Autonomic Dysreflexia

What is autonomic dysreflexia?

Autonomic dysreflexia (AD) is a disease of the nervous system characterized by excessive involuntary reactions to external stimuli. It’s also referred to as autonomic hyperreflexia.

The involuntary reactions of the nervous system can cause:

  • the blood pressure to peak
  • rapid heartbeat
  • constriction of peripheral blood vessels
  • other changes in the autonomic functions of the body

Autonomic dysreflexia is common amongst people whose seventh to twelfth thoracic vertebra have been damaged due to injuries. People with multiple sclerosis, Guillain-Barre syndrome, or certain brain injuries can also suffer from autonomic dysreflexia. Certain medications can also give off autonomic dysreflexia as a side effect.

AD can be a threat to life and hence should be treated as an emergency.

It can cause:

How autonomic dysreflexia happens in the body

For you to have a grasp of AD, you must first understand the autonomic nervous system (ANS). The ANS is in charge of controlling involuntary functions of the body such as:

  • water and electrolytes regulation
  • sexual response
  • blood pressure
  • metabolism
  • body temperature
  • digestion
  • urination
  • heart rates
  • breathing rates
  • production of body fluids
  • defecation

The ANS has two subtypes:

  • parasympathetic autonomic nervous system (PANS)
  • sympathetic autonomic nervous system (SANS)

How they work

The actions of SANS and PANS are opposing to each other. By acting in opposite ways, the involuntary functions of the body are being able to be put under control. That is to say, any overreaction in PANS will cause SANS to be activated.

Here’s a typical example. Your body will activate a flight-or-fight reaction courtesy of the sympathetic nervous system when you see a bear. When the flight-or fight reaction is activated, your heart and blood vessels will do more work by increasing both heart rate and blood pressure.

What if later get to find out it wasn’t a bear in the first place? When the body realizes this, the PANS will be activated to ‘calm’ the activities of the heart and blood vessels.

Autonomic dysreflexia
Photo Credit: ResearchGate

What happens in autonomic dysreflexia?

In AD, the sympathetic nervous system responds to stimuli in ways out of the normal. And when the SANS does this, the PANS finds it difficult to go into action to ‘calm’ the SANS down.

After having a spinal injury, your lower body can still produce reasonable numbers of nerve signals. These spinal signals relate information about the state of digestion in your stomach to the brain. It also sends signals about the state of the bowel and bladder per time.

However, the signals still reach aspects of the sympathetic and parasympathetic autonomic nervous systems that function below the part of the spinal cord where the injury is.

The brain is connected directly to the spinal cord. The injury in the spinal cord will, therefore, hinder the brain from receiving signals from the lower part of the spinal cord that has no injuries. What this also means is that even when the PANS and SANS send signals, the brain will not be able to respond to them because it doesn’t get to reach the brain. The consequence of this is disunity between the actions of the SANS and PANS.

Symptoms of autonomic dysreflexia

The symptoms of AD may include:

  • skin flushing
  • dilated pupils
  • irregular heartbeat
  • anxiety
  • a pounding headache
  • profuse sweating on the forehead
  • lightheadedness
  • high blood pressure
  • dizziness
  • nasal congestion
  • confusion

Triggers of autonomic dysreflexia

Triggers of AD include anything that sends signals to both SANS and PANS.

They include:

  • a distended bladder
  • a blocked catheter
  • urinary retention
  • a urinary tract infection
  • bladder stones
  • constipation
  • a bowel impaction
  • hemorrhoids
  • skin irritations
  • pressure sores
  • tight clothing

How autonomic dysreflexia is diagnosed

AD requires that a medical doctor treats it without hesitation.

The treatment will be from the perspective of which symptoms are apparent. The pulse and blood pressure rate will also be considered in the treatment.

After the symptoms have been attended to by the doctor, further tests and examinations can then be carried out to diagnose what the problem actually is. The outcome of the test and examinations will help the doctor to know what to do next with you.

Treatment of autonomic dysreflexia

AD’s treatment usually has two objectives – to get rid of the stimuli triggering the overreactions and two, to lower your blood pressure. Emergency measures involve:

  • maintaining a sitting position so that blood can flow to the feet
  • removing any tight clothing that are on you
  • checking for any catheter that has been blocked
  • using a catheter to drain a distended bladder
  • removing any object that is in contact with your skin
  • stopping drafts of air from blowing on you
  • getting rid of any fecal impaction
  • bringing your blood pressure back to normal through the use of medications i.e. vasodilators

Prevention of autonomic dysreflexia

AD’s prevention and long-term treatment involve identifying and addressing the trigger.

The following can be adopted for AD’s long term treatment:

  • medication changes
  • dietary changes that can improve elimination
  • enhancing the management of urinary catheters
  • medications for managing high blood pressure
  • medications or a pacemaker to control your heart rate
  • self-management

What is the long-term outlook?

The outlook for autonomic dysreflexia will be uncertain if the trigger is not known or is known but difficult to control. But an AD with a well-managed trigger offers a good outlook.

Autonomic dysreflexia can be episodic. If it occurs repeatedly, the blood pressure will be affected and this can ultimately result in a cardiac arrest or stroke.

You should work closely with your doctor so you can take precautionary measures to avoid its likely triggers.

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