A 55-year-old woman with a history of a brainstem stroke develops rhythmic involuntary movements of her soft palate. MRI shows enlargement and increased signal of the left inferior olivary nucleus. Which tract was damaged by the original stroke?

• A Left central tegmental tract ✓
• B Right medial lemniscus
• C Left spinothalamic tract
• D Left inferior cerebellar peduncle

Explanation

Palatal myoclonus with hypertrophic olivary degeneration follows interruption of the Guillain-Mollaret triangle: dentate nucleus, contralateral red nucleus, and inferior olive. The red nucleus connects to the ipsilateral inferior olive through the central tegmental tract, so a tegmental stroke denervates the olive, which undergoes transsynaptic hypertrophy rather than atrophy. The inferior cerebellar peduncle carries olivocerebellar output but damaging it does not produce olivary hypertrophy.

Reference: Snell's Clinical Neuroanatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.