From the Guidelines
Autonomic nervous system disorders are primarily caused by damage or dysfunction in the nerves that control involuntary bodily functions, resulting from various underlying conditions, including diabetes mellitus, autoimmune disorders, infections, genetic disorders, toxin exposure, physical trauma, and neurodegenerative diseases, as supported by the most recent and highest quality study 1.
Underlying Conditions
The conditions that underlie autonomic nervous system disorders can be categorized into several groups, including:
- Diabetes mellitus, which leads to diabetic autonomic neuropathy, as discussed in 1 and 1
- Autoimmune disorders, such as Guillain-Barré syndrome, multiple sclerosis, and rheumatoid arthritis
- Infections, like HIV, botulism, and Lyme disease
- Genetic disorders, including familial dysautonomia and Fabry disease
- Toxin exposure, particularly heavy metals, certain medications, and alcohol
- Physical trauma affecting the brain or spinal cord
- Neurodegenerative diseases, such as Parkinson's disease and multiple system atrophy, as mentioned in 1, 1, and 1
Pathophysiology and Treatment
The pathophysiology of autonomic nervous system disorders typically involves damage to small nerve fibers that carry autonomic signals, disruption of neurotransmitter function, or impairment of central nervous system control centers that regulate autonomic responses, as explained in 1. Treatment approaches vary based on the specific underlying cause but often focus on managing symptoms and addressing the primary condition when possible.
Clinical Evaluation and Management
According to the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1, referral for autonomic evaluation can be useful to improve diagnostic and prognostic accuracy in selected patients with syncope and known or suspected neurodegenerative disease. The care of patients with neurogenic orthostatic hypotension is complex and requires a knowledgeable care provider in the pathophysiology of the autonomic nervous system and the pharmacology of treatments for neurodegenerative disease.
From the Research
Conditions Underlying Autonomic Nervous System Disorders
The autonomic nervous system (ANS) is vulnerable to disruption by various disease processes, leading to numerous symptoms involving the cardiovascular, gastrointestinal, and urogenital systems. Some of the conditions that underlie autonomic nervous system disorders include:
- Primary etiologies such as:
- Secondary etiologies such as:
- Orthostatic intolerance syndromes, including:
- Small fiber neuropathies, which can be associated with autonomic failure, pain, or their combinations 6
- Other specific autonomic syndromes, such as:
Pathophysiology and Clinical Features
The pathophysiology of autonomic dysfunction involves degeneration of the intermediolateral cell columns or disease or damage to descending pathways that synapse on the intermediolateral column cells 5. The peripheral autonomic nervous system may be damaged in isolation or in association with a generalized peripheral neuropathy 5. The clinical features of autonomic dysfunction can include symptoms such as orthostatic hypotension, constipation, urinary dysfunction, erectile dysfunction, and pure autonomic failure 2, 3.
Diagnosis and Treatment
Diagnosis of autonomic dysfunction can be made using various tests, including heart rate and plasma norepinephrine responses to orthostatic stress, and cardiac sympathetic denervation diagnosed with MIBG scintigraphy or 18F-DA PET scanning 2. Treatment of autonomic dysfunction depends on the underlying cause and can include medications, lifestyle modifications, and other interventions 2, 3.