Use of nerve conduction studies in carpal tunnel syndrome.

This review article examines the use of nerve conduction studies in the management of carpal tunnel syndrome. These studies should be understood not as a test that determines the diagnosis but as a measure of impaired nerve function. They are sensitive indicators of local demyelination and axonal loss that can detect and quantify these changes before the appearance of clinical signs, providing information that cannot be obtained with the unaided senses of the physician, nor by any other investigation. They are the best available indicator of overall disease severity, correlating with symptoms and anatomical change in the median nerve. They have some prognostic value for surgical outcome and are sufficiently sensitive to change for the evaluation of treatment response. When surgery does not yield the expected improvement in symptoms, they can help to establish whether decompression has been achieved provided preoperative results are available for comparison.

Do nerve conduction studies or ultrasound imaging correlate more closely with subjective symptom severity in carpal tunnel syndrome?

INTRODUCTION/AIMS: Previous studies have reported weak correlations between neurophysiological measurements and subjective severity of symptoms in carpal tunnel syndrome, with Pearson r ≤ 0.26. We hypothesize that this resulted in part from patient-to-patient variability in the assessment of subjective severity using tools such as the Boston Carpal Tunnel Questionnaire. To compensate for this, we aimed to assess within-patient differences in symptom and test result severity. METHODS: In our study we used retrospective data from 13 005 patients with bilateral electrophysiological results and 790 patients with bilateral ultrasound imaging drawn from the Canterbury CTS database. Measures of neurophysiological (nerve conduction studies [NCS] grade) and anatomical (cross-sectional area on ultrasound) severity within individual patients were compared between the right and left hands, eliminating individual variation in the way in which patients interpret the questionnaire. RESULTS: There was a correlation found between right-hand NCS grade and symptom severity score (Pearson r = -0.302, P < .001, n = 13,005), but not between right-hand cross-sectional area and symptom severity (Pearson r = 0.058, P = .10, n = 790). In the within-subject analyses, there were significant correlations between symptoms and NCS grade (Pearson r = 0.6, P < .001, n = 6521) and between symptoms and cross-sectional area (Pearson r = 0.3. P < .001, n = 433). DISCUSSION: The simple correlation between symptomatic and electrophysiological severity was comparable with previous studies, but within-patient analysis revealed that the relationship was stronger than previously reported and strong enough to be clinically useful. The relationship between symptoms and cross-sectional area measurement on ultrasound imaging was weaker.

Local corticosteroid injection versus placebo for carpal tunnel syndrome.

BACKGROUND: Carpal tunnel syndrome (CTS) is a very common clinical syndrome manifested by signs and symptoms of irritation of the median nerve at the carpal tunnel in the wrist. Direct and indirect costs of CTS are substantial, with estimated costs of two billion US dollars for CTS surgery in the USA in 1995 alone. Local corticosteroid injection has been used as a non-surgical treatment for CTS many years, but its effectiveness is still debated. OBJECTIVES: To evaluate the benefits and harms of corticosteroids injected in or around the carpal tunnel for the treatment of carpal tunnel syndrome compared to no treatment or a placebo injection. SEARCH METHODS: We used standard, extensive Cochrane search Methods. The searches were 7 June 2020 and 26 May 2022. SELECTION CRITERIA: We included randomised controlled trials (RCTs) or quasi-randomised trials of adults with CTS that included at least one comparison group of local injection of corticosteroid (LCI) into the wrist and one group that received a placebo or no treatment. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methods. Our primary outcome was 1. improvement in symptoms at up to three months of follow-up. Our secondary outcomes were 2. functional improvement, 3. improvement in symptoms at greater than three months of follow-up, 4. improvement in neurophysiological parameters, 5. improvement in imaging parameters, 6. requirement for carpal tunnel surgery, 7. improvement in quality of life and 8. ADVERSE EVENTS: We used GRADE to assess the certainty of evidence for each outcome. MAIN RESULTS: We included 14 trials with 994 participants/hands with CTS. Only nine studies (639 participants/hands) had useable data quantitatively and in general, these studies were at low risk of bias except for one quite high-risk study. The trials were conducted in hospital-based clinics across North America, Europe, Asia and the Middle East. All trials used participant-reported outcome measures for symptoms, function and quality of life. There is probably an improvement in symptoms measured at up to three months of follow-up favouring LCI (standardised mean difference (SMD) -0.77, 95% confidence interval (CI) -0.94 to -0.59; 8 RCTs, 579 participants; moderate-certainty evidence). Up to six months this was still evident favouring LCI (SMD -0.58, 95% CI -0.89 to -0.28; 4 RCTs, 234 participants/hands; moderate-certainty evidence). There is probably an improvement in function measured at up to three months favouring LCI (SMD -0.62, 95% CI -0.87 to -0.38; 7 RCTs, 499 participants; moderate-certainty evidence). We are uncertain if there is a difference in median nerve DML at up to three months of follow-up (mean difference (MD) -0.37 ms, 95% CI -0.75 to 0.02; 6 RCTs, 359 participants/hands; very low-certainty evidence). The requirement for surgery probably reduces slightly in the LCI group at one year (risk ratio 0.84, 95% CI 0.72 to 0.98; 1 RCT, 111 participants, moderate-certainty evidence). Quality of life, measured at up to three months of follow-up using the Short-Form 6 Dimensions questionnaire (scale from 0.29 to 1.0; higher is better) probably improved slightly in the LCI group (MD 0.07, 95% CI 0.02 to 0.12; 1 RCT, 111 participants; moderate-certainty evidence). Adverse events were uncommon (low-certainty evidence). One study reported 2/364 injections resulted in severe pain which resolved over "several weeks" and 1/364 injections caused a "sympathetic reaction" with a cool, pale hand that completely resolved in 20 minutes. One study (111 participants) reported no serious adverse events, but 65% of LCI-injected and 16% of the placebo-injected participants experienced mild-to-moderate pain lasting less than two weeks. About 9% of participants experienced localised swelling lasting less than two weeks. Four studies (229 participants) reported that they experienced no adverse events in their studies. Three studies (220 participants) did not specifically report adverse events. AUTHORS' CONCLUSIONS: Local corticosteroid injection is effective for the treatment of mild and moderate CTS with benefits lasting up to six months and a reduced need for surgery up to 12 months. Where serious adverse events were reported, they were rare.

Body mass index changes: an assessment of the effects of age and gender using the e-norms method.

BACKGROUND: To validate e-norms methodology in establishing a reference range for body mass index measures. A new method, the extrapolated norms (e-norms) method of determining normal ranges for biological variables is easy to use and recently was validated for several biological measurements. We aimed to determine whether this new method provides BMI results in agreement with established traditionally collected BMI values. METHODS: We applied the e-norms method to BMI data from 34,384 individuals and compared the ranges derived from this method with those from a large actuarially based study and explored differences in the normal range by gender, and age. RESULTS: The e-norms derived range of healthy BMI in adults is from 22.7 to 30.6, and showed that BMI is consistently higher in men than in women and increases with age, except in subjects aged 80-98 years in whom healthy BMI appears to be lower. CONCLUSIONS: Our e-norms derived healthy BMI ranges agree with traditionally obtained actuarially based methods, supporting the validity and ease of use of our method.

Is it time to revisit the Boston Carpal Tunnel Questionnaire? New insights from a Rasch model analysis.

BACKGROUND: The Boston Carpal Tunnel Questionnaire (BCTQ) is a patient-reported outcome measure (PROM) used to measure symptom severity and function in carpal tunnel syndrome (CTS). Despite its wide use, investigation of its measurement properties using modern psychometric methodologies is limited. METHODS: Completed BCTQ data collected routinely in the Canterbury carpal tunnel clinic was used to investigate the structural validity and measurement properties of the BCTQ through application of a Rasch model analytic approach. RESULTS: A total of 600 patients with electrodiagnostically confirmed CTS in their right hand were randomly selected from the database and analyzed. Mean age was 48.8 y, and 73% were women. Initial analysis showed that the 19 items could not be reliably added up to form a single linear construct. All subsequent analyses were done by subscale only. The Symptom Severity Subscale (SSS) displayed a large amount of local dependence. This could be accommodated through the creation of four clinically derived testlets, allowing for the ordinal SSS raw score to be transformed to a linear measure. The Functional Status Subscale (FSS) displayed a number of issues regarding its psychometric integrity. These include scale and item fit, targeting, differential item functioning, and dimensionality. CONCLUSIONS: This study shows that a single total score generated across all BCTQ items is not psychometrically valid, and that the SSS and FSS subscales should be treated separately. We propose a modified scoring system for the SSS, resulting in a linear measure that can be used in the analysis of future and existing datasets.

Ultrasound therapy adds no benefit to splinting in carpal tunnel syndrome.

INTRODUCTION: Therapeutic ultrasound has been suggested as a treatment for carpal tunnel syndrome (CTS), but existing trial evidence is of poor quality and inconclusive. METHODS: We conducted a randomized, controlled trial of therapeutic ultrasound in mild to moderate CTS. Forty patients were treated with wrist splints plus either real or sham therapeutic ultrasound and followed for 1 year posttreatment. The primary outcome was change in symptom severity scale score. Secondary outcomes were functional status scale score, nerve conduction studies, and ultrasound imaging of the median nerve. RESULTS: Both groups showed significant clinical and neurophysiological improvement at 6 and 12 months compared with baseline. There were no significant differences between groups at any time. In a multivariate analysis, the only independently significant predictors of the primary outcome were pretreatment symptom severity and additional treatments during follow-up. DISCUSSION: We found no clinically significant benefit from ultrasound treatment for CTS.

Indications for neuromuscular ultrasound: Expert opinion and review of the literature.

Over the last two decades, dozens of applications have emerged for ultrasonography in neuromuscular disorders. We wanted to measure its impact on practice in laboratories where the technique is in frequent use. After identifying experts in neuromuscular ultrasound and electrodiagnosis, we assessed their use of ultrasonography for different indications and their expectations for its future evolution. We then identified the earliest papers to provide convincing evidence of the utility of ultrasound for particular indications and analyzed the relationship of their date of publication with expert usage. We found that experts use ultrasonography often for inflammatory, hereditary, traumatic, compressive and neoplastic neuropathies, and somewhat less often for neuronopathies and myopathies. Usage significantly correlated with the timing of key publications in the field. We review these findings and the extensive evidence supporting the value of neuromuscular ultrasound. Advancement of the field of clinical neurophysiology depends on widespread translation of these findings.

Nerve conduction studies and EMG in carpal tunnel syndrome: Do they add value?

This paper summarises the views of four experts on the place of neurophysiological testing (EDX) in patients presenting with possible carpal tunnel syndrome, in guiding their treatment, and in reevaluations. This is not meant to be a position paper or a literature review, and heterogeneous viewpoints are presented. Nerve conduction studies should be performed in patients presenting with possible carpal tunnel syndrome to assist diagnosis, and may need to be repeated at intervals in those managed conservatively. There is evidence that local corticosteroid injection is safe and effective for many patients, thereby avoiding or deferring surgical decompression. All patients should undergo EDX studies before any invasive procedure for CTS (injection or surgery). Needle EMG studies are not obligatory, but may be needed in those with severe disease and those in whom an alternate or concomitant diagnosis is suspected.

A prognostic model for the patient-reported outcome of surgical treatment of carpal tunnel syndrome.

INTRODUCTION: Many prognostic factors have been studied in carpal tunnel decompression, but most studies consider only a subset of variables. METHODS: Three thousand three hundred thirty-two operations were used to develop prognostic models, and 885 operations were used for validation. Outcome recorded on a Likert scale was dichotomized into success or failure. Modeling was performed with both logistic regression and artificial neural networks using 87 candidate variables. RESULTS: Both approaches produced predictive multivariate models for outcome with areas under a receiver operating characteristic curve of 0.7 in the validation data set. Patients with moderately severe nerve conduction abnormalities, night waking, a family history of carpal tunnel syndrome, a good response to corticosteroid injection, and women have better outcomes. Greater functional impairment, diabetes, hypertension, and surgery on the dominant hand are associated with poorer outcomes. DISCUSSION: A multivariate model partially predicts the outcome of carpal tunnel surgery, aids decision making, and helps to manage patient expectations. Muscle Nerve 58:784-789, 2018.

Safety of corticosteroid injection for carpal tunnel syndrome.

The risks of corticosteroid injection for carpal tunnel syndrome, principally intraneural injection and tendon rupture, are known only from anecdotal reports. The literature does not allow an accurate estimate of their incidence or that of lesser side effects such as local pain. We have encountered only four serious complications in 9515 injections. We asked patients about possible side effects at routine follow-up, 6 weeks after 689 injections with 40 mg triamcinolone. Possible side effects were reported after 33% of injections. The commonest was short-lived local pain, which occurred in 13% of injected limbs, all cases having resolved within 3 weeks. No cases of intraneural injection or tendon rupture occurred, even after repeated injection. Most adverse effects were transient, but 13 hands exhibited persistent skin depigmentation or subcutaneous atrophy. This data provides the best current estimate of the risks of carpal tunnel injection and may be used to inform patients considering this intervention. LEVEL OF EVIDENCE: IV.

Electrophysiological/sonographic mapping of the superficial peroneal nerve to facilitate biopsy under local anaesthesia.

The anatomical surface markings for the superficial peroneal nerve have been described and it may be preferred for biopsy in cases of suspected vasculitis as biopsy of the peroneus brevis muscle increases diagnostic yield. The procedure is however unfamiliar to many surgeons and the anatomical variability of the subcutaneous part underestimated. Where the nerve has some preserved sensory nerve action potential it may be mapped pre-operatively, greatly facilitating minimally traumatic biopsy with potential logistical and wound healing advantages. We review the literature relating to the anatomical course of the nerve and present a case illustrating the advantages of pre-operative mapping, given its location in the anterior compartment of the leg 26% of the time.

The relationship of nerve fibre pathology to sensory function in entrapment neuropathy.

Surprisingly little is known about the impact of entrapment neuropathy on target innervation and the relationship of nerve fibre pathology to sensory symptoms and signs. Carpal tunnel syndrome is the most common entrapment neuropathy; the aim of this study was to investigate its effect on the morphology of small unmyelinated as well as myelinated sensory axons and relate such changes to somatosensory function and clinical symptoms. Thirty patients with a clinical and electrophysiological diagnosis of carpal tunnel syndrome [17 females, mean age (standard deviation) 56.4 (15.3)] and 26 age and gender matched healthy volunteers [18 females, mean age (standard deviation) 51.0 (17.3)] participated in the study. Small and large fibre function was examined with quantitative sensory testing in the median nerve territory of the hand. Vibration and mechanical detection thresholds were significantly elevated in patients with carpal tunnel syndrome (P<0.007) confirming large fibre dysfunction and patients also presented with increased thermal detection thresholds (P<0.0001) indicative of C and Aδ-fibre dysfunction. Mechanical and thermal pain thresholds were comparable between groups (P>0.13). A skin biopsy was taken from a median nerve innervated area of the proximal phalanx of the index finger. Immunohistochemical staining for protein gene product 9.5 and myelin basic protein was used to evaluate morphological features of unmyelinated and myelinated axons. Evaluation of intraepidermal nerve fibre density showed a striking loss in patients (P<0.0001) confirming a significant compromise of small fibres. The extent of Meissner corpuscles and dermal nerve bundles were comparable between groups (P>0.07). However, patients displayed a significant increase in the percentage of elongated nodes (P<0.0001), with altered architecture of voltage-gated sodium channel distribution. Whereas neither neurophysiology nor quantitative sensory testing correlated with patients' symptoms or function deficits, the presence of elongated nodes was inversely correlated with a number of functional and symptom related scores (P<0.023). Our findings suggest that carpal tunnel syndrome does not exclusively affect large fibres but is associated with loss of function in modalities mediated by both unmyelinated and myelinated sensory axons. We also document for the first time that entrapment neuropathies lead to a clear reduction in intraepidermal nerve fibre density, which was independent of electrodiagnostic test severity. The presence of elongated nodes in the target tissue further suggests that entrapment neuropathies affect nodal structure/myelin well beyond the focal compression site. Interestingly, nodal lengthening may be an adaptive phenomenon as it inversely correlates with symptom severity.

Prospective analysis of the accuracy of diagnosis of carpal tunnel syndrome using a web-based questionnaire.

OBJECTIVE: To confirm the accuracy of a diagnostic questionnaire for carpal tunnel syndrome (CTS) when presented via a public website rather than on paper. DESIGN: Prospective comparison of the probability of CTS as assessed by the web-based questionnaire at http://www.carpal-tunnel.net with the results of nerve conduction studies. SETTING: Subregional neurophysiology laboratory serving a population of 700,000 in East Kent, UK. PARTICIPANTS: 2821 individuals who were able to complete an online diagnostic questionnaire out of 4899 referred for initial diagnostic testing for new presentations with suspected CTS from April 2011 to March 2013. No exclusions were made on grounds of age, gender or coincident pathology. Main outcome measure--nerve conduction results confirming CTS. The severity of median nerve impairment demonstrated was also assessed using a validated neurophysiological scale. RESULTS: The web-based questionnaire accurately estimates the probability of CTS being confirmed on nerve conduction studies. Using a website diagnostic score of ≥40% as an example cut-off value the questionnaire achieves 78% sensitivity and 68% specificity in predicting the finding of evidence of CTS on nerve conduction studies. The web-based version of the diagnostic questionnaire was as accurate as the original paper version with an area under the receiver operating characteristic curve of 0.79. There was also a significant correlation between the diagnostic score given by the website and the severity of CTS with higher scores being associated with greater nerve dysfunction (r=0.3, p<0.00001). CONCLUSIONS: Completion of the symptom questionnaire on the website by patients at home provides a prediction of the likelihood of CTS which is sufficiently accurate to be used in initial planning of investigation and treatment.

Ultrasound imaging of the median nerve as a prognostic factor for carpal tunnel decompression.

INTRODUCTION: The diagnostic value of ultrasound imaging in carpal tunnel syndrome is established, but reports on its prognostic value have been contradictory. METHODS: This investigation was an observational study of subjective surgical results, evaluated by symptom severity and functional status scales, and an ordinal scale for overall outcome, for 145 carpal tunnel decompressions in relation to preoperative measurement of median nerve cross-sectional area. RESULTS: The surgical success rate was 86%. In univariate analyses no significant correlation existed between outcome and preoperative cross-sectional area, nor with preoperative nerve conduction studies or patient variables, except for body mass index and gender. A multivariate model including electrophysiological, imaging, and patient variables was moderately predictive of success with an area under the receiver operating characteristic curve of 0.82. CONCLUSIONS: Cross-sectional area alone is unlikely to be a sufficiently reliable predictor of outcome for use in counseling individual patients, but imaging results may be useful in multivariate prognostic models.

Effectiveness of second corticosteroid injections for carpal tunnel syndrome.

INTRODUCTION: A single local corticosteroid injection is an effective treatment for carpal tunnel syndrome. No study has specifically examined the effectiveness of a second injection on relapse after primary injection. METHODS: We identified a cohort of patients who had received an initial corticosteroid injection into 1 wrist and then, at a later date, a second injection into the same wrist. We compared the change in the Boston Symptom Severity Scale (SSS) and Functional Status Scale (FSS) between first and second injections. RESULTS: In 229 patients who received 2 injections the mean improvement on the SSS was 1.2 (SD = 0.8) for the first injection and 1.3 (SD = 0.9) for the second, which was not statistically significant. Improvement in FSS for the first injection was 0.4 (SD = 0.8) and 0.7 (SD = 0.8) for the second, which was statistically significant (P < 0.001). CONCLUSION: Second corticosteroid injections appear to be at least as effective as the first.

Questionnaire tools for the diagnosis of carpal tunnel syndrome from the patient history.

INTRODUCTION: There remains no "gold standard" for the diagnosis of carpal tunnel syndrome (CTS). Clinical diagnosis is often held to be paramount but depends on the skills of the individual practitioner. We describe two mathematical approaches to the analysis of a history obtained by questionnaire. METHODS: We used two earlier instruments, a conventional logistic regression analysis, and an artificial neural network to analyze data from 5860 patients referred for diagnosis of hand symptoms. We evaluated their ability to predict whether nerve conduction studies would show evidence of CTS using receiver operating characteristic curves. RESULTS: Both new instruments outperformed the existing tools, achieving sensitivity of 88% and specificity of 50% in predicting abnormal median nerve conduction. When combined, 96% sensitivity and 50% specificity were achieved. CONCLUSION: The combined instrument can be used as a preliminary screening tool for CTS, for self-diagnosis, and as a supplement to diagnosis in primary care.