Autonomic Dysreflexia

Autonomic dysreflexia (AD), also known as autonomic hyperreflexia, is a potentially life threatening condition which can be considered a medical emergency requiring immediate attention. AD occurs most often in spinal cord-injured individuals with spinal lesions above the T6 spinal cord level; although, it has been known to occur in patients with a lesion as low as T10.

Acute AD is a reaction of the autonomic (involuntary) nervous system to overstimulation. It is characterised by severe paroxysmal hypertension (episodic high blood pressure) associated with throbbing headaches, profuse sweating, nasal stuffiness, flushing of the skin above the level of the lesion, bradycardia, apprehension and anxiety, which is sometimes accompanied by cognitive impairment. The sympathetic discharge that occurs is usually 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.