Our bodies have many automatic functions that are controlled by the brain. After a severe brain injury, our ability to control these automatic functions can be reduced.

What is dysautonomia?

Automatic functions include breathing, body-temperature control, heart rate and blood pressure. There is a delicate balance between all of these functions, and they are usually adjusted automatically. We are only aware of it when something unusual happens (e.g. when we are sick we can get a high temperature).

Sometimes, after a severe brain injury, our ability to control these automatic functions is disturbed. There can be under- or overactivity. The brain can respond to a gentle stimulus, like being touched or hearing a noise, with an exaggerated reaction (e.g. lots of body movements, high temperature, high blood pressure or severe sweating). This may occur unexpectedly and without any obvious cause. This is called dysautonomia, meaning disordered automatic function.

Quite often the signs of dysautonomia may not show until after ventilation in intensive care has been ceased and sedation such as morphine has been stopped. Sedatives can help treat the syndrome, but often other treatment is needed. Children cannot stay heavily sedated for long periods or other complications will also develop.

The overactivity often occurs in episodes or 'bursts'. There may be an obvious trigger to start the episode, such as a painful stimulus like taking blood tests, or there may be no trigger at all that we can identify. These episodes usually start suddenly and stop suddenly, like turning a tap on and off. Several or many episodes may occur in one day (this is sometimes called 'storming'). The bedside charts and parents' observations may help to work out some triggers.

What are the features?

• higher temperature
• a lot of sweating
• an increase in heart rate
• an increase in breathing rate and laboured breathing
• agitation
• increased muscle stiffness (spasticity)
• large (dilated) pupils

What is the treatment?

A variety of actions may be useful in treating children with dysautonomia. You can:

• provide a quiet and calm environment for the child, with soft lighting and little stimulation
• allow them plenty of rest and sleep
• restrict visitors to allow only a few people in the room at any one time (usually a maximum of three to four people)
• place the child in a comfortable position (often bent a little at the hips and knees)
• give them plenty of fluids to prevent dehydration and provide nutrition (this may need to be given via a tube or through an intravenous drip)
• ensure appropriate treatment of pain, fractures, skin wounds, urine infections or constipation

Medications

One or more drugs are often needed. It takes quite a long time to achieve the right combination of drug treatments before the dysautonomia is controlled. With time, the body will again learn to control the automatic responses. Medicines usually have to be reduced slowly once control seems reasonably good, because stopping too quickly may lead to a relapse. During this time, careful fluid and nutrition balance are very important.

Medications that help include:

• diazepam to help with muscle stiffness and used as a mild sedative
• propranolol, clonidine or bromocriptine can help control pulse, sweating, blood pressure and high temperatures
• baclofen or dantrolene may be useful to treat the muscle stiffness (spasticity)

All drugs have some side effects and the effects of any drug combination must be carefully checked by looking at blood test results. Dysautonomia usually settles with time, as the symptoms of the child's brain injury settle. This can take a few days or many weeks. The problem does not recur later in the child's life.

Key points to remember

• Dysautonomia occurs when our ability to control automatic body functions is disturbed.
• Dysautonomia can occur after a brain injury.
• Medications and other treatments can be used to reduced dysautonomia.
• Dysautonomia usually settles with time.

For more information

• The Royal Children's Hospital
  Paediatric Rehabilitation Service
  T: (03) 9345 9300
  E: rehab.service@rch.org.au
• The Children's Hospital at Westmead Brain injury Service
• Kids Health Info series of fact sheets listed under 'Brain injury'

Developed by The Royal Children's Hospital Paediatric Rehabilitation Service based on information from the Brain Injury Service at Westmead Children’s Hospital. We acknowledge the input of RCH consumers and carers.

Reviewed September 2020.

Kids Health Info is supported by The Royal Children’s Hospital Foundation. To donate, visit www.rchfoundation.org.au.