MRCP Part 1 Neurology and Psychiatry — Questions and Answers
Question 1: A 30-year-old woman presents with optic neuritis. MRI brain shows periventricular white matter lesions. CSF shows oligoclonal bands not matched in serum. What is the most likely diagnosis?
- Multiple sclerosis (Correct answer)
- Neuromyelitis optica
- Acute disseminated encephalomyelitis
- CNS lymphoma
Correct answer: Multiple sclerosis
Multiple sclerosis (MS) is characterised by demyelinating lesions disseminated in time and space. Optic neuritis is a common presenting feature, and periventricular white matter lesions on MRI with unmatched CSF oligoclonal bands strongly support the diagnosis according to the McDonald criteria.
Question 2: A 72-year-old man presents with a resting tremor, bradykinesia, and rigidity. Which neurotransmitter deficiency is primarily responsible?
- Dopamine (Correct answer)
- Serotonin
- Acetylcholine
- GABA
Correct answer: Dopamine
Parkinson's disease results from degeneration of dopaminergic neurones in the substantia nigra pars compacta, leading to dopamine deficiency in the nigrostriatal pathway. The cardinal features are resting tremor, bradykinesia, rigidity, and postural instability.
Question 3: A patient presents with sudden onset worst headache of their life, neck stiffness, and photophobia. CT head is normal. What is the next most appropriate investigation?
- Lumbar puncture (after 12 hours from onset) (Correct answer)
- MRI brain
- CT angiography immediately
- Repeat CT head in 24 hours
Correct answer: Lumbar puncture (after 12 hours from onset)
When subarachnoid haemorrhage (SAH) is suspected but CT head is negative (sensitivity drops after 6 hours), lumbar puncture should be performed at least 12 hours after symptom onset to allow time for xanthochromia to develop. Xanthochromia (yellow discolouration from bilirubin) distinguishes SAH from a traumatic tap.
Question 4: A 65-year-old right-handed man suddenly develops expressive dysphasia with comprehension preserved. He can understand commands but struggles to produce fluent speech. Which area of the brain is most likely affected?
- Broca's area (left inferior frontal gyrus) (Correct answer)
- Wernicke's area (left superior temporal gyrus)
- Right inferior frontal gyrus
- Bilateral occipital lobes
Correct answer: Broca's area (left inferior frontal gyrus)
Broca's area, located in the left inferior frontal gyrus (in right-handed individuals), is responsible for speech production. Damage causes expressive (non-fluent) dysphasia where comprehension is preserved but speech output is effortful and telegraphic.
Question 5: A 25-year-old woman presents with episodic severe unilateral headache with visual aura lasting 20 minutes followed by nausea and photophobia. She has 4 attacks per month. What is the most appropriate prophylactic medication?
- Propranolol (Correct answer)
- Sumatriptan
- Paracetamol
- Codeine phosphate
Correct answer: Propranolol
Propranolol is a first-line prophylactic agent for migraine recommended by NICE. Prophylaxis is considered when patients have 4 or more attacks per month. Topiramate and amitriptyline are alternatives. Sumatriptan is an acute treatment, not prophylaxis.
Question 6: A patient with depression has been started on an SSRI. When counselling about side effects, how long should you advise before full therapeutic effect is expected?
- 4-6 weeks (Correct answer)
- 24-48 hours
- 7 days
- 3 months
Correct answer: 4-6 weeks
SSRIs typically take 4-6 weeks to achieve full therapeutic effect in depression. Patients should be counselled about this delay and warned that side effects (nausea, anxiety, insomnia) may occur earlier. Close follow-up is important, particularly in the first few weeks due to potential increased suicidality risk before mood improves.
