Coverage Policy Manual
Policy #: 1998141
Category: Medicine
Initiated: August 1998
Last Review: October 2018
  Current Perception Threshold Test

Determination of current perception threshold has the potential for evaluation of patient with peripheral nervous system diseases resulting in altered cutaneous sensation.  It may be used as a substitute for standard nerve conduction studies in diagnosing carpal or tarsal tunnel syndrome.
FDA approval of devices for measurement of current perception threshold initially occurred in the 1980s.  A 1998 assessment by the American Association of Electrodiagnostic Medicine (AAEM) questions the effectiveness of this testing.  A review was done of five clinical reports published since the technology was introduced as a way to diagnose median nerve entrapment at the wrist.  The criteria against which these studies were measured are:
    • prospective study;
    • clinical diagnosis of carpal tunnel syndrome independent of the results of electrodiagnostic tests;
    • sufficiently detailed description of the stimulating and recording methods to permit duplication of studies;
    • limb temperature monitored and reported;
    • reference values reported in the article are obtained either with concomitant studies of a reference population or with previous but identical studies of a reference population in the same laboratory; and
    • criteria of abnormality obtained from the reference population and defined in statistical terms (mean, standard deviation, and/or range).  None of the reviewed studies met more than three of the six criteria.
There is a HCPCS code, G0255, (Current perception threshold/sensory nerve conduction test, (SNCT) per limb, any nerve ) Another distinction between a nerve conduction test and the current perception threshold test is that the former is performed in a laboratory setting, while the latter is performed in an office setting. Codes 95907-95913 might now be incorrectly reported for these services.

The use of the Nervespace Digital Electroneurometer, the Neurometer CPT,  the Pressure-Specifying Sensory Device (PSSD), or any similar device, does not meet member benefit certificate primary coverage criteria that there be scientific evidence of effectiveness in improving health outcomes.
For contracts without primary coverage criteria, the use of the Nervespace Digital Electroneurometer, the Neurometer CPT, the Pressure-Specifying Sensory Device (PSSD), or any similar device  is considered investigational.  Investigational services are an exclusion in the member certificate of coverage.

Quantitative sensory testing (QST) can either be used as the initial diagnostic test or as a monitoring test in patients to assess ongoing sensory deficits. The type of data required to validate QST in these 2 different settings are different. For example, as an initial diagnostic test, one would like to see standard measures of diagnostic performance, such as sensitivity, specificity, positive and negative predictive values as compared to conventional tests, such as monofilament testing, pinprick, etc. In some cases, QST has been proposed as an alternative to nerve conduction studies, and, in this setting, one would like to compare the diagnostic performances of these 2 tests. When used as a monitoring technique, test/retest reliability is an important outcome, as well as defining a clinically significant change in sensory perception. As with any diagnostic test, it is important to evaluate how the results of the test will be used to enhance patient management, either in terms of instituting more prompt or more effective therapy, or in the avoidance of more invasive tests, such as nerve conduction studies.
In a 2003 report, the American Academy of Neurology (AAN) noted QST should not be used as a sole method for diagnosis of pathology.  The AAN indicated QST poses technical challenges in the methodology of testing, reproducibility, and psychophysical factors that limit the objectivity of testing results. Siao and Cros noted in a review that QST is influenced by many extraneous factors and may be subject to misinterpretation and misuse.  In addition, normal reference levels do not exist, and the reproducibility of QST has not been firmly established. Also, there are no generally recognized standards for QST techniques, performance, and interpretation.
Current Perception Threshold Testing
In 1999, the American Association of Electrodiagnostic Medicine (AAEM) published a technology review of the Neurometer® device.  This evaluation suggested the following criteria for the evaluation of the device:
    • A prospective study
    • Independent ascertainment of the clinical condition evaluated
    • A detailed description of the methodology
    • Attention to testing conditions that could potentially affect the results
    • A suitable reference population from the same laboratory
    • Criteria for abnormality obtained from the reference population and defined in statistical terms.
The AAEM assessment concluded that there is inadequate scientific literature meeting the above criteria to validate the clinical role of current perception threshold testing. Much of the literature compares the results of Neurometer® testing to nerve conduction studies in patients with known disease. In many instances the results of the Neurometer® testing demonstrated more numerous or pronounced abnormalities compared to nerve conduction studies, which was consistent with the hypothesis that abnormalities of small nerve fibers precede those of large nerve fibers tested in nerve conduction studies. However, this observation could also be related to the fact that use of the Neurometer® involves testing at multiple sites with 3 different frequencies and that any identified abnormality is considered significant. Testing the perception threshold at different frequencies is designed to evaluate the function of different subclasses of nerve fibers. However, this hypothesis has not been adequately evaluated, in part due to a lack of a diagnostic gold standard for comparison purposes. In this situation, validation of a diagnostic technology requires study of how the technique is used in the management of the patient and whether subsequent changes in the management of the patient are associated with improved health outcomes. Finally, results of the Neurometer® testing are compared to a normal reference population. The review by the AAEM found that the source of the normal values was not apparent from the published literature. The AAEM assessment concluded with the following recommendations regarding research to validate the clinical utility of the Neurometer®:
    • Reference values need to be established for well-characterized and representative populations.
    • Reproducibility and interoperator variability of the Neurometer® CPT normal values need to be established and expressed statistically in control subjects and patients with specific diseases.
    • The sensitivity and specificity need to be established and compared to an appropriate standard.
    • In promotional material, the Medi-Dx 7000™ device is presented as an alternative to the Neurometer® with the capability of identifying abnormalities in branches of individual nerves. A literature review failed to identify any articles in the published peer-reviewed literature specifically focusing on the Medi-Dx 7000™ device.
In an updated review of the literature, 2 studies reported on attempts to establish the diagnostic utility of current perception threshold testing. In Yamashita, 48 patients with lumbar radiculopathy were compared with 11 healthy controls to evaluate current perception thresholds using the Neurometer®.  The authors reported finding significantly higher current perception threshold values in the affected legs of patients with lumbar radiculopathy at 2000, 250, and 5 Hz frequencies than in the unaffected legs. Current perception threshold values in the affected legs were also significantly higher in control subjects at 2000 and 250 Hz frequencies but not significantly different at 5 Hz. The authors concluded that current perception threshold testing may be useful in quantifying sensory nerve dysfunction in patients with radiculopathy. However, there was no discussion of how this quantification could be used in the management of the patient.
Park and colleagues attempted to validate current perception threshold testing against the gold standard references for thermal sensory testing and von Frey tactile hair stimulation in a randomized, double-blind, placebo-controlled trial on 19 healthy volunteers. The authors reported finding that all current perception threshold measurements showed a higher degree of variability than thermal sensory testing and von Frey measurements, but concluded that there is some evidence that similar fiber tracts may be measured, especially C-fiber tract activity at 5 Hz, with current perception threshold, thermal sensory, and von Frey testing methods. However, none of these studies sufficiently address the AAEM recommendations for research to validate the clinical utility of current perception threshold testing.
Pressure-Specified Sensory Testing
A review of the literature on pressure-specified sensory device (PSSD) testing found insufficient evidence to demonstrate that PSSD testing will provide any further information than what can ordinarily be determined during standard evaluation and management of patients 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, NCV testing. While PSSD may be a useful adjunct in neurosensory testing, no clinical trials were identified that demonstrated that use of the PSSD resulted in earlier and/or more accurate diagnoses of nerve damage and improved patient outcomes. Nor were any studies found that examined this technology for patient selection criteria for carpal or tarsal tunnel release, plexus neurolysis, etc. In addition, no clinical practice guidelines were found that addressed the use of PSSD. As noted here, in the evaluation of current perception threshold testing, further research is needed to validate the clinical utility of PSSD; to establish reference values for well-characterized and representative populations; to establish normal values in control subjects and patients with specific diseases to reduce interoperator variability and increase reproducibility; and to establish sensitivity and specificity comparisons to appropriate standards.
2006 Update
A literature review was conducted for the period of March 2005 through July 2006. No clinical studies were found that would alter the policy statement noted above. While studies using these technologies continue, the impact of this testing on improving clinical outcomes has not been shown. There also continues to be questions about the performance of the test; one recent study noted “significant” variability in thermal perception thresholds during a 1-hour time in 24 female volunteers.
2007-2008 Update
A search of the MEDLINE database was performed for the period of August 2006 through February 2008. A multicenter study funded by a pharmaceutical company compared vibration threshold testing (CASE IV, biothesiometer, C64 graduated tuning fork) with standard nerve conduction studies (NCS) in 195 (86% follow-up) subjects with diabetes mellitus. The tests were performed independently by trained technicians; all NCS evaluations were sent to a central reading center. Intra-class correlation coefficients for the tests ranged from 0.81 to 0.95, indicating excellent to highly reproducible results. Correlation coefficients for the various vibration QST instruments were moderate at -0.55 (CASE IV vs. tuning fork) to 0.61 (CASE IV vs. biothesiometer). In contrast, the correlation coefficient between CASE IV and a composite score for nerve conduction was low (r = 0.24). These results indicate that vibration threshold testing could not replace NCS testing, but might provide a complementary outcome measure. Overall, questions remain about the clinical utility of sensory nerve conduction threshold testing. Evidence is insufficient to demonstrate an improvement in health outcomes. Therefore, the policy statement remains unchanged.
Physician Specialty Society and Academic Medical Center Input
In response to the request for input from Physician Specialty Societies and Academic Medical Centers, input was received through the American Academy of Neurology and one academic medical center regarding use of quantitative sensory testing while the policy was under review. Input from both sources agreed with the policy statement that QST is considered investigational, as adopted in the policy in April 2008.
A 2003 report from the American Academy of Neurology concluded that QST is probably (level B recommendation) an effective tool in the documentation of sensory abnormalities and in documenting changes in sensory thresholds in longitudinal evaluation of patients with diabetic neuropathy. Evidence was weak or insufficient to support the use of QST in patients with other conditions (small fiber sensory neuropathy, pain syndromes, toxic neuropathies, uremic neuropathy, acquired and inherited demyelinating neuropathies, or malingering). General recommendations indicated that QST results should not be the sole criterion used to diagnose structural pathology, or either a peripheral or central nervous system (CNS) origin. Abnormalities on QST must be interpreted in the context of a thorough neurologic examination and other appropriate testing, such as electromyography (EMG), nerve biopsy, skin biopsy, or appropriate imaging studies.
The American Association of Electrodiagnostic Medicine published a technology literature review on quantitative sensory testing (light touch, vibration, thermal, and pain) in 2004. The review concluded that QST is a reliable psychophysical test of large- and small-fiber sensory modalities, but is highly dependent on the full cooperation of the patient. Abnormalities do not localize dysfunction to the central or peripheral nervous system, and no algorithm can reliably distinguish between psychogenic and organic abnormalities. The AAEM technology review also indicated that QST has been shown to be reasonably reproducible over a period of days or weeks in normal subjects, but for individual patients, more studies are needed to determine the maximum allowable difference between 2 QSTs that can be attributed to experimental error.
In 2004 the European Federation of Neurological Societies published guidelines on neuropathic pain assessment. The task force concluded that QST is helpful to quantify the effects of treatments on allodynia and hyperalgesia (grade A recommendation), but recommends the use of simple tools such as a brush and high-threshold von Frey filaments. Because QST abnormalities are also found in non-neuropathic pains, QST abnormalities cannot be taken as a conclusive demonstration of neuropathic pain. The recommendations also indicated that QST is expensive and time consuming, and thus difficult to use in clinical practice.
2012 Update
A search of the MEDLINE database conducted through July 2012 did not reveal any new information that would prompt a change in the coverage statement.
2013 Update
A search of the MEDLINE database through July 2013 did not reveal any new literature that would prompt a change in the coverage statement. No comparative studies evaluating the impact of current perception testing on patient management decisions or health outcomes were identified.
Limited published evidence is available on the diagnostic performance of current perception threshold testing. Several studies have compared current perception threshold testing to other testing methods, but sensitivity and specificity have not been reported. For example, in 2012, Ziccardi and colleagues evaluated 40 patients presenting with trigeminal nerve injuries involving the lingual branch (Ziccardi, 2012).   Patients underwent current perception threshold testing, as well as standard clinical sensory testing. Statistically significant correlations were found between findings of electrical stimulation testing at 250 Hz and the reaction to pinprick testing (p=0.02), reaction to heat stimulation (p=0.01) and reaction to cold stimulation (p=0.004). In addition, significant correlations were found between electrical stimulation at 5 Hz and the reaction to heat stimulation (p=0.017), reaction to cold stimulation (p=0.004), but not the reaction to pinprick testing (p=0.096).
2014 Update
A literature search conducted through September 2014 did not reveal any new information that would prompt a change in the coverage statement. The key identified literature is summarized below.
A 2014 study by Ahmed et al addressed how QST might be used in practice, although it did not directly study clinical utility (Ahmad, 2014). The study was prospective and included 124 opioid-naïve patients scheduled for abdominal myomectomy or hysterectomy. Patients underwent preoperative thermal QST, conducted by the same investigator. Tests included warm and cold sensation in which patients activated a button as soon as they felt a temperature change and warm and cold pain modalities in which the button was pressed when pain thresholds were reached.
The primary outcome was morphine use in the 24 hours after surgery. Intravenous morphine was administered post-surgery such that an individual’s pain level rated less than 4 on a 0 to 10 scale; pain was assessed upon arrival and every 6 hours thereafter. In addition, a patient-controlled analgesia system was used to deliver morphine in the first 24 hours. Preoperative heat and cold pain thresholds were significantly correlated with 24-hour morphine consumption. Patients with initial heat pain thresholds above the median and cold pain thresholds above the median used more morphine (a median of 19 mg more, p=0.004). The authors stated that findings could be used to stratify patients pre-operatively based on their baseline thermal QST scores and manage patients’ more or less aggressively depending on their QST test findings. However, since the study did not prospectively manage patients and opioid administration was individualized to each patient; it is not clear how management would differ if QST scores had been incorporated in the management strategy.
2016 Update
A literature search conducted through September 2016 did not reveal any new information that would prompt a change in the coverage statement. The key identified literature is summarized below.
A 2015 study by Vuilleumier and colleagues evaluated reliability of QST in a low-back pain population; it included evaluation of thermal QST using an FDA-approved device by Medoc (Vuilleumier, 2015). A total of 89 patients participated in 2 QST sessions conducted at least 7 days apart. The median of 3 thermal perception trials on the first day was compared to the median on the second day (between-session reliability). Several measures of reliability were reported, ie the coefficient of variability (CV), the intraclass correlation coefficient (ICC) and the coefficient of reliability (CR). The reliability of heat pain detection and tolerance at the arm and leg were considered to be acceptable, with between-session CVs ranging from 1.8-6.1%. However, cold pain detection at the arm or leg did not have acceptable reliability, with between-session CVs ranging from 44- 87%.
2017 Update
A literature search conducted using the MEDLINE database through September 2017 did not reveal any new information that would prompt a change in the coverage statement.
2018 Update
A literature search was conducted through September 2018.  There was no new information identified that would prompt a change in the coverage statement.  The key identified literature is summarized below.
Vibration Perception Testing
Clinically Valid
Goel et al published a cross-sectional study comparing the diagnostic performance of several testing methods to detect early symptoms of diabetic peripheral neuropathy (Goel, 2017). Five hundred twenty-three patients with type 2 diabetes between the ages of 18 and 65 (mean, 49.4 years) were first assessed with the modified Neuropathy Disability Score as the reference standard; then both feet were tested with electrochemical skin conductance, VPT, and Diabetic Neuropathy Symptom Score. For feet electrochemical skin conductance less than 60 μS, VPT, and Diabetic Neuropathy Symptom Score, the sensitivity was 85%, 72%, and 52%, respectively; specificity was 85%, 90%, and 60%, respectively. There was a significant inverse linear relation between VPT and feet electrochemical skin conductance (r
= -0.45, p<0.001); feet electrochemical skin conductance was determined to be superior to VPT for identifying early signs of diabetic peripheral neuropathy (DPN). The study lacked follow-up data.
Azzopardi et al published a prospective multicenter cross-sectional study comparing 3 types of vibration screening used to diagnose DPN (Azzopardi, 2018). The study collected data from 100 patients (age range, 40-80 years) who had type 2 diabetes for at least 10 years. Each participant was assessed with a VibraTip (not registered with FDA), neurothesiometer, and 128-Hz tuning fork in both feet. Vibrations were not perceived by 28.5% of patients when using VibraTip, 21% using a neurothesiometer, and 12% using a tuning fork; a small-to-moderately strong association (Cramer’s V, 0.167) was found between the instruments. The study lacked a criterion standard for assessing neuropathy. The authors concluded that multiple methods of assessment would be necessary to avoid a false-negative diagnosis.
Thermal Sensory Testing
Clinically Valid
Anand et al assessed 30 patients with nonfreezing cold injury, or trench foot, described as a peripheral vaso-neuropathy (Anand, 2017). The authors evaluated use of skin biopsies immunohistochemistry, clinical examination of the feet, including pinprick, as well as QST assessments, and NCSs as diagnostic tools. Abnormal pinprick sensation was reported in 67% of patients. Monofilament perception threshold was abnormal in 63% of patients, 40% for VPT thresholds, and between 67% and 83% for the various thermal thresholds; NCSs showed 23% of subjects had axonal neuropathy. It was noted that performing QST could be difficult for patients with cutaneous hypersensitivity and severe limb pain. No study limitations were reported.

95926Short-latency somatosensory evoked potential study, stimulation of any/all peripheral nerves or skin sites, recording from the central nervous system; in lower limbs
95927Short-latency somatosensory evoked potential study, stimulation of any/all peripheral nerves or skin sites, recording from the central nervous system; in the trunk or head
G0255Current perception threshold/sensory nerve conduction test, (SNCT) per limb, any nerve

References: Abraham A, Albulaihe H, Alabdali M, et al.(2015) Elevated vibration perception thresholds in CIDP patients indicate more severe neuropathy and lower treatment response rates. PLoS One. 2015;10(11):e0139689. PMID 26545096

Ahmad S, De Oliveira GS, Jr., Bialek JM, et al.(2014) Thermal quantitative sensory testing to predict postoperative pain outcomes following gynecologic surgery. Pain Med. May 2014;15(5):857-864. PMID 24517836

Am Association of Electrodiagnostic Medicine Technology Review: Nervespace Digital Electroneurometer. Muscle Nerve 1999; Sup 8; S243-6.

Anand P, Privitera R, Yiangou Y, et al.(2017) Trench foot or non-freezing cold injury as a painful vaso-neuropathy: clinical and skin biopsy assessments. Front Neurol. Front Neurol. Sep 2017;8:514. PMID 28993756

Azzopardi K, Gatt A, Chockalingam N, et al.(2018) Hidden dangers revealed by misdiagnosed diabetic neuropathy: A comparison of simple clinical tests for the screening of vibration perception threshold at primary care level. Prim Care Diabetes. Apr 2018;12(2):111-115. PMID 29029862

Baquis GD, Brown, WF, Capell JT, et al.(1999) Technology Review: The Neurometer Current Perception Threshold (CPT). Am Assoc Electrodiagnostic Med 1999; Sup 8:S247-S259.

Chaudhry V.(1997) Nervespace Digital Electroneurometer. Muscle and Nerve 1997; Sept 1200-1203.

Goel A, Shivaprasad C, Kolly A, et al.(2017) Comparison of electrochemical skin conductance and vibration perception threshold measurement in the detection of early diabetic neuropathy. PLoS One. Sep 2017;12(9):e0183973. PMID 28880907

Lefaucheur JP, Wahab A, Plante-Bordeneuve V, et al.(2015) Diagnosis of small fiber neuropathy: A comparative study of five neurophysiological tests. Neurophysiol Clin. Dec 2015;45(6):445-455. PMID 26596193

NK Pressure-Specified Sensory Device™ (Sensory Management Services LLC) for Tarsal Tunnel Syndrome Diagnosis. Hayes Brief: Oct 2006.

Peripheral nerve decompression for diabetic neuropathy. Hayes Brief: May 2006.

Vuilleumier PH, Biurrun Manresa JA, Ghamri Y, et al.(2015) Reliability of quantitative sensory tests in a low back pain population. Reg Anesth Pain Med. Jul 28 2015. PMID 26222349

Ziccardi VB, Dragoo J, Eliav E et al.(2012) Comparison of current perception threshold electrical testing to clinical sensory testing for lingual nerve injuries. J Oral Maxillofac Surg 2012; 70(2):289-94.

Group specific policy will supersede this policy when applicable. This policy does not apply to the Wal-Mart Associates Group Health Plan participants or to the Tyson Group Health Plan participants.
CPT Codes Copyright © 2019 American Medical Association.