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Correspondence to Dr Tychicus Chen; [email protected]
Description
A 26-year-old man, right-handed, otherwise healthy warehouse worker presented with painless left-hand weakness. He noticed difficulty with fine finger movements and thumb articulation that had been gradually worsening over the past 2 years. He denied any sensory changes or involvement of any other muscles. There was no history of recent trauma, neck pain or bulbar symptoms. He had no regular medications. On examination, mental status and cranial nerve testing were unremarkable. Tone was normal. He had atrophy of the left first dorsal interosseus (FDI) and tremulous movements of the left digits with irregular jerky movements suggestive of polyminimyoclonus (video 1). Weakness in his left hand was measured by Medical Research Council grade: left FDI (4−/5), second palmar interosseus (3/5), abductor digiti minimi (4/5), flexor pollicis longus (FPL, 4−/5) and abductor pollicis brevis (4+/5); with normal strength in all other muscle groups. Right arm and leg strength, reflexes, sensation and gait were normal.
MRI of the cervical spine without contrast revealed left hemicord flattening between C5 and C7 without cord compression, with epidural venous distension on flexion view (figure 1), characteristic of Hirayama disease. Sensory and motor nerve conduction studies were unremarkable, whereas electromyography showed chronic neurogenic changes in the left FPL, flexor digitorum profundus (median) and FDI muscles. He was treated conservatively with...