A study of the occupations in twenty-two cases of carpal-tunnel syndrome involving thirty-four hands suggests that repeated, forceful flexion of the wrist and fingers is frequently a precipitating factor.
Hereditary predisposition and regional congenital abnormalities may also contribute to the development of median-nerve compression.
Quantitative measurements of the median nerve and transverse carpal ligament in wrists operated upon for the carpal-tunnel syndrome and in normal hands at autopsy have been compared. There is no evidence that hypertrophy of the transverse carpal ligament plays a role in the production of compression of the median nerve. Pseudoneuroma involves the portion of the nerve lying proximal to the ligament, but occasionally extends into the proximal third of the carpal tunnel where any demonstrable constriction of the nerve is usually located.
Studies of the pressure developed within the canal during wrist movements show that increased pressure develops in the proximal half during both flexion and extension of the wrist, whereas the distal half of the canal develops increased pressure during extension only.