BlueCross and BlueShield of Montana Medical Policy/Codes
Autonomic Nervous System (ANS) Testing
Chapter: Medicine: Tests
Current Effective Date: March 15, 2014
Original Effective Date: November 26, 2013
Publish Date: January 15, 2014
Revised Dates: January 15, 2014

The autonomic nervous system (ANS) regulates physiologic processes, such as blood pressure, heart rate, body temperature, digestion, metabolism, fluid and electrolyte balance, sweating, urination, defecation, sexual response, and other processes. Regulation occurs without conscious control, i.e., autonomously. The ANS has two major divisions: the sympathetic and parasympathetic systems. Many organs are controlled primarily by either the sympathetic or parasympathetic system, although they may receive input from both; occasionally, functions are reciprocal (e.g., sympathetic input increases heart rate; parasympathetic decreases it).

The sympathetic nervous system is catabolic and activates fight-or-flight responses. Thus, sympathetic output increases heart rate and contractility, bronchodilation, hepatic glycogenolysis and glucose release, BMR (basal metabolism rate), and muscular strength; it also causes sweaty palms. Less immediately-life-preserving functions (e.g., digestion, renal filtration) are decreased.

The parasympathetic nervous system is anabolic; it conserves and restores. Gastrointestinal secretions and motility (including evacuation) are stimulated, heart rate is slowed, and blood pressure decreases.

Disorders of the ANS can affect any system of the body; they can originate in the peripheral or central nervous system and may be primary or secondary to other disorders. Symptoms suggesting autonomic dysfunction include orthostatic hypotension, heat intolerance, nausea, constipation, urinary retention or incontinence, nocturia, impotence, and dry mucous membranes. If a patient has symptoms suggesting autonomic dysfunction, cardiovagal, adrenergic, and sudomotor tests are usually done to help determine severity and distribution of the dysfunction.

Cardiovagal innervation testing evaluates heart rate response to deep breathing and to the Valsalva maneuver, via electrocardiogram rhythm strip. If the ANS is intact, heart rate varies with these maneuvers; the ratio of longest to shortest R-R interval (Valsalva ratio) should be 1.4 or greater.

Vasomotor adrenergic innervation testing evaluates response of beat-to-beat blood pressure to the head-up tilt and Valsalva maneuver. The head-up tilt shifts blood to dependent parts, causing reflex responses. The Valsalva maneuver increases intrathoracic pressure and reduces venous return, causing blood pressure changes and reflex vasoconstriction. In both tests, the pattern of responses is an index of adrenergic function.

The quantitative sudomotor axon reflex test (QSART) evaluates integrity of postganglionic neurons using iontophoresis; electrodes filled with acetylcholine are placed on the legs and wrist to stimulate sweat glands, and the volume of sweat is then measured. The test can detect decreased, absent, or persistent (after stimulus discontinuation) sweat production. The silastic sweat imprint differs from QSART in that the recording is an imprint of the sweat droplets appearing as indentations on silastic material.

The thermoregulatory sweat test (TST) evaluates both preganglionic and postganglionic pathways. After a dye is applied to the skin, patients enter a closed compartment that is heated to cause sweating. Sweating causes the dye to change color, so that areas of anhidrosis and hypohidrosis are apparent and can be calculated as a percentage of body surface area.

Sympathetic skin response (SSR) provides an index of sweat production by measuring change in skin resistance following random electrical stimulation over the palms and soles.

Quantitative direct and indirect axon reflex testing (QDIRT) is defined by Illigens and Gibbons (2009) as a novel new technique to evaluate the postganglionic sympathetic cholinergic sudomotor function by measuring the direct and axon-reflex mediated sweat response in a dynamic fashion. Sweat glands are stimulated by acetylcholine iontophoresis and sweat is displayed via an activator dye followed by digital photographs over time.

Pupillometry measures the responses of the pupil to light. Evaluating pupil size and response to light is an established tool in the clinical setting. Traditionally, this is measured using a penlight and a pupil gauge, which may be subjective. The NeurOptics® NPi™-100 Pupillometer is a hand-held, portable, infrared device used to measure pupil size and the pupillary light reflex. (11)

A variety of monitoring and testing equipment can be used for ANS testing; one example is the ANX 3.0™. In 1994, the Ansar Group, Inc. received U.S. Food and drug Administration (FDA) 510(K) clearance for their new autonomic nervous system monitoring technology; in 2004 Ansar introduced the ANX 3.0, which is their latest generation non-invasive, real-time, digital monitor of autonomic nervous system functioning. The ANX 3.0 monitors both branches of the ANS simultaneously.


Each benefit plan, summary plan description or contract defines which services are covered, which services are excluded, and which services are subject to dollar caps or other limitations, conditions or exclusions. Members and their providers have the responsibility for consulting the member's benefit plan, summary plan description or contract to determine if there are any exclusions or other benefit limitations applicable to this service or supply. If there is a discrepancy between a Medical Policy and a member's benefit plan, summary plan description or contract, the benefit plan, summary plan description or contract will govern.


Autonomic nervous system (ANS) testing, including parasympathetic function (cardiovagal innervation), sympathetic adrenergic function (vasomotor adrenergic innervation), and sudomotor function (quantitative sudomotor axon reflex test [QSART], thermoregulatory sweat test [TST], and silastic sweat imprint test), may be considered medically necessary for use as a diagnostic tool to evaluate symptoms of vasomotor instability after more common causes have been excluded by other testing, for any of the following:

  1. Diagnose the presence of autonomic neuropathy in a patient with signs or symptoms suggesting a progressive autonomic neuropathy, including:
    • Diabetic neuropathy,
    • Amyloid neuropathy,
    • Sjogren’s syndrome,
    • Idiopathic neuropathy,
    • Pure autonomic failure,
    • Multiple system dystrophy;
  2. Evaluate the severity and distribution of a diagnosed progressive autonomic neuropathy;
  3. Differentiate the diagnosis between certain complicated variants of syncope from other causes of loss of consciousness;
  4. Evaluate inadequate response to beta blockade in vasodepressor syncope;
  5. Evaluate distressing symptoms in the patient with a clinical picture suspicious for distal small fiber neuropathy in order to diagnose the condition;
  6. Differentiate the cause of postural tachycardia syndrome;
  7. Evaluate change in type, distribution or severity of autonomic deficits in patients with autonomic failure;
  8. Evaluate the response to treatment in patients with autonomic failure who demonstrate a change in clinical exam;
  9. Diagnose axonal neuropathy or suspected autonomic neuropathy in the symptomatic patient;
  10. Evaluate and diagnose sympathetically maintained pain, as in reflex sympathetic dystrophy or causalgia; or
  11. Evaluate and treat patients with recurrent unexplained syncope to demonstrate autonomic failure.

Autonomic nervous system (ANS) testing is considered experimental, investigational and unproven for all other indications that do not meet the above criteria, including but not limited to:

  1. Screening or routine testing of patients without signs or symptoms of autonomic dysfunction, including patients with diabetes, hepatic or renal disease;
  2. Testing for the sole purpose of monitoring disease intensity or treatment efficacy in diabetes, hepatic or renal disease;
  3. Patients with a clearly diagnosed somatic neuropathy, especially demyelinating neuropathies;
  4. Patients with uncomplicated vasovagal syncope;
  5. General diagnosis of conditions including, but not limited to:
    • Asthma,
    • Anxiety and/or stress,
    • General wellness,
    • Obesity,
    • Psychological conditions,
    • Post-partum dysfunctions, or
    • Sleep apnea.

Sympathetic skin response (SSR) testing is considered experimental, investigational and unproven.

Quantitative direct and indirect axon reflex testing (QDIRT) is considered experimental, investigational and unproven.

Quantitative pupillometry is considered experimental, investigational and/or unproven to evaluate the autonomic nervous system function.


In 1996, the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology issued an assessment of clinical autonomic testing, which concluded the following:

  • Cardiovagal heart rate tests (heart rate response to deep breathing, Valsalva ratio, heart rate response to standing) have a high sensitivity and specificity, and are safe, valuable, cost-effective, well-standardized, and reproducible;
  • Adrenergic tests (beat-to-beat blood pressure recordings of the Valsalva maneuver, blood pressure and heart rate response to standing) are established tests that enhance sensitivity and specificity of laboratory evaluation of adrenergic function;
  • Quantitative sudomotor axon reflex testing (QSART) test has a high sensitivity, specificity and reproducibility, and confounding variables are well-known;
  • Thermoregulatory sweat test (TST) is now well-standardized, has a high sensitivity, and has good specificity when combined with QSART;
  • Sweat imprint test is an established test that seems to be sensitive and quantitative;
  • Sympathetic skin response test has relatively low sensitivity, uncertain specificity, and habituates; this test is being replaced by better tests, such as QSART or sweat imprint.

2010 Update

A search of peer reviewed literature through May 2010 identified no new clinical trial publications or any additional information that would change the coverage position of this medical policy.

2012 Update

Post-ganglionic sudomotor function is currently evaluated using QSART or silicone impressions. In a 2008 study, Gibbons et al. hypothesized that high resolution digital photography has advanced sufficiently to allow quantitative direct and indirect testing of sudomotor function (QDIRT) with spatial and temporal resolution comparable to these techniques. In their study, 10 healthy subjects (7 male, 3 female) participated in 8 test visits. Experiments were performed at a room temperature of 24–26°C. Sweat responses were quantified on alternating ventral forearms by silicone impression and QDIRT at each visit. Thus, each control subject had silicone impressions and QDIRT performed 8 times. QDIRT was performed 4 times using the indicator dye povidone-iodine and 4 times using alizarin red. Only results from the ipsilateral forearms were compared.

In order to identify the sensitivity of QDIRT to variables that could affect the sudomotor response, four of the above healthy subjects underwent additional testing on the anterior thighs to determine the effects of hydration and caffeine. Subjects were tested after a 12 hour overnight fluid restriction; the test was then repeated after hydration with 40 ounces of fluid. Subjects were also tested before and after ingestion of 12 ounces of coffee to determine the effects of caffeine on the sweat response assessed by QDIRT. Ten additional subjects (5 male, 5 female) also underwent a test of QDIRT (using alizarin red), silicone impression and QSART on the dorsal aspect of the distal right foot. These tests were performed on 3 different test days, under the same testing conditions.

The percent area of sweat photographically imaged correlated with silicone impressions at 5 minutes on the forearm (r = 0.92, p<0.01) and dorsal foot (r=0.85, p<0.01). The number of sweat droplets assessed with QDIRT correlated with the silicone impression although the droplet number was lower (162±28 vs. 341±56, p<0.01; r =0.83, p<0.01). QDIRT and QSART sudomotor assessments measured at the dorsum of the foot correlated (sweat response (r=0.63, p<0.05) and sweat onset latency (r=0.52, p<0.05).

The authors concluded that QDIRT measured both the direct and indirect sudomotor response with spatial resolution similar to silicone impressions, and with temporal resolution that is similar to QSART; QDIRT provides a novel tool for the evaluation of post-ganglionic sudomotor function. However, there are limitations to QDIRT. Ambient room temperature and humidity need to be controlled to prevent cool dry air from causing evaporation of sweat production. The study did not control temperature at the testing site; only ambient temperature was controlled in this study. Additional investigation is necessary to determine the utility of QDIRT in disease states that alter sudomotor structure or function.

In addition, a search of peer reviewed literature through June 2012 identified no new clinical trial publications or any additional information that would change the coverage position of this medical policy.

2014 Update

Most patients with autonomic disorders show evidence of sympathetic or parasympathetic deficits in the pupil that can be detected using a combination of clinical signs, pupillometric tests, and pharmacological tests. Caution is needed in the interpretation of these tests, particularly if the deficits are mixed (i.e. sympathetic and parasympathetic) or bilateral. The pattern of autonomic disturbance in the pupils often correlates poorly with autonomic function elsewhere, but may have diagnostic value in discriminating between different underlying conditions. (12)

Several studies were found in which pupillometry was used as a measurement in research trials, and several non-randomized trials were noted to support use of pupillometry. However, no well-constructed randomized controlled trials were located that support pupillometry for the diagnosis of autonomic nervous system disorders.


Disclaimer for coding information on Medical Policies           

Procedure and diagnosis codes on Medical Policy documents are included only as a general reference tool for each policy. They may not be all-inclusive.           

The presence or absence of procedure, service, supply, device or diagnosis codes in a Medical Policy document has no relevance for determination of benefit coverage for members or reimbursement for providers. Only the written coverage position in a medical policy should be used for such determinations.           

Benefit coverage determinations based on written Medical Policy coverage positions must include review of the member’s benefit contract or Summary Plan Description (SPD) for defined coverage vs. non-coverage, benefit exclusions, and benefit limitations such as dollar or duration caps.

ICD-9 Codes

249.6, 250.6, 250.60, 250.61, 250.62, 250.63, 277, 277.3, 277.30, 277.31, 277.39, 277.7, 278.00, 278.01, 278.02, 327.2, 327.20, 327.21, 327.23, 327.27, 327.29, 337, 337, 337.0, 337.00, 337.09, 337.1, 337.2, 337.20, 337.21, 337.22, 337.29, 337.9, 356, 356.0, 356.1, 356.2, 356.3, 356.4, 356.8, 356.9, 357.2, 357.4, 357.81, 427.89, 493, 493.0, 493.00, 493.01, 493.02, 493.1, 493.10, 493.11, 493.12, 493.2, 493.20, 493.21, 493.22, 493.8, 493.9, 493.90, 493.91, 493.92, 649.10, 649.11, 649.12, 649.13, 649.14, 710.2, 780.2, 780.51, 780.53, 780.57, 780.8, 785.0

Procedural Codes: 95921, 95922, 95923, 0341T
  1. Low, P., Ferguson, J.H., et al. (The Therapeutics and Technology Assessment Subcommittee). Assessment:  Clinical autonomic testing. American Academy of Neurology (1996) 1-10.
  2. Assessment: Clinical Autonomic Testing—Report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. American Academy of Neurology Practice Committee (1996).
  3. Cariga, P., Catley, M., et al. Characteristics of habituation of the sympathetic skin response to repeated electrical stimuli in man. Clinical neurophysiology (2001 October) 112(10):1875-80.
  4. Oskarsson, B., Quan, D., et al. Idiopathic orthostatic hypotension and other autonomic failure syndromes. eMedicine Specialties (2006 December 8). Available at (accessed – 2008 March 31).
  5. Recommended Policy for Electrodiagnostic Medicine. Rochester, Minnesota:  American Association of Neuromuscular & Electrodiagnostic Medicine, with American Academy of Neurology and American Academy of Physical Medicine and Rehabilitation (2008).
  6. Gibbons CH, Illigens BMW, et al. QDIRT: Quantitative Direct and Indirect Testing of Sudomotor Function. Neurology. 2008; 70(24): 2299–304.
  7. Illigens BMW and CH Gibbons. Sweat testing to evaluate autonomic function. Clin Auton Res. 2009; 19(2): 79–87.
  8. J.D. England, J.D., Gronseth, G.S., et al. Practice Parameter: The Evaluation of Distal Symmetric Polyneuropathy: The Role of Autonomic Testing, Nerve Biopsy, and Skin Biopsy (An Evidence-Based Review) Report of the American Academy of Neurology, the American Association of Neuromuscular and Electrodiagnostic Medicine, and the American Academy of Physical Medicine and Rehabilitation. PM&R 1:1 (14-22) (2009 January).
  9. Autonomic Nervous System Function Testing. CMS Medicare Local Coverage Determination (LCD) L3672 (2006 April 4) Available at <> (accessed – 2010 June 14).
  10. ANSAR ANX 3.0. The Ansar Group, Inc. Available at (accessed –2010 June 14).
  11. Automated pupillometry in neurocritical care. Neuroptics. Available at: (accessed October 9, 2013).
  12. Bremner F. Pupil evaluation as a test for autonomic disorders. Clin Auton Res. 2009 Apr; 19(2):88-101. Epub 2009 Feb 3.
August 2013  New 2013 BCBSMT medical policy.
March 2014 Document updated. The following was added: Quantitative pupillometry is considered experimental, investigational and/or unproven to evaluate the autonomic nervous system function. CPT/HCPCS code(s) updated.
®Registered marks of the Blue Cross and Blue Shield Association, an association of independent Blue Cross and Blue Shield Plans. ®LIVE SMART. LIVE HEALTHY. is a registered mark of BCBSMT, an independent licensee of the Blue Cross and Blue Shield Association, serving the residents and businesses of Montana.
CPT codes, descriptions and material only are copyrighted by the American Medical Association. All Rights Reserved. No fee schedules, basic units, relative values or related listings are included in CPT. The AMA assumes no liability for the data contained herein. Applicable FARS/DFARS Restrictions Apply to Government Use. CPT only © American Medical Association.
Autonomic Nervous System (ANS) Testing