Understanding Dysautonomia & The COMPASS-31 Instrument

The autonomic nervous system (ANS) controls virtually every involuntary physiological mechanism required for human homeostasis: cardiac chronotropy, vascular tone, gastrointestinal peristalsis, pupillary reflexes, thermoregulation, and bladder emptying. When viral infections (such as Epstein-Barr Virus, SARS-CoV-2, or HHV-6) trigger neuro-immune inflammation or autoantibodies against adrenergic and cholinergic receptors, the autonomic regulatory loop decouples—a pathological condition known as dysautonomia.

Historically, measuring autonomic impairment required lengthy 200-question questionnaires. In 2012, researchers at the Mayo Clinic Autonomic Disorders Laboratory (Sletten et al., PMID: 23218856) developed and validated the COMPASS-31 (Composite Autonomic Symptom Score-31). By refining the instrument into 31 targeted questions across 6 core physiological domains with weighted multipliers, the COMPASS-31 achieved high sensitivity and specificity in distinguishing healthy controls from patients with objective autonomic neuropathy, POTS, and post-viral exhaustion.

The 6 Autonomic Domains Explained

• 1. Orthostatic Intolerance (Weight: 40.0): The largest single contributor to the score. Measures cerebral hypoperfusion, dizziness, lightheadedness, and cognitive deficits upon assuming an upright posture due to impaired venous return.
• 2. Vasomotor (Weight: 5.0): Assesses microvascular sympathetic regulation. Evaluates Raynaud's-like color blanching, livedo reticularis (mottled skin), and acrocyanosis (blood pooling in feet and hands).
• 3. Secretomotor (Weight: 7.0): Measures postganglionic sudomotor and glandular parasympathetic innervation (anhidrosis, hyperhidrosis, severe xerostomia, and dry eyes).
• 4. Gastrointestinal (Weight: 25.0): Quantifies enteric nervous system dysmotility, including delayed gastric emptying (gastroparesis), early satiety, severe bloating, episodic diarrhea, and constipation.
• 5. Bladder (Weight: 10.0): Assesses pelvic parasympathetic and sympathetic bladder innervation, including urinary urgency, neurogenic detrusor overactivity, and incomplete emptying.
• 6. Pupillomotor (Weight: 5.0): Quantifies pupillary sphincter and dilator tone, including severe photophobia (inability to constrict in bright light) and blurred near/far accommodation.

Dysautonomia vs POTS: What Is the Difference?

A frequent point of confusion among patients and clinicians is the distinction between dysautonomia and POTS. Dysautonomia is the broad categorical umbrella covering any dysfunction of the autonomic system. POTS (Postural Orthostatic Tachycardia Syndrome) is one specific subtype of dysautonomia characterized primarily by an abnormal orthostatic heart rate acceleration without hypotension.

Types of POTS Explained: Neuropathic, Hyperadrenergic & Hypovolemic

In modern neuro-cardiology, POTS is recognized not as a single uniform illness, but as a clinical syndrome with multiple overlapping pathophysiological mechanisms:

• 1. Neuropathic POTS: Characterized by small-fiber autonomic neuropathy affecting distal sympathetic nerves in the lower extremities and splanchnic circulation. Because blood vessels cannot constrict upon standing, gravity forces blood to pool in the legs and abdomen, triggering secondary compensatory cardiac tachycardia.
• 2. Hyperadrenergic POTS: Driven by an overactive central sympathetic nervous system. Standing serum norepinephrine levels frequently exceed 600–1000 pg/mL. Patients experience dramatic tremors, cold sweaty palms, anxiety surges, visual tunnel vision, and a paradoxical increase in systolic blood pressure upon standing.
• 3. Hypovolemic POTS: Marked by a 10% to 20% deficit in absolute circulating red blood cell volume and plasma volume, frequently coupled with paradoxically low or normal renin and aldosterone levels (the "renin-aldosterone paradox").
• 4. Autoimmune / Post-Viral POTS: Emerging research in ME/CFS and Long COVID reveals functional autoantibodies targeting alpha-1 adrenergic, beta-1/2 adrenergic, and muscarinic M2/M4 cholinergic receptors, disrupting autonomic signaling cascades.

Clinical Next Steps & Testing Recommendations

If your COMPASS-31 score exceeds 16 points, or if your orthostatic score is elevated, consider the following evidence-based clinical steps:

1. Perform a Bedside NASA 10-Minute Lean Test: A validated, zero-cost passive stand test with comparable diagnostic yield to tilt table testing. You can use our interactive NASA 10-Minute Lean Test Clinical Monitor to record baseline supine vitals and minute-by-minute upright heart rate and blood pressure.
2. Implement Non-Pharmacological Blood Volume Expansion: Consume 2.5 to 3.5 liters of fluid daily paired with 8–10 grams of salt (sodium chloride) or standardized WHO Oral Rehydration Solution (ORS) using the SGLT-1 co-transporter. See our complete Dysautonomia & POTS Treatment Protocol.
3. Request Formal Autonomic Reflex Testing: Consult an autonomic neurologist or electrophysiologist for a Tilt Table Test (HUTT), Quantitative Sudomotor Axon Reflex Test (QSART), and 24-hour ambulatory blood pressure monitoring.