[Compression of the ulnar nerve at the wrist (author's transl)].

Compressions of the ulnar nerve at the wrist in or beyond the canal de Guyon are comparative rare. Those originating from compression in the sulcus ulnaris at the elbow are much more common. The clinical symptoms are typical: Weakness of the small muscles of the hand, loss of sensibility and pain. The diagnosis can be made on the clinical picture. It has to be confirmed by electromyography. Surgery should be performed as early as possible to avoid permanent damage to the nerve. Any delay can cause irreversible loss of function of the ulnar nerve. As causes of the compression of the ulnar nerve tumours, inflammation of the sourrounding tissue or trauma have been described. In this paper we report about compression of the ulnar nerve in the canal de Guyon due to a thrombosed aneurysme of the ulnar artery. This condition is quite rare. It is characterized through sudden onset of pain in the hand. Immediate surgery with decompression of the nerve, as we did in our case, will result in complete recovery.