[Occupationally-induced carpal tunnel syndrome]

In Western Europe the Carpal-tunnel syndrome (CTS) is rarely regarded as a work injury, but in the USA this syndrome is usually considered to be work-related compression of a peripheral nerve, and the labour unions are already concerned about it. The median nerve can be squeezed by the flexor tendons of the index and middle fingers. These tendons pass dorsally from the median nerve through the carpal canal, where the nerve is subject to pressure when the tendons stretch whilst the wrist is flexed. Measurements in the carpal canal confirm this mechanism and show that, whilst grasping with the muscle-strength necessary for many jobs, the pressure for the median nerve can rise as high as 450 mm Hg, if the wrist is in volar flexion. Among my own patients, 51% of the men and 28% of the women with CTS reported a clear connection between the onset of symptoms and an unfamiliar use of the hands. All these different activities had in common grasping with a volar flexed wrist. A dorsal splint was constructed, with a double joint that permits dorsal and lateral movements of the hand, but blocks flexion. Of 58 patients who carried on their working activities wearing this splint, 52 answered a questionnaire. Of the 42 patients without a prior CTS operation, 32 had remained perfectly well with the splint, 3 not at all. Two of the 10 patients with prior CTS operation reported no benefit. 13 of the 58 patients had a further operation following splint-treatment. It is concluded that proper design of the workplace and instruction of the workers could prevent many cases of work-related CTS.