To Reveal the Impact of a Constant Current Repetitive Electrical Epidural Stimulation on Regeneration of the Contused Rat Spinal Cord

Background: Does repetitive electrical stimulation promote recovery of the rat contused spinal cord? Study Design: An experimental rat model of spinal cord contusion with subsequent therapeutic intervention was usedto reveal the impact of a constant current repetitive electrical epidural stimulation on the regeneration of the contused rat spinal cord. Experiments were performed in the animal laboratory of a University Neurosurgical Department Methods: Male Sprague-Dawley rats were anesthesized with nembutal applied intraperitoneally and underwent laminectomy at Th 8. The spinal cord was then lesioned by graded epidural compression. Motor and somatosensory evoked potentials from the hind limbs as well as F waves from the sciatic nerves were recorded before and after lesioning of the cord. After that, a stimulation unit was inserted subcutaneously and stimulating electrodes were placed epidurally. The stimuli applied were constant current (14µA) monophasic pulses at 8Hz in the treatment group. A control group received an inactive stimulator. The animals were followed clinically and electrophysiologically for a survival period of 3 and 50 days. Results: No significant differences were seen when comparing both groups either with regard to functional outcome or with respect to the electrophysiological results. Clinical testing revealed recovery of hindlimb function from a mean Basso-Beattie-Bresnahan-/Inclined plane test-score of 6.7/3.8 on day 1 to 9.7/4.6 on day 3 and finally to 17/7.6 on day 50. This was accompanied by a significant increase in F-wave amplitudes whereas amplitudes of somatosensory and motor evoked potentials remained significantly depressed. Conclusions: Constant current repetitive epidural stimulation does not enhance functional or electrophysiological recovery in rats after acute spinal cord injury.