The clinical value of thumb sensory nerve conduction velocity in diagnosis of carpal tunnel syndrome

Objective:To investigate the method of diagnosis of mild carpal tunnel syndrome(CTS)using thumb sensory nerve conduction velocity(SCV).Methods:Eighteen patients(26 hands)with normal latency of wrist sensation action potentials were studied.The sensory nerve conduction velocitys(SCV)were recorded.The SCV in the median and radial nerve in the thumb finger,SCV in the median nerve in the middle finger were recorded.The results were compared with those in 15 normal age-matched controls(30 hands).Results:The abnormal rate from median nerve in the middle finger was 50%.The abnormal rate of the difference in SCV between median and radial nerve in the thumb finger was 84.6%.A double-peak wave was recorded in the median nerve at the wrist after stimulation of the affected thumb finger in 8 cases(12 hands),but not found in control hands.Conclusion:The difference of SCV between the median and radial nerve is one of the sensitive indicators for early diagnosis of carpal tunnel syndrome.