Spine and scalp somatosensory evoked potentials in normal subjects and patients with spinal cord disease: evaluation of afferent transmission.

Spine and scalp somatosensory evoked potentials (SEPs) to peroneal nerve stimulation were recorded from 20 normal subjects using 1 restricted and 3 open frequency filter bandpasses. Spine to spine and spine to scalp propagation velocities were calculated. Of those recording parameters investigated, optimal recordings were obtained using an open bandpass (5-1500 or 30-1500 Hz) and recording from 3 surface spine bipolar channels and 1 scalp bipolar channel. This method was then investigated in 40 patients with disease of the spinal cord and peripheral nervous system. Focal spinal cord compressive lesions generally resulted in slowing of spine to spine and spine to scalp propagation velocities. Diffuse or multifocal lesions of the spinal cord generally resulted in the absence of scalp responses. Although there was no consistent correlation of the SEP findings with the sensory exam, there was a correlation of the SEP findings with the clinical prognosis.