Use of sciatic neurogenic motor evoked potentials versus spinal potentials to predict early-onset neurologic deficits when intervention is still possible during overdistraction.

Spinal evoked potentials, sciatic neurogenic motor evoked potentials, and somatosensory evoked potentials were recorded before and after overdistraction of the spinal cord, and compared with the clinical status of 14 pigs. The sciatic neurogenic motor evoked potential consisted of two components: fast and slow. The fast component was more sensitive and associated to a greater degree with motor function in wake-up tests than the slow component somatosensory evoked potential and spinal evoked potential. Furthermore, the loss of only the fast component in the initial status allowed the possibility of improvement of motor activity in the final wake-up test. The peripheral neurogenic motor evoked potentials recording yielded more information about spinal cord function: motor and sensory. The current study suggests that a peripheral response is a better index to the onset of overdistraction and to the efficiency of intervention, when the neurologic deficit after overdistraction of the spine is reversible.