Autonomic dysreflexia (AD) is a potentially life threatening condition common in people who have experienced spinal cord injury in the upper back. AD occurs when an injury disrupts the nervous system’s typical functioning.

During an AD episode, pain or discomfort may occur below the site of the injury. Alternatively, a person may not feel any pain.

AD occurs as a result of a disruption to the autonomic nervous system. This part of the nervous system maintains the body’s automatic functions, such as breathing, digestion, and blood pressure regulation.

The disruption can cause potentially life threatening complications such as stroke.

This article reviews what AD is, as well as its potential symptoms, causes, diagnosis, and more.

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To understand AD, a person needs to first understand the autonomic nervous system.

This part of the nervous system regulates every body function that a person does not need to consciously control. This includes hundreds of tasks, such as:

  • sexual arousal
  • heartbeat
  • blood pressure regulation
  • itching
  • sweating
  • breathing
  • digestion
  • body temperature regulation

The autonomic nervous system consists of two parts that work together:

  • Sympathetic nervous system: responsible for speeding up the body’s reactions
  • Parasympathetic nervous system: responsible for slowing down the body’s reactions

When the body is threatened, the sympathetic nervous system takes over, readying the body’s fight or flight response. Otherwise, the two halves of the system work together to keep the body in balance.

AD is a disruption to the functioning of this system. It typically occurs when injury to the spinal cord is at or above the T6 level, which is around the middle of the back. The higher the injury, the higher the risk of AD.

When the injury occurs at or above the T6 level, the autonomic nervous system still works, but the brain may misinterpret its messages.

As a result of the disruption, even minor events can trigger a person’s fight or flight response, because the brain cannot signal the sympathetic nervous system to stop the reaction.

This unregulated reaction can lead to potentially life threatening complications.

Symptoms can range from mild to severe. People may experience one, several, or all of the potential symptoms of AD.

The most common symptom is a severe headache. However, other symptoms can occur with or without a headache.

A person at risk of AD should not ignore even mild symptoms since this condition can lead to potentially life threatening complications.

Potential symptoms include:

Most people who develop AD (48–70%) have an injury to their spinal cord at or above the T6 level. AD is least likely to occur in people with an injury below T10.

Less commonly, nontraumatic disruption of the spinal cord and upper central nervous system structures can cause AD. For example, an individual with advanced cancer may develop AD if metastatic tumors affecting the spinal cord or brain appear above T6.

Certain stimuli can trigger AD by causing a nervous system response. This happens when the stimulus is below the level of the spinal injury. The most common AD trigger is bladder distension, typically resulting from a full bladder.

Other common triggers for AD include:

Doctors can often diagnose AD with a combination of blood pressure increases, knowledge of a spinal cord injury, and any presenting symptoms.

In some cases, a person may start to recognize symptoms and seek help figuring out the cause of AD.

A doctor can use blood pressure readings to help diagnose AD. To do this, they need to establish a baseline after the initial injury. They can then check for elevated blood pressure to diagnose a potential case of AD.

Blood tests and other diagnostic tests cannot check for AD.

AD can lead to potentially serious and even life threatening complications. One of the most serious complications is stroke.

High blood pressure associated with AD can lead to several complications, including:

Treatment for AD involves finding the source of the symptoms. A person experiencing symptoms should alert any caregiver as soon as possible and start figuring out what might be causing AD.

Though the steps can vary, a person should:

  • Monitor blood pressure: A person or their caregiver should run a blood pressure check every 5 minutes and administer medication if needed.
  • Find the trigger: This may include assessing the fullness of the bladder and bowels, checking the skin for sores, and checking for broken bones or other potential causes.
  • Seek immediate medical attention: A person should call 911 or seek emergency medical services if they cannot identify a trigger or if high blood pressure does not reduce.

The best prevention for AD in someone with a spinal injury is ongoing personal care.

A person can take steps such as:

  • maintaining a regular toilet schedule to prevent bladder and bowel distension
  • regularly checking for urinary tract infections
  • taking steps to avoid skin injuries such as sunburn and cuts
  • regularly checking their skin for potential issues, such as pressure sores or ulcers
  • using effective safety equipment to minimize the risk of falls
  • wearing loose-fitting clothing and avoiding tying shoes too tightly

There is no way to prevent a spinal cord injury. However, a person can take some steps to minimize their risk, including:

  • wearing a seat belt while riding in a vehicle
  • not driving while under the influence of alcohol or drugs
  • avoiding gun-related injuries by practicing proper firearm safety
  • wearing a helmet when engaging in any sport or activity that could result in head injury, such as biking, skiing, or football

The outlook for AD is generally good when a person or their caregiver recognizes the symptoms and takes immediate steps to address the condition.

However, if a person does not receive prompt and adequate treatment for AD, it can lead to serious complications such as stroke. AD complications can be life threatening.

A person with a spinal cord injury above T6 should learn the symptoms of AD. This will allow them to start monitoring their condition and quickly detect any possible symptoms.

A person or their caregiver should contact emergency services if they cannot find the source of the AD or if the person’s blood pressure remains elevated. In some cases, a person may need hospitalization until doctors can find a cause.

The following sections provide answers to frequently asked questions about AD.

What is the best position for a patient experiencing autonomic dysreflexia?

When a person suspects they are experiencing AD, they should sit upright.

This can help them find the potential problem and allow their legs to dangle.

A caregiver should help a person loosen any potentially restrictive clothing.

What is silent autonomic dysreflexia?

Silent AD occurs when a person does not experience any symptoms. AD can also be silent if a person does not report symptoms or if caregivers or medical professionals do not take the symptoms seriously.

A person should always report symptoms if they are at risk of developing AD, even if the symptoms are mild.

What can trigger autonomic dysreflexia?

Several stimuli can trigger AD. The most common triggers are issues with the bladder, such as UTIs or bladder distension.

Other potential triggers are cuts, bruises, bowel issues, tight clothing, and several other generally mild conditions that can cause the nervous system to activate.

AD occurs most often in people with spinal injuries at or above the T6 level.

It is the result of an automatic nervous system response due to disruptions between the brain and the part of the nervous system that would usually moderate the response.

AD has many potential triggers, but bladder issues are the most common. A person should figure out the cause of the AD and monitor their blood pressure to help prevent potentially life threatening complications.

If caregivers or medical professionals promptly address the triggers of the AD episode, a person has a generally good outlook.