Autonomic hyperreflexia is an abnormal triggering of the autonomic nervous system. It occurs after a spinal cord injury. The body is unable to turn off the nerves that cause blood pressure to rise.
Normally, the autonomic nervous system controls blood pressure automatically. It does this by commanding muscles around blood vessels to tighten or relax in order to raise or lower blood pressure. The nervous system can monitor blood pressure and continually adjusts the commands to keep blood pressure normal.
When a person has a spinal cord injury, the damage to the nerve pathways in the spinal cord can result in the loss of their ability to control the responses of the blood vessels. If the damage is at or above the middle of the back (the level called T6 for the sixth of the twelve thoracic vertebrae), the person may develop autonomic hyperreflexia. Damage to the spinal cord at lower levels will not cause this condition.
In autonomic hyperreflexia, the autonomic nervous system can still cause the blood pressure to rise. But it cannot easily cause it to come back down.
Autonomic hyperreflexia can cause the person's blood pressure to rise to a danger level. Symptoms may include: blurred visionexcessive sweatingpounding headacheredness of the facestuffy nose
The severity of the symptoms can depend on how high the blood pressure goes. The symptoms go away quickly once the blood pressure drops to healthy levels.
Below the level of damage in the spinal cord, the person usually is paralyzed and cannot feel normal sensations. Autonomic hyperreflexia occurs when an irritating stimulus occurs that the person cannot feel.
The most common cause is a very full bladder. The bladder sends signals through the nervous system to the brain. The signals cannot get through because of the spinal cord damage. The person cannot feel that the bladder is full and needs to be emptied. But the automatic part of the nervous system that controls the blood pressure is triggered nonetheless and causes the blood pressure to go up.
Other common causes are a full bowel, an infection, or a sore on the skin. Women with spinal cord injuries who have menstrual cramps may also have autonomic hyperreflexia. Sometimes the trigger is as simple as accidentally sitting on a hard object or having clothing bunched up.
A person with a spinal cord injury needs to learn the symptoms and causes of autonomic hyperreflexia. Keeping the bladder and bowel empty, taking good care of the skin, and avoiding infections are also key actions that can help. A person with spinal cord injury should be educated about this condition as part of his or her rehabilitation process.
Usually the person begins to feel the symptoms and quickly recognizes the autonomic hyperreflexia. Checking the blood pressure can confirm the hyperreflexia. It is important to begin right away to look for the cause and fix it.
Once the cause of the autonomic hyperreflexia is removed, the condition goes away quickly. There are no long-term effects if the hyperreflexia is treated promptly. If treatment is not quick enough or is inadequate, the person may have a stroke. The stroke may cause speech impairments, cognitive impairments, and mobility impairments.
There are no risks to others.
Autonomic hyperreflexia is a medical emergency. If the blood pressure stays high or continues to go up, a stroke can occur. Fortunately, the condition is easy to treat by removing whatever is causing the autonomic hyperreflexia. This means emptying the bladder or bowels and making sure the person is not sitting on bunched-up clothing or a hard object.
If the person is lying down, sitting up can help lower the blood pressure. Once the cause is removed, the symptoms improve quickly. If the cause cannot be found or the problem persists, the person or caregiver will need to contact emergency medical services right away. Medicines can be used to bring the blood pressure down to normal.
Side effects vary depending on the medicines used to lower the blood pressure but may include allergic reactions.
Autonomic hyperreflexia goes away quickly once the cause is removed. Because the problem can return, care must always be taken to prevent another episode.
Usually, the person will notice symptoms as they occur. Thus, he or she can make sure the problem is quickly taken care of. When an episode occurs unexpectedly, the person should notify the healthcare provider. Any new or worsening symptoms should be reported as well.
Acute management of autonomic dysreflexia: adults with spinal cord injury presenting to health-care facilities, Paralyzed Veterans of America, Consortium for Spinal Cord Injury, 1997
Rehabilitation/restorative care in the community, Hoeman, 1990