MRCP Part 1 Neurology and Psychiatry 2 — Questions and Answers
Question 1: A 78-year-old man presents with visual hallucinations, fluctuating cognition, and parkinsonism that preceded dementia onset. What is the most likely diagnosis?
- Dementia with Lewy bodies (Correct answer)
- Alzheimer's disease
- Vascular dementia
- Frontotemporal dementia
Correct answer: Dementia with Lewy bodies
Dementia with Lewy bodies (DLB) is characterised by the core features of fluctuating cognition, recurrent visual hallucinations, and spontaneous parkinsonism. REM sleep behaviour disorder is also a core feature. Importantly, patients with DLB are exquisitely sensitive to neuroleptics, which should be avoided.
Question 2: A 40-year-old man presents with bilateral lower limb weakness that ascended over 5 days following a respiratory infection. Reflexes are absent and CSF shows raised protein with normal cell count. What is the diagnosis?
- Guillain-Barre syndrome (Correct answer)
- Multiple sclerosis
- Myasthenia gravis
- Motor neurone disease
Correct answer: Guillain-Barre syndrome
Guillain-Barre syndrome (GBS) is an acute inflammatory demyelinating polyneuropathy that typically follows infection (commonly Campylobacter jejuni). It presents with ascending weakness, areflexia, and albuminocytological dissociation in CSF (raised protein, normal cells). Respiratory function must be monitored closely.
Question 3: Which cranial nerve is most commonly affected in raised intracranial pressure, causing a false localising sign?
- Abducens nerve (CN VI) (Correct answer)
- Oculomotor nerve (CN III)
- Trochlear nerve (CN IV)
- Facial nerve (CN VII)
Correct answer: Abducens nerve (CN VI)
The abducens nerve (CN VI) has the longest intracranial course and is most susceptible to stretching from raised intracranial pressure. This causes a lateral rectus palsy (inability to abduct the eye) which is a false localising sign — it does not indicate the site of the pathology.
Question 4: A patient presents to A&E having taken 40 paracetamol tablets 4 hours ago. The plasma paracetamol level is above the treatment line on the nomogram. What is the antidote?
- N-acetylcysteine (NAC) (Correct answer)
- Flumazenil
- Naloxone
- Activated charcoal
Correct answer: N-acetylcysteine (NAC)
N-acetylcysteine (NAC) is the antidote for paracetamol overdose. It works by replenishing glutathione stores and enhancing sulphation, preventing accumulation of the toxic metabolite NAPQI. It is most effective within 8 hours of ingestion but can still be beneficial up to 24 hours and beyond.
Question 5: A 55-year-old man presents with progressive weakness affecting both upper and lower motor neurones but with no sensory involvement. Fasciculations are noted in multiple limbs. What is the most likely diagnosis?
- Motor neurone disease (amyotrophic lateral sclerosis) (Correct answer)
- Multiple sclerosis
- Guillain-Barre syndrome
- Cervical myelopathy
Correct answer: Motor neurone disease (amyotrophic lateral sclerosis)
Motor neurone disease (MND/ALS) characteristically presents with mixed upper and lower motor neurone signs WITHOUT sensory involvement. Fasciculations, progressive weakness, and wasting are typical. The combination of UMN and LMN signs without sensory loss is virtually pathognomonic.
Question 6: A 22-year-old university student presents with low mood, anhedonia, poor concentration, early morning wakening, and weight loss for 3 months. She expresses passive suicidal ideation. According to NICE, what severity of depression is this?
- Moderate to severe depression (Correct answer)
- Mild depression
- Subthreshold depressive symptoms
- Psychotic depression
Correct answer: Moderate to severe depression
This patient has five core and additional symptoms of depression persisting for over 2 weeks, with functional impairment and suicidal ideation, indicating moderate to severe depression. NICE recommends a combination of antidepressant medication and high-intensity psychological therapy (CBT or IPT) for this severity.
MRCP Part 1 Neurology and Psychiatry 2
A 78-year-old man presents with visual hallucinations, fluctuating cognition, and parkinsonism that preceded dementia onset.
What is the most likely diagnosis?