Dysautonomia or autonomic dysfunction is a condition in which the autonomic nervous system does not work properly.
The autonomic nervous system regulates internal organs, controls heart rate, blood pressure, sweating, digestion, respiration, pupillary reactivity, urination, and sexual arousal.
Autonomic fibers are small, lightly myelinated and unmyelinated.
The autonomic nervous system acts unconsciously via efferent motor fibers and autonomic dysfunction manifests as an organ malfunction.
It 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).
Generalized autonomic failure is a type of dysautonomia with autonomic hyperactivity due to damage of both sympathetic and parasympathetic systems.
A restricted sympathetic or parasympathetic failure leads to unopposed actions of each other.
Autonomic symptoms can be divided into orthostatic, non-orthostatic, and diffuse.
Orthostatic symptoms are typically related to cerebral hypo perfusion manifesting as lightheadedness.
Frequent nonorthostatic symptoms include constipation, bladder problems, cold or hot intolerance, excessive sweating or loss of sweating, and erectile dysfunction.
Common complaints of autonomic symptoms include fatigue, headaches, and insomnia.
Reduced or elevated core temperatures may indicate abnormal hypothermic function.
Pupillary abnormalities, dry mouth and dry eyes may be present and dysautonomia.
Autonomic overactivity can be generalized or restrictive.
Dysautonomia can be continuous or paroxysmal, acute, subacute, or chronic preganglionic, postganglionic, or mixed.
Many small sensory fibers are located in close proximity with autonomic fibers and frequently are damaged together.
Damage of small sensory fibers is typically associated with burning pain on the feet or hands, and frequently with lightning like or lancinating pain, aching or uncomfortable paresthesias (dysesthesias) or with pain to nonpainful stimuli (allodynia).
Vibration sensing proprioception are modalities transmitted by large fibers and they should be normal aim, while pain temperature sensation at the distal leg is abnormal in small fiber neuropathy.
Deep tendon reflexes should be normal, and there should not be muscle weakness in small fiber neuropathy.
Dysautonomia may affect the functioning of the heart, bladder, intestines, sweat glands, pupils, and blood vessels.
Has many causes, not all of which may be classified as neuropathic.
Dysautonomia seen in Parkinson’s disease, HIV/AIDS, multiple system atrophy, autonomic failure, postural orthostatic tachycardia syndrome, Ehlers-Danlos syndrome, autoimmune autonomic ganglionopathy, and autonomic neuropathy.
Caused by inadequacy of sympathetic, or parasympathetic, components of autonomic nervous system.
Risk factors:
Alcoholism and Diabetes
The diagnosis of dysautonomia requires functional testing of the autonomic nervous system.
Testing requires focusing on the affected organ systems and identifying underlying disease processes that may have led to the development of autonomic neuropathy.
A medical history including review of medications is necessary, and emphasis placed on the problem onset of acute, subacute, or chronic nature, and its rapid or slow progression, and severity from mild to severe.
The use of drugs, alcohol, diet, supplements, toxic exposures, history of Lyme disease, history of travel, or risk behavior need to be analyzed.
Dysautonomia features include simultaneous involvement of multiple organ systems and fluctuations of symptoms from day to day or from position to position.
A voiding and gastrointestinal history and complaints are required for adequate assessment of neurogenic bladder and gastric motility disorders.
Treatment varies from supportive care to to specific and direct actions in some disease processes.
The symptoms vary widely for each individual, and are due to inefficient or unbalanced efferent signals sent via The autonomic sympathetic and parasympathetic nervous systems.
The primary symptoms include:
Anhydrosis
Anxiety
Blurry or double vision
Bowel incontinence
Brain fog
Constipation
Dizziness
Difficulty swallowing
Exercise intolerance
Insomnia
Hypotension
Orthostatic hypotension
Syncope
Tachycardia
Tunnel vision
Urinary incontinence or urinary retention
Vertigo
Weakness
Physical examination findings including postural variations in blood pressure, heart rate, pupillary light reflex, skin temperature, skin color, and patterns of sweating.
Blood pressure and heart rate are measured in supine position and during standing.
The pressure and pulse should be checked for at least 10 minutes after standing as orthostatic hypotension without a compensatory increase in heart rate usually indicates autonomic failure.
Causes of dysautonomia:
The most common causes of dysautonomia include:
Alcoholism
Amyloidosis
Autoimmune diseases
Craniocervical instability
Diabetes
Eaton-Lambert syndrome
Ehlers-Danlos syndrome
Guillain-Barré syndrome
HIV and AIDS
Lyme disease
Multiple sclerosis
Multiple system atrophy
Paraneoplastic syndrome
Parkinson’s disease
Spinal cord injury
Surgery or injury involving the nerves
Toxicity (vincristine)
Sympathetic nervous system (SNS) predominant dysautonomia is common along with: fibromyalgia, chronic fatigue syndrome, irritable bowel syndrome, and interstitial cystitis.
Anxiety can sometimes physically manifest symptoms resembling autonomic dysfunction.
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 slows down the heart rate and aids in digestion, for example.
Symptoms typically arise from abnormal responses of either the sympathetic or parasympathetic systems based on situation or environment.
Dysautonomia diagnosis depends on the function of three autonomic functions – cardiovagal, adrenergic, and sudomotor.
To make a diagnosis: measurements of blood pressure and heart rate while lying flat, and after at least 3 minutes of standing, autonomic reflex screen, tilt table test, and testing of the sudomotor response.
Additional tests and examinations:
Ambulatory blood pressure and EKG monitoring
Cold pressor test
Deep breathing
Hyperventilation test
Nerve biopsy for small fiber neuropathy
Quantitative sudomotor axon reflex test
Testing for orthostatic intolerance
Thermoregulatory sweat test
Tilt table test
Valsalva maneuver
The treatment of dysautonomia is difficult, due to its different symptoms.
A combination of drug therapies is often required to manage the process symptomatically.
Immunomodulatory therapy is used for autoimmune induced dysautonomia.
Control of blood glucose is important for diabetes.
Proton-pump inhibitors and H2 receptor antagonists used for digestive symptoms such as acid reflux.
Genitourinary autonomic neuropathy medications may include a guanine monophosphate type-5 phosphodiesterase inhibitor.
For hyperhidrosis, anticholinergic agents such as trihexyphenidyl or scopolamine can be used.
Intracutaneous injection of botulinum toxin type A can be used for management of hyperhidrosis, in some cases.
The prognosis of dysautonomia depends on the underlying cause.
Dysautonomia due to central nervous system degeneration such as Parkinson’s disease or multiple system atrophy have a generally poorer long-term prognosis.
Dysautonomia could lead to pneumonia, acute respiratory failure, or sudden cardiopulmonary arrest.
Autonomic dysfunction symptoms such as orthostatic hypotension, gastroparesis, and gustatory sweating are associated with more severe disease.