Post Head Injury Autonomic Complications Clinical Presentation

Updated: Jul 05, 2023
  • Author: Stephen Kishner, MD, MHA; Chief Editor: Elizabeth A Moberg-Wolff, MD  more...
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ADS usually occurs in the setting of severe TBI associated with DAI. ADS must be distinguished from other syndromes presenting similarly; a diagnosis of ADS is one of exclusion, because there are no pathognomonic tests or findings.

The other syndromes to consider include neuroleptic malignant syndrome, serotonin syndrome, malignant hyperthermia, and thyroid storm. [3, 9]

The use of neuroleptics generally is contraindicated in patients with brain injuries, and so classic neuroleptic malignant syndrome is unlikely to be encountered in these patients. However, withdrawal of premorbidly used dopaminergic agents or the use of metoclopramide can precipitate neuroleptic malignant syndrome, so this condition must be considered.

The use of serotonergic agents is common in persons with brain injury; consideration of serotonin syndrome is therefore essential.

Malignant hyperthermia mainly occurs after surgery during which there was exposure to anesthetic agents, particularly succinylcholine. Malignant hyperthermia in the rehabilitation setting most often is seen in patients with spinal cord injury, because of their increased susceptibility.

Thyroid storm is a potential complication of trauma to the neck, if excess thyroid hormone is released from the injured thyroid gland.

An observational study by Hinson et al indicated that early fever following a TBI, particularly within the initial 24 hours, may predict the onset of ADS. [10]



Patients with ADS present with a combination of typical physical findings. The elevation of temperature may vary in severity from low-grade to high fever. Fever frequently and justifiably prompts a detailed search for infectious etiologies. The individual's temperature may vary from being elevated to being within the reference range, or it may stay elevated. One important aspect of elevated temperature in persons with TBI is that intracerebral temperature may significantly exceed measured body temperature due to impaired blood flow in the injured area. Thus, temperature control should be prompt and aggressive in individuals with TBI. Cephalosporins, ibuprofen, and H2 blockers help to reduce the fever and/or help to treat the cause of fever; therefore, they frequently are used in patients with TBI.

Findings of ADS, which may be prominent during the intensive care stages of the case, include the following:

  • Hypertension

  • Fever

  • Tachycardia

  • Tachypnea

  • Pupillary dilation

  • Extensor posturing

  • Diaphoresis

The combination of all findings does not always occur. Tachycardia, fever, and hypertension often are the main presenting signs.

Because the syndrome includes features in common with acute infection, ruling out infection is paramount.



The cause of ADS is dysregulation of the ANS due to injury to 1 or more parts of the brain that contribute to the ANS. (See Pathophysiology.)