Investigation of segmental carpal tunnel pressure in patients with idiopathic carpal tunnel syndrome--is it necessary to release the distal aponeurotic portion of the flexor retinaculum in endoscopic carpal tunnel release surgery?

Segmental carpal tunnel pressure was measured in 12 hands of 11 idiopathic carpal tunnel syndrome patients before and after two-portal endoscopic carpal tunnel release. We aimed to determine at which part of the carpal tunnel the median nerve could be compressed, and to evaluate whether carpal tunnel pressure could be reduced sufficiently at all segments of the carpal tunnel after the surgery. Pressure measurements were performed using a pressure guide wire. The site with the highest pressure corresponded to the area around the hamate hook; the pressure in the area distal to the flexor retinaculum could be pathogenically high (more than 30 mmHg) before the surgery. The two-portal endoscopic carpal tunnel release achieved sufficient pressure reduction in all segments of the carpal tunnel when the flexor retinaculum and the fibrous structure between the flexor retinaculum and the palmar aponeurosis were completely released.