[Studies on motor action potentials following transcranial stimulation and somatosensory evoked potentials including...

The motor action potential (MAP) following transcranial stimulation and absolute refractory time (ART) in somatosensory evoked potential (SSEP) were investigated after experimental spinal cord injuries in rabbits. The thoracic cords were injured at the level of the 11th vertebrae by Allen's method. The paralysis after the trauma was classified into 4 groups depend on its severity; severe, mild, transient and non palsy group. A single transcranial stimulation evoked the double MAPs (MAP1 and MAP2) which were characteristic for the palsy groups. The amplitude of the MAP1 was greater than MAP2 in the transient palsy group, while that of the MAP1 was lower than MAP2 in both severe and mild palsy groups. The amplitude of the MAP was significantly reduced in all injured animals. There was no correlation between the amplitude or latency of the SSEP and the severity of the palsy. However, the ART of the SSEP was considerably prolonged in all injured animals regardless of the severity of the palsy.