What is autonomic dysreflexia?

Autonomic dysreflexia (AD) is a potentially life-threatening medical emergency that affects people with spinal cord injuries at the T6 level or higher. Although rare, some people with T7 and T8 injuries can develop AD. For most people, AD can be easily treated as well as prevented. The key is knowing your baseline blood pressure, triggers, and symptoms.

When triggered, AD requires quick and correct action or there may be serious consequence such as a stroke. Because many health professionals are not familiar with this condition, it is important for people who are at risk for AD, including the people close to them, to recognize the symptoms and know how to act.

It’s important for at-risk individuals to know their baseline blood pressure values and to communicate to healthcare providers how to identify as well as manage an AD emergency.

Some of the signs of AD include high blood pressure, pounding headache, flushed face, sweating above the level of injury, goose flesh below the level of injury, nasal stuffiness, nausea, and a slow pulse (slower than 60 beats per minute). Symptoms will vary based on the individual.

Causes of AD

Autonomic dysreflexia is caused by an irritant below the level of injury, including:

  • Bladder: irritation of the bladder wall, urinary tract infection, blocked catheter or overfilled collection bag.
  • Bowel: distended or irritated bowel, constipation or impaction, hemorrhoids or anal infections.
  • Other causes include skin infection or irritation, cuts, bruises, abrasions or pressure sores (decubitus ulcers), ingrown toenails, burns (including sunburn and burns from hot water) and tight or restrictive clothing.

AD can also be triggered by sexual activity, menstrual cramps, labor and delivery, ovarian cysts, abdominal conditions (gastric ulcer, colitis, peritonitis) or bone fractures.

What to do when AD is triggered

If AD is suspected, the first thing to do is sit up or raise the head to 90 degrees. If you can lower your legs, do so. Next, loosen or remove any constricting clothing , and be sure to check your blood pressure every five minutes.

An individual with SCI above T6 often has a normal systolic blood pressure in the 90-110 mm Hg range.

  • A blood pressure reading of 20mm to 40mm Hg above baseline in adults may be a sign of autonomic dysreflexia.
  • 15mm above baseline in children, and 15mm to 20mm above baseline in adolescents may be a sign of autonomic dysreflexia .

Most importantly, locate and remove the offending stimulus, if possible. Begin by looking for your most common causes: bladder, bowel, tight clothing, skin issues. Keep in mind as you remove the cause that your AD may get worse before it gets better.

What happens during an episode of AD?

Autonomic dysreflexia indicates over-activity of the autonomic nervous system – the part of the system that controls things you don't have to think about, such as heart rate, breathing and digestion.

A noxious stimulus (would be painful if one could sense it) below the injury level sends nerve impulses to the spinal cord; they travel upward until blocked at the level of injury.

Since these impulses cannot reach the brain, the body doesn't respond as it would normally. A reflex is activated that increases activity of the sympathetic portion of the autonomic nervous system. This results in a narrowing of the blood vessels, which causes a rise in blood pressure.

Nerve receptors in the heart and blood vessels detect this rise in blood pressure and send a message to the brain. The brain then sends a message to the heart, causing the heartbeat to slow down and the blood vessels above the level of injury to dilate. However, since the brain is not able to send messages below the level of injury, blood pressure cannot be regulated. The body is confused and can't sort out the situation.

Generally speaking, medications are used only if the offending stimulus cannot be identified and removed, or when an episode of AD persists even after the suspected cause has been removed.

A potentially useful agent is nitroglycerine paste (applied topically above level of injury). Nifedipine and nitrates are commonly used, in immediate-release form. Hydralazine, mecamylamine, diazoxide, and phenoxybenzamine might also be used.

If an erectile dysfunction drug (e.g. Cialis, Viagra) has been used within 24-hours, other medications should be considered as blood pressure could drop dangerously low.

For the most part, autonomic dysreflexia can be prevented. Keep catheters clean and adhere to your catheterization and bowel schedules.

Download a life-saving AD wallet card

In collaboration with the nursing and medical staff at International Center for Spinal Cord Injury at Kennedy Krieger Institute we designed an AD card for both the patient and the physician.

Our cards are created to fit in a wallet with a tri-fold design that will allow you to write all your baseline blood pressure, level of injury, emergency numbers, etc.

One of the folds is written specifically for the physician. In the event of an AD crisis, you can pull the "Attention Physician" flap to the front. This allows first responders to see your personal information on one side and directions to treat AD on the other.

Your baseline blood pressure determines what your AD numbers are and helps identify the best treatment for you. Most individuals living with quadriplegia have low blood pressure but few emergency room doctors and rescue squads realize this fact. Learn your baseline blood pressure if you don't know it already.

The new AD cards are available for both adults and children/teens (their treatment and numbers differ). The inside of the card is a quick reference for the individual living with paralysis and/or their caregivers.

Please fill in your important information – we suggest using a fine point sharpie, but a regular pen also works if you press firmly.

Copies are available online for download, or you can call the PRC directly at 800-539-7309 and ask to speak to an information specialist.

Video on autonomic dysreflexia

Autonomic dysreflexia (AD) is a potentially life threatening condition that can be considered a medical emergency. AD requires quick and correct action. Surprisingly many medical professionals have never heard of this condition. Have you?

Resources on AD

For more information on autonomic dysreflexia and additional resources from trusted Reeve Foundation sources, please download our fact sheet on AD and check out our repository of fact sheets on hundreds of topics ranging from aging with a spinal cord injury to secondary complications of paralysis.

The information contained in this card and web page is presented for the purpose of informing you about paralysis and its effects. Nothing contained herein is to be construed or intended as a medical diagnosis or treatment. Contact your physician or other qualified healthcare provider should you have questions on your health, treatment, or diagnosis.

This project was supported, in part, by grant number 90PRRC0002, from the U.S. Administration for Community Living, Department of Health and Human Services, Washington, D.C. 20201. Grantees undertaking projects under government sponsorship are encouraged to express freely their findings and conclusions. Points of view or opinions do not, therefore, necessarily represent official Administration for Community Living policy.