Pain and motor function in carpal tunnel syndrome: a clinical, neurophysiological and psychophysical study

Effects of mirror therapy on pain, sensitivity and functionality in patients with unilateral carpal tunnel syndrome. Randomised control trial

PURPOSE

To investigate the effects of mirror therapy (MT) and therapeutic exercise (TE) with the unaffected hand, on pain, sensitivity and functionality in individuals with unilateral carpal tunnel syndrome (CTS).

MATERIAL AND METHODS

A randomized controlled trial was carried out. Thirty-nine adults with unilateral CTS were included and randomly allocated to a six-week training programme based on MT (n = 20) or TE (n = 19). Visual Analogue Scale, Semmes-Weinstein monofilament test, Two-point discrimination (2PD), Disabilities of the Arm, Shoulder and Hand (DASH) and Boston Carpal Tunnel Questionnaire (BCTQ) were assessed before (T0) and after the intervention (T1), and at one-month follow-up (T2).

RESULTS

At T1, MT and TE showed significant improvements in pain (p = 0.001 and p = 0.03, respectively), however, only MT maintained the achieved effects at T2 (p = 0.01). In addition, 2PD significantly improved in MT in the first (p = 0.04) and fourth fingers (p = 0.02) at T1. The DASH score decreased at T1 in MT (p < 0.001) and TE (p = 0.01). Additionally, the BCTQ score improved in MT (p < 0.001), and TE (p < 0.001) at T1. The effects were maintained at T2 for DASH and BCTQ scores.

CONCLUSIONS

Training of the unaffected hand resulted in a significant improvement of the affected hand in both groups; nevertheless, MT achieved a longer duration of the effects.

Dropping Objects in Carpal Tunnel Syndrome: Clinical and Electrophysiological Features

Background Dysfunction in both afferent sensory and efferent motor components of the median nerve may contribute to the manifestation of the symptom of dropping objects (DO) in carpal tunnel syndrome (CTS). The objective of this study was to compare the clinical and electrophysiological characteristics of CTS patients with dropping objects (wDO) and those without dropping objects (w/oDO). The study evaluated the correlation between DO symptoms and median partial conduction block, as well as the reduction in median motor conduction velocity at the wrist. Methodology An examination for CTS and the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) were performed. Median and ulnar sensory and motor nerve conduction studies were conducted in both upper extremities, and the percentage decrease in the median compound motor action potential amplitude at the wrist level was calculated. Results The study included 201 female participants aged between 22 and 88 years, comprising 57 patients with CTSwDO, 78 patients with CTSw/oDO, and 66 healthy controls. In the CTSwDO group, compared to the CTSw/oDO group, BCTQ scores were significantly higher, the prevalence of sensory deficits was more pronounced, and a larger number of hands, both dominant and non-dominant, were classified as stage 3 or higher in the clinical CTS classification. However, no correlation was found between the presence of DO symptoms and any neurophysiological findings. Conclusions DO may be a symptom of clinical severity in CTS, as previously reported. No neurophysiological parameter that could be associated with DO was identified.

Predictors of pain intensity in carpal tunnel syndrome: Development and validation of a model

OBJECTIVE

Pain often accompanies carpal tunnel syndrome and affects patients' health-related quality of life. The aim was to develop and validate a predictive model for the pain intensity of carpal tunnel syndrome using demographic, clinical, electrophysiological, and ultrasound findings.

METHODS

We conducted a secondary analysis of data from a large sample of patients (May 2017 to December 2022) with carpal tunnel syndrome. A total of 520 (53.0 %) mild, 276 (28.1 %) moderate, and 186 (18.9 %) severe syndromes were included in the complete data set of 982 hands (61.1 % female). The mean age was 57.8 (10.7) years and the median duration [interquartile range] of the symptoms was 4 [2,10] months. A regression model was developed and validated to predict pain intensity on a numerical rating scale using a tree-based machine learning algorithm.

RESULTS

The validation of the regression model showed good performance with a root mean squared error, R-squared, and mean absolute error of 1.35, 0.42, and 1.05, respectively. Overall, the top significant predictors of pain intensity were compound motor nerve action potential latency, nocturnal pain, and thenar weakness. These were followed by the cross-sectional area of the median nerve, sensory nerve action potential, bowing of the flexor retinaculum, disease duration, and body mass index. We did not find strong associations between the median nerve transcarpal latency, age, sex, and diabetes with the pain intensity of carpal tunnel syndrome.

CONCLUSION

Our model showed good performance in predicting the subjective pain intensity of carpal tunnel syndrome, even in the context of non-linear relations.

Carpal tunnel syndrome

Median neuropathy at the wrist, commonly referred to as carpal tunnel syndrome (CTS), is the most common entrapment neuropathy. It is caused by chronic compression of the median nerve at the wrist within the space-limited carpal tunnel. Risk factors that contribute to the etiology of compression include female gender, obesity, work-related factors, and underlying medical conditions, such as hypothyroidism, pregnancy, and amyloidosis. The diagnosis is made on clinical grounds, although these can be confounded by anatomical variations. Electrodiagnostic studies, which are specific and sensitive in diagnosing CTS, support the diagnosis; however, a subgroup may present with normal results. The advent of imaging techniques, including ultrasound and MRI, further assists the diagnostic process. The management of CTS is divided into the nonsurgical approaches that include hand therapy, splinting and corticosteroid injection, and surgical decompression of the carpal tunnel. Although several surgical techniques have been developed, no one method is more effective than the other. Each of these management approaches are effective at providing symptom relief and are utilized at different severities of the condition. There is, however, a lack of consensus on standardized diagnostic criteria, as well as when and to whom to refer patients for surgery.

Psychophysiological and Neurophysiological Correlates of Dropping Objects from Hands in Carpal Tunnel Syndrome

BACKGROUND

Dropping objects from hands (DOH) is a common symptom of carpal tunnel syndrome (CTS). We evaluated the clinical, neurophysiological, and psychophysiological features of 120 CTS patients to elucidate the DOH pathophysiology. Forty-nine healthy controls were included.

METHODS

In the patients, the Boston Carpal Tunnel Questionnaire (BCTQ), the Douleur Neuropathique 4 questions (DN4), and a numeric rating scale for pain (NRS) were evaluated. In patients and controls, we evaluated bilateral median and ulnar motor and sensory nerve conduction studies, cutaneous silent period and cutaneomuscular reflexes (CMR) of the abductor pollicis brevis, cold-detection threshold (CDT) and heat-pain detection threshold (HPT) at the index, little finger, and dorsum of the hand, and vibratory detection threshold at the index and little finger by quantitative sensory testing.

RESULTS

CTS with DOH had higher BCTQ, DN4 and NRS, lower median sensory action potential, longer CMR duration, lower CDT and higher HPT at all tested sites than controls and CTS without DOH. Predictive features for DOH were abnormal CDT and HPT at the right index and dorsum (OR: 3.88, p: 0.03) or at the little finger (OR: 3.27, p: 0.04) and a DN4 higher than 4 (OR: 2.16, p < 0.0001).

CONCLUSIONS

Thermal hypoesthesia in median and extra-median innervated territories and neuropathic pain are predictive of DOH in CTS.

Carpal Tunnel Syndrome: Neuropathic Pain Associated or Not with a Nociplastic Condition

Carpal tunnel syndrome (CTS) has been traditionally classified as primarily a neuropathic condition with or without pain. Precision medicine refers to an evidence-based method of grouping patients based on their susceptibility to biology, prognosis of a particular disease, or in their response to a specific treatment, and tailoring specific treatments accordingly. In 2021, the International Association for the Study of Pain (IASP) proposed a grading system for classifying patients into nociceptive, neuropathic, or nociplastic phenotypes. This position paper presents data supporting the possibility of subgrouping individuals with specific CTS related-pain into nociceptive, neuropathic, nociplastic or mixed-type phenotypes. Carpal tunnel syndrome is a neuropathic condition but can also be comorbid with a nociplastic pain condition. The presence of extra-median symptoms and the development of facilitated pain processing seem to be signs suggesting that specific CTS cases can be classified as the nociplastic pain phenotype. The clinical responses of therapeutic approaches for the management of CTS are inconclusive. Accordingly, the ability to identify the predominant pain phenotype in patients with CTS could likely be problematic for producing efficient treatment outcomes. In fact, the presence of a nociplastic or mixed-type pain phenotype would explain the lack of clinical effect of treatment interventions targeting the carpal tunnel area selectively. We propose a clinical decision tree by using the 2021 IASP classification criteria for identifying the predominant pain phenotype in people with CTS-related pain, albeit CTS being a priori a neuropathic pain condition. The identification of a nociplastic-associated condition requires a more nuanced multimodal treatment approach to achieve better treatment outcomes.

Innovative Quantitative Assessment of Hand Function in Carpal Tunnel Syndrome

BACKGROUND

Carpal tunnel syndrome (CTS) compromises fine sensorimotor function during activities of daily living and affects a large number of individuals with high burden costs for society. The purpose of this study was to quantitatively characterize fine movement skills in CTS patients preoperatively and at 1 month postoperatively by means of a sensor-engineered glove, in order to provide new insights for evaluative and finally therapeutic purposes.

METHODS

Forty-one CTS patients and 41 age- and gender-matched healthy controls (HC) were analyzed by adopting the engineered glove Hand Test System (HTS), which previously demonstrated its reliability and sensitivity to detect hands dysfunction in several neurological diseases. A sub-group of 11 CTS subjects was re-tested 1 month after surgery. Three parameters-touch duration (TD), inter-tapping interval (ITI), and movement rate (MR)-were considered to characterize hand function.

RESULTS

The affected hand of CTS patients generally showed worst finger opposition performances than HC. Comparing the dominant hand, all parameters were able to significantly discriminate CTS patients from HC. Considering the nondominant hand, the best performing parameter in discriminating CTS from HC was TD. The follow-up assessment at 1 month after surgery showed that considered parameters were able to monitor patients' recovery. In particular, the TD parameter recorded at the 3 different assigned task modalities resulted significantly enhanced.

CONCLUSIONS

Results of this pilot study proved the validity of the parameters obtained through the sensor-engineered glove to assess objectively hand functional status and surgical outcomes in CTS.

A preliminary study of radioulnar wrist compression in improving patient-reported outcomes of carpal tunnel syndrome

Previous studies have shown radioulnar wrist compression augments carpal arch space. This study investigated the effects of radioulnar wrist compression on patient-reported outcomes associated with carpal tunnel syndrome. Subjects underwent thrice-daily (15 min each time 45 min daily) wrist compression over 4 weeks with an additional four weeks of follow-up without treatment. Primary outcomes included Boston Carpal Tunnel Questionnaire symptom and functional severity scales (SSS and FSS) and symptoms of numbness/tingling based on Visual Analog Scales. Our results showed that radioulnar wrist compression improved SSS by 0.55 points after 2 weeks (p < 0.001) and 0.51 points at 4 weeks (p < 0.006) compared to the baseline scale. At the four-week follow-up, SSS remined improved at 0.47 points (p < 0.05). Symptoms of numbness/tingling improved at two and 4 weeks, as well as the follow-up (p < 0.05). Hand motor impairment such as weakness had a lower frequency across carpal tunnel syndrome sufferers and does not significantly improve (p > 0.05). Radioulnar wrist compression might be an effective alternative treatment in improving sensory related symptoms in patients with mild to moderate carpal tunnel syndrome.

Comparison of clinical findings and electromyography results in patients with preliminary diagnosis of carpal tunnel syndrome

OBJECTIVE

To evaluate the link between EMG findings and clinical status, the Boston questionnaire and the severity of pain in patients with pre-diagnosis of carpal tunnel syndrome.

METHODS

A total of 85 patients (133 hands) who presented to the Physical Therapy and Rehabilitation outpatient clinic consecutively with complaints of numbness, tingling, pain and weakness in their hands were evaluated for their demographic and clinical features. After the initial evaluation, the diagnosis of CTS was confirmed by EMG. Visual analog scale (VAS), the Boston Questionnaire (Symptom Severity Scale = SSS, Functional Status Scale = FSS) and nerve conduction study results (sensory conduction velocity = SCV, distal motor latency = DML, compound muscle action potential = CMAP) were enrolled.

RESULTS

Eighty-five patients (58 female and 27 male) participated in this study yielding 133 hands (73 right hands, 60 right hands) with CTS. The mean age was 48.3 ± 10.41 years. Of all patients, 68.2 % were female and 31.8 % were male. A statistically significant relationship was found between SSS and duration of symptoms, VAS, both right and left SCV, DML and CMAP. A statistically significant relationship was found between FSS and duration of symptoms, VAS and only right SCV, DML and CMAP.

CONCLUSION

The diagnosis of CTS should be evaluated not only as an electrodiagnostic finding, but also the clinical picture of the patients. According to our results, both SSS and FSS had good correlations with VAS and the findings of EMG. Therefore, the Boston Questionnaire can provide a standardized measure of symptom severity and functional status in patients with CTS.

Sonographic evaluation of the abductor pollicis brevis muscle reflects muscle strength recovery after carpal tunnel release

PURPOSE

This study aimed to examine the associations between sonographic measurements of the abductor pollicis brevis (APB), grip and pinch strength, and distal motor latency (DML) in patients with carpal tunnel syndrome (CTS) before and after surgery.

METHODS

We prospectively studied patients (46 hands) who underwent 1 year of postoperative follow-up after endoscopic carpal tunnel release. The patients underwent ultrasound (US) scans, grip and pinch strength assessment, a nerve conduction study, and patient-reported outcome measures (Carpal Tunnel Syndrome Instrument and Michigan Hand Outcomes Questionnaire) before and 1 year after surgery. The standardized response mean was calculated to compare the sensitivity of clinical changes in these measurements.

RESULTS

US measurements (thickness of the APB and the cross-sectional area of the APB) and muscle strength (grip strength, key pinch, and tip pinch) were greater, and DML was reduced after surgery compared with those before surgery (all P < 0.05). Patient-reported outcome measures also showed clinical improvement 1 year after surgery (P < 0.05). US measurements of the APB were significantly correlated with grip and pinch strength (all P < 0.05), but not with DML, before surgery and 1 year after surgery. The standardized response mean showed a large responsiveness for US measurements of the APB and patient-reported outcome measures.

CONCLUSION

US evaluation of the APB after CTS can complement the evaluation of grip and pinch strength in the clinical setting. Postoperative recovery of the APB leads to improved motor dysfunction in CTS. Therefore, US measurement of the APB could be a useful tool for evaluating motor function.

Understanding the Psychophysiological Mechanisms Related to Widespread Pressure Pain Hyperalgesia Underpinning Carpal Tunnel Syndrome: A Network Analysis Approach

OBJECTIVE

Current evidence suggests that carpal tunnel syndrome (CTS) involves widespread pressure pain sensitivity as manifestion of central sensitization. This study aimed to quantify mechanisms driving widespread pressure pain hyperalgesia in CTS by using network analysis.

DESIGN

Cross-sectional.

SETTING

Urban hospital.

SUBJECTS

120 women with CTS who participated in a previous randomized clinical trial.

METHODS

Pain intensity, related-function, symptom's severity, depressive levels, and pressure pain threshold (PPTs) over median, radial and ulnar nerves, the cervical spine, the carpal tunnel, and the tibialis anterior were collected. Network analysis was used to quantify the adjusted correlations between the modelled variables, and to determine the centrality indices of each variable (i.e., the degree of connection with other symptoms in the network).

RESULTS

The estimated network showed several local associations between clinical variables and the psychophysical outcomes separately. The edges with the strongest weights were between PPT over the median and radial nerves (ρ: 0.34), function and depressive levels (ρ: 0.30), and PPT over the carpal tunnel and tibialis anterior (ρ: 0.29). The most central variables were PPT over the tibialis anterior (the highest Strength centrality), and PPT over the carpal tunnel (the highest Closeness and Betweenness centrality).

CONCLUSIONS

This is the first study to apply network analysis to understand the multivariate mechanisms of individuals with CTS. Our findings support a model where clinical, depression, and widespread pressure pain sensitivity are connected, albeit within separate clusters. Clinical implications of current findings, such as developing treatments targeting these mechanisms, are also discussed.

Spectral Clustering Reveals Different Profiles of Central Sensitization in Women with Carpal Tunnel Syndrome

Identification of subgroups of patients with chronic pain provides meaningful insights into the characteristics of a specific population, helping to identify individuals at risk of chronification and to determine appropriate therapeutic strategies. This paper proposes the use of spectral clustering (SC) to distinguish subgroups (clusters) of individuals with carpal tunnel syndrome (CTS), making use of the obtained patient profiling to argue about potential management implications. SC is a powerful algorithm that builds a similarity graph among the data points (the patients), and tries to find the subsets of points that are strongly connected among themselves, but weakly connected to others. It was chosen due to its advantages with respect to other simpler clustering techniques, such as k-means, and the fact that it has been successfully applied to similar problems. Clinical (age, duration of symptoms, pain intensity, function, and symptom severity), psycho-physical (pressure pain thresholds—PPTs—over the three main nerve trunks of the upper extremity, cervical spine, carpal tunnel, and tibialis anterior), psychological (depressive levels), and motor (pinch tip grip force) variables were collected in 208 women with clinical/electromyographic diagnosis of CTS, whose symptoms usually started unilaterally but eventually evolved into bilateral symmetry. SC was used to identify clusters of patients without any previous assumptions, yielding three clusters. Patients in cluster 1 exhibited worse clinical features, higher widespread pressure pain hyperalgesia, higher depressive levels, and lower pinch tip grip force than the other two. Patients in cluster 2 showed higher generalized thermal pain hyperalgesia than the other two. Cluster 0 showed less hypersensitivity to pressure and thermal pain, less severe clinical features, and more normal motor output (tip grip force). The presence of subgroups of individuals with different altered nociceptive processing (one group being more sensitive to pressure pain and another group more sensitive to thermal pain) could lead to different therapeutic programs.

Long-term patient observation after conservative treatment of carpal tunnel syndrome: a summary of two randomised controlled trials

Background

Physiotherapy of carpal tunnel syndrome (CTS) involves manual therapy based on neurodynamic techniques. Until now, two randomized controlled trials have shown that immediately after therapy, CTS patients who received neurodynamic techniques had significant improvement in nerve conduction, pain, symptom severity (SSS), functional state (FSS), muscle strength (MS) and two-point discrimination (2PD). However, long-term effects seem to be more important, as they are the only ones that can significantly improve the patient's health and influence economic and social costs. Thus, the objective of this study was to evaluate the long-term (six months) effects of neurodynamic techniques in the conservative treatment of CTS patients.

Methods

Carpal tunnel syndrome patients (107) from two previously published randomised clinical trials were observed for six months after the treatment based on neurodynamic techniques.

Results

The sensory conduction velocity, motor conduction velocity, and motor latency were not subject to statistically significant changes within six months after therapy (p > 0.05). In both groups, there was further pain reduction (p < 0.05). In Group B, the symptom severity improved significantly (p < 0.05), while the functional status in both groups remained unchanged (p > 0.05). In both groups, there was muscle strength improvement (p < 0.05). Two-point discrimination remained unchanged six months after the therapy.

Conclusion

The use of manual therapy based on neurodynamic techniques maintains the beneficial effects 6 months after therapy in CTS patients.

Quantitative evaluation of hand motor function using a gyrosensor in mild and moderate carpal tunnel syndrome

INTRODUCTION

The objective of this study was to determine whether patients with carpal tunnel syndrome (CTS) manifest changes in early-stage motor function and to investigate the utility of a gyrosensor for quantitative evaluation of motor function.

METHODS

Angular velocity signal was measured during finger tapping in 52 patients with mild-to-moderate CTS and 45 controls. Four finger-tapping performance (FTP) values-root-mean-squared (RMS) velocity, RMS angle, peak power, and total power-were derived from the signal.

RESULTS

All FTP values were significantly lower in patients with CTS than in controls (P = 0.001 or P < 0.001). There were no significant differences between the mild and moderate CTS subgroups.

DISCUSSION

FTP measurement with a gyrosensor represents a valuable tool for the evaluation of median nerve motor function in patients with CTS. It facilitates the detection of subclinical motor dysfunction in patients with early stage CTS. Muscle Nerve 59:465-469, 2019.

Carpal tunnel syndrome: just a peripheral neuropathy?

Carpal tunnel syndrome (CTS) is considered just a peripheral neuropathy of the upper extremity associated to the compression of the median nerve. There is evidence suggesting the presence of complex sensitization mechanisms in CTS. These processes are manifested by symptoms in extra-median regions and the presence of bilateral sensory and motor impairments. These sensory and motor changes are not associated to electrodiagnostic findings. The presence of sensitization mechanisms suggests that CTS should not be considered just as a peripheral neuropathy. The presence of altered nociceptive gain processing should be considered for therapeutic management of CTS by considering the application of therapeutic interventions that modulate nociceptive barrage into the CNS.

A novel chronic nerve compression model in the rat

Current animal models of chronic peripheral nerve compression are mainly silicone tube models. However, the cross section of the rat sciatic nerve is not a perfect circle, and there are differences in the diameter of the sciatic nerve due to individual differences. The use of a silicone tube with a uniform internal diameter may not provide a reliable and consistent model. We have established a chronic sciatic nerve compression model that can induce demyelination of the sciatic nerve and lead to atrophy of skeletal muscle. In 3-week-old pups and adult rats, the sciatic nerve of the right hind limb was exposed, and a piece of surgical latex glove was gently placed under the nerve. N-butyl-cyanoacrylate was then placed over the nerve, and after it had set, another piece of glove latex was placed on top of the target area and allowed to adhere to the first piece to form a sandwich-like complex. Thus, a chronic sciatic nerve compression model was produced. Control pups with latex or N-butyl-cyanoacrylate were also prepared. Functional changes to nerves were assessed using the hot plate test and electromyography. Immunofluorescence and electron microscopy analyses of the nerves were performed to quantify the degree of neuropathological change. Masson staining was conducted to assess the degree of fibrosis in the gastrocnemius and intrinsic paw muscles. The pup group rats subjected to nerve compression displayed thermal hypoesthesia and a gradual decrease in nerve conduction velocity at 2 weeks after surgery. Neuropathological studies demonstrated that the model caused nerve demyelination and axonal irregularities and triggered collagen deposition in the epineurium and perineurium of the affected nerve at 8 weeks after surgery. The degree of fibrosis in the gastrocnemius and intrinsic paw muscles was significantly increased at 20 weeks after surgery. In conclusion, our novel model can reproduce the functional and histological changes of chronic nerve compression injury that occurs in humans and it will be a useful new tool for investigating the mechanisms underlying chronic nerve compression.

Facilitatory and inhibitory pain mechanisms are altered in patients with carpal tunnel syndrome

Preliminary evidence from studies using quantitative sensory testing suggests the presence of central mechanisms in patients with carpal tunnel syndrome (CTS) as apparent by widespread hyperalgesia. Hallmarks of central mechanisms after nerve injuries include nociceptive facilitation and reduced endogenous pain inhibition. Methods to study nociceptive facilitation in CTS so far have been limited to quantitative sensory testing and the integrity of endogenous inhibition remains unexamined. The aim of this study was therefore to investigate changes in facilitatory and inhibitory processing in patients with CTS by studying hypersensitivity following experimentally induced pain (facilitatory mechanisms) and the efficacy of conditioned pain modulation (CPM, inhibitory mechanisms). Twenty-five patients with mild to moderate CTS and 25 age and sex matched control participants without CTS were recruited. Increased pain facilitation was evaluated via injection of hypertonic saline into the upper trapezius. Altered pain inhibition through CPM was investigated through cold water immersion of the foot as the conditioning stimulus and pressure pain threshold over the thenar and hypothenar eminence bilaterally as the test stimulus. The results demonstrated that patients with CTS showed a greater duration (p = 0.047), intensity (p = 0.044) and area (p = 0.012) of pain in response to experimentally induced pain in the upper trapezius and impaired CPM compared to the control participants (p = 0.006). Although typically considered to be driven by peripheral mechanisms, these findings indicate that CTS demonstrates characteristics of altered central processing with increased pain facilitation and reduced endogenous pain inhibition.

Effects of Carpal Tunnel Syndrome on Force Coordination and Muscle Coherence during Precision Pinch

Carpal tunnel syndrome (CTS), caused by entrapment of the median nerve in the carpal tunnel, impairs hand function including dexterous manipulation. The purpose of this study was to investigate the effects of CTS on force coordination and muscle coherence during low-intensity sustained precision pinch while the wrist assumed different postures. Twenty subjects (10 CTS patients and 10 asymptomatic controls) participated in this study. An instrumented pinch device was used to measure the thumb and index finger forces while simultaneously collecting surface electromyographic activities of the abductor pollicis brevis (APB) and first dorsal interosseous (FDI) muscles. Subjects performed a sustained precision pinch at 10% maximum pinch force for 15 sec with the wrist stabilized at 30° extension, neutral, or 30° flexion using customized splints. The force discrepancy and the force coordination angle between the thumb and index finger forces were calculated, as well as the β-band (15-30 Hz) coherence between APB and FDI. The index finger applied greater force than the thumb (p < 0.05); this force discrepancy was increased with wrist flexion (p < 0.05), but was not affected by CTS (p > 0.05). The directional force coordination was not significantly affected by wrist posture or CTS (p > 0.05). In general, digit force coordination during precision pinch seems to be sensitive to wrist flexion, but is not affected by CTS. The β-band muscular coherence was increased by wrist flexion for CTS patients (p < 0.05), which could be a compensatory mechanism for the flexion-induced exacerbation of CTS symptoms. This study demonstrates that wrist flexion negatively influences muscle and force coordination in CTS patients supporting the avoidance of flexion posture for symptom exacerbation and functional performance.

Evaluating neuropathic complaints by DN4 and LANSS scales after local corticosteroid therapy in carpal tunnel syndrome

BACKGROUND/PURPOSE

The purpose of this study was to evaluate the neuropathic symptoms after local steroid injection in CTS. Since 2001, neuropathic pain scales have been used in the assessment and follow-up of neuropathic pain. DN4 and LANSS pain questionnaires have been applied to groups, mostly consisted of radiculopathy and polyneuropathy cases, before and after various treatments and the results have been compared with the electrophysiologic findings. However to our knowledge there is yet no such study focusing on neuropathic complaints and the relationship between neuropathic pain and electrophysiological findings before and after local corticosteroid injection.

METHODS

Forty-one patients aged 22-65 years and diagnosed with carpal tunnel syndrome by nerve conduction studies who were also found to have neuropathic symptoms were included in the study. All patients received local steroid injection into the carpal tunnel while the questionnaires and nerve conduction studies were performed before and 2 months after the injection.

RESULTS

Local steroid injection was found effective on clinical and electrophysiologic parameters as well as on DN4 and LANSS scores in CTS patients (p< 0.05). Electrophysiologic severity exhibited no statistically significant relationship with DN4 and LANSS scores, before and after treatment (p> 0.05).

CONCLUSION

These findings suggests that the treatment of neuropathic complaints should be planned independently from the electrophysiologic findings and minimally invasive local steroid injection appears to be effective with regard to clinical and electrophysiologic aspects in CTS patients with neuropathic complaints.

Two-point discrimination and kinesthetic sense disorders in productive age individuals with carpal tunnel syndrome

Objectives:

The aim of this study was to evaluate two-point discrimination (2PD) sense and kinesthetic sense dysfunctions in carpal tunnel syndrome (CTS) patients compared with a healthy group.

Methods:

The 2PD sense, muscle force, and kinesthetic differentiation (KD) of strength; the range of motion in radiocarpal articulation; and KD of motion were assessed.

Results:

The 2PD sense assessment showed significantly higher values in all the examined fingers in the CTS group than in those in the healthy group (p<0.01). There was a significant difference in the percentage value of error in KD of pincer and cylindrical grip (p<0.01) as well as in KD of flexion and extension movement in the radiocarpal articulation (p<0.01) between the studied groups.

Conclusions:

There are significant differences in the 2PD sense and KD of strength and movement between CTS patients compared with healthy individuals.

Identification of Subgroups of Women with Carpal Tunnel Syndrome with Central Sensitization

OBJECTIVE

Identification of subjects with different sensitization mechanisms can help to identify better therapeutic strategies for carpal tunnel syndrome (CTS). The aim of the current study was to identify subgroups of women with CTS with different levels of sensitization.

METHODS

A total of 223 women with CTS were recruited. Self-reported variables included pain intensity, function, disability, and depression. Pressure pain thresholds (PPT) were assessed bilaterally over median, ulnar, and radial nerves, C5-C6 joint, carpal tunnel, and tibialis anterior to assess widespread pressure pain hyperalgesia. Heat (HPT) and cold (CPT) pain thresholds were also bilaterally assessed over the carpal tunnel and the thenar eminence to determine thermal pain hyperalgesia. Pinch grip force between the thumb and the remaining fingers was calculated to determine motor assessment. Subgroups were determined according to the status on a previous clinical prediction rule: PPT over the affected C5-C6 joint < 137 kPa, HPT on affected carpal tunnel <39.6ºC, and general health >66 points.

RESULTS

The ANOVA showed that women within group 1 (positive rule, n = 60) exhibited bilateral widespread pressure hyperalgesia (P < 0.001) and bilateral thermal thresholds (P < 0.001) than those within group 2 (negative rule, n = 162). Women in group 1 also exhibited higher depression than those in group 2 (P = 0.023). No differences in self-reported variables were observed.

CONCLUSION

This study showed that a clinical prediction rule originally developed for identifying women with CTS who are likely to respond favorably to manual physical therapy was able to identify women exhibiting higher widespread pressure hyper-sensitivity and thermal hyperalgesia. This subgroup of women with CTS exhibiting higher sensitization may need specific therapeutic programs.

Confirmatory Factor Analysis of the Boston Carpal Tunnel Questionnaire

PURPOSE

Carpal tunnel syndrome (CTS) is one of the most common hand problems and a major cause of work disability. The purpose of this study was to use confirmatory factor analysis (CFA) to assess the factor structure of the Boston Carpal Tunnel Questionnaire (BCTQ) in patients with CTS.

METHODS

One hundred and twenty-three patients with CTS were recruited from two hospitals. Each patient completed the functional status scale and the symptom severity scale of the BCTQ. CFA was used to assess the model fit between the data and pre-established theoretical measurement models.

RESULTS

CFA showed that all three-factor models were better than the original two-factor model. Among the three-factor models, the simplified model, with 11 items assessing daytime pain, nocturnal numbness/tingling, and hand function was the best, for the model fit the data better than did the other models. Specifically, the Comparative Indices were larger than 0.95 (Tucker-Lewis Index and Comparative Fit Index values), and the Absolute Fit Indices and information-theoretic measures were the smallest. Moreover, all factor loadings were significant and high in magnitude (ranging from 0.66 to 0.99), the composite reliabilities exceeded 0.60 (ranging from 0.78 to 0.94), and the average variance extracted exceeded 0.50 (ranging from 0.61 to 0.89).

CONCLUSION

The simplified model showed the highest reliability and validity, and the factor structure was the simplest/clearest one. The simplified model is recommended for clinical use due to its convenience and precision for assessing the problems of patients with CTS.

Assessment from Functional Perspectives: Using Sensorimotor Control in the Hand as an Outcome Indicator in the Surgical Treatment of Carpal Tunnel Syndrome

To investigate whether sensorimotor control of the hand could be an outcome indicator after carpal tunnel release (CTR), this work examined changes in the results of patients’ manual tactile test (MTT), pinch-holding-up activity (PHUA), two-point discrimination (2PD) and Semmes-Weinstein monofilament (SWM) tests. Participants included 30 predominantly sensory neuropathy CTS patients, as confirmed by a nerve conduction study. The MTT, precision pinch performance in PHUA and traditional sensibility (2PD and SWM) tests were used to examine different aspects of sensory status at the time-points of two weeks before operation and one month post-operation, with a single-blind design. The results showed significant improvements in the sensory function as detected by the 2PD and SWM tests (p<0.001) and sensorimotor function as detected by the MTT (p<0.001) and PHUA test (p<0.05) for patients receiving CTR. The responsiveness of the SWM, MTT and PHUA tests (effect size>0.5, p<0.01) are better than that of two-point discrimination test (effect size<0.5, p<0.001). However, pinch strength saw a decline compared to baseline with a moderate effect sizes (effect size = 0.7, p<0.001). This cohort study found that the MTT and PHUA test can both meet all the statistical criteria with regard to assessing treatment outcomes for patients with CTS. In addition, the results of this work provide clinicians with the information that the sensorimotor functions of the hands, as assessed by MTT and PHUA, are responsive to clinical changes due to CTR.

Carpal tunnel syndrome impairs thumb opposition and circumduction motion

BACKGROUND

Carpal tunnel syndrome is associated with sensory and motor impairments resulting from the compressed and malfunctioning median nerve. The thumb is critical to hand function, yet the pathokinematics of the thumb associated with carpal tunnel syndrome are not well understood.

QUESTIONS/PURPOSES

The purpose of this study was to evaluate thumb motion abnormalities associated with carpal tunnel syndrome. We hypothesized that the ranges of translational and angular motion of the thumb would be reduced as a result of carpal tunnel syndrome.

METHODS

Eleven patients with carpal tunnel syndrome and 11 healthy control subjects voluntarily participated in this study. Translational and angular kinematics of the thumb were obtained using marker-based video motion analysis during thumb opposition and circumduction movements.

RESULTS

Motion deficits were observed for patients with carpal tunnel syndrome even though maximum pinch strength was similar. The path length, normalized by palm width of the thumb tip for the patients with carpal tunnel syndrome was less than for control participants (opposition: 2.2 palm width [95% CI, 1.8-2.6 palm width] versus 3.1 palm width [95% CI, 2.8-3.4 palm width], p < 0.001; circumduction: 2.2 palm width [95% CI, 1.9-2.5 palm width] versus 2.9 palm width [95% CI, 2.7-3.2 palm width], p < 0.001). Specifically, patients with carpal tunnel syndrome had a deficit of 0.3 palm width (95% CI, 0.04-0.52 palm width; p = 0.022) in the maximum position of their thumb tip ulnarly across the palm during opposition relative to control participants. The angular ROM also was reduced for the patients with carpal tunnel syndrome compared with the control participants in extension/flexion for the metacarpophalangeal (opposition: 34° versus 58°, p = .004; circumduction: 33° versus 58°, p < 0.001) and interphalangeal (opposition: 37° versus 62°, p = .028; circumduction: 41° versus 63°, p = .025) joints.

CONCLUSIONS

Carpal tunnel syndrome disrupts kinematics of the thumb during opposition and circumduction despite normal pinch strength.

CLINICAL RELEVANCE

Improving understanding of thumb pathokinematics associated with carpal tunnel syndrome may help clarify hand function impairment associated with the syndrome given the critical role of the thumb in dexterous manipulation.

Assessing weakness in patients with ulnar neuropathy: comparison between a custom hand muscle dynamometer and a pinch dynamometer

OBJECTIVE

The aim of this study was to compare the use of a custom intrinsic hand dynamometer (HD) with that of a standard pinch dynamometer (PD) in assessing strength in patients with ulnar neuropathy at the elbow.

DESIGN

Nine patients (age, 53 ± 3 yrs) with clinical and electrophysiological features of ulnar neuropathy at the elbow with conduction block (CB) were studied. All underwent bilateral ulnar motor nerve conduction studies recording from the first dorsal interosseous and a quantitative measurement of strength of the first dorsal interosseous using a custom-made HD and a standard PD.

RESULTS

The maximal strength of the ulnar neuropathy at the elbow-affected side (16.2 ± 8.0 N) was found to be significantly lower than that of the unaffected side (27.9 ± 11.2 N), as measured by HD. Strength differences were not significant between the affected (62.7 ± 26.4 N) and unaffected sides (48.0 ± 20.5 N) using PD. HD force decrement (in comparison with the unaffected limb) correlated strongly with CB percentage (r = 0.74). No relationship was found between PD and CB (r = 0.05).

CONCLUSIONS

HD was better able to measure the weakness of affected muscles than did PD, and its results correlated well with the extent of electrophysiological CB. Therefore, a custom HD would provide a better indication of disease severity, progression, or improvement in strength in studies of ulnar neuropathy at the elbow with CB.

Feasibility of a novel functional sensibility test as an assisted examination for determining precision pinch performance in patients with carpal tunnel syndrome

To understand the feasibility of a novel functional sensibility test for determining precision pinch performance in patients with carpal tunnel syndrome, this study investigates the validity, sensitivity and specificity of functional sensibility derived from a pinch-holding-up activity (PHUA) test. Participants include 70 clinically defined carpal tunnel syndrome (CTS) patients with 119 involved hands and 70 age- and gender-matched controls. To examine the discriminating ability of the functional sensibility test, the differences in the ability of pinch force adjustments to the inertial load of handling object between CTS and control subjects are analyzed. The results of functional sensibility are correlated with the severity of CTS to establish concurrent validity. The receiver operating characteristic (ROC) curve is constructed to demonstrate the accuracy of the proposed test. The functional sensibility score significantly discriminates the patients and control groups (respectively, 12.94±1.72 vs. 11.51±1.15N in peak pinch force (FP_Peak), p<0.001; 2.92±0.41 vs. 2.52±0.24 in force ratio, p<0.001) and is moderately correlated (r = 0.42–0.54, p<0.001) with the results of traditional sensibility tests (touch-pressure threshold and two-point discrimination test). In addition, there is a statistical difference in the results of functional sensibility (p<0.001) among the subgroups of CTS severity based on electrophysiological study. The sensitivity and specificity are 0.79 and 0.76, respectively, for the functional sensibility test. The areas under the ROC curve are 0.85 and 0.80 for the force ratio and FP_Peak, respectively. In conclusion, the functional sensibility test could be feasibly used as a clinical tool for determining both the sensibility and precision pinch performance of hands for the patients with CTS.

Relationship between electrodiagnostic severity and neuropathic pain assessed by the LANSS pain scale in carpal tunnel syndrome

OBJECTIVE

The aim of the study was to investigate the relationship between the presence of neuropathic pain assessed by the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) scale and electrophysiological findings in patients with carpal tunnel syndrome (CTS).

METHODS

We studied 124 hands with idiopathic CTS with pain complaints involving hand and wrist. All hands were assessed by the LANSS with which a score of 12 or more is defined as pain dominated by neuropathic mechanisms. These hands were assigned to minimal, mild, moderate, severe, or extreme severe groups according to the results of the median nerve conduction studies.

RESULTS

A LANSS score ≥ 12, suggestive of pain dominated by neuropathic mechanisms, was defined in 59 (47.6%) CTS hands. Pain intensity was significantly higher in CTS hands with a LANSS score ≥ 12 (P < 0.001). Among electrophysiological findings, compound muscle action potential amplitude was significantly lower in hands with a LANSS score ≥ 12 compared with hands with a LANSS score < 12 (P = 0.020). Severity of CTS was not significantly different between LANSS ≥ 12 and LANSS < 12 groups. Electrophysiological severity was significantly higher in CTS hands with evoked pain (P = 0.005) and allodynia (P < 0.001) in LANSS subscore analysis.

CONCLUSION

We suggest that the presence of pain dominated by neuropathic mechanisms in CTS is not related to electrophysiological CTS severity. Neuropathic pain should be assessed carefully in patients with CTS, and an appropriate treatment plan should be chosen, taking into account the clinical and electrophysiological findings together with the true pain classification.

Clinical application of computerized evaluation and re-education biofeedback prototype for sensorimotor control of the hand in stroke patients

Background

Hemianaesthesia patients usually exhibit awkward and inefficient finger movements of the affected hands. Conventionally, most interventions emphasize the improvement of motor deficits, but rarely address sensory capability and sensorimotor control following stroke. Thus it is critical for stroke patients with sensory problems to incorporate appropriate strategies for dealing with sensory impairment, into traditional hand function rehabilitation programs. In this study, we used a custom-designed computerized evaluation and re-education biofeedback (CERB) prototype to analyze hand grasp performances, and monitor the training effects on hand coordination for stroke patients with sensory disturbance and without motor deficiency.

Methods

The CERB prototype was constructed to detect momentary pinch force modulation for 14 sub-acute and chronic stroke patients with sensory deficiency and 14 healthy controls. The other ten chronic stroke patients (ranges of stroke period: 6–60 months) were recruited to investigate the effects of 4-weeks computerized biofeedback treatments on the hand control ability. The biofeedback procedures provide visual and auditory cues to the participants when the interactive force of hand-to-object exceeded the target latitude in a pinch-up-holding task to trigger optimal motor strategy. Follow-up measurements were conducted one month after training. The hand sensibility, grip forces and results of hand functional tests were recorded and analyzed.

Results

The affected hands of the 14 predominant sensory stroke patients exhibited statistically significant elevation in the magnitude of peak pinch force (p = 0.033) in pinching and lifting-up tasks, and poor results for hand function tests (p = 0.005) than sound hands did. In addition, the sound hands of patients were less efficient in force modulation (p = 0.009) than the hands of healthy subjects were. Training with the biofeedback system produced significant improvements in grip force modulation (p = 0.020) and better performances in the subtests of pin insertion (p = 0.019), and lifting of lightweight objects (p = 0.005).

Conclusions

The CERB prototype can provide momentary and interactive information for quantitative assessing and re-educating force modulation appropriately for stroke patients with sensory deficits. Furthermore, the patients could transfer the learned strategy to improve hand function.

Diurnal variation in clinical and electrophysiologic parameters associated with carpal tunnel syndrome

OBJECTIVE

Patients with carpal tunnel syndrome (CTS) often report aggravated symptoms in the early morning. In this study, we aimed to identify diurnal variations in clinical and electrophysiologic parameters of patients with CTS.

DESIGN

A cross-sectional clinical and electrophysiologic study was designed. First, electrophysiologic examinations were performed at 2 p.m. to confirm the diagnosis of patients who had been clinically labeled with CTS. Patients who were electrophysiologically and clinically diagnosed with CTS were included in the study, and electrophysiologic examinations were repeated at 7 p.m. and 7 a.m. A total of 64 hands with CTS (27 bilateral, 10 unilateral) and 40 control hands were studied. Grip and pinch strength of all the patients included in the study were measured using a hand dynamometer. Finally, a CTS clinical symptom severity scale and functional status scale were used to measure the symptoms and functional impairment, respectively.

RESULTS

The median motor nerve distal latency and median F-minimum latency were found to be prolonged in the CTS group in the morning, and the grip strength was also markedly reduced at this time. Similar results were obtained for the median palm mixed nerve conduction velocity and amplitude.

CONCLUSIONS

This study demonstrated that the clinical and electrophysiologic parameters of CTS patients were clearly different in the morning hours, with the symptoms of CTS manifesting at that time.

Effect of demyelinating ulnar nerve injury on strength and fatigue

OBJECTIVES

Conduction block (CB) from focal neuropathy is often associated with weakness and fatigue in affected muscles. Ulnar neuropathy at the elbow (UNE) provides an excellent model to examine the relationships between electrophysiologically defined CB and quantitative measurement of weakness and fatigue.

METHODS

Eight healthy control subjects (47 ± 14 years) and nine patients (53 ± 3 years) with clinical and electrophysiological features of UNE with CB were studied. All underwent bilateral, ulnar motor nerve conduction studies recording from the first dorsal interosseous muscle as well as quantitative measurement of strength and fatigue of the first dorsal interosseous with a custom dynamometer.

RESULTS

Strength and fatigue were similar in the dominant and nondominant hands of control subjects and unaffected limb in patients. Varying degrees of conduction block (14-62%, mean 36%) and conduction slowing (31 m/s ± 7) were observed in those with UNE. CB was associated with significant reductions in strength (42%) and fatigue (23%) on a timed fatigue task. The reductions in strength (r = 0.74) and fatigue (r = 0.60) were strongly correlated with the degree of CB.

CONCLUSIONS

CB in UNE defined by electrophysiological criteria was strongly correlated with weakness and fatigue in the first dorsal interosseous. Fatigue may be simply related to the reduction in strength, but activity or frequency dependent CB may also contribute.

[Diagnostic pitfalls in carpal tunnel syndrome]

BACKGROUND

This review focuses on the main aspects of positive and differential diagnosis of carpal tunnel syndrome (CTS) in different clinical situations encountered in daily practice.

STATE OF THE ART

Authentic CTS can be discovered in situations, which alter the usual presentation or therapeutic management. This is the case for instance in pregnant women or in the elderly subject or with acute motor forms where CTS discloses a focal intratunnel disorder (neuroma, lipoma, arterial condition, bone disorder) or a general disease (hereditary neuropathy, amylosis). In certain situations, the clinical manifestations suggest a more proximal compression of the medial nerve (round pronator, Struthers arcade, or superficial flexor) or an inflammatory condition (mononeuritis, inflammatory demyelinising neuropathy). Locoregional disease may also be involved, for instance a plexus (thoracobrachial outlet syndrome, post-radiation plexitis) or radicular condition. The clinical presentation of diffuse polyneuropathy with initial manifestations involving the upper limb (ganglioneuropathies, polyradiculoneuritis, small-fiber neuropathies) may also be misleading. Finally central conditions can sometimes be confused with CTS.

CONCLUSION

A rigorous physical examination and an electroneuromyogram are determining to avoid diagnostic pitfalls.

Ulnar nerve impairment at the wrist does not contribute to extramedian sensory symptoms in carpal tunnel syndrome

OBJECTIVE

Extramedian spread of sensory symptoms is frequent in carpal tunnel syndrome (CTS) but its mechanisms are unclear. We explored the possible role of subtle ulnar nerve abnormalities in the pathogenesis of extramedian symptoms.

METHODS

We recruited 350 CTS patients. After selection, 143 patients (225 hands) were included. The hand symptoms distribution was graded with a diagram into median (MED) and extramedian (EXTRAMED) pattern. We tested the correlation of ulnar nerve conduction measures with the distribution and the severity of symptoms involving the ulnar territory. The clinical significance of ulnar nerve conduction findings was explored with quantitative sensory testing (QST).

RESULTS

EXTRAMED distribution was found in 38.7% of hands. The ulnar neurographic measures were within normal values. Ulnar nerve sensory measures were significantly better in EXTRAMED vs MED hands and not significantly correlated to ulnar symptoms severity. Ulnar and median nerve sensory measures were significantly correlated. QST showed normal function of ulnar nerve alphabeta-fibers.

CONCLUSIONS

Ulnar nerve sensory abnormalities do not contribute to the spread of sensory symptoms into the ulnar territory.

SIGNIFICANCE

Our data favour the hypothesis that spinal and supraspinal neuroplastic changes may underlie extramedian spread of symptoms in CTS.