Abstract
Short latency somatosensory evoked potentials (sSEP) were recorded in 47 patients with cervical myelopathy, and the results obtained were compared with clinical symptoms and changes in the waveform of evoked spinal cord action potentials.
sSEPs were classified into three types according to the changes in the waveform: type 1; normal waveform (18 cases), type 2; longer latency or reduced amplitude of sSEP (20 cases), type 3; no observable sSEP (9 cases).
Decompression surgery on the spine was performed in 29 cases (including 9 type 1 cases, 13 type 2 cases and 7 type 3 cases). Changes in sSEP waveform was correlated to clinical symptoms (JOA score) and disability periods. In some cases, type 2 sSEP approached normal waveform after the operation, and there was an improvement in clinical symptoms.
Evoked spinal cord action potentials were recorded during the operation in 15 cases (4 type 1 cases, 6type 2 cases and 5 type 3 cases), and the location of the disc lesioned was inferred in all cases except inone case of type 1. In 3 type 1 cases, only one disc was lesioned. In all type 2 and type 3 cases, more than two discs were lesioned. It was therefore considered that when only one disc was lesioned, sSEP did not necessarily exhibit abnormalities.
