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Autonomic Dysreflexia Executive Summary

What is autonomic dysreflexia?

Autonomic dysreflexia (AD) is a potentially life-threatening condition that can affect people who have had a spinal cord injury at the level of T6 or above (sometimes as low as T8, though rare – nerves from T6 control a large group of blood vessels that supply the lower body and many of the organs of the abdomen, such as the stomach and intestines; generally speaking, the higher the level of injury, the more likely it is that the circulatory system will be affected) (Krassioukov et al. 2003; Curt et al. 1997; Mathias & Frankel 1988). People with complete injuries are more often affected than people with incomplete injuries.

AD is a medical emergency that requires an immediate response. It occurs more often in the long term phase of SCI, but can happen in the first few months after injury as well. Episodes of autonomic dysreflexia are usually brief in duration and in most cases have an identifiable trigger that causes the episode (Teasell et al. 2000; Karlsson 1999; Mathias & Frankel 1988; Elliott & Krassioukov 2006).

What are the signs and symptoms of autonomic dysreflexia?

The main sign of autonomic dysreflexia is a sudden rise in blood pressure. An increase of 20 to 30 mmHg above your patient’s normal systolic blood pressure is considered to indicate autonomic dysreflexia. Since the normal blood pressure of a person with a spinal cord injury can often be 15 to 20 mmHg lower than a person without a spinal cord injury, blood pressure can be in the range of ‘normal’ or ‘slightly elevated’ and still indicate an episode of AD.

Signs and symptoms of autonomic dysreflexia:


  • Sudden rise in blood pressure of 20 to 30 mmHg above the person’s normal systolic blood pressure (main symptom)
  • Change in heart rate – usually a slow heart rate which can sometimes become rapid or irregular
  • Pounding or throbbing headache
  • Profuse sweating, flushing or blotching of the skin above the level of injury
  • Goosebumps or hair standing on end above the level of injury
  • Dry and pale skin below the level of injury
  • Increased number and severity of muscle spasms
  • Metallic taste in the mouth
  • Feeling anxious or a feeling of impending doom
  • Nasal congestion
  • Blurred vision
  • Seeing spots
  • Nausea
  • Difficulty breathing or a feeling of chest tightness

This rise in blood pressure is usually accompanied by other symptoms. These can range from not feeling anything or having some mild discomfort and a headache to a life-threatening emergency where symptoms can be severe. Symptoms can range from not feeling anything or having some mild discomfort and a headache to a life threatening emergency where symptoms can be severe. It is important for patients and clinicians to be able to recognize the symptoms of AD so you can act accordingly. Clinicians should also be aware that in some individuals with SCI, AD could occur without any symptoms and this condition known as a silent or asymptomatic AD (Ekland et al. 2008; Linsenmeyer et al. 1996).

While autonomic dysreflexia happens most often in the long term stage after injury, it can happen on occasion in the immediate post-injury period.

Why does autonomic dysreflexia happen?

Autonomic dysreflexia is the result of overactivity of the sympathetic nervous system in response to a strong sensory stimulus below the level of injury. This stimulus is often something that is noxious or irritating, such as a wound or tight clothing, but can also be a normal function of the body, such as an overly full bladder or bowel. In response to this stimulus, the sympathetic nervous system signals the arteries to constrict, which increases blood pressure. This increase in blood pressure is followed by a slowing of the heart rate which can then sometimes become irregular. Because of the damage to the spinal cord, the body can’t effectively control the blood pressure and restore it to normal, resulting in autonomic dysreflexia. The most common trigger is irritation of the bladder or bowel.


Triggers of autonomic dysreflexia


Bladder issues

  • Urinary tract infection
  • Urinary retention
  • Blocked catheter
  • Overfilled collection bag

Skin issues

  • Pressure ulcers
  • Extreme heat or cold
  • Pressure or pinching of the skin
  • Ingrown toenails
  • Burns
  • Tight clothing
  • Any direct irritant below the level of the injury

Other causes

  • Heterotopic ossification
  • Acute abdominal conditions (such as ulcers)
  • Fractures



Bowel issues

  • Distention or irritation of the bowel
  • Constipation or impaction of the bowel
  • Hemorrhoids
  • Infection or irritation of the bowel

Sexual activity and reproductive processes

  • Overstimulation
  • Reproductive activity
  • Menstrual cramping
  • Labor and delivery




What to do if your patient has autonomic dysreflexia

1.    Move patient into an upright sitting position

2.    Check blood pressure, and re-check every 5 minutes

3.    Loosen tight clothing

4.    Search for and eliminate the cause of the incident where one can be identified

a.    Check bladder

b.    Check bowel

c.     Check skin

5.    Seek medical attention if there is no reduction in blood pressure after following these steps

Source: Consortium for Spinal Cord Medicine 2001).

What should I do if my patient has an episode of Autonomic Dysreflexia?

Autonomic Dysreflexia is a medical emergency and requires immediate treatment. The most effective treatment strategy is to identify the trigger of the episode and reduce the stimulation that is causing it. The goal of intervention is to alleviate symptoms and avoid the complications associated with uncontrolled hypertension (Vallès et al. 2005; Eltorai et al. 1992; Pine et al. 1991; Yarkony et al. 1986).

If the conservative treatments for autonomic dysreflexia are not effective in reducing blood pressure and it remains at or above 150 mmHg, drug treatments are used. This involves the use of fast-acting anti-hypertensive drugs to rapidly lower the elevated blood pressure.

Which prevention methods are effective?

Preventing an AD episode is far more effective than treating one (Braddom & Rocco 1991). Researchers have done studies on a number of different treatments to see which ones are helpful in preventing incidents of autonomic dysreflexia (Courtois et al. 2012; Krassioukov et al. 2009).

Capsaicin: Studies have shown that administering the chemical compound Capsaicin, and its more concentrated cousin Resiniferatoxin, into the bladder by a catheter, can decrease the number of episodes of AD during bladder procedures (Igawa et al. 2003; Kim et al. 2003; Giannantoni et al 2002).

Surgical bladder augmentation: Some early evidence suggests that surgery to augment the bladder may also reduce or resolve episodes of AD (Ke & Kuo 2010; Perkash 2007; Sidi et al. 1990; Barton et al. 1986).

Sacral denervation: Sacral deafferentation surgery may reduce bladder-related episodes of AD (Hohenfellner et al. 2001; Kutzenberger 2007).

Botulinum toxin: One study has demonstrated that injections of Botulinum toxin into the muscles of the bladder is effective in reducing episodes of AD (Fougere, Currie, Nigro, Stothers, Rapoport, and Krassioukov, 2016), which is supported by previous findings (Chen & Kuo 2012; Chen et al. 2008; Kuo 2008; Schurch et al. 2000; Dykstra et al 1988).

Anticholinergic medications: The use of anticholinergic medications does not appear to be effective in preventing AD during bladder procedures (Giannantoni et al. 1998).

Lidocaine: A lidocaine anal block has been found to limit the AD response in patients undergoing anorectal procedures. Topical lidocaine may prevent AD during digital bowel stimulation, but not during anorectal procedures (Furusawa et al. 2009; Cosman & Vu 2005; Cosman et al. 2002).

Anesthesia for use during pregnancy and labour: Studies have found that the use of adequate anesthesia (spinal or epidural if possible) is needed with vaginal, Caesarean, or instrumental delivery to prevent AD during labour. Epidural anesthesia is preferred and effective for most women with SCI (Skowronski & Hartman 2008; Cross et al. 1992; Cross et al. 1991; Hughes et al. 1991).

Anesthesia for use during general surgery: Anesthesia should be used during surgery for people with SCI despite the apparent lack of sensation, in order to prevent AD. Anesthesiologists and surgeons dealing with patients with SCI need to be able to recognize, prevent and manage it (Eltorai et al. 1997; Lambert et al. 1982).

Topical anesthesia during functional electrical stimulation (FES) treatment: Studies have found that the application of topical anesthesia is not effective in preventing AD during FES treatment. More research is required to understand how to prevent AD during FES (Matthews et al. 1997).

 Stoma surgery: There is preliminary evidence that stoma surgery may reduce the number of incidents of autonomic dysreflexia, if other treatments have failed to improve management of neurogenic bowel (Coggrave et al. 2012).

Where can I find more information?

For more information please click through the rest of the Autonomic Dysreflexia chapter (https://scireproject.com/evidence/rehabilitation-evidence/autonomic-dysreflexia-re/) and consult a Doctor who specializes in SCI and/or Cardiovascular issues.