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.
Blue Cross and Blue Shield of Montana (BCBSMT) may consider 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) 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:
- 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;
- Evaluate the severity and distribution of a diagnosed progressive autonomic neuropathy;
- Differentiate the diagnosis between certain complicated variants of syncope from other causes of loss of consciousness;
- Evaluate inadequate response to beta blockade in vasodepressor syncope;
- Evaluate distressing symptoms in the patient with a clinical picture suspicious for distal small fiber neuropathy in order to diagnose the condition;
- Differentiate the cause of postural tachycardia syndrome;
- Evaluate change in type, distribution or severity of autonomic deficits in patients with autonomic failure;
- Evaluate the response to treatment in patients with autonomic failure who demonstrate a change in clinical exam;
- Diagnose axonal neuropathy or suspected autonomic neuropathy in the symptomatic patient;
- Evaluate and diagnose sympathetically maintained pain, as in reflex sympathetic dystrophy or causalgia; or
- Evaluate and treat patients with recurrent unexplained syncope to demonstrate autonomic failure.
BCBSMT considers autonomic nervous system (ANS) testing experimental, investigational and unproven for all other indications that do not meet the above criteria, including but not limited to:
- Screening or routine testing of patients without signs or symptoms of autonomic dysfunction, including patients with diabetes, hepatic or renal disease;
- Testing for the sole purpose of monitoring disease intensity or treatment efficacy in diabetes, hepatic or renal disease;
- Patients with a clearly diagnosed somatic neuropathy, especially demyelinating neuropathies;
- Patients with uncomplicated vasovagal syncope;
- General diagnosis of conditions including, but not limited to:
- Anxiety and/or stress,
- General wellness,
- 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.
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.
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.
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.
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.