Changes in Dermatomal Somatosensory Evoked Potentials according to Stimulation Intensity and Severity of Carpal Tunnel Syndrome

Objective : To investigate the change of latency of cervical dermatomal somatosensory evoked potential (DSEP) according to stimulation intensity (SI) and severity of carpal tunnel syndrome (CTS). Methods : Stimulation sites were the C6, C7, and C8 dermatomal areas. Two stimulation intensities 1.5xsensory threshold (ST) and 2.5xST were used on both normal and CTS patients. Results : In moderate CTS, the latencies of C6 and C7 DSEP during 1.5xST SI and those of C7 DSEP during 2.5xST SI were significantly delayed compared with the values of normal subjects. Significant correlation between the latency of C7 DSEP of 2.5xST stimulation and the median sensory nerve conduction velocity was observed. Conclusion : We suggest that these data can aid in the diagnosis of cervical sensory radiculopathy using low stimulation intensity and of those who have cervical sensory radiculopathy combined with CTS patients.