Ulnar nerve conduction abnormalities in carpal tunnel syndrome.

INTRODUCTION

The aim of this study was to verify the involvement of ulnar nerve fibers in cases of carpal tunnel syndrome (CTS) and investigate the correlation between ulnar nerve conduction parameters and extra-median spread of symptoms.

METHODS

Electrophysiological studies were conducted in 93 CTS and 76 control hands. Patients were analyzed with regard to symptoms in the fifth finger.

RESULTS

In the CTS cases, ulnar distal motor latency (DML) and distal sensory latency (DSL) were significantly longer, and amplitudes were lower than in controls. Increased median nerve DML correlated with increased ulnar nerve DSL and decreased sensory amplitudes and conduction velocities (SCVs). In cases with symptoms in the fifth finger, ulnar nerve SCVs and amplitudes were lower than in patients without symptoms.

CONCLUSIONS

Pathological processes leading to median neuropathy in CTS may affect ulnar nerve motor and sensory fibers in the Guyon canal. This may explain the extra-median spread of sensory symptoms in CTS patients.