1. Aetna considers quantitative sensory testing (QST) experimental and investigational for the management of individuals with neuropathy or any other diagnoses because its diagnostic value has not been established.

2. Aetna considers current perception threshold (CPT) testing experimental and investigational because the effectiveness and clinical applicability of this testing in diagnosing and/or managing diabetic peripheral neuropathy or other diseases has not been established.

3. Aetna considers voltage-actuated sensory nerve conduction threshold (VsNCT) testing experimental and investigational because its clinical value has not been established in the peer reviewed published medical literature.

Quantitative sensory tests are techniques employed to measure the intensity of stimuli needed to produce specific sensory perceptions. They are used to evaluate a sensory detection threshold or other sensory responses from supra-threshold stimulation. The common physical stimuli are (i) touch-pressure, (ii) vibration, and (iii) coolness, warmth, cold pain, and heat pain. In QST, the subject must be able to comprehend what is being asked by the test, alert and not taking mind-altering medications, and not biased to a certain test outcome.

Abnormal or elevated QST measurements are not specific in the diagnosis of any particular type of neuropathy, and in fact do not necessarily indicate any form of peripheral neuropathy. There are no prospective clinical studies demonstrating that quantitative tests of sensation improve the management and clinical outcomes of patients over standard qualitative methods of sensory testing.

The vibrometer is a device used for measuring sensation/sensitivity to vibration. Testing of vibration sense can be adequately performed with a tuning fork of 128 Hz.

The American Academy of Neurology evaluated the clinical utility, efficacy, and safety of QST (Shy et al, 2003). The authors concluded that QST is a potentially useful tool for measuring sensory impairment for clinical and research studies. However, QST results should not be the sole criteria used to diagnose pathology. Because malingering and other non-organic factors can influence the test results, QST is not currently useful for the purpose of resolving medicolegal matters. Well-designed studies comparing different QST devices and methodologies are needed and should include patients with abnormalities detected solely by QST.

The American Association of Electrodiagnostic Medicine (Chong and Cros, 2004) stated that available literature data do not allow conclusions regarding the relative merits of individual QST instruments.

Current perception threshold (CPT) testing (also known as sensory nerve conduction threshold testing) entails the quantification of the sensory threshold to transcutaneous electrical stimulation. It has been used to examine sensory nerves. In general, CPT testing falls into the general category of QST. CPT testing has been studied for a wide range of clinical applications such as evaluation of peripheral neuropathies, detection of carpal tunnel syndrome, spinal radiculopathy, evaluation of the effectiveness of peripheral nerve blocks, quantification of hypoesthetic and hyperesthetic conditions and differentiation of psychogenic from neurological disorders. The Neurometer® Current Perception Threshold (Neurotron, Inc., Baltimore, MD) and the Medi-Dx 7000™ (Neuro Diagnostic Associates, Inc., Laguna Beach, CA) are two devices cleared by the FDA through the 510k process for the use of measuring the threshold for sensory nerve conduction. These devices have been used to detect metabolic, toxic, acquired, hereditary, compression, traumatic, and other peripheral neuropathies as well as sensory impairments resulting from central nervous system pathology. However, the effectiveness and clinical applicability of CPT testing in diagnosing and/or managing a disease has not been established.

A study by Tack et al (1994) compared CPT testing at different frequencies with standardized clinical examination scores. The authors concluded that CPT testing “seemed rather insensitive at detecting neuropathy”. Compared with standard clinical examination, CPT testing “is only of limited value, mainly because of high variability and poor reproducibility”.

An assessment on the use of electroneurometer in the diagnosis of carpal tunnel syndrome (CTS) conducted by the American Association of Electrodiagnostic Medicine (David et al, 2003) reached the following conclusions:

It is the opinion of the American Association of Electrodiagnostic Medicine (AAEM) that all of the literature reviewed and describing the nervepace digital electroneurometer (NDE) and neurosentinel (NS) are flawed. Limb temperature, which affects the speed of nerve conduction, was controlled in only one study. In most reports, reference populations were not studied to provide a scientifically based source for control values. Standard statistical measures of latency values (mean, standard deviation, and range) were not specified in most reports. Moreover, most studies comparing NDE and NS to standard nerve conduction studies (NCSs) make an incorrect assumption: that distal motor latency or an isolated digital sensory latency values are sensitive measures for diagnosing median nerve entrapment at the wrist. In fact, detailed sensory NCSs, including segmental stimulation across the palm-to-wrist segment or in comparison to adjacent sensory nerves, is by far the more sensitive technique in this regard and is probably the earliest finding in median nerve entrapment at the wrist. It is the opinion of the AAEM that the NDE, as well as the newer NS, are experimental and are not effective substitutes for standard electrodiagnostic studies in clinical evaluation of patients with suspected CTS.

The Medi-Dx 7000™ (Neuro Diagnostic Associates) is a voltage-actuated sensory nerve conduction test (VsNCT) device. The device was cleared by the FDA based on a 510(k) application.  An updated version of the Medi-DX 7000 is the Neural-Scan™ (Neuro Diagnostic Associates, Inc.), which is a current potential threshold test with a potentiometer.  The V-sNCT measures the voltage amplitude necessary to cause a discernable nerve impulse. VsNCT results are adjusted and compared to population means. The most severe hypoesthesia is considered the primary lesion. There is no peer-reviewed published medical literature on the use of voltage-actuated sensory nerve conduction tests and their impact on clinical outcomes.

In March 2004, the Center for Medicare and Medicaid Services (CMS) reaffirmed its non-coverage policy on the current perception threshold and sensory nerve conduction threshold test (sNCT). CMS (2004) concluded that “there continues to be insufficient scientific or clinical evidence to consider the sNCT test and the device used in performing this test as reasonable and necessary”.

In a review on the usefulness and limitations of QST in neuropathic pain states, Hansson et al (2007) stated that there is a lack of specificity of current QST databases; thus QST can not be used alone for diagnosis of a neurological lesion. The authors also noted that QST is not useful in predicting which patients with post-herpetic neuralgia (PHN) or peripheral neuropathy would benefit from lidocaine patches. Also, serial QST evaluations in patients with acute herpes zoster failed to predict who would develop PHN. Furthermore, the authors stated that the expected role of QST in the definition of a mechanisms-based approach to neuropathic pain has not yet been met.