dysautonomia

dysautonomia

Autonomic Dysfunction · G90.3

Autonomic dysfunction is a condition in which the regulatory function of the autonomic nervous system (sympathetic and parasympathetic nerves) is reduced or operates abnormally, resulting in various abnormalities in involuntary body functions such as cardiovascular, digestive, urinary, sweating, and temperature regulation.

At a glance

Dysautonomia is not a single disease but a concept that encompasses dysfunction of the autonomic nervous system. Typical symptoms include orthostatic hypotension, postural tachycardia syndrome (POTS), vasovagal syncope, sweating disorders, gastrointestinal motility disorders, and bladder dysfunction. The causes are diverse, including diabetic autonomic neuropathy, Parkinson's disease, autoimmune disease, chronic stress, and small fiber neuropathy, and customized treatment is required depending on the cause [1].

Definition and Overview

Autonomic dysfunction is a general term for a condition in which the autonomic nervous system, which consists of the sympathetic nervous system and the parasympathetic nervous system, fails to normally regulate involuntary body functions such as cardiovascular, digestive, urogenital, sweating, breathing, and temperature control.

Dysautonomia is not a single disease name, but a general term for autonomic dysfunction caused by various causes and mechanisms, and has a wide spectrum from functional (reversible) to those accompanying progressive neurodegenerative diseases.

Classification

Primary dysautonomia

Pure autonomic failure (PAF): Progressive orthostatic hypotension as the main symptom, accumulation of non-alphasynuclein
Multiple system atrophy (MSA): Combination of Parkinson's symptoms, cerebellar symptoms, and autonomic dysfunction
Autonomic dysfunction associated with Parkinson's disease

secondary dysautonomia

Diabetic autonomic neuropathy: A serious complication of diabetic neuropathy. Includes cardiovascular, gastrointestinal, urinary, and sweating dysfunction
Autoimmune autonomic neuropathy: Caused by anti-ganglionic acetylcholine receptor antibodies (ganglionic AChR Ab)
Accompanied by small fiber neuropathy: sweating and vasomotor control abnormalities due to damage to skin small fibers
Functional dysautonomia related to chronic stress and burnout
Autonomic dysfunction related to COVID-19 sequelae (Long COVID)

Main clinical expressions

cardiovascular symptoms

Orthostatic hypotension: A decrease in systolic blood pressure ≥ 20 mmHg within 3 minutes after standing.
Postural orthostatic tachycardia syndrome (POTS): Increased heart rate ≥ 30 beats/min after standing up
Vasovagal syncope: Reflex syncope during prolonged standing, pain, or emotional stimulation.
Tachycardia or bradycardia at rest, decreased exercise tolerance

Digestive system symptoms

Gastroparesis: delayed stomach emptying, early satiety, nausea
Intestinal motility abnormalities: constipation, diarrhea, abdominal pain
Difficulty swallowing

abnormal sweating

anhidrosis: decreased or absent sweating
hyperhidrosis: excessive local or generalized sweating
Compensatory hyperhidrosis: excessive proximal sweating with decreased distal sweating.

Other symptoms

Bladder dysfunction: delayed urination, nocturia, urinary incontinence
Pupil abnormalities: delayed dilation, abnormal light reflection
Chronic fatigue, cognitive decline

diagnosis

Heart rate variability (HRV) analysis

HRV is the most widely used noninvasive indicator of autonomic function. Evaluate sympathetic-parasympathetic balance by analyzing time domain (RMSSD, SDNN) and frequency domain (LF, HF power).

Tilt-table test

Assess the cardiovascular response to passive standing to diagnose orthostatic hypotension, POTS, and neurocardiac syncope.

Valsalva maneuver test

Sympathetic and parasympathetic reflex functions are quantitatively evaluated through change patterns in heart rate and blood pressure during forced expiration (Valsalva).

Sweating function test

The function of the sweat control nerve is evaluated using the quantitative sudomotor axon reflex test (QSART) and thermoregulatory sweat test.

blood tests and more

Fasting blood sugar, HbA1c (diabetes or not), anti-ganglionic AChR antibodies, nerve conduction studies, and skin biopsy for small nerve fiber density are used to determine the cause.

treatment

Treatment by cause

In diabetic autonomic neuropathy, strict blood sugar control is most important in suppressing progression. For autoimmune autonomic neuropathy, immunotherapy such as steroids, immunoglobulin (IVIG), and plasmapheresis may be effective.

Management by symptom

Orthostatic hypotension: increased water and salt intake, compression stockings, fludrocortisone, midodrine
POTS: fluid intake, lower extremity strengthening exercises, beta blockers, ivabradine.
Gastroparesis: small meals, gastrointestinal motility stimulant (metoclopramide)
Neurocardiac syncope: lifestyle modifications, beta blockers

autonomic nerve control treatment

Stellate ganglion block suppresses sympathetic nerve hyperactivation and helps restore autonomic balance. Transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and HRV biofeedback training are used as adjunctive treatments for functional dysautonomia.

Frequently asked questions

Q01What symptoms do I experience if I have dysautonomia?

Because the symptoms are diverse, diagnosis is often delayed. Main symptoms include dizziness or fainting when standing up, heart palpitations or slow pulse, digestive problems (stomach bloating, constipation, alternating diarrhea), excessive or reduced sweating, fatigue, headache, sleep disturbance, and numbness in the hands and feet. A characteristic of autonomic nervous system abnormalities is that symptoms appear across multiple organ systems.

Q02How is dysautonomia diagnosed?

It is evaluated by autonomic function tests such as heart rate variability (HRV) analysis, standing tilt table test (tilt table test), Valsalva maneuver test, and sweating function test (QSART). Blood tests (blood sugar, autoantibodies), nerve conduction tests, and small fiber nerve biopsies may be necessary to determine the cause.

Q03Why does dysautonomia occur?

There are various causes, including neurodegenerative diseases such as diabetic autonomic neuropathy, Parkinson's disease and multiple system atrophy, autoimmune autonomic neuropathy, small fiber neuropathy, chronic stress, aftereffects of COVID-19 (Long COVID), and hereditary autonomic diseases. It is important to find the cause and treat it.

Q04Is dysautonomia treatable?

It varies depending on the cause. The key to diabetic autonomic neuropathy is blood sugar control, and symptoms of orthostatic hypotension can be controlled by increasing water and salt intake, compression stockings, and drug treatment. For autoimmune causes, immunotherapy may be effective. Autonomic nerve control treatments (stellate ganglion block, TMS, etc.) can help restore autonomic balance.

Q05Can stress cause dysautonomia?

Chronic stress continuously activates the hypothalamus-pituitary-adrenal axis (HPA axis), causing chronic hyperactivation of the sympathetic nervous system. If this condition persists, decreased parasympathetic nerve activity, decreased HRV, and various physical function abnormalities may occur [3]. Chronic stress is one of the important functional causes of dysautonomia.

Q06Is there anything that patients with dysautonomia should be careful about in their daily lives?

If you have orthostatic hypotension, change your position slowly rather than standing up quickly, and drink enough water (2-3L per day) and appropriate salt. Caution is required as standing for long periods of time or in a high temperature environment can worsen the decline in blood pressure. Regular light exercise helps restore autonomic balance.

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