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Azathioprine – Pancytopenia and TPMT — SCE Neurology MCQ

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HardMultiple Sclerosis & CNS InflammationAzathioprine – Pancytopenia and TPMTSCE Neurology

A 37-year-old with previously unexplained childhood epilepsy and mild cognitive impairment develops progressive ataxia, myoclonus and visual symptoms. EEG shows an unusually strong photoparoxysmal response at low flash frequencies of 2–3 Hz. Which diagnostic category should now be specifically revisited?

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Correct answer: A — Adult-onset neuronal ceroid lipofuscinosis (Kufs disease)

Explanation lettering: E = shown as A · A = shown as D · D = shown as E

E is correct: photosensitivity at unusually low stimulation frequencies, particularly 1–3 Hz, is an important clue to neuronal ceroid lipofuscinosis, including adult-onset Kufs disease, in a patient with progressive myoclonus, ataxia and cognitive or visual decline. Mitochondrial and other progressive myoclonic epilepsies remain differential diagnoses, but the question asks which category this EEG clue specifically reopens. Juvenile myoclonic epilepsy does not explain progressive neurological deterioration; an autoimmune label does not fit the lifelong course.

Reference: Investigating adults with early-onset epilepsy and intellectual or physical disability: https://pn.bmj.com/content/19/2/115