Overview
The autonomic nervous system controls involuntary physiologic functions including heart rate digestion respiratory rate and vascular tone. It comprises sympathetic and parasympathetic divisions with opposing effects to maintain homeostasis. Autonomic dysfunction affects multiple organ systems.
Sympathetic Pathways
Sympathetic fibers originate in the thoracolumbar spinal cord and mediate fight or flight responses increasing heart rate and vasoconstriction. Overactivity contributes to hypertension and arrhythmia. Testing and imaging evaluate structural and functional causes.
Parasympathetic Pathways
Parasympathetic fibers arise from cranial nerves and the sacral spinal cord promoting rest digest and repair functions. Vagal tone influences cardiac and gastrointestinal activity. Dysfunction leads to orthostatic intolerance and gastrointestinal dysmotility.
Clinical Relevance
Autonomic disorders include dysautonomia neurogenic orthostatic hypotension and autonomic neuropathy. Testing includes tilt table autonomic reflex and specialized imaging when indicated. Management targets symptom control and underlying causes.