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Lambert-Eaton myasthenic syndrome — SCE Neurology MCQ

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HardNeuromuscularLambert-Eaton myasthenic syndromeSCE Neurology

A smoker develops proximal weakness, dry mouth and erectile dysfunction. Reflexes are reduced at rest but facilitate after maximal contraction; electrophysiology shows a low CMAP with marked high-frequency increment. What is the most important next management step?

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Correct answer: B — Small-cell-lung-cancer evaluation with amifampridine and immune treatment planning

The best answer is “Small-cell-lung-cancer evaluation with amifampridine and immune treatment planning”. The clinical and electrophysiological pattern identifies Lambert–Eaton myasthenic syndrome, which has a strong small-cell-lung-cancer association in a smoker; treatment and repeated malignancy surveillance proceed alongside options such as amifampridine. “Treat as myasthenia gravis without malignancy screening” is less appropriate because ocular-bulbar myasthenia lacks the characteristic autonomic syndrome and presynaptic increment “Use long-term corticosteroids alone without addressing autonomic symptoms” is less appropriate because immune treatment may help but cannot replace cancer evaluation and symptomatic therapy “Reassure because post-exercise facilitation excludes neuromuscular disease” is less appropriate because facilitation is a positive presynaptic junction sign “Perform brain biopsy for a central motor disorder” is less appropriate because the weakness localises to neuromuscular transmission rather than brain tissue

Reference: Firdapse 10 mg tablets: SmPC. https://www.medicines.org.uk/emc/product/11539/smpc