Sensory nerve evoked responses in spinal cord injury

Previous studies have documented the presence of fibrillations, positive waves, and decreased motor evoked response amplitudes in spinal cord injury (SCI) subjects. The purpose of this study was to further evaluate sensory nerve status in this population. Twenty-eight subjects with SCI for at least five months and evidence of spasticity were included. Sural sensory and tibial motor evoked response amplitudes were measured. The mean sural sensory amplitude was 8.0 +/- 5.9 microV (normal = 15.0 +/- 5.3 microV). The mean tibial motor amplitude was 5.1 +/- 4.3 mV (normal = 11.7 +/- 3.8 mV). In six subjects with significantly reduced sural sensory amplitudes, more extensive electrodiagnostic testing was performed. These studies showed diffusely decreased lower extremity sensory and motor evoked response amplitudes and diffuse positive waves and fibrillations in no particular distribution. Thus, subjects with SCI may have sensory as well as motor nerve abnormalities. An intact connection between the second order and primary sensory neuron may be necessary for maintenance of axonal integrity of the primary neuron.