Causes of ulnar tunnel syndrome: a retrospective study of 31 subjects.

PURPOSE: The purposes of this study were to determine the distribution of causes and sites of nerve compression in the ulnar tunnel (Guyon's canal), and investigate the relationship between ulnar tunnel syndrome (UTS) and other conditions associated with it.

METHODS

We performed a retrospective review of 31 patients diagnosed with and treated for UTS to determine the most common cause of compression and the sites of compression, systemic illnesses associated with UTS, and postoperative results.

RESULTS

The cause of ulnar nerve compression was idiopathic in 14, trauma in 8, a thrombosis in 2, proliferation of synovium in 2, a prominent hook of the hamate in 1, a schwannoma in 1, postoperative swelling in 1, an aberrant fibrous band in 1, and a ganglion in 1. The sites of compression were classified into 3 zones. Twenty-eight cases had compression in zone 1, 6 in zone 2, and 19 in zone 3. Seventeen cases (55%) had compression in more than 1 zone. Twenty-two cases (71%) were associated with carpal tunnel syndrome (CTS). Twelve (86%) of the 14 idiopathic UTS cases were associated with CTS. The relationship between idiopathic UTS and CTS was not statistically significant. Six cases were associated with diabetes mellitus.

CONCLUSIONS

The most common cause of UTS in our series was idiopathic. Most idiopathic UTS cases were associated with CTS. The clinical symptoms of UTS improved after surgery in all cases. Therefore because of the presence of multiple compression sites of the ulnar nerve in the hand, for UTS patients we believe that the release of Guyon's canal and/or the pisohamate tunnel is an effective way not only to relieve symptoms but also to determine the real cause of compression.