An Unusual Radial Neuropathy.

A 23-year-old woman presented to her physician for left forearm pain of insidious onset, inability to extend the wrist, and numbness in the dorsal hand. An electromyogram (EMG) and nerve conduction study (NCS) demonstrated radial neuropathy, while magnetic resonance imaging (MRI) of the left elbow/forearm, performed 2 months later, revealed edema and atrophy of the wrist extensor muscles, but no compressive lesion. Following a lack of improvement and consultation with an orthopaedic surgeon, a second, more detailed EMG/NCS was performed, revealing a severe radial motor and sensory neuropathy, with compression between the lateral and long heads of the triceps.