Dysautonomia

Disclaimer: This information sheet is for education purposes only. Please consult with your doctor or other health professional to make sure this information is right for your child.

What is it?

Our bodies have many `automatic' functions, which are controlled mainly by the brain. These include breathing, 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 eg sickness which can cause a high temperature. The blood pressure is also affected by the state of all the blood vessels - such as how relaxed or tight they are, how much blood is flowing through them, and by how well the kidneys are working. The amount of perspiration or sweating also changes depending on body temperature and how hard the muscles are working.

Sometimes, after a severe brain injury, the control by the brain of these automatic functions is disturbed. There can be under or over-activity. The brain can respond to a gentle stimulus, like being touched or hearing a noise, with an exaggerated reaction eg lots of body movement, high temperature (without any infection), high blood pressure or severe sweating etc. This may occur `out of the blue' without any obvious cause. This is called Dysautonomia, meaning disordered autonomic 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 very long periods, or other complications will also develop.

The over-activity often occurs in episodes or `bursts' and there may be an obvious trigger to start them, 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?

• Elevated temperature
• Profuse sweating
• Increase in heart rate
• Increase in respiratory rate and laboured breathing
• Agitation
• Increased muscle stiffness (spasticity)
• Large pupils

What is the treatment?

A variety of actions may be useful in treating dysautonomia.

• Provide a quiet, calm surrounding for the child, with soft lighting and little stimulation.
• Allow them plenty of rest and sleep.
• Restrict visitors - with few people allowed in the room at any one time (usually a maximum of 3-4 people).
• Placing the child in a comfortable position (often bent a little at the hips and knees).
• Give them plenty of fluids to prevent dehydration, and nutrition (this may need to be given either via a tube or through an intravenous drip).
• 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. Then with time, the body learns to control the automatic responses. Medicines usually have to be reduced slowly, once control seems reasonably good, as stopping too quickly may lead to a rebound.

During this time careful fluid and nutrition balance are very important.

• Valium (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 child's brain injury symptoms settle. This can take many weeks or a few days. The problem does not recur later in the child's life.

Rehabilitation Department The Children's Hospital at Westmead Cnr Hawkesbury Rd & Hainsworth St, Westmead Locked Bag 4001, Westmead, 2145 Tel: (02) 9845 2132 - Fax: (02) 9845 0685 http://www.chw.edu.au/rehabilitation/