Dysautonomia
Classification and external resources
ICD-10	G90.
ICD-9	337.9
MeSH	D001342

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),^[1] Ehlers-Danlos syndrome, 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.^[2]

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—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^[3] (fainting)

Other symptoms frequently associated with dysautonomia include: headaches, pallor, malaise, facial flushing, salt cravings, constipation, diarrhea, nausea, acid reflux, visual disturbances, orthostatic hypotension, numbness, nerve pain, trouble breathing, chest pains, in some cases loss of consciousness and seizures. ^[3] A full list of symptoms may be found at the Dysautonomia Information Network.^[4]