Dysautonomia
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Dysautonomia, autonomic failure, or autonomic dysfunction is a condition in which the autonomic nervous system (ANS) does not work properly. This condition may affect the functioning of the heart, bladder, intestines, sweat glands, pupils, and blood vessels. Dysautonomia has many causes, not all of which may be classified as neuropathic.<ref name=nih/> A number of conditions can feature dysautonomia, such as Parkinson's disease, Long COVID, multiple system atrophy, dementia with Lewy bodies,<ref name="Palma2018" /> Ehlers–Danlos syndromes,<ref>Template:Cite journal</ref> autoimmune autonomic ganglionopathy and autonomic neuropathy,<ref>Template:Cite journal</ref> HIV/AIDS,<ref>Template:Cite journal</ref> mitochondrial cytopathy,<ref name=":0">Template:Cite journal</ref> pure autonomic failure, autism, and postural orthostatic tachycardia syndrome.<ref name="pmid38692780" />
Diagnosis is made by functional testing of the ANS, focusing on the affected organ system. Investigations may be performed to identify underlying disease processes that may have led to the development of symptoms or autonomic neuropathy. Symptomatic treatment is available for many symptoms associated with dysautonomia, and some disease processes can be directly treated. Depending on the severity of the dysfunction, dysautonomia can range from being nearly symptomless and transient to disabling and/or life-threatening.<ref name="aagtreatment">Template:Cite journal</ref>
Signs and symptoms
Dysautonomia, a complex set of conditions characterized by autonomic nervous system (ANS) dysfunction, manifests clinically with a diverse array of symptoms of which postural orthostatic tachycardia syndrome (POTS) stands out as the most common.<ref name="pmid38692780">Template:Cite journal</ref>
The symptoms of dysautonomia, which are numerous and vary widely for each person, are due to inefficient or unbalanced efferent signals sent via both systems.Template:Medical citation needed Symptoms in people with dysautonomia include: Template:Div col
- Anhydrosis or hyperhidrosis<ref name=emed/>
- Blurry or double vision<ref name=emed/>
- Bowel incontinence<ref name=emed/>
- Brain fog<ref name=emed/>
- Constipation<ref name=pat/>
- Dizziness<ref name=pat/>
- Difficulty swallowing<ref name=med/>
- Exercise intolerance<ref name=emed/>
- Low blood pressure<ref name=pat/>
- Orthostatic hypotension<ref name="emed">Template:Cite web</ref><ref name="pmid38692780" />
- Sleep apnea<ref name=pat/>
- Syncope<ref name=pat/>
- Tachycardia<ref name=nih/>
- Tunnel vision<ref name=pat/>
- Urinary incontinence or urinary retention<ref name=emed/>
Causes
Dysautonomia may be due to inherited or degenerative neurologic diseases (primary dysautonomia)<ref name=nih/> or injury of the autonomic nervous system from an acquired disorder (secondary dysautonomia).<ref name=emed/><ref>Template:Cite journal</ref> Its most common causes include:
In the sympathetic nervous system (SNS), predominant dysautonomia is common along with fibromyalgia, chronic fatigue syndrome, irritable bowel syndrome, and interstitial cystitis, raising the possibility that such dysautonomia could be their common clustering underlying pathogenesis.<ref>Template:Cite journal</ref>
In addition to sometimes being a symptom of dysautonomia, anxiety can sometimes physically manifest symptoms resembling autonomic dysfunction.<ref>Template:Cite journal</ref><ref>Template:Cite book</ref><ref>Template:Cite book</ref> A thorough investigation ruling out physiological causes is crucial, but in cases where relevant tests are performed and no causes are found or symptoms do not match any known disorders, a primary anxiety disorder is possible but should not be presumed.<ref>Template:Cite book</ref> For such patients, the anxiety sensitivity index may have better predictivity for anxiety disorders while the Beck Anxiety Inventory may misleadingly suggest anxiety for patients with dysautonomia.<ref>Template:Cite journal</ref>
Mitochondrial cytopathies can have autonomic dysfunction manifesting as orthostatic intolerance, sleep-related hypoventilation, and arrhythmias.<ref name=":0" /><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
Mechanism
The autonomic nervous system is a component of the peripheral nervous system and comprises two branches: the sympathetic nervous system (SNS) and the parasympathetic nervous system (PSNS). The SNS controls the more active responses, such as increasing heart rate and blood pressure. The PSNS, for example, slows down the heart rate and aids digestion. Symptoms typically arise from abnormal responses of either the sympathetic or parasympathetic systems based on situation or environment.<ref name=nih/><ref>Template:Cite webTemplate:Dead linkTemplate:Cbignore</ref><ref name="concussionalliance.org" />
Diagnosis
Diagnosis of dysautonomia depends on the overall function of three autonomic functions—cardiovagal, adrenergic, and sudomotor. A diagnosis should, at a minimum, include measurements of blood pressure and heart rate while lying flat and after at least three minutes of standing. The best way to make a diagnosis includes a range of testing, notably an autonomic reflex screen, tilt table test, and testing of the sudomotor response (ESC, QSART or thermoregulatory sweat test).<ref name=nih2/>
Additional tests and examinations to diagnose dysautonomia include:
Tests to elucidate the cause of dysautonomia can include:
- Evaluation for acute (intermittent) porphyria<ref name=emed/>
- Evaluation of brain and spinal magnetic resonance imaging for myelopathy, stroke and multiple system atrophy
- Evaluation of cerebrospinal fluid by lumbar puncture<ref name=emed/> for infectious/ inflammatory diseases
- Evaluation of MIBG myocardial scintigraphy and DaT scan for Parkinson's disease, dementia with Lewy bodies and pure autonomic failure
- Evaluation of nerve conduction study for autonomic neuropathy
Vegetative-vascular dystonia
Particularly in the Soviet and post-Soviet medical literature,<ref name=":1">Template:Cite journal</ref><ref>Template:Cite journal</ref> a subtype of dysautonomia that particularly affects the vascular system has been called vegetative-vascular dystonia.<ref>Template:Cite journal</ref> The term "vegetative" reflects an older name for the autonomic nervous system: the vegetative nervous system.Template:Citation needed
Despite official recognition by the medical institutions in the USSR and some other Warsaw-pact countries (and their successor countries), it has also been described as a form of Culture-bound syndrome.<ref name=":1" />
A similar form of this disorder has been historically noticed in various wars, including the Crimean War and American Civil War, and among British troops who colonized India. This disorder was called "irritable heart syndrome" (Da Costa's syndrome) in 1871 by American physician Jacob DaCosta.<ref>Template:Cite journal</ref>
Management
Treatment of dysautonomia can be difficult; since it is made up of many different symptoms, a combination of drug therapies is often required to manage individual symptomatic complaints. In the case of autoimmune neuropathy, treatment with immunomodulatory therapies is done. If diabetes mellitus is the cause, control of blood glucose is important.<ref name=emed/> Treatment can include proton-pump inhibitors and H2 receptor antagonists used for digestive symptoms such as acid reflux.<ref>Template:Cite web</ref>
To treat genitourinary autonomic neuropathy, medications may include sildenafil (a guanine monophosphate type-5 phosphodiesterase inhibitor). To treat hyperhidrosis, anticholinergic agents such as trihexyphenidyl or scopolamine can be used. Intracutaneous injection of botulinum toxin type A can also be used in some cases.<ref>Template:Cite web</ref>
Transvascular autonomic modulation, a procedure similar to balloon angioplasty, is not approved in the United States to treat autonomic dysfunction.<ref>Template:Cite web</ref>
Prognosis
The prognosis of dysautonomia depends on several factors; people with chronic, progressive, generalized dysautonomia in the setting of central nervous system degeneration such as Parkinson's disease or multiple system atrophy generally have poorer long-term prognoses. Dysautonomia can be fatal due to pneumonia, acute respiratory failure, or sudden cardiopulmonary arrest.<ref name="nih">Template:Cite web</ref> Autonomic dysfunction symptoms such as orthostatic hypotension, gastroparesis, and gustatory sweating are more frequently identified in mortalities.<ref>Template:Cite journal</ref>
See also
- Autonomic neuropathy
- Dopamine beta hydroxylase deficiency
- Familial dysautonomia
- Orthostatic intolerance
- Postural orthostatic tachycardia syndrome
- Reflex syncope
References
Further reading
External links
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