Evidence of improvement in distal conduction of ulnar nerve sensory fibers after carpal tunnel release.

Abstract

The aim of this study was to verify any effect of carpal tunnel release (CTR) on distal ulnar nerve conduction findings, using the database of a previous study performed to establish a protocol for CTR outcome. The motor and sensory ulnar distal conduction findings of 251 consecutive hands belonging to 217 patients (175 women and 42 men; mean age, 55.6 years) with idiopathic carpal tunnel syndrome (CTS) were reanalyzed before and 1 and 6 months after CTR. Before surgery, 115 hands (45.8%) showed reduction of ulnar nerve sensory action potential (SAP) amplitude; this number was reduced significantly to 85 (33.9%) after CTR. The SAP amplitude and sensory conduction velocity values of the ulnar nerve showed significant improvement 1 month after CTR; SAP amplitude values showed further significant improvement 6 months after CTR. Patients' ages and occupations were independent predictors of reduced baseline SAP amplitudes of the ulnar nerve in CTS. These results demonstrate an improvement in conduction values in sensory ulnar fibers in a percentage of patients with CTS after CTR, providing further support for the conclusion that in CTS ulnar fibers may be subject to compressive forces in the Guyon canal as a consequence of high pressure in the carpal tunnel.