What are "Sympathetic Storms"?

I was trying to find information on these storms Aidan is having and found this Fact Sheet from the Brain Injury Association of Queensland (Australia). I think it does a good job of explaining things in medical terms, while at the same time taking the time to explain what many of the medical terms mean.

Sympathetic Storms are a common but only recently understood possible complication following a traumatic head injury. For the hospital staff they represent both a challenge and a key risk factor for the patient. For family and friends, they can be as frightening as they are confusing. Although “storming” or similar symptoms have been described for the greater part of the twentieth century, it is only in recent years that concensus has arisen over the cause, description and management of storms.

ALTERNATIVE TERMS
The first and biggest problem is nomenclature: There is not yet any one single agreed-upon term for for the same set of symptoms, and medical history is littered with alternatives. A letter to the editor of the Mayo Clinic Proceedings, titled Nomenclature of Paroxysmal Sympathetic Storms1 lists six alternative terms, collated from a review of the literature dating back to 1956. The most comprehensive description I have seen, Post Head Injury Autonomic Complications2, lists four extra terms. Riding Out The storm: Sympathetic Storming after Traumatic Brain Injury3 lists an additional seven. These seventeen additional terms are listed in the box to the right.

With delicious understatement, the writer of Nomenclature of Paroxysmal Sympathetic Storms, Ian Baguley from Westmead Hospital, Sydney, states “Obviously, the lack of standardised nomenclature is a major problem with research into this condition.”
However, although there are good reasons for medical practitioners to use terms such as PAID, “sympathetic storms” appears to be the most common name and the most descriptive to non-specialists, and is the one we will use here.

ALTERNATIVE NAMES

• Acute midbrain syndrome
  
• Autonomic Dysfunction Syndrome (ADS)
  
• Autonomic storming
  
• Brain-stem attacks
  
• Central dysregulation
  
• Diencephalic autonomic Epilepsy
  
• Diencephalic Seizure
  
• Dysautonomia
  
• Hyperpyrexia associated with muscle contraction
  
• Hypothalamic-midbrain dysregulation syndrome
  
• Neurostorming
  
• Paroxysmal autonomic instability with dystonia (PAID)
  
• Sympathoadrenal response
  
• Tonic cerebellar fits
  
• Tonic decerebrate spasms
  
• Tonic fit
  
• Traumatic apallic syndrome

DESCRIPTION
The clinical description of sympathetic storming includes a temperature of 38.5C, Hypertension, a pulse of at least 130 beats per minute, a respiratory rate of at least 40 breaths per minute, intermittent agitation, diaphoresis (profuse sweating) and dystonia (rigidity or decerebrate posturing for at least 3 days with at least 1 cycle per day). Decerebrate posturing is “an abnormal body posture indicated by rigid extension of the arms and legs, downward pointing of the toes, and backward arching of the head.”4 These symptoms may not all occur.

Cause
The cause of these storms has only recently been understood. Due to the symptoms, the first theories were that the storm is caused by an epilepsy-type electrical discharge within the brain. However, current understanding is that it is due to “dysregulation of the autonomic nervous system due to injury of one or more parts of the brain that contribute thereunto.”

Sympathetic v. Parasympathetic
Briefly, sympathetic storming is excessive, uncontrolled activation (“storming”) of the Sympathetic Nervous System (SNS). The SNS is responsible for control of arousal: increasing heart-rate, respiration, perspiration, release of adrenaline and other activating hormones, sexual arousal, the “fight or flight response” etc. The Parasympathetic Nervous System (PNS) is responsible for de-arousal: lowering heart-rate, ceasing production of adrenaline, etc. A sympathetic surge following trauma, the “stress response”, is itself natural and helps the body compensate for the immediate effects of the injury. Sympathetic storming occurs when the SNS produces this stress response repeatedly and without further external stimuli - a storm of chemicals and physiological reactions.

The SNS is regulated by the brain
More specifically, the Hypothalamus, a small area of the brain at the top of the Brain Stem that regulates body temperature, appetite and the release of many hormones, over-stimulates the sympathetic nervous system by flooding the bloodstream with chemicals normally associated with stress. During this storm, the parasympathetic nervous system cannot cope and fails to control the arousal. The hypothalamus itself may be damaged, or it may be responding to damage in other areas of the brain.

Incidence
Traumatic brain injury is not the only possible cause of sympathetic storming, but is the most common: Hydrocephalus, brain tumours, subarachnoid haemorrhaging and intracerebral haemorrhaging may also result in sympathetic storming. 15-33% of patients with a brain injury develop sympathetic storming. Age, sex, mode of injury or severity of Coma do not appear to make a difference. It does appear to be more common following diffuse axonal injury (injury to neurons throughout the brain) and injury to the brainstem, which is responsible for controlling fundamental life processes such as breathing, heartbeat and the sleep-wake cycle.

Diagnosis
Although sympathetic storming is rare without an identified cause, there is no simple process of diagnosis and it is a diagnosis of exclusion: Other, testable, causes need to be considered and eliminated before a diagnosis of sympathetic storming can be made. The practical significance of this is that treatment may differ between sympathetic storming and other, similar-looking conditions. In particular, infections (particularly if they result in meningitis), serotonin syndrome due to inappropriate medication or thyroid storming from an injured thyroid gland (a particular problem with a traumatic injury that may have also caused traumatic twisting or wrenching of the neck) may all cause the same symptoms and yet have radically different treatments.

TREATMENT
Treatment for sympathetic storming is symptomatic. As with many other ABI-related conditions, the symptoms are treated independently and there is no specific treatment for the underlying cause (neural damage). Due to the wide array of neurotransmitters that are involved in the management of the SNS, a wide array of medications that impact upon those neurotransmitters may be useful. Temperature can be addressed using a range of medications that directly influence body temperature or that influence underlying causes, such as inflammation or decreased Cerebral blood flow. Beta-blockers or other heart medications may be used to treat arrhythmia or Tachycardia.

RISKS AND OUTCOMES
Sympathetic storming is associated with increased risks of death, cardiac arrest, cerebral haemorrhage or elevated cerebral temperature, which can itself lead to secondary injury. Severe muscle rigidity can result in muscle rupture or the breakdown of muscle fibres, a process called rhabdomyolysis. Sympathetic storming is also associated with an increased length of stay in rehabilitation services and less favourable rehabilitation outcomes.

The symptoms of sympathetic storming can interfere with physical, occupational or speech therapy due to their unpredictabilit and physical nature, and this delay in rehabilitation can adversely affect progress.

References and More information:
http://www.mayoclinicproceedings.com/inside.asp?AID=2496&UID=
http://www.emedicine.com/pmr/topic108.htm
http://www.medscape.com/viewarticle/469858_print (requires free registration)
http://www.nlm.nih.gov/medlineplus/ency/article/003299.htm

Copyright Brain Injury Association of Queensland, Inc, Australia, 2007. This is one of a range of fact sheets made available by the Brain Injury Association of Queensland. While all care has been taken to ensure information is accurate, these fact sheets are only intended as a guide and proper medical or professional advice and information should be sought. The Association will not be held responsible for any injuries or damages that arise from following the information provided in these fact sheets. You can visit the Association’s website at www.braininjury.org.au or send emails to biaq@braininjury.org.au.