Clinical manifestations of malfunctioning sympathetic mechanisms in tetraplegia.

Patients who are tetraplegic with cervical spinal cord transection do not appear to have cerebral control over the sympathetic nervous system. Soon after transection they are often in a state of spinal shock during which even isolated spinal cord sympathetic activity is absent. This affects, in particular, the cardiovascular system and other homeostatic mechanisms which are dependent on appropriate regulation of the vasculature, such as thermoregulation. After a few weeks isolated spinal cord activity returns but the absence of control absence of control by the brain results in sympathetic malfunction of various systems. Inappropriate inactivity therefore occurs during postural change and causes orthostatic hypotension, while over-activity, which results in the syndrome of autonomic dysreflexia and hypertension, occurs if spinal sympathetic reflexes are activated. Examples are provided of clinical effects of sympathetic malfunction in tetraplegics in relation to circulatory, thermoregulatory, pupillary, genital, gastrointestinal and urinary tract function.