Neuromyelitis optica spectrum disorder — SCE Neurology MCQ

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HardMSNeuromyelitis optica spectrum disorderSCE Neurology

Six months after a small right dorsal pontine infarct interrupting the central tegmental tract, a patient develops pendular nystagmus and palatal tremor. MRI now shows enlargement and T2 hyperintensity of which structure?

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Correct answer: C — Right inferior olivary nucleus

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

C is correct: the central tegmental tract descends ipsilaterally from the red nucleus to the inferior olive, so a right-sided tract lesion causes delayed right hypertrophic olivary degeneration. This trans-synaptic degeneration is paradoxically associated with enlargement rather than atrophy and can generate oculopalatal tremor. A dentate or superior-cerebellar-peduncle lesion instead causes contralateral olivary change. The subthalamic nucleus lies outside the dentato-rubro-olivary triangle.

Reference: Oculopalatal tremor: a clinical and radiological review: https://pn.bmj.com/content/16/3/243