Reference Data of Cervical Dermatomal Somatosensory Evoked Potentials Using Low Intensity Stimulation and Report of 2 Cases

ABSTRACT

OBJECTIVE: To establish reference data for dermatomal somatosensory evoked potentials (DSEP) using a stimulation intensity lower than what is conventionally utilized. METHOD: Fifty subjects (25 older adults>48 years old; 25 younger adults<32 years old) without history of neck pain or cervical spine surgery were enrolled. The DSEP study was performed with stimulation intensities of 1.0, 1.5, and 2.5 times sensory threshold (ST) on right arms for C5, C6, C7, and C8 dermatomes. RESULTS: The mean latencies of DSEP stimulating C5, C6, C7, and C8 dermatomes with 1.5 times ST intensity were 17.6+/-1.7 ms, 22.2+/-2.1 ms, 22.8+/-1.4 ms, and 22.6+/-1.8 ms, respectively. The mean amplitude (N1P1) of DSEP stimulating C5, C6, C7, and C8 dermatomes with 1.5 times ST intensity were 0.9+/-0.4 microV, 0.9+/-0.5 microV, 1.0+/-0.6 microV, and 1.1+/-0.8 microV, respectively. The C5, C6, C7, and C8 DSEP were evoked in 84%, 98%, 100%, and 96% of cases with 2.5 times ST compared to 64%, 56%, 60%, and 62% with 1.5 times ST, respectively. When one DSEP was not evoked, the DSEP of the opposite side was evoked only in 2 subjects. CONCLUSION: This study provides the reference data of DSEP with lower stimulation intensities than are conventionally utilized. Additionally, two cases of clinical significance were reported.