Estimation of cervical cord dysfunction by somatosensory evoked potentials

The purpose of this study was to examine the relationship of abnormal short-latency somatosensory evoked potentials (SSEPs) recorded by a noncephalic reference montage with clinical variables in cervical myelopathy patients and to reexamine the diagnostic utility of SSEPs in such patients. We studied cervical SSEPs elicited by stimulating the median and ulnar nerves in 87 patients. Our grade classification of spinal N13, which is based on the normal limits of latencies or amplitudes, corresponded well with the clinical variables and is of value when trying to localize the cervical lesion segmentally. The N9-P14 interpeak latency in response to ulnar nerve stimulation correlated well with lower extremity function (r = -0.440, P <0.0001). We suggest a combined assessment of N13 amplitude, and N9-N13 and N9-P14 interpeak latencies to estimate dorsal column and dorsal horn function separately in patients with cervical myelopathy.