Effects of wrist splinting for carpal tunnel syndrome and motor nerve conduction measurements

Background: Carpal tunnel syndrome (CTS) is one of the most common disease among the entrapment neuropathies. Wrist splinting has been conventionally used for the CTS treatment. The purposes of this study were to assess the efficacy of wrist splinting for CTS, and to evaluate the value of the motor nerve conduction measurement as a prognostic indicator for CTS. Methods: Two hundred and fourteen hands with CTS were treated by wrist splinting, and reviewed after a mean follow up of seven months. Severity of symptoms were minimal lesions in 177 hands, intermediate lesions in 33 hands, and severe lesions in four hands. Motor nerve conduction measurement was performed in all cases before and after treatment, and distal latency (DL) and amplitude on compound muscle action potential (CMAP) from the abductor pollicis brevis (APB) muscle were analyzed. Results: According to Kelly's grading of outcome, results were excellent in 41 hands, good in 110 hands, fair in 45 hands, and poor in 18 hands. Excellent or good results were obtained in 131 hands (74 percent) with minimal lesions, 20 hands (61 percent) with intermediate lesions, and in no cases with severe lesions. The ratio of excellent or good results was 79 percent in patients in whom DL of pre-treatment APB-CMAP was less than 8 milliseconds (ms), and 62 percent in patients whose DL was 8 ms or more, which showed a significant difference. In nine hands whose pre-treatment APB-CMAP was unrecordable, the results were good in one hand, fair in five, and poor in three. Conclusions: Wrist splinting is most effective in cases of minimal or intermediate lesions with DL of APB-CMAP less than 8 ms. If relief of symptoms is not obtained after five months of treatment by splinting, that would be the limit of splinting. Surgical release is recommended for cases with severe lesions and with unrecordable APB-CMAP.