Medical Policy

This document addresses quantitative sensory testing (QST) used for the noninvasive evaluation of sensory nerve function in individuals with symptoms of neurologic damage or those at risk for such damage. QST systems can assess and quantify the physical stimuli required for sensory perception to occur. Various testing modalities used in QST can evaluate the sensory nerves involved in touch, pressure, pain, thermal (warm and cold), and vibration.

This document highlights two QST methods: threshold testing, also known as current perception sensory nerve conduction threshold testing, and pressure-specified sensory device testing.

Investigational and Not Medically Necessary:

Quantitative sensory testing including, but not limited to current perception threshold testing, also known as sensory nerve conduction threshold testing, and pressure-specified sensory device testing is considered investigational and not medically necessary.

Summary

Although extensively studied, QST remains methodologically inconsistent and clinically unvalidated. Thresholds change with equipment and protocol, the method lacks reference ranges and minimal clinically important differences, and test-retest studies reveal wide limits of agreement. Composite thermal metrics achieve only moderate accuracy, and data from large populations indicate that single-modality tests cannot distinguish between chronic pain syndromes and controls. Reflecting these shortcomings, the American Academy of Neurology (AAN) advises against QST as a standalone diagnostic tool. Because no evidence shows that QST results can reliably guide management or improve outcomes, all modalities, including current perception threshold and pressure-specified sensory testing, are considered investigational.

Discussion

Quantitative Sensory Testing

QST can be used either as an initial diagnostic test or as a monitoring test in individuals with sensory deficits. QST has been proposed as an alternative to nerve conduction testing, but QST is able to evaluate large, small, and unmyelinated nerve fibers, whereas nerve conduction studies are limited to large fiber nerves. When used as a monitoring technique, test and retest reliability are important factors. QST is a psychophysiological test much like audiometry and ophthalmological refraction but, unlike those tests, the clinically significant change for QST has not been defined, and reference standards have been difficult to establish.

A 2021 international consensus on pain assessment in chronic pancreatitis published by Drewes endorsed QST only in specialist centers to phenotype nociceptive profiles (strong recommendation, moderate evidence), preferably with non‑invasive somatic stimuli (conditional) and, more tentatively, to forecast treatment response (weak). The same document repeatedly labels QST a “research tool,” underscoring limited generalizability and uncertain outcome impact.

In addition, a guideline from the European Academy of Neurology (EAN) and  the European Pain Federation (EPF) (Truini, 2023) gives only a weak endorsement for thermal‑mechanical QST as an adjunct in specialized centers to document somatosensory damage when diagnosing neuropathic pain. Given the narrow specialist scope of both guidelines, neither establishes general clinical utility for QST.

Additional research indicates that combining multiple thermal QST parameters can enhance diagnostic accuracy. In a retrospective analysis of 384 individuals evaluated for polyneuropathy, the presence of either an abnormal cold-detection threshold or warm-detection threshold yielded 69 % sensitivity and 70 % specificity for small-fiber impairment (Galosi, 2025). The same composite reached 78 % sensitivity and 70 % specificity for definitive small-fiber neuropathy. When that composite result was integrated with small-fiber-related clinical signs (thermal or pain hypoesthesia), specificity climbed to 100 % while sensitivity remained 78 %, producing a positive predictive value of 100 % and a negative predictive value of 97 %.

In a reaffirmed 2025 report, the Therapeutics and Technology Assessment Subcommittee of the AAN stated that QST should not be used as a sole method for diagnosis of pathology. The AAN indicated that QST poses technical challenges in test methodology and reproducibility, plus psychophysical factors that limit objectivity. The authors also noted that QST is influenced by many extraneous factors and may be subject to misinterpretation and misuse. In addition, normal reference values vary between various methodologies. The reproducibility of QST has not been firmly established as there is significant variability between the different testing techniques and interpretation of results. In a review of technology literature concerning QST, the American Association of Electrodiagnostic Medicine (Chong, 2004) concluded, the “Literature data do not allow a conclusion regarding the relative merits of individual QST instruments.”

Pattern-based analytics may further enhance QST’s clinical relevance. In a prospective cohort of 75 individuals diagnosed with acute somatosensory-stroke, a gradient-boosting classifier to analyze 6 QST features measured before the onset of pain (Asseyer, 2025). The gradient-boosting classifier is an ensemble of decision trees that iteratively re-weights misclassified observations. This model predicted central post-stroke pain with 84.6 % overall accuracy, receiver operating characteristic - area under the curve (ROC-AUC, 0.85), 75 % recall, and 75 % precision. Notably, about 80 % of both pain and non-pain stroke participants exhibited bilateral QST abnormalities, challenging the use of the ipsilesional side as an internal control. These findings suggest that multi-parameter QST signatures, interpreted through machine-learning models, may offer prognostic insight that single thresholds cannot. Larger multi-center trials are needed to confirm the results of this study.

Addressing technical hurdles, Klit and colleagues (2025) compared the conventional Method-of-Limits (MoL) with the adaptive Psi staircase in 43 adults with diabetic neuropathy (38 included in the pin-electrode analysis). The Psi algorithm converged after 20-30 stimuli and required, on average, 29 fewer stimuli than MoL, saving roughly one minute per assessment. Despite a strong correlation between methods (r=0.95), broad limits of agreement (−42 % to +84 %) indicated the two approaches should not be interchanged for single-participant decisions. These results demonstrate that newer staircase algorithms can improve efficiency without completely eliminating individual-level variability.

A systematic review and meta-analysis of 25 publications (Petersen, 2023) analyzing the use of QST for pain management for knee osteoarthritis. It showed some predictive value in QST parameters, the review cautioned about publication bias and heterogeneity among studies necessitating additional research.

Rhee (2024) published results from a large, population-based cohort (n= 3022) of community-dwelling twins showed that none of 10 individual QST modalities (thermal, mechanical, or pain thresholds) distinguished participants with chronic widespread pain, dry-eye disease, or irritable-bowel syndrome from controls. Mann-Whitney U p-values ranged from 0.076 to 0.874, and mixed-effects logistic models likewise failed to reach significance. This finding reinforces that single-modality QST remains an imprecise phenotyping tool for heterogeneous chronic-pain syndromes.

Sensory Nerve Conduction Threshold Testing

Sensory nerve conduction threshold testing has been investigated for a broad range of clinical applications including 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 neurologic disorders.

Freeman and colleagues (2003) reported on a case series that examined the differentiation between QST results for small and large fiber sensory loss among individuals with peripheral neuropathy, normal controls, and a group of normal participants who were asked to attempt simulating sensory loss during the testing. All participants were tested for cold and vibration perception levels with the CASE IV sensory testing system. There were no differences between performance characteristics in the two simulation trials. Responses to null stimuli did not differentiate between groups. Freeman and colleagues concluded, “Test performance characteristics do not permit discrimination among subjects simulating sensory loss, subjects with normal responses, and subjects with peripheral neuropathy.”

In 2003, the Centers for Medicare and Medicaid Services (CMS) issued a decision memorandum in support of a national non-coverage determination for sensory nerve conduction threshold testing, which considered both the Neurometer and the Medi-Dx 7000^TM device (Neuro Diagnostic Associates, Inc., Laguna Beach, CA). CMS established the following principles in assessing these devices:

• The device must have conclusive diagnostic ability as supported by strong test performance (that is, an accepted reference standard against which to compare the sensory nerve perception threshold testing devices both in terms of sensitivity and specificity), definition of normative values; and/or
• The quantitative information provided actually affected individual management and led to an improvement in individual net health outcomes.

The CMS document noted,

Relatively simple, non-invasive tests might have a value in the initial assessment of symptomatic patients to determine if more invasive tests are warranted. Sensory nerve conduction threshold testing is considered by some to be such a device. However, the evidence still must demonstrate that the simpler test has an acceptable level of validity otherwise it cannot reliably predict who will need more invasive tests.

Based on their extensive analysis, CMS concluded, “Based on the evidence as a whole, CMS concludes that the use of any type of sensory nerve conduction testing device … to diagnose sensory neuropathies or radiculopathies in Medicare beneficiaries is not reasonable and necessary.”

Pressure-Specified Sensory Device Testing

The Pressure-Specified Sensory Device (PSSD) is a form of QST which assesses large myelinated sensory nerve function by a computer-based form of two-point discrimination testing. There is insufficient evidence to demonstrate PSSD testing provides any further information than standard evaluation and management of individuals with potential nerve compression, disease, or damage. Standard evaluation and management consist of physical examination techniques and may include Semmes-Weinstein monofilament testing and, in some more complex cases, nerve conduction velocity testing. While PSSD may be a useful adjunct in neurosensory testing, no clinical trials were identified demonstrating the use of the PSSD resulted in earlier or more accurate diagnosis of nerve damage and improved individual outcomes. In addition, no clinical practice guidelines were found addressing the use of PSSD.

Results of three  studies  provide limited evidence PSSD may be more sensitive than some existing tests (Radoiu, 2005; Siemionow, 2006; Wood, 2005). However, the number of individuals evaluated was limited in size in each study: Wood evaluated 17 individuals with diabetic ulceration or amputation, Siemionow assessed 25 with peripheral nerve dysfunction, and Radoiu prospectively tested 35 participants with chronic nerve compression and neuropathy, finding PSSD to have higher sensitivity than other methods.  More robust studies are needed to confirm the clinical utility and establish validated reference values for PSSD.

Quantitative Sensory Testing

QST systems quantify the intensity of stimulus required for sensory perception. Stimuli used in QST include touch, pressure, pain, thermal (warm and cold), vibratory, or electric current. Depending on the type of stimuli used, QST can assess small or large fiber dysfunction. QST with touch and vibration can evaluate large myelinated A alpha and A beta sensory fibers. Thermal stimuli can assess small myelinated fibers and unmyelinated sensory nerve function. Low strength alternating electrical currents of selected frequencies are also reported to selectively stimulate different axons.

QST has been proposed for use in the diagnosis and management of a variety of conditions such as diabetic neuropathy and other uremic and toxic neuropathies, as well as carpal tunnel syndrome and other nerve entrapment/compression disorders or damage.

Because QST evaluates an individual’s subjective response to objective physical sensory stimuli, it is psychophysical in nature. This requires the tested individual to be alert, able to follow directions, and cooperative. Due to the subjective component of testing, psychological factors must be taken into consideration during testing and in evaluating test results, thus reducing the degree of objectivity that QST can provide.

Sensory Nerve Conduction Threshold Testing

Sensory nerve conduction threshold testing, which also may be referred to as current perception threshold testing, involves measuring the minimal amount of transcutaneous (across the skin) electrical stimulation required to evoke a sensation in the individual. An area of the skin that corresponds to a specific nerve is tested. It is proposed that the extent of nerve damage an individual has suffered can be determined by measuring the amount of electrical stimulation needed for the individual to feel the stimuli. In theory, the greater the degree of nerve damage, the greater the quantity of electrical stimulation required to trigger a response in the nerve fibers and then be perceived. Sensory nerve conduction threshold testing differs from some other forms of quantitative sensory testing (QST) in that it employs electrical stimulation to generate a response from the axons while other forms of QST use non-electrical physical stimuli of the sensory receptors being tested.

In sensory nerve conduction threshold testing, three different frequencies of electrical stimuli are typically used, each targeting a specific type of nerve fiber:

• At 2000 Hz, selective stimulation occurs, targeting A-beta fibers, which are large, myelinated fibers that conduct sensations related to touch, vibration, and mild pressure.
• 250 Hz selectively stimulates A-delta fibers, which are smaller, myelinated fibers that conduct sensations related to cold temperatures and some pain.
• 5 Hz selectively stimulates C fibers, which are unmyelinated and conduct sensations related to warmth and some types of pain.

The U.S. Food and Drug Administration (FDA) has cleared multiple devices for quantitative sensory testing (QST), including various modalities for measuring sensory nerve function. For current perception threshold testing specifically, the FDA has cleared the Neurometer^® (Neurotron, Inc., K853608, cleared 1986) and the Medi-Dx 7000 (Neuro-Diagnostic Associates, K964622, cleared 1997), which is marketed as the Neural-Scan™. The Neural-Scan is a current perception threshold test with a potentiometer.

In addition to these current perception threshold devices, the FDA has cleared devices for other QST modalities, including pressure-specified sensory testing, vibration perception, thermal/heat pain thresholds, and general pain threshold assessment.

Pressure-Specified Sensory Testing

Pressure-specified sensory testing is a method to assess nerve function by quantifying the thresholds of pressure detected with light, static, and moving touch. The Pressure-Specified Sensory Device^™ (Sensory Management Services LLC, Baltimore, MD) consists of one or two blunt probes and sensitive transducers to measure and record the perception thresholds of pressure on the surface of the body in grams per square millimeter. The technique is an advanced modification of the two-point discrimination methodology. The device has been used to aid in the diagnosis and assessment of nerve function, including diabetic peripheral neuropathy, carpal tunnel syndrome, and other nerve entrapment or compression syndromes, and postoperative assessment of sensory outcomes after liposuction and breast reduction mammaplasty. The Pressure-Specified Sensory Device received FDA 510(k) marketing clearance in August 1994.

The following codes for treatments and procedures applicable to this document are included below for informational purposes. Inclusion or exclusion of a procedure, diagnosis or device code(s) does not constitute or imply member coverage or provider reimbursement policy. Please refer to the member's contract benefits in effect at the time of service to determine coverage or non-coverage of these services as it applies to an individual member.

When Services are Investigational and Not Medically Necessary:
For the following procedure codes, or when the code describes a procedure indicated in the Position Statement section as investigational and not medically necessary.

Peer Reviewed Publications:

1. Asseyer S, Panagoulas E, Maidhof J, et al. Prediction of central post-stroke pain by quantitative sensory testing. Ann Neurol. 2025; 97(3):507-520.
2. den Bandt HL, Paulis WD, Beckwée D, et al. Pain mechanisms in low back pain: a systematic review with meta-analysis of mechanical quantitative sensory testing outcomes in people with nonspecific low back pain. J Orthop Sports Phys Ther. 2019; 49(10):698-715.
3. Freeman R, Chase KP, Risk MR. Quantitative sensory testing cannot differentiate simulated sensory loss from sensory neuropathy. Neurology. 2003; 60(3):465-470.
4. Galosi E, Litewczuk D, De Stefano G, et al. Diagnostic accuracy of quantitative sensory testing for detecting small fiber impairment in polyneuropathy and diagnosing small fiber neuropathy. Pain. 2025; Jun 19. Epub ahead of print.
5. Hubscher M, Moloney N, Leaver A, et al. Relationship between quantitative sensory testing and pain or disability in people with spinal pain - a systematic review and meta-analysis. Pain. 2013; 154(9):1497-1501.
6. Klit FØ, Bollerslev VM, Borbjerg MK, et al. Improving perception threshold tracking for rapid evaluation of diabetic peripheral neuropathy. Muscle Nerve. 2025; 71(2):183-190.
7. Nogueira MP, Paley D, Bhave A, et al. Nerve lesions associated with limb-lengthening. J Bone Joint Surg Am. 2003; 85-A(8):1502-1510.
8. Petersen KK, Kilic K, Hertel E, et al. Quantitative sensory testing as an assessment tool to predict the response to standard pain treatment in knee osteoarthritis: a systematic review and meta-analysis. Pain Rep. 2023; 8(4):e1079.
9. Radoiu H, Rosson GD, Andonian E, et al. Comparison of measures of large-fiber nerve function in patients with chronic nerve compression and neuropathy. J Am Podiatr Med Assoc. 2005; 95(5):438-445.
10. Rhee A, Granville Smith I, Compte R, et al. Quantitative sensory testing and chronic pain syndromes: a cross-sectional study from TwinsUK. BMJ Open. 2024; 14:e085814.
11. Siao P, Cros DP. Quantitative sensory testing. Phys Med Rehabil Clin N Am. 2003; 14(2):261-286.
12. Siemionow M, Zielinski M, Sari A. Comparison of clinical evaluation and neurosensory testing in the early diagnosis of superimposed entrapment neuropathy in diabetic patients. Ann Plast Surg. 2006; 57(1):41-49.
13. Sorensen L, Molyneaux L, Yue DK. The level of small nerve fiber dysfunction does not predict pain in diabetic neuropathy: a study using quantitative sensory testing. Clin J Pain. 2006; 22(3):261-265.
14. Technology Review: the Neurometer Current Perception Threshold (CPT). American Association of Electrodiagnostic Medicine Equipment and Computer Committee. American Association of Electrodiagnostic Medicine. Muscle Nerve. 1999; 22(4):523-531.
15. Vuilleumier PH, Biurrun Manresa JA, Ghamri Y, et al. Reliability of quantitative sensory tests in a low back pain population. Reg Anesth Pain Med. 2015; 40(6):665-673.
16. Wood WA, Wood MA, Werter SA, et al. Testing for loss of protective sensation in patients with foot ulceration: a cross-sectional study. J Am Podiatr Med Assoc. 2005; 95(5):469-474.

Government Agency, Medical Society, and Other Authoritative Publications:

1. Centers for Medicare and Medicaid Services. National Coverage Determination. Sensory Nerve Conduction Threshold Tests (sNCTs). NCD# 160.23. Effective 4/1/2004. Available at: https://www.cms.gov/medicare-coverage-database/search.aspx?redirect=Y&from=Overview&list_type=ncd. Accessed on July 16, 2025.
2. Centers for Medicare and Medicaid Services. Decision Memorandum. Reconsideration of national coverage determination: sensory nerve conduction threshold testing. July 8, 2003. Available at: http://www.cms.gov/medicare-coverage-database/details/nca-decision-memo.aspx?NCAId=26&NCDId=270&ncdver=2&NcaName=Electrodiagnostic+Sensory+Nerve+Conduction+Threshold&IsPopup=y&bc=AAAAAAAACAAAAA%3D%3D&. Accessed on July 16, 2025.
3. Chong PS, Cros DP. American Association of Electrodiagnostic Medicine Review: quantitative sensory testing equipment and reproducibility studies. 2004. Available at: https://www.aanem.org/docs/default-source/documents/practice/qsttechniques.pdf?sfvrsn=5d0a3517_1/qstTechniques. Accessed on July 16, 2025.
4. Chong PS, Cros DP. American Association of Electrodiagnostic Medicine Practice topic in electrodiagnostic medicine. American Association of Electrodiagnostic Medicine. Technology literature review: quantitative sensory testing. Muscle Nerve. 2004b; 29(5):734-747.
5. Drewes AM, van Veldhuisen CL, Bellin MD, et al. Assessment of pain associated with chronic pancreatitis: an international consensus guideline. Pancreatology. 2021; 21(7):1256-1284.
6. Shy ME, Frohman EM, So YT, et al. Quantitative sensory testing: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Reaffirmed February 8, 2025. Neurology. 2003; 60(6):898-904.
7. Truini A, Aleksovska K, Anderson CC, et al. Joint European Academy of Neurology-European Pain Federation-Neuropathic pain special interest group of the international association for the study of pain guidelines on neuropathic pain assessment. Eur J Neurol. 2023; 30(8):2177-2196.

Current Perception Threshold Testing
Medi-Dx 7000
Neural-Scan
Neurometer
Pressure-Specified Sensory Device Testing
Sensory Nerve Conduction Threshold Testing
VsNCT (Voltage-Actuated Sensory Nerve Conduction Threshold)

The use of specific product names is illustrative only. It is not intended to be a recommendation of one product over another, and is not intended to represent a complete listing of all products available.

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