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Autonomic Dysfunction After Concussion: Symptoms, Diagnosis, and Recovery

Older woman feeling the effects of autonomic dysfunction after concussion

Autonomic dysfunction is one of the many possible side effects of a concussion. It’s also one of the most dangerous.

Unfortunately, most people with autonomic dysfunction do not recognize its symptoms, and therefore live with it for years without seeking treatment.

To help you better understand this problem, you’re about to learn the causes and symptoms of autonomic dysfunction after concussion.

What Is Autonomic Dysfunction?

Autonomic dysfunction (also called dysautonomia) refers to a dysfunction of the autonomic nervous system (ANS).

The autonomic nervous system is a network involving the amygdala, hypothalamus, and brain stem, among other areas. It controls all involuntary bodily functions, such as:

  • Blood vessel dilation or constriction
  • Heart rate
  • Blood pressure
  • Digestion
  • Adrenal gland function
  • Thermoregulation (regulating body temp)

The ANS has two distinct branches, called the sympathetic and parasympathetic nervous systems, each with its own purpose:

  • Sympathetic nervous system (SNS). This branch controls the body’s “fight or flight” response. When the sympathetic nervous system activates, your body releases adrenaline, which triggers a cascade of responses such as increased heart rate and rapid breathing.
  • Parasympathetic nervous system (PNS). This response counters the sympathetic response by dampening adrenaline and lowering heart rate and blood pressure.

If an injury damages the parts of the brain that control this process, the parasympathetic nervous system cannot respond. As a result, the SNS will continue to put the body into a state of distress.

If the brain injury was severe, the sympathetic response will be strong and will flood the body with adrenaline and other hormones. If this goes on too long, autonomic dysfunction or storming after brain injury will occur.

Symptoms of Autonomic Dysfunction After Concussion

Woman experiencing symptoms of autonomic dysfunction after concussion


In the past, autonomic dysfunction was believed to only occur after severe brain injuries. However, recent studies have shown that ANS problems are a common and “previously unrecognized cause of dizziness following concussions.”

While not as severe as storming, autonomic dysfunction after concussion can still cause serious side effects. Some of these include:

  • Decreased immune system
  • Dizziness and fainting upon standing up
  • High or low blood pressure
  • Light sensitivity
  • Hyperhidrosis (excessive sweating)
  • Digestive problems
  • Cold or heat sensitivity

Depending on how much of your ANS was damaged after your concussion, you can experience one or all of these symptoms, and their effects can range from mild to severe.

In addition, autonomic dysfunction, if left untreated for too long, can cause cardiac problems, including arrhythmias, arterial blockage, and heart failure.

That’s why it’s crucial to diagnose and treat autonomic dysfunction as soon as possible.   

Diagnosing Autonomic Dysfunction

man doing stress test to diagnose autonomic dysfunction after concussion


The best way to diagnose autonomic dysfunction is by measuring heart rate variability (HRV).

To do this, a doctor will give the patient a Holter monitor that records heart function for 24 hours. A Holter monitor is noninvasive and attached to your chest via electrodes, which allows you to continue with normal daily activities.

If you do not have autonomic dysfunction, there will be continuous variations in the heart rate, sometimes slightly elevated, sometimes low. This indicates that the ANS is functioning well and keeping the body regulated.

If autonomic dysfunction is present, however, the heart rate will not show as much variation. It will either be consistently high or low. That’s because there is no longer any back and forth between the sympathetic and parasympathetic responses.

Other methods for diagnosing autonomic dysfunction after concussion include a pupillary light reflex test, eyeball pressure test, and graded exercise testing.

Treating Autonomic Dysfunction After Brain Injury

In the vast majority of cases, autonomic dysfunction will resolve once the brain heals from its concussion.

If symptoms persist or are too severe, the best approach is to treat the symptoms. For example, beta-blockers will help manage irregular heartbeats, and blood pressure meds can keep your blood pressure from getting too high or low.

Some diet changes will also help regulate digestion if that is affecting you. In addition, some natural remedies for post-concussion syndrome might be able to reduce your symptoms.

However, since treatment can get complicated if you have multiple symptoms, it is recommended that you seek help from a neurologist or neuroendocrinologist before trying anything new.

Featured Image: ©iStock/PORNCHAI SODA

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