Dysautonomia

Dysautonomia (autonomic dysfunction) is a broad term that describes any disease or malfunction of the autonomic nervous system. This includes postural orthostatic tachycardia syndrome (POTS), inappropriate sinus tachycardia (IST), vasovagal syncope, mitral valve prolapse dysautonomia, pure autonomic failure, neurocardiogenic syncope (NCS), neurally mediated hypotension (NMH), autonomic instability and a number of lesser-known disorders such as cerebral salt-wasting syndrome. Dysautonomia is associated with Lyme disease, primary biliary cirrhosis, multiple system atrophy (Shy-Drager syndrome), Ehlers-Danlos syndrome (EDS), and Marfan syndrome for reasons that are not fully understood. In a study on orthostatic intolerance and EDS it is suggested the occurrence of these syndromes together can be attributed to the abnormal connective tissue in dependent blood vessels of those with EDS, which permits veins to distend excessively in response to ordinary hydrostatic pressures. This in turn leads to increased venous pooling and its hemodynamic and symptomatic consequences.

Presentation
Symptoms of dysautonomia are numerous and vary widely from person to person. Since dysautonomia is a full-body condition, a large number of symptoms may be present that can greatly alter a person's quality of life. Each patient with dysautonomia is different&mdash;some are affected only mildly while others are left completely bedridden and disabled.

The primary symptoms that present in patients with dysautonomia are:


 * Excessive fatigue
 * Excessive thirst (polydipsia)
 * Lightheadedness, dizziness or vertigo
 * Feelings of anxiety or panic (not mentally induced )
 * Rapid heart rate or slow heart rate
 * Orthostatic hypotension, sometimes resulting in syncope (fainting)

Other symptoms frequently associated with dysautonomia include: headaches, pallor, malaise, facial flushing, salt cravings, mydriasis, constipation, diarrhea, nausea, acid reflux, visual disturbances, orthostatic hypotension, numbness, nerve pain, trouble breathing, chest pains, in some cases loss of consciousness and seizures. A full list of symptoms may be found at the Dysautonomia Information Network.

Causes
Causes of dysautonomias are not fully understood, but they are thought to include:


 * Autoimmune disorders, especially Lyme disease and Type I diabetes
 * Bad body posture (causes compression of important arteries and/or nerves)
 * Brain injury
 * Degenerative neurological diseases such as Parkinson's disease
 * Exposure to chemicals (e.g., most commonly, pyridoxine)
 * Genetic factors
 * Hereditary connective tissue diseases, especially Ehlers-Danlos Syndrome
 * Pregnancy
 * Physical trauma or injury which damages the autonomic nervous system, as with Cerebral salt-wasting syndrome.
 * Viral illness
 * Mitochondrial Diseases

Management
In some cases, a cardiac ablation procedure can be performed to stop the heart symptoms completely. It is not recommended in POTS patients, and can in fact worsen tachycardia. Medications are also used to stabilize the condition on a long-term basis. Benzodiazepines can be used for some of the physical problems such as anxiety. In many cases treatment of primary dysautonomia is symptomatic and supportive. Measures to combat orthostatic intolerance include elevation of the head of the bed, frequent small meals, a high-salt diet, fluid intake, and compression stockings. Drugs such as fludrocortisone, midodrine, ephedrine and SSRIs can also be used to treat symptoms. Treating dysautonomia can be difficult and usually requires a combination of drug therapies.

Prognosis
The outlook for patients with dysautonomia depends on the particular diagnostic category. There is no way of predicting whether symptoms of dysautonomia will resolve over time, or continue over the entire course of one's lifespan. Some forms of dysautonomia are not life threatening, even if life changing in the form of minor to major limitations in activities of daily living. However patients with Ehlers-Danlos Syndrome, Marfan Syndrome or Parkinson's disease have a chronic, progressive, generalized form of dysautonomia in the setting of central nervous system degeneration, leading to a generally poor long-term prognosis. Patients can die from pneumonia, acute respiratory failure, or sudden cardiopulmonary arrest.

There is some evidence that dysautonomia may be a factor in SIDS (sudden infant death syndrome).

History
In the nineteenth and earlier twentieth centuries, a diagnosis that was almost solely given to women was called "neurasthenia," or a "weak nervous system." (During World War One, doctors began to apply it to men exhibiting symptoms of what is now called post-traumatic stress disorder.) These women would present symptoms of fatigue, weakness, dizziness and fainting, and the doctor's orders would simply be bed rest. Some of these women died, while many others recovered. No one understood where the problems came from. With the advances in modern medicine, diagnostic criteria and treatment for various forms of dysautonomia have sharpened. Doctors and researchers are including males in their subject population for this disorder.

The prototype of dysautonomia is the ancient scourge of beriberi, a nutritional deficiency disease due to excess of simple carbohydrate and concomitant vitamin B1 deficiency. In the early stages this results in loss of functional efficiency in the central control mechanisms of the autonomic nervous system. If the nutritional deficiency continues, there is gradual degeneration of the system. Other vitamin deficiencies have been implicated in causing dysautonomia and unlike the genetically determined forms of the disease, are treatable.