What Is It, Causes, Signs, Symptoms, Diagnosis, and More
Editors:Alyssa Haag,Ian Mannarino, MD,Kelsey LaFayette, DNP, ARNP, FNP-C
Illustrator:Jessica Reynolds, MS
Copyeditor:Stacy M. Johnson, LMSW
What is dysautonomia?
Dysautonomia is the improper functioning of the autonomic nervous system (ANS), which controls involuntary bodily functions such as breathing, heart rate, blood pressure, digestion, body temperature, hormonal function, bladder function, and sexual function among others. Under typical conditions, the autonomic nervous system increases cardiovascular sympathetic outflow and decreases parasympathetic outflow when an individual rises from sitting to standing. The increase in sympathetic response results in peripheral vasoconstriction of blood vessels, increased cardiac rate, and increased contractile force of heart muscle, which allows for maintained perfusion to the brain and other vital organs. When dysautonomia occurs, the body’s reflexive increase in sympathetic response and decrease in parasympathetic response does not happen properly. While dysautonomia generally involves failure of the autonomic nervous system to react, excessive or overactive ANS actions can also occur.
Overall, dysautonomia is relatively common, affecting 70 million people worldwide. It can be congenital (i.e., inherited at birth) or sporadic (i.e., arises from a mutation during an individual's lifetime). Inherited dysautonomia is more common among the Ashkenazi Jewish population.
What causes dysautonomia?
Familial dysautonomia is caused by a specific genetic mutation in the gene inhibitor of kappa B kinase complex-associated protein (i.e., IKBKAP, also known as ELP10). It is typically inherited in an autosomal recessive pattern, meaning that two copies of the gene must be passed down for the offspring to inherit the disease. When inherited, dysautonomia is known as familial dysautonomia, hereditary sensory neuropathy type 3, hereditary sensory and autonomic neuropathy 3, or Riley Day syndrome.
Conversely, sporadic dysautonomia, which arises without an underlying cause, is also known as primary dysautonomia and results from a failure of the autonomic nervous system to communicate with the rest of the body. Primary dysautonomia can lead to other conditions such as neurocardiogenic syncope (i.e., vasovagal syncope), postural orthostatic tachycardia syndrome (POTS); multiple system atrophy; and pure autonomic failure. Neurocardiogenic syncope is the most common form of dysautonomia. It results in occasional or frequent fainting spells when the body overreacts to intense emotion or fears (e.g., the sight of blood), dehydration, or extreme pain. Heart rate and blood pressure drop suddenly, resulting in reduced blood flow to the brain, causing a brief loss of consciousness.
On the other hand, POTS leads to tachycardia upon standing, resulting in shortness of breath, chest pain, and fainting. POTS is typically caused by a reduction in intravascular volume, which contributes to decreased venous return to the heart, reflex tachycardia, and orthostatic intolerance. On the other hand, POTS leads to tachycardia upon standing, resulting in shortness of breath, chest pain, and fainting. Multiple system atrophy causes incontinence, decreased blood pressure, and erectile dysfunction.
The cause of multiple system atrophy is generally unknown; however, the condition has been associated with deterioration and atrophy of portions of the brain and a build-up of a protein called alpha-synuclein. The affected regions (e.g., cerebellum, basal ganglia, and brainstem) regulate internal body functions, digestion, and motor control. Symptoms include muscle stiffness, muscle weakness, blurred vision, and difficulty with bladder control.
Lastly, pure autonomic failure is a neurodegenerative disorder of the autonomic system that results in orthostatic hypotension. It is typically caused by an unusual accumulation of α-synuclein in autonomic nerves. Flare-up symptoms can be caused by various triggers such as heat, pain, stress, or overexertion.Dysautonomia can also arise as a consequence of another disease, at which point it is referred to as secondary dysautonomia. Secondary dysautonomia can be associated with medications (including first-generation or typical antipsychotics), trauma, or other conditions, including diabetes mellitus, amyloidosis, sarcoidosis, and certain autoimmune diseases (e.g., rheumatoid arthritis, systemic lupus erythematosus, and Sjogren syndrome). Recent volume loss from diarrhea or vomiting can also result in the symptoms of dysautonomia. Degenerative neurological diseases, such as Parkinson disease, present with motor abnormalities and varying degrees of autonomic failure. Neurological orthostatic hypotension is prevalent in 20 to 60 percent of those with Parkinson disease, and prevalence increases with age and disease duration. Additionally, dementia with Lewy bodies usually presents with cognitive impairment accompanied by parkinsonism features and autonomic dysfunction.
What are the signs and symptoms of dysautonomia?
The primary signs and symptoms of dysautonomia include orthostatic hypotension, or a fall in blood pressure upon standing; impotence, or erectile dysfunction, in those assigned as male at birth; hypertension or hypotension; and a rapid increase in pulse rate. Other symptoms include dizziness, vertigo; lightheadedness associated with syncope or fainting; shortness of breath; heart palpitations; chest pain or discomfort, blurred vision, difficulty swallowing, nausea and vomiting, and hypoglycemia.In general, symptoms of dysautonomia can either be acute and reversible or chronic and progressive. Neurological symptoms can also manifest, including mood swings, anxiety, forgetfulness, migraines, urinary incontinence, and weakness. Other symptoms of familial dysautonomia include prolonged breath-holding, poor bladder control, delayed growth, loss of balance, and frequent lung infections.
How is dysautonomia diagnosed?
Dysautonomia is diagnosed after a thorough patient history and physical exam. The healthcare professional will typically receive a detailed medication list to assess medications that might be causing the symptoms, followed by a thorough review of their medical history to assess for recent volume loss. Clinicians may also evaluate for evidence of personal neurological history and family history of dysautonomia.The healthcare professional may perform a tilt table test, during which the individual lies on a table that lifts and lowers to different angles. During this test, the individual is connected to equipment that measures blood pressure, oxygen levels, and heart activity. They are subsequently tilted at different angles to assess how their nervous system regulates and normalizes blood pressure and heart rate. Those with dysautonomia may experience syncope while tilted over 180 degrees due to an inability to regulate the nervous system. Other diagnostic tests include breathing tests which measure how the heart rate responds to breathing slowly and deeply for 1.5 minutes at a rate of six breaths per minute; sweating tests which measure the nerves that control sweating; general blood work to look for underlying medical causes (e.g., hematocrit, electrolytes, blood urea nitrogen, creatinine, glucose); and 12-lead electrocardiogram.
How is dysautonomia treated?
While there is currently no cure for dysautonomia, treatment is focused on managing the symptoms. To combat orthostatic hypotension, one can try a high-salt diet (e.g., adding three to five grams daily to their meals), drinking more water daily, and elevating the head of their bed. A clinician may administer bolus intravenously in emergent situations to increase blood pressure. Medications such as fludrocortisone and midodrine can increase blood pressure and be used to treat orthostatic hypotension.
Secondary forms of dysautonomia may improve with treatment of the underlying condition. Those with chronic and progressive dysautonomia generally have a poor prognosis, as death can occur from pneumonia, acute respiratory failure, or sudden cardiopulmonary arrest.
What are the most important facts to know about dysautonomia?
Dysautonomia is a general term that refers to disorders affecting the autonomic nervous system, which controls involuntary functions such as breathing, heart rate, blood pressure, sexual function, and more. Dysautonomia can be sporadic or genetic, or it can be a result of another pre-existing condition, such as diabetes mellitus, amyloidosis, lupus, Parkinson disease, or dementia with Lewy bodies. The sporadic form of dysautonomia leads to neurocardiogenic syncope, postural orthostatic tachycardia syndrome, multiple system atrophy, and pure autonomic failure. In all four cases, autonomic nervous system dysfunction results in syncope, tachycardia, dizziness, vertigo, and erectile dysfunction. Diagnosis is typically made on a physical exam with the aid of tilt table test, breathing tests, and laboratory testing. Treatment involves management of the symptoms, such as greater intake of salt and water in the diet, or taking medications, such as fludrocortisone and midodrine, if the individual has low blood pressure. If the symptoms are secondary to another cause, treating the underlying disease may help their dysautonomia.
Watch related videos:
Related linksIntroduction to the somatic and autonomic nervous systems
Nervous system anatomy and physiology
Parasympathetic nervous system
Resources for research and reference
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