Where should patients go for autonomic testing?

Referral for Autonomic Testing: Specialized Centers and Criteria

Patients requiring autonomic testing should be referred to specialized autonomic function laboratories in cardiology or neurology departments where testing can be performed by specialists trained in autonomic function testing and interpretation. 1

Appropriate Clinical Settings for Autonomic Testing

• Autonomic testing should be performed in a dedicated laboratory with specialized equipment including beat-to-beat blood pressure monitoring, ECG monitoring, motorized tilt table, and other specialized equipment depending on the range of testing needed 1
• Testing should ideally be performed before noon in a quiet environment with temperature controlled between 21-23°C 1
• Patients should fast for 3 hours before testing and avoid nicotine, caffeine, theine, or taurine-containing drinks on the day of examination 1

Patient Selection for Referral

Recommended for Autonomic Testing:

• Patients with known or suspected neurodegenerative disease where autonomic evaluation can improve diagnostic and prognostic accuracy 1
• Patients with Parkinsonism or other central nervous system features 1
• Individuals with peripheral neuropathies or diseases associated with peripheral neuropathy 1
• Patients with progressive autonomic dysfunction without central or peripheral nervous system features 1
• Patients with postprandial hypotension 1
• Individuals with known or suspected neuropathic postural tachycardia syndrome (POTS) 1
• Patients with hypermobile Ehlers-Danlos syndrome (hEDS) who have refractory GI symptoms and orthostatic intolerance after exclusion of medication side effects and appropriate lifestyle modifications 1

Testing for POTS:

• Referral to specialty practices (cardiology or neurology) for POTS testing is recommended for patients with symptomatic increase in heart rate of 30 beats/min or more with 10 minutes of standing 1
• POTS can be diagnosed through postural vital signs during an active stand or head-up tilt table test in the absence of orthostasis 1

Components of Comprehensive Autonomic Testing

• Cardiovagal function tests: Heart rate variability to deep breathing, Valsalva maneuver response 1
• Adrenergic function tests: Blood pressure and heart rate responses to Valsalva maneuver and head-up tilt 2
• Sudomotor function tests: Quantitative sudomotor axon reflex test and thermoregulatory sweat test 2

Special Considerations

• No single autonomic function test can provide a comprehensive assessment of the autonomic nervous system; different clinical questions require different batteries of tests 1
• The care of patients with neurogenic orthostatic hypotension is complex, especially in individuals with neurodegenerative disease 1
• Autonomic testing should be performed by specialists who understand the pathophysiology of the autonomic nervous system and the pharmacology of treatments for neurodegenerative disease 1
• For patients with suspected mast cell activation syndrome (MCAS), referral to an allergy specialist or mast cell disease research center is recommended for additional specialized testing 1

Pitfalls and Caveats

• Avoid testing during acute illness, stressful conditions, fever, infection, or dehydration 1
• Testing should not be performed during hypoglycemia or marked hyperglycemia 1
• Tests should be performed at least 2 hours after short-acting insulin administration 1
• Consider appropriate wash-out of interfering drugs, particularly diuretics, sympatholytic agents, and psychoactive drugs 1
• Test results should be interpreted with caution in the presence of respiratory or cardiovascular diseases, particularly heart failure 1
• Age-related normal reference values are required to correctly interpret the results of heart rate-based cardiovascular tests 1

By following these guidelines, clinicians can ensure appropriate referral for autonomic testing that will lead to accurate diagnosis and improved patient outcomes.