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Storming After Brain Injury: Understanding Paroxysmal Sympathetic Hyperactivity

doctors rushing to help patient who is storming after brain injury

Storming after brain injury is one of the ways a patient’s body responds to the stress of a severe TBI. It causes distressing symptoms such as elevated heart rates, high temperatures, and rigid body postures.

Although storming can be frightening to witness, family members should understand that it is a normal TBI side effect and may even indicate increased brain activity.

This article will discuss the causes behind storming after brain injury, as well as symptoms and treatment.

What is Storming after Brain Injury? 

Storming after brain injury refers to an excessive response of the sympathetic nervous system (SNS). The SNS controls your body’s “fight or flight” response, which occurs when your brain detects imminent danger.

When the sympathetic nervous system activates, your body releases adrenaline, which triggers a cascade of responses such as increased heart rate and rapid breathing.

In a healthy person, the sympathetic response helps them handle whatever danger is present. Once the threat passes the parasympathetic response kicks in. This response relaxes the body by lowering blood pressure and bringing heart rate and breathing back to normal.

After a severe brain injury, however, this process no longer functions properly. Because of the damage the brain sustained, it cannot tell whether the body is still in danger or not. It therefore releases a continuous flood of adrenaline and other hormones into the bloodstream.

But because the brain is damaged, the parasympathetic cannot respond to calm the body down. As a result, the body enters a state called paroxysmal sympathetic hyperactivity, also known as storming.

Symptoms of Paroxysmal Sympathetic Hyperactivity

young woman in hospital bed, unconscious and receiving oxygen because she is storming after brain injury

Storming is a sudden physiological response with specific, identifiable signs. The most common symptoms of paroxysmal sympathetic hyperactivity include: 

  • Fever over 101 degrees Fahrenheit (38.5 degrees Celsius)
  • Hypertension
  • Heart rate over 130 bpm
  • Respiratory rate over 40 breaths per minute
  • Profuse sweating (diaphoresis)
  • Rigid arm and leg muscles
  • Downward pointed toes and backward arched spine and neck (decerebrate posturing)

Most patients who experience storming after brain injury are in a coma or similar state of consciousness, which means they are not aware of what is happening. Storming typically appears within the first few hours or days after injury but can continue for several weeks or months after.

Causes and Prevalence of Storming after Brain Injury

Storming occurs in 15-33% of comatose traumatic brain injury patients.

Most storming episodes after brain injury are unprovoked. However, some frequent triggers include:

  • Changes in medication
  • Repositioning
  • Environmental stimulation (such as alarms)
  • Fever

Storming most frequently occurs after severe traumatic brain injuries and is commonly associated with hypoxic injuries, intracerebral hemorrhages, and hydrocephaly.

The exact cause of paroxysmal sympathetic hyperactivity is not clear. Researchers know that it is due to increased activity of the sympathetic nervous system, but why this only happens in some but not all patients remains a mystery.

Is Neurostorming a Sign of Recovery?

Neurostorming typically occurs as the person progresses through the stages of recovery. In particular, the increase in sympathetic activity may be a sign of increased brain activity.

However, while neurostorming may be an initial positive sign, the effects of storming after brain injury can be devastating if left untreated. 

For example, prolonged fever and hypertension can result in secondary brain injuries that will severely harm recovery. High blood pressure and fever can also lead to cardiac failure and kidney dysfunction, among other things.

In addition, decerebrate posturing can cause permanent muscular and skeletal damage if left too long. Therefore, it is crucial to treat storming after brain injury quickly and effectively.

Most treatments of sympathetic storming use medication to address the symptoms, such as lowering the person’s blood pressure and/or eliminating their fever. 

How Family Members Can Help Prevent Sympathetic Storming

Storming after brain injury is a serious condition. However, family members should not worry that their loved one’s condition is worsening if storming occurs. As frightening as storming looks, it is a normal effect of severe TBI.

Still, many people feel helpless when they witness a sympathetic storm. Fortunately, there are several ways you can help:

  • Educate yourself and others. Learn the various signs and symptoms of storming after brain injury (such as the ones listed above).
  • Alert nursing staff. Once you know what storming looks like, you can alert nursing staff before symptoms get too severe. Alarms only go off when symptoms are critical, but the actual storm starts well before that. If you see your loved one’s temperature or heart rate start climbing, call for a nurse.
  • Take preventative measures. Finally, you can take steps to prevent storming from occurring. For example, using a cool cloth to keep their temperature down, gently massaging their arms and legs, and speaking softly to them are all effective measures. Even though your loved one might be unconscious, their brain can still react to stress. So try to keep their room calm and relaxing.

These are just a few of the best ways you can help your loved one safely get through storming after brain injury.

Above all, it’s important to remember that storming typically only lasts a few weeks. If all goes well, once it passes, your loved one should begin to recover consciousness again. After that, they will need your help to make a good recovery from brain injury.

Featured Image: ©iStock/gorodenkoff

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