Quantitative vibration threshold testing in carpal tunnel syndrome: analysis strategies for optimizing reliability

Pain mechanisms in carpal tunnel syndrome: a systematic review and meta-analysis of quantitative sensory testing outcomes

ABSTRACT

Carpal tunnel syndrome (CTS) is the most common nerve compression in the arm. A mix of peripheral and central contributions on quantitative sensory testing (QST) has been reported in the literature. Thus, this systematic review or meta-analysis aimed to identify the dominant sensory phenotype and draw conclusive evidence about the presence of central sensitization (CS) in CTS. Based on an a priori published protocol and using PRISMA guidelines, 7 databases were searched (Embase, Web of Science, Scopus, PubMed, SAGE, EBSCOhost, and ProQuest). Eligible studies compared the QST findings of individuals with subacute and chronic CTS with those of healthy controls through thermal, mechanical, and vibration detection thresholds; thermal, pressure, and mechanical pain thresholds; mechanical pain sensitivity; presence of allodynia; wind-up ratio; and conditioned pain modulation. Thirty-seven studies were included in the qualitative analysis. Results showed a significant loss of all detection thresholds of hand median nerve territories and hand extramedian areas (little finger and hand dorsum) in CTS (P < 0.05) but no significant difference (P > 0.05) in wind-up ratio, cold, heat, or mechanical pain thresholds of the median nerve territories. Furthermore, there was a significant increase in mechanical pain sensitivity in median nerve territories and remotely in the forearm (P < 0.05) and a significant gain in pressure and heat pain thresholds in the carpal area (P < 0.05). Conditioned pain modulation was impaired in CTS. Hypoesthesia and increased thermal and mechanical pain ratings are the dominant sensory phenotype with inconclusive evidence about CS in CTS due to the heterogenous results of thermal and mechanical pain thresholds.

Examining practice effects in repeated measurements of vibration perception thresholds on finger pulps of healthy individuals - Is it possible to improve your results over a clinically relevant test interval?

Aims

To investigate practice effects in a test-retest situation, where vibration perception thresholds (VPT) were measured in healthy subjects using a multi-frequency test method.

Methods

In eight consecutive tests, VPTs were tested in the pulps of the index and little fingers at seven frequencies (8, 16, 32, 64, 125, 250 and 500 Hz). Subjects were twenty healthy adults aged 26 to 65 years (mean 46.0 ± 11.1 years; 10 male and 10 female). The subjects were examined at six tests with intervals of one month (mean 33 ± 6; time 0 to month 5) and at two additional tests with prolonged intervals (month 12 and 18). Linear mixed model analysis was performed to investigate differences over the subsequent test occasions. To examine where potential practice effects occurred, a pairwise comparison with Bonferroni correction was made.

Results

Small decreases in VPTs were found in 8 out of the 14 frequencies (index finger: 8, 16, 32, 250 and 500 Hz; little finger: 16, 250 and 500 Hz) within the test period from time 0 to month 5. In tests at 12 and 18 months, VPTs were increased compared to month 5, but lowered in comparison with time 0. Hence, minor significant decreases were found in three frequencies for the index finger (125, 250 and 500 Hz) and one frequency for the little finger (250 Hz) when examining VPTs with prolonged time intervals.

Conclusions

When evaluating vibration perception thresholds in a clinically relevant time period of once or twice a year, no consideration of practice effects is necessary when interpreting the results.

Hand Pain and Sensory Deficits: Carpal Tunnel Syndrome

The Academy of Orthopaedic Physical Therapy and the Academy of Hand and Upper Extremity Physical Therapy have an ongoing effort to create evidence-based clinical practice guidelines (CPGs) for orthopaedic and sports physical therapy management and prevention of musculoskeletal impairments described in the World Health Organization's International Classification of Functioning, Disability and Health (ICF). This particular guideline focuses on hand pain and sensory deficits in carpal tunnel syndrome. J Orthop Sports Phys Ther 2019;49(5):CPG1-CPG85. doi:10.2519/jospt.2019.0301.

Comparison of 2 methods of neuropathic pain assessment in carpal tunnel syndrome and hand functions

OBJECTIVE

To compare the effectiveness of the Leeds Assessment of Neuropathic Symptoms and Signs Scale (LANSS) to the painDETECT questionnaire (PD-Q) in Carpal Tunnel Syndrome (CTS), and determine if there are any differences between hand related functions in the 2 questionnaires.

METHODS

This prospective clinical trial was conducted from April to July 2014. Ninety patients with a positive Tinel or Phalen sign were recruited. Hands were evaluated by electromyography and grouped according to mild, moderate or severe involvement. Neuropathic pain was analysed by the LANSS and the PD-Q; hand functions were evaluated by the Duruoz Hand Index (DHI), Semmes Weinstein monofilaments and grip strength.

RESULTS

Electromyographic findings revealed 32.9% of hands had mild, 61.8% had moderate and 5.3% had severe CTS. There was a correlation between the LANSS scores and the Visual Analogue Scale (VAS) pain, while the PD-Q scores were correlated with the VAS pain, DHI and Semmes Weinstein Monofilaments (SWM). Comparison of the hand related parameters of the questionnaires showed there was a statistically significant difference between the 2 groups with respect to the DHI and SWM tests in the PD-Q. However, there was no difference in the LANSS.

CONCLUSION

Although there was a significant correlation between the LANSS and PD-Q scores, the PD-Q scores revealed better correlation coefficients in VAS pain, DHI scores and SWM tests. In conclusion, the PD-Q seems to be better than the LANSS both in neuropathic pain and in detecting functions related to hand abilities.

The Impact of Sensory, Motor and Pain Impairments on Patient- Reported and Performance Based Function in Carpal Tunnel Syndrome

Background:

Research has suggested that persistent sensory and motor impairments predominate the symptoms experienced by patients with carpal tunnel syndrome (CTS); with intermittent pain symptoms, being less predominant.

Objective:

The study aims to determine the relative contribution of sensory, motor and pain impairments as contributors to patient-report or performance-based hand function.

Methods:

Fifty participants with a diagnosis of CTS confirmed by a hand surgeon and electrodiagnosis were evaluated on a single occasion. Impairments were measured for sensibility, pain and motor performance. A staged regression analysis was performed. In the first step, variables with each of the 3 impairment categories were regressed on the Symptom Severity Scale (SSS) to identify the key variables from this domain. Models were created for both self report (Quick Disabilities of arm, shoulder and hand- Quick DASH) and performance based (Dexterity) functional outcomes. Backward regression modelling was performed for SSS and then, to allow comparability of the importance of different impairments across models, the 7 significant variables from the SSS model were forced into the models.

Results:

Variables: age, touch threshold and vibration threshold of the little finger of unaffected hand, median-ulnar vibration threshold ratio of affected hand, mean pain tolerance of unaffected hand, grip strength and pinch strength of affected hand, explained 31%, 36% and 63% of the variance in SSS, Quick DASH and dexterity scores, respectively.

Conclusion:

Hand function in patients with CTS is described by variables that reflect sensory status of the median and ulnar nerves, the persons pain threshold, grip and pinch strength impairments and age.

Psychophysical and Patient Factors as Determinants of Pain, Function and Health Status in Shoulder Disorders

Objective:

To estimate the extent to which psychophysical quantitative sensory test (QST) and patient factors (gender, age and comorbidity) predict pain, function and health status in people with shoulder disorders. To determine if there are gender differences for QST measures in current perception threshold (CPT), vibration threshold (VT) and pressure pain (PP) threshold and tolerance.

Design:

A cross-sectional study design.

Setting:

MacHAND Clinical Research Lab at McMaster University.

Subjects:

34 surgical and 10 nonsurgical participants with shoulder pain were recruited.

Method:

Participants completed the following patient reported outcomes: pain (Numeric Pain Rating, Pain Catastrophizing Scale, Shoulder Pain and Disability Index) and health status (Short Form-12). Participants completed QST at 4 standardized locations and then an upper extremity performance-based endurance test (FIT-HaNSA). Pearson r’s were computed to determine the relationships between QST variables and patient factors with either pain, function or health status. Eight regression models were built to analysis QST’s and patient factors separately as predictors of either pain, function or health status. An independent sample t-test was done to evaluate the gender effect on QST.

Results:

Greater PP threshold and PP tolerance was significantly correlated with higher shoulder functional performance on the FIT-HANSA (r =0.31-0.44) and lower self-reported shoulder disability (r = -0.32 to -0.36). Higher comorbidity was consistently correlated (r =0.31-0.46) with more pain, and less function and health status. Older age was correlated to more pain intensity and less function (r =0.31-0.57). In multivariate models, patient factors contributed significantly to pain, function or health status models (r² =0.19-0.36); whereas QST did not. QST was significantly different between males and females [in PP threshold (3.9 vs. 6.2, p < .001) and PP tolerance (7.6 vs. 2.6, p < .001) and CPT (1.6 vs. 2.3, p =.02)].

Conclusion:

Psychophysical dimensions and patient factors (gender, age and comorbidity) affect self-reported and performance-based outcome measures in people with shoulder disorders.

Triggering of Carpal Tunnel Syndrome Symptoms in Patients Using Urban Public Transportation

Background: Carpal tunnel syndrome (CTS) is the most common compressive neuropathy found in clinical practice. Recent studies evaluated which external factors could be involved in the CTS symptoms, including prolonged exposure to vibration, especially in the upper limb. This study investigated signs and symptoms in patients with CTS after using urban transport on (1) both upper limbs, (2) how long before these symptoms appear, and (3) the hands position or body reaction during the act of pressing the safety bars. Methods: The study was conducted from July 2012 to April 2013. A total of 205 (178 women and 27 men) patients were evaluated. CTS was diagnosed in 285 hands. All participants answered a questionnaire formulated by the authors. The questionnaire was applied by researchers who were single-blinded and not involved in the research. Results: Most of the participants (87%) were women, but there was no statistical significance in age between groups (women = 51.24 ± 8.47 years, men = 51.10 ± 6.52 years, P > .05). The symptoms appeared significantly in the first 15 minutes after boarding when compared with patients who had no symptoms during the journey. There was no difference between hands position along the journey and the onset of symptoms. Conclusions: The onset of symptoms in patients with CTS using urban public transportation most commonly occurred in the first 15 minutes after boarding. Public transport vibration seems to be, at least in part, directly related to the development of symptoms. Questionnaires for the assessment of paresthesia symptoms during the use of public transport may be useful for CTS diagnosis.

The relationship between the Patient-rated Ulnar Nerve Evaluation and the common impairment measures of grip strength, pinch strength, and sensation

STUDY DESIGN

Prospective cohort study.

INTRODUCTION

Grip strength, pinch strength, and sensory threshold are common evaluations used on a daily basis. Identifying how these variables relate to function for patients allows these assessments to be used for screening to identify who may benefit from surgical intervention, and provides valuable information about what impairments patients think are important with respect to functional use of their upper extremity. Therapists can use this information to focus rehabilitation programs on the most important impairments.

PURPOSE

To evaluate the relationship between the Patient-rated Ulnar Nerve Evaluation (PRUNE) and impairment measures of grip strength, pinch strength, and one-point sensory threshold.

METHODS

Data was prospectively collected from 77 patients before surgery and during regular time points for 2 years following surgery. Patients completed the PRUNE, grip and pinch strength measures, and a one-point sensory threshold evaluation. Correlations between these variables were calculated at baseline, 2 years after surgery, and for change scores during the 2-year follow up. A multiple regression analysis was used to determine the contribution of the impairment variables for determining functional change.

RESULTS

Grip strength showed moderate, statistically significant correlation with PRUNE scores at both baseline (r = -0.38) and at two years (r = -0.29). There was also a statistically significant correlation between one point sensory threshold for the small finger at two years (r = 0.36), but not at baseline. Change in grip strength (r = -0.28) and pinch strength (r = -0.30) both demonstrated significant correlations with PRUNE change scores. Overall, changes in grip strength, pinch strength, and sensation accounted for 20% of the variance in PRUNE changes.

CONCLUSION

Since grip strength was most highly correlated with PRUNE scores at baseline and at two years, rehabilitation programs that target grip strengthening is supported. While neither grip nor pinch strength were significant contributors to the regression when used together, each showed significant contributions to PRUNE variability when used in the model independently. Therefore, a combination of grip and pinch strengthening may be important during rehabilitation for improving functional results in patients that undergo surgical intervention for cubital tunnel syndrome.

LEVEL OF EVIDENCE

2b.

Test-retest reliability of neurophysiological tests of hand-arm vibration syndrome in vibration exposed workers and unexposed referents

Background

Exposure to hand-held vibrating tools may cause the hand-arm vibration syndrome (HAVS). The aim was to study the test-retest reliability of hand and muscle strength tests, and tests for the determination of thermal and vibration perception thresholds, which are used when investigating signs of neuropathy in vibration exposed workers.

Methods

In this study, 47 vibration exposed workers who had been investigated at the department of Occupational and Environmental Medicine in Gothenburg were compared with a randomized sample of 18 unexposed subjects from the general population of the city of Gothenburg. All participants passed a structured interview, answered several questionnaires and had a physical examination including hand and finger muscle strength tests, determination of vibrotactile (VPT) and thermal perception thresholds (TPT). Two weeks later, 23 workers and referents, selected in a randomized manner, were called back for the same test-procedures for the evaluation of test-retest reliability.

Results

The test-retest reliability after a two week interval expressed as limits of agreement (LOA; Bland-Altman), intra-class correlation coefficients (ICC) and Pearson correlation coefficients was excellent for tests with the Baseline hand grip, Pinch-grip and 3-Chuck grip among the exposed workers and referents (N = 23: percentage of differences within LOA 91 – 100%; ICC-values ≥0.93; Pearson r ≥0.93). The test-retest reliability was also excellent (percentage of differences within LOA 96–100 %) for the determination of vibration perception thresholds in digits 2 and 5 bilaterally as well as for temperature perception thresholds in digits 2 and 5, bilaterally (percentage of differences within LOA 91 – 96%). For ICC and Pearson r the results for vibration perception thresholds were good for digit 2, left hand and for digit 5, bilaterally (ICC ≥ 0.84; r ≥0.85), and lower (ICC = 0.59; r = 0.59) for digit 2, right hand. For the latter two indices the test-retest reliability for the determination of temperature thresholds was lower and showed more varying results.

Conclusion

The strong test-retest reliability for hand and muscle strength tests as well as for the determination of VPTs makes these procedures useful for diagnostic purposes and follow-up studies in vibration exposed workers.

The construct validity and responsiveness of sensory tests in patients with carpal tunnel syndrome

Background and Purpose :

Sensory evaluation is fundamental to evaluation of patients with Carpal Tunnel Syndrome (CTS). The purpose of this study was to determine the construct validity and responsiveness for sensory threshold tests in patients with CTS.

Methods :

Sixty-three patients diagnosed with CTS were evaluated prior to orthotic intervention and again at follow up at 6 and 12 weeks. Sensory tests included touch threshold PSSD (Pressure Specified Sensory Device) and vibration threshold (Vibrometer). Construct validity was assessed by comparing sensory tests to hand function, and dexterity testing using Spearman rho (r_s). Patients were classified as either responders or non-responders to orthotic intervention based on the change score of the Symptom Severity Scale (SSS) of 0.5. Responsiveness of the sensory tools was measured using ROC (receiver operating characteristic) curves, SRM (Standardized Response Mean), and ES (Effect Sizes).

Results :

The PSSD had low to moderate correlations (r_s ≤ 0.32) while Vibrometer scores had moderate correlations (r_s = 0.36 - 0.41) with dexterity scores. The Clinically Important Difference (CID) for the PSSD was estimated at 0.15 g/mm² but was not discriminative. The Vibrometer demonstrated moderate responsiveness, with a SRM = 0.61 and an ES = 0.46 among responders. The PSSD had a SRM = 0.09 and an ES = 0.08 and showed low responsiveness for patients with a clinically important improvement in symptoms.

Conclusion :

Measurement properties suggest that the Vibrometer was preferable to the PSSD because it was more correlated to hand function, and was more responsive. Clinicians may choose use the Vibrometer opposed to the PSSD for determining important change in sensation after orthotic intervention.

Effect of coating over the handle of a drill machine on vibration transmissibility

This study was to see the effect of different coatings on the handle of hand-held drilling machines. Out of five different handles chosen for this study, including one handle uncoated. Root mean square (rms) values of the vibration levels (acceleration) were recorded at the surface of handle and wrist of the operators. Results showed that maximum vibrations were reduced by coating of handle coated with rubber sheet and Rexene (H4) followed by handle coated with cotton sandwiched between jeans cloth (H5). Equivalent vibrations transmitted through coating of handles coated with sponge and velvet (H2) and jute and cotton (H3) were of almost same magnitude and these two coated handles were able to reduce least vibration transmitted. Transmissibility of vibrations along dominant (Z) direction was analyzed using ANOVA. Results showed that coating on handles significantly affected vibration transmitted in Z direction. Vibration transmissibility ratios were found to be 0.354, 0.571, 0.408, 0.4326, and 0.3555 for handles H1, H2, H3, H4 and H5 respectively.

Sensory nerve action potentials and sensory perception in women with arthritis of the hand

Background

Arthritis of the hand can limit a person’s ability to perform daily activities. Whether or not sensory deficits contribute to the disability in this population remains unknown. The primary purpose of this study was to determine if women with osteoarthritis (OA) or rheumatoid arthritis (RA) of the hand have sensory impairments.

Methods

Sensory function in the dominant hand of women with hand OA or RA and healthy women was evaluated by measuring sensory nerve action potentials (SNAPs) from the median, ulnar and radial nerves, sensory mapping (SM), and vibratory and current perception thresholds (VPT and CPT, respectively) of the second and fifth digits.

Results

All SNAP amplitudes were significantly lower for the hand OA and hand RA groups compared with the healthy group (p < 0.05). No group differences were found for SNAP conduction velocities, SM, VPT, and CPT.

Discussion

We propose, based on these findings, that women with hand OA or RA may have axonal loss of sensory fibers in the median, ulnar and radial nerves. Less apparent were losses in conduction speed or sensory perception.

A blinded placebo-controlled randomized trial on the use of astaxanthin as an adjunct to splinting in the treatment of carpal tunnel syndrome

BACKGROUND

Nutritional supplementation is a potential adjunct in the conservative management of carpal tunnel syndrome (CTS). This study investigated whether astaxanthin (a beta-carotenoid) increased the effectiveness of splinting in managing CTS.

METHODS

This is a triple-blinded randomized controlled trial where 63 patients with electrodiagnostically confirmed CTS were randomly allocated into either the experimental group (n = 32) (astaxanthin-4-mg capsules + splinting) or the control group (n = 31) (placebo + splinting). Medications were taken for 9 weeks followed by a 3-week washout. The primary outcome measure was the Symptom Severity Scale (SSS). Secondary outcome measures in the study included physical impairments, disability, and health status measures. Electrodiagnostic testing was performed before entry into the study and again at 12 weeks. All other outcomes were measured at baseline, 6, and 12 weeks.

RESULTS

There was a reduction in symptoms as measured by the SSS over the course of treatment in both groups (p = 0.002), but no differences between the groups (p = 0.18). The Disability of Arm, Shoulder and Hand questionnaire and the Short Form 36-item Health Survey showed no effects over time or between treatment groups. The baseline difference between the groups in the level of total cholesterol and low-density lipoproteins remained constant over the course of the study. Impairment measures demonstrated no significant changes in grip, dexterity, or sensation.

CONCLUSION

At present, the role for astaxanthin as an adjunct in conservative management of CTS has not been established.

Progress in vibrotactile threshold evaluation techniques: a review

Vibrotactile threshold (VT) testing has been used for nearly a century to investigate activation of human somatosensory pathways. This use of vibrotactile stimuli provides a versatile tool for detecting peripheral neuropathies, and has been broadly used for investigation of carpal tunnel syndrome. New applications include investigation of drug-induced neuropathies and diabetes-related neuropathies. As a feedback device, the vibrotactile stimuli could be used as an information delivery system for rehabilitative feedback devices for upper limb musculoskeletal disorders or as information channels for the visually impaired. This review provides a comprehensive review of the advancement in VT measurement techniques over time and a comparison of these techniques in terms of various hardware features used and the testing protocols implemented. The advantages and limitations of these methods have been discussed along with specific recommendations for their implementation and suggestions for incorporation into clinical practice.

Developing biologically-based assessment tools for physical therapy management of neck pain

SYNOPSIS

Neck pain is a common and episodic condition that is treated using a spectrum of interventions known to be moderately effective but is associated with a significant incidence of chronic pain. Recently, there has been increased focus on defining biological aspects of neck pain. Studies have indicated that neurophysiological, biomechanical, and motor control abnormalities are present and may be useful either in prognosis or classification. We review some of these findings in the context of our own work defining biological markers that may form the basis for clinical tests that can be used for prognosis, classification, or outcome evaluation in patients with neck pain. We have identified abnormalities in neurophysiology using quantitative sensory testing (vibration, touch, and current perception) and response to cold provocation that are related to neck disability. We have identified altered muscle biochemistry by measuring circulating muscle proteins in a lumbar surgery model and are now applying those methods to whiplash injury. We have incorporated capnography into treatment to address central physiological changes present in some patients by monitoring and training CO2 levels. We have developed an innovative new test, the Neck Walk Index, that captures abnormal control of head movement during slow gait as a means of differentiating patients with neck pain from either unaffected controls or individuals with other pathologies. We have used time-varying 3-dimensional joint orientation kinematics to assess deficits in motor control during an upper extremity reach task, the results showing that poor coordination and control of the shoulder girdle leads to shoulder guarding and inconsistencies in elbow joint movement. Despite some promising early results, future research is needed to determine how these measures help clinicians to diagnose, evaluate, and forecast future outcome for patients who present with neck pain.

LEVEL OF EVIDENCE

Diagnosis, level 5.

Clinical diagnosis of carpal tunnel syndrome: a systematic review

The purposes of this systematic review were to examine the properties of clinical tests used in the diagnosis of carpal tunnel syndrome (CTS) and to provide estimates of their sensitivity and specificity. A literature search was conducted using two databases-PubMed and the Cumulative Index to Nursing and Allied Health Literature (CINAHL)-from 1986 to June 2003, and hand-searching reference lists of retrieved articles. Two reviewers evaluated the papers for quality using an evaluation tool developed by one of the authors. Estimates of sensitivity and specificity were determined by averaging values across studies weighted by sample size. Although 60 studies were reviewed in detail, many were of poor quality (mean quality score was 6.6 of 12, with only 15 of 60 obtaining a score of 8 or greater). The most frequently studied test was Phalen's, with an overall estimate of 68% sensitivity and 73% specificity. Next was Tinel's, with estimates of 50% and 77%, and then carpal compression, with estimates of 64% and 83% for sensitivity and specificity, respectively. Two-point discrimination and testing of atrophy or strength of the abductor pollicis brevis proved to be specific but not very sensitive. The estimates determined in this review should help therapists choose clinical tests with the appropriate balance of sensitivity and specificity required for diagnosing carpal tunnel syndrome in their specific clinical environments.

Clinical and electrodiagnostic testing of carpal tunnel syndrome: a narrative review

Carpal Tunnel Syndrome (CTS) is a pressure-induced neuropathy that causes sensorimotor disturbances of the median nerve, which impair functional ability. A clear history that elicits relevant personal and work exposures and the nature of symptoms can lead to a high probability of a correct diagnosis. Hand diagrams and diagnostic questionnaires are available to provide structure to this process. A variety of provocative tests have been described and have variable accuracy. The Phalen's wrist flexion and the carpal compression tests have the highest overall accuracy, while Tinel's nerve percussion test is more specific to axonal damage that may occur as a result of moderate to severe CTS. Sensory evaluation of light touch, vibration, or current perception thresholds can detect early sensory changes, whereas 2-point discrimination changes and thenar atrophy indicate loss of nerve fibers occurring with more severe disease. Electrodiagnosis can encompass a variety of tests and is commonly used to assess the presence/severity of neuropathic changes and to preclude alternative diagnoses that overlap with CTS in presentation. The pathophysiologic changes occurring with different stages of nerve compression must be considered when interpreting diagnostic test results and predicting response to physical therapy management.