PREDICTING ACUTE DENERVATION IN CARPAL-TUNNEL SYNDROME

Objective: To determine which nerve conduction parameters can predict the presence of acute denervation in carpal tunnel syndrome. Setting: The electrodiagnostic laboratories of a hospital and a county hospital district. Design: A retrospective review. Patients: A total of 1,590 consecutive cases from January 1992 to June 1996, diagnosed as having median neuropathy at the wrist. Main Outcome Measures: Evidence of acu te denervation on needle electromyography of the abductor pollicis bre vis and its relationship to patient age, gender, and parameters obtain ed from nerve conduction studies, including median sensory latency and amplitude, and median motor latency and amplitude. Results: Logistic regression analysis identified gender, median motor latency, and media n motor amplitude (all p less than or equal to .008) as contributing t o the prediction of denervation. Needle examination of the cases with a median motor amplitude < 7mV detected 95.3% (141/148) of all cases w ith denervation and could have spared 52% (708/1,362) of the populatio n from a needle examination of the abductor pollicis brevis. Conclusio n: The median motor amplitude can predict the presence of acute denerv ation in the thenar muscles in median neuropathy at the wrist and poss ibly eliminate a painful needle examination of the median-innervated t henar muscles in over 50% of the cases. (C) 1998 by the American Congr ess of Rehabilitation Medicine and the American Academy of Physical Me dicine and Rehabilitation.