Dysautonomia: Definition, Pathophysiology, and Clinical Manifestations

Definition and Pathophysiology

Dysautonomia refers to dysfunction of the autonomic nervous system, which can manifest in various forms with fundamentally different underlying mechanisms, as stated by the European Heart Journal 2
The autonomic nervous system consists of the parasympathetic and sympathetic nervous systems, which integrate control of heart rate, blood pressure, body temperature, and other involuntary functions, according to Clinical Gastroenterology and Hepatology 4
When dysfunction occurs, defects may appear at various levels from peripheral nerves, autonomic ganglia, the spinal cord, and/or the brain, resulting in cardiac, respiratory, alimentary, urinary, reproductive, ocular, and sudomotor defects, as reported by Clinical Gastroenterology and Hepatology 4

Familial dysautonomia (Riley-Day syndrome, hereditary sensory and autonomic neuropathy type III) is a genetic disorder associated with abnormality of sensory and autonomic nerves, decreased sensation of pain, and decreased production of tears, as described in Circulation 1
Postural orthostatic tachycardia syndrome (POTS) is defined in adults as an increase in heart rate of ≥30 beats/min within 10 minutes of upright posture (≥40 beats/min in adolescents) with absence of orthostatic hypotension, according to Clinical Gastroenterology and Hepatology 5
Autoimmune autonomic ganglionopathy is associated with small cell lung cancer, involving antibodies against neuronal acetylcholine receptors in autonomic ganglia, as reported by Chest 6

Orthostatic intolerance is characterized by the presence of symptoms (dizziness, lightheadedness, nausea, dyspnea, vision changes) occurring specifically when assuming or maintaining upright position, as stated in Circulation 1
Gastrointestinal symptoms of dysautonomia include nausea, abdominal pain, vomiting, diarrhea, bloating, and severe constipation, according to Clinical Gastroenterology and Hepatology 5

Inadequate monitoring of blood pressure when initiating treatment is a common pitfall in managing dysautonomia, as noted by Praxis Medical Insights: Practical Summaries of Clinical Guidelines 7