Dysautonomia is a broad term that describes any disease or malfunction of the autonomic nervous system
Autonomic nervous system
The autonomic nervous system is the part of the peripheral nervous system that acts as a control system functioning largely below the level of consciousness, and controls visceral functions. The ANS affects heart rate, digestion, respiration rate, salivation, perspiration, diameter of the pupils,...

. This includes postural orthostatic tachycardia syndrome
Postural orthostatic tachycardia syndrome
Postural orthostatic tachycardia syndrome is a condition of dysautonomia, more specifically orthostatic intolerance, in which a change from the supine position to an upright position causes an abnormally large increase in heart rate, called tachycardia...

 (POTS), inappropriate sinus tachycardia
Inappropriate sinus tachycardia
Inappropriate Sinus Tachycardia is a rare type of cardiac arrhythmia, within the category of supraventricular tachycardia , although doctors believe it stems from dysautonomia, a disturbance and/or failure of the autonomic nervous system....

 (IST), vasovagal syncope
Vasovagal syncope
A vasovagal episode or vasovagal response or vasovagal attack is a malaise mediated by the vagus nerve. When it leads to syncope or "fainting", it is called a vasovagal syncope, which is the most common type of fainting.There are a number of different syncope syndromes which all fall under the...

, mitral valve prolapse dysautonomia, pure autonomic failure
Pure autonomic failure
Pure autonomic failure, also known as Bradbury-Eggleston syndrome or idiopathic orthostatic hypotension, is a form of dysautonomia that first occurs in middle age or later in life; men are affected more often than women...

, neurocardiogenic syncope (NCS), neurally mediated hypotension (NMH), autonomic instability and a number of lesser-known disorders such as cerebral salt-wasting syndrome
Cerebral salt-wasting syndrome
Cerebral salt-wasting syndrome is a rare endocrine condition featuring hyponatremia and dehydration in response to trauma/injury or the presence of tumors in or surrounding the brain...

. Dysautonomia is associated with Lyme disease
Lyme disease
Lyme disease, or Lyme borreliosis, is an emerging infectious disease caused by at least three species of bacteria belonging to the genus Borrelia. Borrelia burgdorferi sensu stricto is the main cause of Lyme disease in the United States, whereas Borrelia afzelii and Borrelia garinii cause most...

, primary biliary cirrhosis, multiple system atrophy
Multiple system atrophy
Multiple system atrophy is a degenerative neurological disorder. MSA is associated with the degeneration of nerve cells in specific areas of the brain. This cell degeneration causes problems with movement, balance and other autonomic functions of the body such as bladder control or blood pressure...

 (Shy-Drager syndrome), Ehlers-Danlos syndrome
Ehlers-Danlos syndrome
Ehlers–Danlos syndrome is a group of inherited connective tissue disorders, caused by a defect in the synthesis of collagen . The collagen in connective tissue helps tissues to resist deformation...

 (EDS), and Marfan syndrome
Marfan syndrome
Marfan syndrome is a genetic disorder of the connective tissue. People with Marfan's tend to be unusually tall, with long limbs and long, thin fingers....

 for reasons that are not fully understood.