Autonomic hyperreflexia. A serious complication of radiological procedures in patients with cervical or upper thoracic spinal cord lesions.

Autonomic hyperreflexia is a reflex response to visceral distension which occurs only in patients with spinal cord lesions above T6. The marked hypertension, which is an integral part of this reflex, may lead to severe morbidity, or even death. The mechanism whereby interruption of the sympathetic outflow from the spinal cord results in autonomic hyperreflexia is described, as well as the clinical signs and symptoms associated with this condition. The value of autonomic hyperreflexia as a clinical indicator of complications in patients with spinal cord lesions is stressed. The diagnosis and treatment of autonomic hyperreflexia which has occurred as a complication of radiological procedures are discussed.