Compression of the ulnar nerve at the wrist secondary to a rheumatoid synovial cyst: case report and review of the literature.

Compression of the ulnar nerve within or near the canal of Guyon has been ascribed to numerous intrinsic and extrinsic factors. The anatomy of the region is discussed, and a review of the reported causes of ulnar nerve compression is presented. A case of ulnar nerve compression at the wrist secondary to a rheumatoid synovial cyst is reported. Prompt decompression resulted in clinical and electromyographic recovery of sesory and motor function.