A 52-year-old man develops progressive severe insomnia with loss of both NREM and REM sleep architecture, followed by autonomic instability, motor signs, and death within 18 months. His father died of an identical illness. Histopathological examination would show neuronal loss predominantly in which structure?

• A Lateral hypothalamus
• B Frontal cortex
• C Pons
• D Thalamus ✓

Explanation

Fatal familial insomnia is an autosomal dominant prion disease caused by the PRNP B178N mutation, characterised by selective degeneration of the anterior and dorsomedial thalamic nuclei, producing intractable insomnia and autonomic dysfunction. The lateral hypothalamus is the site of orexin neuron loss in narcolepsy, which is the fact that kills the most tempting distractor.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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