Subacute High-Grade Ulnar Neuropathy Without Trauma: A Case of Cubital Tunnel Syndrome.

Cubital tunnel syndrome (CuTS) typically presents gradually, and an acute overnight onset of severe ulnar neuropathy is rare. A 46-year-old female recreational pickleball player awoke with a right-hand claw deformity and sensory loss without preceding symptoms or trauma. Examination showed intrinsic weakness and decreased ulnar sensation; electrodiagnostic studies revealed subacute on chronic axonal and demyelinating changes at the elbow consistent with moderate CuTS. She underwent cubital tunnel release one week after onset, with rapid sensory improvement but delayed motor recovery. This case highlights an atypical acute presentation of CuTS and underscores the importance of prompt evaluation and timely intervention to mitigate persistent deficits.