FOREARM VELOCITY IN CARPAL-TUNNEL SYNDROME - WHEN IS SLOW TOO SLOW

Objective: To correlate the frequency of superimposed processes (SPs) such as radiculopathies, polyneuropathies, and plexopathies with media n motor forearm conduction velocity (MMFCV) in patients with carpal tu nnel syndrome (CTS). Design: All cases of diagnosed CTS were retrospec tively analyzed for evidence of SPs. Setting: Electrophysiology labora tory of a tertiary care center. Participants: One hundred fifty-five p atients (44 men, 111 women), ages 19 to 94, who were referred for and met electrophysiologic criteria for CTS, both with and without MMFCV s lowing. Main Outcome Measure: The frequency of SPs in patients with no , mild: moderate, and severe MMFCV slowing. Results: A total of 192 ar ms from 155 patients were studied. Of 14 arms with mild slowing (MMFCV of 47.0 to 49.9 m/sec), 2 (14%) had an SP. Of 15 arms with moderate s lowing (MMFCV of 43.0 to 46.9 m/sec), 4 (46%) had an SP. Of 9 arms wit h severe slowing (MMFCV of < 43.0 m/sec), 4 (44%) had an SP. The frequ ency of SPs in both the moderate and severe groups was significantly h igher than that in patients with a normal MMFCV (p < .01); of 154 arms with a normal MMFCV, only 9 (6%) had an SP. Conclusion: In cases of C TS, the finding of moderate to severe slowing of MMFCV (< 47.0 m/sec) should prompt a careful electrophysiologic investigation to exclude an SP. (C) 1998 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.