Cold effect in median nerve conductions in clinical carpal tunnel syndrome with normal nerve conduction studies

•Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy.•CTS can be observed in either one hand or both.•Diagnosed is based on clinics and nerve conduction studies (NCS)•In some case with clinic CTS, the nerve conduction study could be normal.•Cold application could determine nerve conduction anomalies İn clinical CTS with normal NCS. Clinical diagnosis of carpal tunnel syndrome (CTS) is confirmed by nerve conduction studies (NCS). In some cases, NCS may be normal. We aimed to demonstrate changes of distal motor latency (DML) and nerve conduction velocity (NCV) pathology of demyelination in entrapment neuropathy with cold application in case of clinical CTS with normal NCS. This prospective, cross-sectional, randomise, case-control involved 15 patients (25 hands) with clinically definite unilateral or bilateral CTS and normal nerve conduction studies (NCS), and 11 controls (22 hands). Ice pack was applied to median nerve trasse at wirst with monitoring skin temperature. NCS of median nerve were examinated again. Increases of DML, decrease of velocity of median nerve were observed in two groups after post-cooling. The change in NCV was greater than the change in DML. Cold effect was evident in DML and NCV in the patient group. This could be sign of the demyelination pathology. We think that cold application is influential to determine electrophysiologic abnormalities in clinic CTS with normal NCS.