Muscle Spasm and Abnormal Postures Resulting from Damage to Interneurones in Spinal Cord

Thorburn13was the first to describe a peculiar posture of the upper extremities following an injury to the cervical spine. It was characterized by abduction of the arms and flexion of the forearms with complete paralysis below the C5 level. Although this posture is not rare in clinical medicine, we have found only a few subsequent reports. That the posture results from paralysis of one segmentally innervated group of muscles with unopposed action of antagonists has become generally accepted.8There are situations where the abnormal posture persists in the absence of volition, or when the overactive muscles cannot be contracted by willed effort. For such states no more satisfactory explanation has been offered since Thorburn first reported the condition. In this communication, we present a clinical and pathologic study of 3 cases with an abnormal posture in one or more extremities, review other reports, and offer an explanation