Autonomic dysreflexia is a medical emergency that can develop within minutes in people with a spinal cord injury at or above the T6 level. The immediate steps are: sit the person upright if they are not already, loosen any tight clothing or constricting devices, check the bladder and bowel first for a trigger, and call 911 if blood pressure stays high or symptoms do not improve quickly. Do not wait to see if it resolves on its own.
What Is Autonomic Dysreflexia and Why Is It an Emergency?
Autonomic dysreflexia is a sudden, exaggerated response of the autonomic nervous system that happens after a spinal cord injury at or above the T6 level. A noxious stimulus below the level of injury — most often a full bladder — sends a signal up the spinal cord. Because the injury blocks the normal descending signals that would regulate blood pressure, the body responds with a massive surge in sympathetic nervous system activity.
Blood vessels below the injury narrow sharply. Blood pressure climbs fast. The heart rate may slow in response. This combination is what makes it dangerous.
Severe episodes can push systolic blood pressure above 200 mmHg. That level of pressure can cause a stroke, seizure, retinal hemorrhage, or death if it is not brought down. This is not a condition to monitor at home and hope for the best. It requires immediate action.
The key fact to understand is that autonomic dysreflexia is a blood pressure emergency, not a pain problem. The headache, sweating, and flushing are symptoms of the pressure spike. Treating the symptoms without finding and removing the trigger will not resolve the episode.
What Are the Warning Signs of Autonomic Dysreflexia?
The most common sign is a sudden, severe headache. It is often described as pounding or throbbing. It comes on fast, usually within a minute or two of the triggering stimulus.
Other signs include:
- Sweating above the level of injury, often on the face, neck, and shoulders
- Flushing or blotchy red skin above the injury level
- Goosebumps or piloerection above the injury level
- Nasal congestion
- Blurred vision or spots in front of the eyes
- A slow heart rate (bradycardia)
- Anxiety or a sense of impending doom
Below the level of injury, the skin may feel cool or pale because of vasoconstriction. Some people also notice increased spasticity or muscle spasms.
Blood pressure is the confirming sign. In someone with a T6 or higher injury, a systolic blood pressure that is 20 to 40 mmHg above their usual baseline is generally considered elevated enough to suspect autonomic dysreflexia. For many people with spinal cord injury, a systolic reading above 150 mmHg warrants immediate action. Some clinical guidance uses a threshold of 150 mmHg systolic as the trigger for treatment, though individual baselines vary.
Not everyone gets a headache. Some people have silent episodes, especially if they have reduced sensation. This is why anyone with a T6 or higher injury who suddenly feels unwell should have their blood pressure checked right away.
How To Treat Autonomic Dysreflexia: Immediate Steps
Act in this order. Do not skip steps because the person says they feel a little better.
Step 1: Sit the person upright.
If they are lying down, sit them up immediately. If they are already sitting, keep them upright. If they are in a wheelchair, make sure it is in the upright position. Gravity helps lower blood pressure by pooling blood in the legs and abdomen. This is the fastest non-drug intervention available.
If the person cannot sit up because of their injury level or other medical reasons, position them as upright as safely possible. Do not force a position that could cause harm.
Step 2: Loosen anything tight.
Remove or loosen tight clothing, belts, shoes, compression stockings, abdominal binders, and leg straps. Anything that puts pressure on the body can be a trigger or make the episode worse.
Step 3: Check the bladder first.
A full or blocked bladder is the most common trigger, accounting for a large share of episodes. If the person has an indwelling catheter, check that it is not kinked, clamped, or blocked. Look for sediment or a full drainage bag.
If the catheter is blocked, it needs to be irrigated or changed. This is a procedure that may need a clinician. If you are trained and equipped to do it, do it now. If not, call for help.
If the person uses intermittent catheterization and has not emptied their bladder recently, catheterize them now.
Step 4: Check the bowel.
If the bladder is not the trigger, check for a bowel problem. Fecal impaction or constipation is the second most common cause. If the person has a bowel program and has not had a bowel movement when expected, this may be the trigger. Digital stimulation or manual removal of stool may be needed. This is a procedure that should only be done by someone trained to do it.
Step 5: Look for other triggers.
If bladder and bowel are not the cause, check for:
- Skin problems: pressure sores, ingrown toenails, burns, or any skin irritation below the injury level
- Fractures or other injuries below the injury level that the person may not feel
- Tight clothing or devices, including leg bags or straps
- Urinary tract infection or bladder stones
- Constipation or hemorrhoids
- Sexual activity or menstrual cramps
- Labor and childbirth in pregnant women
Step 6: Call 911 if blood pressure stays high.
If systolic blood pressure remains above 150 mmHg after sitting upright and removing the trigger, call 911. If you have been prescribed a rapid-acting blood pressure medication for this purpose, give it as directed by your clinician. Do not give medication that was not prescribed for this situation.
If the person has severe headache, vision changes, chest pain, difficulty breathing, or loss of consciousness, call 911 immediately regardless of blood pressure readings.
Continue monitoring blood pressure every few minutes until help arrives or the episode resolves.
What Medications Are Used for Autonomic Dysreflexia?
Medication is used when sitting upright and removing the trigger does not bring blood pressure down fast enough, or when the trigger cannot be removed immediately.
The medications most commonly used in acute episodes are rapid-acting antihypertensives. Nifedipine and captopril are among those that have been studied for this purpose. Some clinicians use nitroglycerin paste or sublingual nitroglycerin. Others use hydralazine or prazosin.
There is no single standard medication protocol that applies to everyone. The choice depends on the person’s medical history, other medications, and the severity of the episode. This is a decision made by a clinician.
What matters for the person with spinal cord injury and their caregivers is this: if you have been given a medication specifically for autonomic dysreflexia, know where it is, know how to give it, and know when to use it. If you have not been given one, do not borrow or improvise. Call 911.
Prevention is also part of management. Some people with frequent episodes are prescribed daily medication to keep blood pressure stable. This is a decision made with a specialist who understands spinal cord injury.
What Should You Do After an Episode?
Once blood pressure returns to normal and symptoms resolve, the episode is over. But the cause may still be present.
If the trigger was a blocked catheter, it needs to be evaluated and possibly changed. If it was constipation, the bowel program may need adjustment. If it was a pressure sore, it needs wound care. If no trigger was found, the person needs a medical evaluation to look for hidden causes such as bladder stones, urinary tract infection, or fractures.
Document what happened. Note the time, the blood pressure readings, the symptoms, what you did, and what seemed to help. This information is valuable for the person’s care team.
Frequent episodes are a sign that something is not right. They should not be treated as normal. Recurrent autonomic dysreflexia can be a sign of an ongoing problem that needs medical attention.
Can Autonomic Dysreflexia Be Prevented?
Not all episodes can be prevented. But many can be reduced by managing the common triggers.
Regular bladder emptying, whether by catheter or intermittent catheterization, reduces the risk of bladder distension. A consistent bowel program reduces the risk of impaction. Daily skin checks help catch pressure sores early. Avoiding tight clothing and constricting devices helps. Treating urinary tract infections promptly helps.
For people with frequent episodes, a clinician may prescribe daily medication to stabilize blood pressure. This is not a cure, but it can reduce the frequency and severity of episodes.
Education matters. Anyone who cares for a person with a T6 or higher spinal cord injury should know the signs of autonomic dysreflexia and what to do. This includes family members, caregivers, and healthcare providers who may not specialize in spinal cord injury.
Frequently Asked Questions
What is the first thing you should do for autonomic dysreflexia?
Sit the person upright immediately and loosen any tight clothing or devices. Then check the bladder and bowel for a trigger.
When should you call 911 for autonomic dysreflexia?
Call 911 if systolic blood pressure stays above 150 mmHg after sitting upright and removing the trigger, or if there is severe headache, vision changes, chest pain, or loss of consciousness.
What blood pressure is considered an emergency in autonomic dysreflexia?
A systolic blood pressure above 150 mmHg is generally considered an emergency in someone with a T6 or higher spinal cord injury. Some clinical guidance uses a rise of 20 to 40 mmHg above the person’s baseline as a warning sign.
Can autonomic dysreflexia go away on its own?
It can resolve if the trigger is found and removed, such as unblocking a catheter or relieving constipation. If the trigger cannot be removed or blood pressure does not come down, it will not resolve on its own and requires emergency medical treatment.
