Autonomic ysreflexia,"AD" or "autonomic hyperreflexia" is a massive sympathetic discharge that can occur in association with spinal cord injury (SCI) or disease (e.g. multiple sclerosis. AD is believed to be triggered by afferent stimuli (nerve signals that send messages back to the spinal cord and brain) which originate below the level of the spinal cord lesion. It is believed that these afferent stimuli trigger and maintain an increase in blood pressure via a sympathetically mediated vasoconstriction in muscle, skin and splanchnic (gut) vascular beds (Karlsson, 1999).