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|Classification and external resources|
|Classification and external resources|
Dysautonomia (or autonomic dysfunction, autonomic neuropathy) is a condition in which the autonomic nervous system (ANS) malfunctions. It is an umbrella term for various forms of ANS malfunction. Dysautonomia is a type of neuropathy affecting the nerves that carry information from the brain and spinal cord to the heart, bladder, intestines, sweat glands, pupils, and blood vessels. Dysautonomia may be experienced in a number of ways, such as difficulty adapting to changes in posture, as well as digestive symptoms.
The diagnosis is achieved through functional testing of the autonomic nervous system, focusing on the organ system affected. Investigations may be performed to identify underlying disease processes that may have led to the autonomic neuropathy that is causing the dysautonomia. Symptomatic treatment is available for many symptoms associated with autonomic neuropathy, and some disease processes can be treated directly.
The symptoms of dysautonomia are numerous and vary widely from person to person depending on the nerves affected and underlying cause. Symptoms often develop gradually over years. Each patient with dysautonomia is different—some are affected only mildly, while others are often left disabled.
The primary symptoms present in patients with dysautonomia include:
Dysautonomia may be due to inherited or degenerative neurologic diseases (primary dysautonomia) or it may occur due to injury of the autonomic nervous system from an acquired disorder (secondary dysautonomia). Side effects of drugs can cause abnormalities in the function of the autonomic nervous system, producing an iatrogenic form of dysautonomia.
The most common causes of dysautonomia include:
Sympathetic nervous system-predominant dysautonomia is common in fibromyalgia, chronic fatigue syndrome, irritable bowel syndrome, and interstitial cystitis, raising the possibility that such dysautonomia could be their common clustering underlying pathogenesis.
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The ANS is a component of the peripheral nervous system and is made up of two branches: the sympathetic Nervous System (SNS) and the parasympathetic nervous system (PNS). The SNS controls the more active "fight or flight" responses such as increasing heart rate and blood pressure. The PNS can be thought of as the "rest and digest" part of the autonomic nervous system, as it slows down the heart rate and aides in digestion. Symptoms typically arise from abnormal responses of either the sympathetic or parasympathetic systems based on situation or environment.
Dysautonomia does not produce unique symptoms. It is the set of symptoms, taken together, that suggests that a dysautonomic state is present. The patient's individual complaints can each be part of another disease process which often leads to misdiagnosis. Collaboration between many specialists is often necessary. Care is primarily directed by a neurologist.
Indications for laboratory evaluation include:
Routine autonomic nervous system dysfunction tests include:
Other tests may be done to check for disorders that can cause the autonomic disorder include:
Treating dysautonomia can be difficult. There is no one scientifically proven treatment for dysautonomia. Since dysautonomia is made up of many different symptoms a combination of drug therapies is often required to manage individual symptomatic complaints.
Drugs such as fludrocortisone, midodrine, ephedrine and SSRIs and anticonvulsants can also be used to treat an assortment of symptoms with varying degrees of success. 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. Proton pump inhibitors and H2 receptor antagonists are used for digestive symptoms such as acid reflux.
Dysautonomia secondary to autoimmune diseases or multiple sclerosis (MS) can often improve if the underlying disorder is diagnosed and therapy targeted for the underlying disorder is successful. Immunosuppressive treatment regimens have varying success in alleviating autonomic symptoms.
The outlook for patients with dysautonomia depends on the particular diagnostic category. Some autonomic nervous system disorders get better when an underlying disease is treated or offending agent is removed.
Patients with chronic, progressive, generalized dysautonomia in the setting of central nervous system degeneration such as Parkinson's disease or multiple system atrophy have a generally poorer long-term prognosis. Death can occur from pneumonia, acute respiratory failure, or sudden cardiopulmonary arrest in such patients.