics and observe for improvement

Answer: Perform stereotactic aspiration for microbiological diagnosis

In managing a brain abscess, stereotactic aspiration is valuable for confirming the organism and decompressing the lesion. Appropriate high-dose IV antibiotics can then be tailored.

3. A 70-year-old woman with a vesicular rash in a dermatomal distribution worries about postherpetic neuralgia. What is the best advice to prevent this complication?

  • Early initiation of antiviral therapy
  • Application of topical corticosteroids
  • Long-term use of gabapentinoids
  • Immediate administration of the zoster vaccine

Answer: Early initiation of antiviral therapy

Shingles (herpes zoster) should be treated promptly with antivirals to reduce the virus’s replication, limiting both acute severity and the likelihood of postherpetic neuralgia.

4. Which nerve is primarily affected in wrist drop, and what is its most common site of injury?

  • Median nerve at the carpal tunnel
  • Ulnar nerve at the cubital tunnel
  • Radial nerve at the midshaft of the humerus
  • Axillary nerve at the shoulder

Answer: Radial nerve at the midshaft of the humerus

Wrist drop is typically due to radial nerve palsy, often occurring with mid-humeral fractures or compression injuries.

5. A 40-year-old man presents with difficulty lifting his right foot. Examination reveals weakness in dorsiflexion and toe extension. What is the most likely site of nerve injury?

  • L5 nerve root
  • Common peroneal nerve at the fibular head
  • Tibial nerve in the popliteal fossa
  • S1 nerve root

Answer: Common peroneal nerve at the fibular head

The common peroneal (fibular) nerve wraps around the neck of the fibula. It is easily compressed or injured, leading to foot drop.

6. What is the most effective initial treatment for a patient with disabling essential tremor?

  • Levodopa
  • Propranolol
  • Primidone
  • Deep brain stimulation

Answer: Propranolol

Propranolol, a nonselective beta-blocker, is the usual first-line treatment for essential tremor. Primidone is another option.

7. Which of the following best describes the mechanism of action of levodopa in Parkinson’s disease?

  • Inhibition of monoamine oxidase B
  • Dopamine receptor agonist
  • Precursor of dopamine that crosses the blood-brain barrier
  • Inhibition of catechol-O-methyltransferase (COMT)

Answer: Precursor of dopamine that crosses the blood-brain barrier

Levodopa is taken up by dopaminergic neurons and converted to dopamine, partially restoring dopaminergic neurotransmission in Parkinson’s disease.

8. A 45-year-old man with Huntington’s disease presents with worsening chorea and behavioural changes. What is the most common cause of death in this condition?

  • Aspiration pneumonia
  • Progressive cognitive decline
  • Heart failure
  • Pulmonary embolism

Answer: Aspiration pneumonia

In Huntington’s, advanced stages lead to significant swallowing difficulties and immobility, making aspiration pneumonia the most frequent cause of death.

9. A 30-year-old woman with myasthenia gravis presents with worsening dyspnoea and dysphagia. What is the most appropriate next step?

  • Start oral pyridostigmine
  • Refer for urgent plasmapheresis or IVIG
  • Arrange pulmonary function tests
  • Administer high-dose corticosteroids

Answer: Refer for urgent plasmapheresis or IVIG

Myasthenic crisis with respiratory involvement is a medical emergency requiring rapid therapy such as IVIG or plasmapheresis, often with ventilatory support.

10. A 12-year-old boy with Duchenne muscular dystrophy develops respiratory failure. The parents request mechanical ventilation, but the boy expresses a desire not to be ventilated. How should the healthcare team proceed?

  • Respect the parents' decision and start ventilation
  • Follow the child’s expressed wishes after assessing his capacity
  • Refer the case to an ethics committee for resolution
  • Proceed with ventilation as a life-saving measure

Answer: Follow the child’s expressed wishes after assessing his capacity

In pediatric cases, if the child is deemed competent (has capacity), their autonomy holds significant weight. A thorough assessment of understanding and consequences is crucial.

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