Brain Damage and Autonomic Symptoms

The autonomic nervous system regulates many functions of the body that are not consciously controlled, such as blood pressure and heart rate. Blood vessels, stomach, intestines, liver, bladder, reproductive organs, lungs, pupils, heart, sweating, salivary and digestive glands are the main organs of the autonomic system. Therefore, the disorder in the autonomic system may give symptoms through these organs. The autonomic nervous system has two branches, the sympathetic and the parasympathetic. The sympathetic system is responsible for the “fight or flight” response from these arms, which have opposite effects. The parasympathetic system is more active in normal times when there is no stress or emergency. The autonomic system is controlled from the hypothalamus in the brain. Brain injuries can lead to disorders in the autonomic nervous system.

Paroxysmal sympathetic hyperactivity (PSH) is an autonomic nervous system related disorder that occurs in 15-33% of people with traumatic brain injury. The onset of complaints may be days or months after the brain injury. It causes symptoms such as accelerated breathing, sweating, agitation (anxious, distressed mood), abnormal posture. Therefore, it is a situation that causes concern for the relatives of the patient.

Over the years, this problem has been called medically in different ways. “Paroxysmal sympathetic storm”, “autonomic dysfunction syndrome”, “central origin fever”, “acute midbrain disorder” are some of them. In the light of current information, the most correct naming of the problem is accepted as paroxysmal sympathetic hyperactivity. The expression paroxysmal refers to the sudden worsening of the condition or its recurrent attacks. Sympathetic refers to the “fight or flight” part of the autonomic nervous system. Hyperactivity describes an increase in activity in the sympathetic system when the “storm” comes.


Symptoms such as increase in blood pressure, increase in heart rate, abnormal acceleration of breathing, increase in body temperature (high fever), abnormal stiffness and deterioration in body posture, excessive sweating are observed. Since these symptoms occur in other problems and diseases, it may not be easy to decide that a person has paroxysmal sympathetic hyperactivity. Other possible diagnoses should be excluded. Hormonal disorders, infections can also cause these symptoms. The characteristic of PSH is the simultaneous, sudden onset of autonomic symptoms and their periodic recurrence.

Who Happens?

PSH occurs mainly in people who have had a traumatic brain injury. While approximately 80% of the cases in the medical literature are of trauma origin, the rest are stroke, anoxic brain injury.are other diseases that can cause brain damage such as hydrocephalus and tumors. Diffuse axonal damage and brain stem damage were associated with PSH at a higher rate. PSH is more common in severe traumatic brain injuries (Glasgow coma score 3-8). These patients have very low neurological abilities and may be in a vegetative or minimally conscious state. Although there are data on who develops PSH, exactly why it occurs has not been clarified yet. It is thought that the imbalance between the sympathetic and parasympathetic systems leads to the result that the parasympathetic system cannot balance the sympathetic system on the tissues. In the first days after the brain trauma, it is not understood whether the patient has PSH or not, as various sedatives and tranquilizers are given to the patient.

PSH may be seen due to decreased control of the cerebral cortex over the brain stem. In addition, various sensory stimuli may cause exacerbations on a hypersympathetic basis. Mild irritating stimuli such as aspiration, positioning, loud noises can trigger this.

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High fever during PSH can increase brain damage. Increased muscle tone and abnormal posture can increase energy expenditure, leading to weight loss and weakening of heart and skeletal muscles. High blood pressure and heart rhythm irregularities can also cause secondary brain damage.


Drugs that suppress the central nervous system and thus the sympathetic system can be used. Active substances such as morphine, fentanyl, and midazolam were used for this purpose. Specific drug treatments to control symptoms may also be given. Beta-blockers, dopamine agonists, muscle relaxants, anti-epileptic drugs can be preferred. Intrathecal baclofen can reduce muscle tone without sedative effects.

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