INTRAOPERATIVE LONG-LATENCY REFLEX ACTIVITY IN IDIOPATHIC SCOLIOSIS DEMONSTRATES ABNORMAL CENTRAL PROCESSING - A POSSIBLE CAUSE OF IDIOPATHIC SCOLIOSIS

Segmental reflex regulation in 37 patients with idiopathic scoliosis a nd 8 patients with nonidiopathic scoliosis was studied by recording ev oked reflex muscle potentials from four muscle groups in each lower ex tremity during partial neuromuscular blockade. Effects on reflex activ ity mediated through descending systems arising in the brain stem were investigated by recording from proximal-distal and flexor-extensor mu scles. Ipsilateral and contralateral long-latency complex polysynaptic activity was present in all 37 patients with idiopathic scoliosis. Th is reflex activity was absent in eight nonidiopathic scoliosis patient s. Long-latency reflex activity may represent segmental disinhibition. The presence of long-latency reflex activity in patients with idiopat hic scoliosis and the absence of this activity in nonidiopathic scolio sis patients with curves of equal magnitude demonstrates that the curv e per se is not responsible for the activity. This would imply that ab normal reflex processing may play a role in the development of the spi nal deformity in patients with idiopathic scoliosis.