Comparison of nerve conduction techniques in 95 mild carpal tunnel syndrome hands

Electrodiagnosis of carpal tunnel syndrome (CTS) were prospectively studied in 95 hands. The following techniques were studied in all hands and when at least one abnormal value was found (onset-measured), it was included on results: 1. wrist-index finger latency (WIF), abnormal > or = 2.8 ms, 140 mm; 2. palm-wrist latency (PW), abnormal > or = 1.8 ms, 80 mm; 3. comparison median/ulnar palm-wrist latency (CPW), abnormal > or = 0.4 ms; 4. comparison median/ulnar latency, wrist-ring finger (CMU), abnormal > or = 0.5 ms, 140 mm; 5. comparison median/radial latency, wrist-thumb (CMR), abnormal > or = 0.4 ms, 100 mm. All 95 CTS hands selected have the WIF <= 3.5 ms (mild CTS). We found the CMR (97.8%) technique the most sensitive for mild CTS electrodiagnosis and the only comparative method with all potentials recordable when compared to CPW (88.4%), PW (84.2%), CMU (72.6%) and WIF (68.4%).