Motor and somatosensory evoked potentials in a primate model of experimental spinal cord injury

Motor and somatosensory evoked potentials (MEP and SSEP) were compared after experimental spinal cord injury in Bonnet monkeys (macaca radiata). The MEP and SSEP changes following graded injuries were related to clinical outcome. Eight healthy mature monkeys with a mean weight of 4.2 + 0.9 Kg were chosen for the study. Graded spinal cord injury was caused using 50, 100, 200, 300 gm-cm force by modified Allens' weight drop device. MEP and SSEP recordings were done before injury and at 0, 2, 4 and 6 hours after injury and on the 7th postoperative day. Neurological assessment was done at 24 hours and on the 7th day following injury. 50, 100, 200 gm-cm force caused partial injuries and 300 gm-cm force caused severe spinal cord injury. The predictive value of MEP and SSEP following partial injuries was 80% and 66.67% respectively. Both MEP and SSEP were 100% predictive in severe injury. MEP and SSEP monitoring can therefore be complementary to each other in predicting the neurological outcome in partial injuries to the spinal cord.