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Autonomic dysreflexia (AD) is a condition where the involuntary nervous system overreacts to external or bodily stimuli. This reaction causes a dangerous spike in blood pressure, racing heart, constriction of peripheral blood vessels, and other changes in the body’s autonomic functions.

AD is also known as Autonomic Hyperreflexia. The condition is most commonly seen in people with spinal cord injuries above the sixth thoracic vertebra (T6). It may also affect people with multiple sclerosis and some head or brain injuries. Sometimes the condition is a side effect of medication or illegal drugs such as cocaine and amphetamines.

AD is potentially life threatening and can result in stroke, retinal haemorrhage, cardiac arrest, and pulmonary edema if not addressed quickly. AD is a very serious condition and is considered to be a medical emergency.


To understand autonomic dysreflexia, it is helpful to know something about the autonomic nervous system (ANS). The ANS is the part of the nervous system responsible for involuntary bodily functions such as:

  • Blood pressure
  • Heart and breathing rates
  • Body temperature
  • Digestion
  • Metabolism
  • Balance of water and electrolytes
  • Production of body fluids
  • Urination
  • Defecation
  • Sexual response.

The ANS is divided into two branches:

  • The sympathetic autonomic nervous system (SANS)
  • The parasympathetic autonomic nervous system (PANS)

The SANS and PANS are like the Yin and Yang of the nervous system. They operate in parallel, but opposite ways to maintain the balance of the involuntary functions in your body. In other words, if the SANS overreacts, the PANS is able to compensate for it.

In AD, both the SANS and PANS are disrupted. As a result, not only can the bodys SANS overreact to stimuli such as a full bladder, but also the PANS cant effectively stop that reaction and may actually make it worse.


Signs and symptoms of AD include:

  • Anxiety and apprehension
  • Irregular or racing heart
  • Nasal congestion
  • High blood pressure
  • Pounding headache
  • Flushing of the skin
  • Profuse sweating, particularly on the fore head
  • Light-headedness, dizziness or confusion.
  • Dilated pupils.


Long term treatment and prevention are aimed at identifying and addressing the underlying issues that trigger AD. A long term treatment plan might include:

  • Change in medication or diet to improve elimination
  • Improved management of urinary catheters.
  • Medications for high blood pressure.
  • Medications or a pacemaker to stabilize the heartbeat.
  • Self-management to avoid triggers.


Emergency responses is aimed at lowering the blood pressure and eliminating the stimuli that are triggering the reaction. Emergency measures may include:

  • Placing the patient in a sitting position to cause blood to flow to the feet.
  • Removing tight clothes and socks.
  • Checking for a blocked catheter.
  • Draining the bladder with a catheter if it is distended.
  • Removing any other potential triggers such as drafts of air blowing on the patient or objects touching the skin.
  • Treating the patient for fecal impaction.
  • Administering vasodilators or other drugs to bring the blood pressure under control.




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