Nerve conduction studies of median motor nerve and median sensory branches according to the severity of carpal tunnel syndrome

Self-Reported Improvement After Carpal Tunnel Release in Patients With Motor Axonal Loss

PURPOSE

Electrodiagnostic studies can identify evidence of sensory and motor axonal loss (AL) in carpal tunnel syndrome (CTS) patients. However, the impact of sensory and motor AL on outcomes following carpal tunnel release (CTR) remains unclear. We hypothesize that patients with no evidence of sensory and motor AL will experience greater improvement following CTR compared to those with evidence of AL.

METHODS

Patients undergoing open and endoscopic CTR by four fellowship-trained orthopedic hand surgeons were identified. Sensory and motor AL were identified using preoperative electromyography and nerve conduction studies. Patients completed the following before surgery and 3-month postoperative patient-reported outcomes: Patient-Reported Outcomes Measurement Information System Upper Extremity (UE) and Pain Interference (PI) as well as Disabilities of the Arm, Shoulder, and Hand (QuickDASH [QD]). Preoperative and postoperative scores, changes in scores, and rates of achieving the minimally clinically important difference (MCID) were compared between patients with and without sensory and motor AL.

RESULTS

One hundred and seventy-five patients were included. Of these, 91 exhibited sensory AL and 98 exhibited motor AL. Demographic matched analysis of patients with and without sensory AL showed no differences in before surgery, after surgery, difference, or proportion meeting MCID for UE, PI, or QD. Matched analysis revealed no difference in preoperative PROMs between patients with and without motor AL. Patients with motor AL had increased postoperative UE (better function), decreased postoperative PI (less PI) and QD (less disability), increased changes in PI and QD, as well as a greater proportion meeting MCID for QD compared to those without motor AL.

CONCLUSIONS

There was no difference in post-CTR improvement between patients with and without sensory AL. However, contrary to our hypothesis, motor AL patients experienced greater postoperative improvement according to QD. These findings suggest surgery should be recommended for severe CTS patients with evidence of AL. These results can better inform physicians and patients as they discuss expectations of CTR outcomes.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognosis II.

Effect of "normal" versus "mild carpal tunnel syndrome" electrodiagnostic report on surgeon decision and patients clinical outcomes

INTRODUCTION

There exist conflicting electrodiagnostic reports between diagnosing mild carpal tunnel syndrome (CTS) and normal results, depending on the interpretation methods used by electrodiagnosticians. This underscores the necessity for precise clinical guidelines. This study aims to assess how the variation between mild and normal electrophysiological reports impacts (1) subsequent clinical outcomes in patients diagnosed with CTS and (2) physicians' decision-making.

METHODS

In a prospective cohort study, we followed 102 patients with suspected CTS who underwent electrodiagnostic studies (EDX). The EDX results for these patients were categorized as either normal or indicative of mild CTS, based on the interpreter's chosen assessment method, which included median-ulnar palmar mixed comparison or median sensory nerve studies. Patient demographics, EDX reports, the choice between surgical or non-surgical treatment, as well as repeated measurements of post-operative pain and paresthesia, were collected at day 0, two weeks, and 12 weeks post treatment.

RESULTS

The study includes an equal number of patients with mild and normal electrodiagnostic reports, totaling 51 individuals in each group, and revealed no significant differences in their demographic and baseline characteristics. Over time, both groups showed a decrease in symptom severity. Nevertheless, the reduction in pain (P = 0.77 at 12 weeks) and paresthesia (P = 0.32 at 12 weeks) showed no significant differences between the two groups. Furthermore, there were no differences observed between the groups concerning the treatment choices made by the surgeon (P = 0.218).

CONCLUSION

When EDX reports indicate either normal or mild CTS, it seems that this interpretation doesn't substantially influence a surgeon's decision in selecting the treatment option or the resulting clinical outcome post-treatment. This highlights the importance of clinical assessment rather than relying solely on EDX reports in managing these patients.

LEVEL OF EVIDENCE

Level II (Prospective cohort study).

Reference Standard of Median Nerve Conduction Study in Korea

OBJECTIVE

To establish the reference standard of the median nerve conduction study (NCS) in Korea.

METHODS

A total of 648 median motor and 602 median sensory NCSs from 349 Korean healthy volunteers were tested and analyzed prospectively. Equipment calibration, assessment of intraand inter-rater reliability, and the NCSs per se were conducted according to a predetermined protocol. A reference standard was established from uncertainty components for the following parameters: the onset and peak latencies; the baseline-to-peak and peak-to-peak amplitudes; the area and duration of the negative wave; and the nerve conduction velocity. The effects of sex, age and stimulation intensity were analyzed.

RESULTS

Each measured value of 648 median motor and 602 median sensory nerves were obtained and presented with both mean and expanded uncertainties, as well as mean and standard deviations. The cut-off values with expanded uncertainty were determined for different age and sex groups. After adjusting for anthropometric covariates, all parameters except duration were affected by age, and sex appeared to influence both duration and area. While stimulation intensity significantly affected some parameters including latencies, the effect sizes were negligible.

CONCLUSION

We propose the median NCS reference standard using the largest Korean dataset ever available. The use of the traceable and reliable reference standard is anticipated to promote more accurate and dependable diagnosis and appropriate management of median neuropathies in Korea.

Carpal tunnel syndrome prediction with machine learning algorithms using anthropometric and strength-based measurement

OBJECTIVES

Carpal tunnel syndrome (CTS) stands as the most prevalent upper extremity entrapment neuropathy, with a multifaceted etiology encompassing various risk factors. This study aimed to investigate whether anthropometric measurements of the hand, grip strength, and pinch strength could serve as predictive indicators for CTS through machine learning techniques.

METHODS

Enrollment encompassed patients exhibiting CTS symptoms (n = 56) and asymptomatic healthy controls (n = 56), with confirmation via electrophysiological assessments. Anthropometric measurements of the hand were obtained using a digital caliper, grip strength was gauged via a digital handgrip dynamometer, and pinch strengths were assessed using a pinchmeter. A comprehensive analysis was conducted employing four most common and effective machine learning algorithms, integrating thorough parameter tuning and cross-validation procedures. Additionally, the outcomes of variable importance were presented.

RESULTS

Among the diverse algorithms, Random Forests (accuracy of 89.474%, F1-score of 0.905, and kappa value of 0.789) and XGBoost (accuracy of 86.842%, F1-score of 0.878, and kappa value of 0.736) emerged as the top-performing choices based on distinct classification metrics. In addition, using variable importance calculations specific to these models, the most important variables were found to be wrist circumference, hand width, hand grip strength, tip pinch, key pinch, and middle finger length.

CONCLUSION

The findings of this study demonstrated that wrist circumference, hand width, hand grip strength, tip pinch, key pinch, and middle finger length can be utilized as reliable indicators of CTS. Also, the model developed herein, along with the identified crucial variables, could serve as an informative guide for healthcare professionals, enhancing precision and efficacy in CTS prediction.

Electrodiagnostic Testing for Carpal Tunnel Syndrome When Routine Median Sensory and Thenar Motor Responses Are Absent

PURPOSE

The cardinal symptoms of carpal tunnel syndrome (CTS) include pain in the affected hand(s). The median/second lumbrical nerve (Med2ndL) seems relatively preserved in severe CTS, with previous small studies suggesting its value in electromyogram to localize a median neuropathy to the wrist when both initial routine sensory and thenar motor responses are absent.

METHODS

This is a retrospective analysis of 208 hands in 183 patients with electrophysiologically markedly severe CTS (absent routine sensory and thenar motor median responses) who underwent stimulation of both the Med2ndL and ulnar/second dorsal interosseous (Uln2ndDIn) motor nerves. A Med2ndL distal latency of ≥ 0.5 milliseconds when compared with the Uln2ndDIn supported the diagnosis of CTS. The presence or absence of hand pain was recorded if these data were available.

RESULTS

Some 83.7% of hands (172/208) in 183 patients with markedly severe CTS had preservation of the Med2ndL meeting criteria for CTS. In those with pain data available, 77.1% (81/105) of hands had no pain. Of those 105 hands, 87 had preservation of the Med2ndL with 79.3% (69/87) demonstrating no pain.

CONCLUSIONS

This is a large study that demonstrates the relative preservation of the Med2ndL response in markedly severe CTS. Assessment of the Med2ndL should be considered to electrophysiologically support CTS when routine sensory and thenar motor responses are absent. In addition, most patients with electrophysiologically markedly severe CTS had no pain.

Carpal tunnel syndrome in rheumatoid arthritis patients: the role of combined ultrasonographic and electrophysiological assessment

Background

Carpal tunnel syndrome (CTS) is known as one of the most common neurological extra-articular manifestations in rheumatoid arthritis (RA) patients. Studies on CTS in RA depend mostly on electrophysiological assessment. Few studies have used ultrasonography for evaluation of the local causes with much focus on wrist arthritis and tenosynovitis as the main cause of entrapment neuropathy of the median nerve in RA. The aim of our study is to assess the local causes of carpal tunnel syndrome in rheumatoid arthritis patients by ultrasonography and whether inflammatory or anomalous variations could affect decision-making and patient management.

Results

Carpal tunnel syndrome was diagnosed in 71 out of 74 examined RA wrists by nerve conduction studies (NCSs) and was categorized from minimal to severe according to Padua et al.’s (Ital J Neurol Sci 18:145–50, 1997) grading criteria. Median nerve CSA at the level of the carpal tunnel inlet and flattening ratio showed statistically significant relation with CTS severity. Bifid MN was found in 20 wrists (10 mild CTS wrists and 10 moderate CTS wrists), a persistent median artery was found in 4 wrists with moderate CTS, and an accessory muscle bundle was present in 3 wrists (2 mild CTS and 1 moderate CTS). The majority of the examined hands (85.1%) showed flexor tendon tenosynovitis at the wrist level and radio-carpal joint synovitis. The US7-joint score using GSUS7 & PDUS7 for synovitis, tenosynovitis and erosions showed significant relation with patients’ disease activity by DAS28 score. Significant relations between CTS severity and the following nerve conduction studies’ parameters, median nerve distal motor latency (DML), motor/sensory NCV, peak sensory latency, amplitude of SNAP, and median-radial latency difference test, were observed.

Conclusion

Synovial inflammation and local causes of median nerve compression such as bifid median nerve, persistent median artery, and accessory muscle bundle are collectively contributing factors in the etiology of carpal tunnel syndrome in rheumatoid arthritis patients. Ultrasonographic visualization of these inflammatory and anomalous variations enables early detection of CTS and highlights the possibility of non-arthritic-related causes. Using the 7-joint ultrasound (US7) score for assessment of synovitis, tenosynovitis, and erosions in rheumatoid arthritis patients is of valuable role in reflecting inflammation and its relation to the development of CTS in RA patients.

Long-Term Outcome of Electrodiagnostic Values and Symptom Improvement After Carpal Tunnel Release: A Retrospective Cohort Study

PURPOSE

The aim of this study was to evaluate electrodiagnostic studies and clinical outcomes after carpal tunnel release surgery in moderate and severe cases of carpal tunnel syndrome (CTS).

METHODS

Seventy-two patients with moderate or severe CTS who underwent carpal tunnel release surgery (46 unilateral; 26 bilateral; total, 98 surgeries) between 2009 and 2014 were included in the study. The cases were divided into 2 groups according to electrodiagnostic results: those with moderate CTS and those with severe CTS. Michigan Hand Outcomes Questionnaire scores and electrodiagnostic data (sensory nerve action potentials and compound muscle action potentials) were recorded before surgery and in postoperative follow-up studies obtained at 3 months, 1 year, and 5 years.

RESULTS

There were 56 surgeries in the moderate CTS group and 42 surgeries in the severe CTS group. Sensory nerve action potentials and compound muscle action potentials were significantly lower in the severe CTS group when compared to the moderate CTS group at all follow-up times. There was a significant difference in Michigan Hand Outcomes Questionnaire scores between the groups before surgery, but no significant differences at the final follow-up. It was found that the values of all parameters (sensory nerve action potentials, compound muscle action potentials, and Michigan Hand Outcomes Questionnaire score) demonstrated significant improvements with time in both the severe and the moderate CTS groups.

CONCLUSIONS

Carpal tunnel release surgery improves symptoms, regardless of the preoperative severity. Postoperative electrodiagnostic study results of patients with moderate CTS improve to a greater degree than those of patients with severe CTS, but all remain abnormal.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognosis IIb.

Ultrasonography in patients with congenital thenar hypoplasia (Cavanagh syndrome) and co-morbid carpal tunnel syndrome

Objective

Patients with congenital thenar hypoplasia (Cavanagh syndrome) may undergo surgical intervention with a mistaken diagnosis of severe carpal tunnel syndrome. Conversely, patients with Cavanagh syndrome can develop co-morbid median nerve entrapment at the carpal tunnel later in life and may go untreated. This study is aimed at evaluating the role of ultrasonography in confirming/ruling out median nerve entrapment at the carpal tunnel in patients with Cavanagh syndrome.

Methods

6 patients with Cavanagh syndrome were identified during a 10-year period from among patients referred for preoperative electrodiagnostic confirmation of carpal tunnel syndrome. All patients underwent ultrasound imaging as well as electrodiagnostic studies including motor conduction study of the median nerve with recording electrodes over the lumbrical muscles.

Results

Age range of patients was 39-76. The right hand was affected in 5 and left hand in 1 patient. Electrodiagnostic studies (EDX) confirmed carpal tunnel syndrome in 4 of the 6 patients. In one patient the nerve conduction studies were non-diagnostic due to absence of compound muscle action potential (CMAP) over the thenar, and the 2nd lumbrical muscles and absent sensory nerve action potentials (SNAP). Ultrasound images confirmed entrapment of median nerve at the carpal tunnel in all 5 patients. The sixth patient was mistakenly diagnosed with severe carpal tunnel syndrome by the referring physician, based on the thenar atrophy; the median nerve was normal in both ultrasound and electrodiagnostic studies.

Conclusion

Ultrasound was useful for confirming/ruling out comorbid carpal tunnel syndrome in all 6 patients with Cavanagh syndrome.

Significance

Ultrasound complements electrodiagnostic study findings in patients with congenital thenar hypoplasia and comorbid carpal tunnel syndrome. It is even more valuable when EDX findings are non-diagnostic due to absent CMAP and SNAP.

Machine learning-based approach for disease severity classification of carpal tunnel syndrome

Identifying the severity of carpal tunnel syndrome (CTS) is essential to providing appropriate therapeutic interventions. We developed and validated machine-learning (ML) models for classifying CTS severity. Here, 1037 CTS hands with 11 variables each were retrospectively analyzed. CTS was confirmed using electrodiagnosis, and its severity was classified into three grades: mild, moderate, and severe. The dataset was randomly split into a training (70%) and test (30%) set. A total of 507 mild, 276 moderate, and 254 severe CTS hands were included. Extreme gradient boosting (XGB) showed the highest external validation accuracy in the multi-class classification at 76.6% (95% confidence interval [CI] 71.2–81.5). XGB also had an optimal model training accuracy of 76.1%. Random forest (RF) and k-nearest neighbors had the second-highest external validation accuracy of 75.6% (95% CI 70.0–80.5). For the RF and XGB models, the numeric rating scale of pain was the most important variable, and body mass index was the second most important. The one-versus-rest classification yielded improved external validation accuracies for each severity grade compared with the multi-class classification (mild, 83.6%; moderate, 78.8%; severe, 90.9%). The CTS severity classification based on the ML model was validated and is readily applicable to aiding clinical evaluations.

Impact of Plasma Xanthine Oxidoreductase Activity on the Mechanisms of Distal Symmetric Polyneuropathy Development in Patients with Type 2 Diabetes

To unravel associations between plasma xanthine oxidoreductase (XOR) and diabetic vascular complications, especially distal symmetric polyneuropathy (DSP), we investigated plasma XOR activities using a novel assay. Patients with type 2 diabetes mellitus (T2DM) with available nerve conduction study (NCS) data were analyzed. None were currently taking XOR inhibitors. XOR activity of fasting blood samples was assayed using a stable isotope-labeled substrate and LC-TQMS. JMP Clinical version 5.0. was used for analysis. We analyzed 54 patients. Mean age was 64.7 years, mean body mass index was 26.0 kg/m², and mean glycated hemoglobin was 9.4%. The logarithmically transformed plasma XOR activity (ln-XOR) correlated positively with hypoxanthine, xanthine, visceral fatty area, and liver dysfunction but negatively with HDL cholesterol. ln-XOR correlated negatively with diabetes duration and maximum intima-media thickness. Stepwise multiple regression analysis revealed ln-XOR to be among selected explanatory factors for various NCS parameters. Receiver operating characteristic curves showed the discriminatory power of ln-XOR. Principal component analysis revealed a negative relationship of ln-XOR with F-waves as well as positive relationships of ln-XOR with hepatic steatosis and obesity-related disorders. Taken together, our results show plasma XOR activity to be among potential disease status predictors in T2DM patients. Plasma XOR activity measurements might reliably detect pre-symptomatic DSP.

Normal reference value of orthodromic and antidromic sensory nerve conduction velocity of median nerve with intact palmaris longus tendon in apparently healthy individuals

OBJECTIVES

The aim of this study was to determine normative electrophysiological reference values of median sensory nerve conduction studies among security guards with the palmaris longus tendon (PLT).

METHODS

Sensory nerve conduction studies of the median nerve using antidromic and orthodromic methods were conducted in the upper limbs of 101 healthy male security guards between the ages of 21 and 42 years. The presence of the PLT was recorded in both hands using a standard test. A scatter plot was used to determine the correlation between different parameters using the ortho and antidromic methods.

RESULTS

The mean age (years), weight (kg), height (cm), and BMI (kg/m2) were 28.77 ± 5.14, 70.53 ± 11.28, 171.71 ± 7.12, and 23.91 ± 3.45, respectively. In the median nerve (sensory) by antidromic method, the mean distal latency (DL) was 2.65 ± 0.33 ms and 2.64 ± 0.37, SNCV (sensory nerve conduction velocity) was 53.45 ± 5.28 m/s and 53.84 ± 5.68 and the amplitude was 27.33 ± 12.38 µV and 29.41 ± 12.97 in the left- and right-hand wrist, respectively. By orthodromic method the DL was 2.54 ± 0.53 ms and 2.51 ± 0.44, SNCV was 55.93 ± 6.09 m/s and 55.93 ± 5.24 and the sensory nerve action potential amplitude was 12.00 ± 8.82 µV and 11.72 ± 6.24 in the left and right hand, respectively. Spearman correlations were used to determine the variables influenced by hand sidedness.

CONCLUSIONS

The normative reference parameters of sensory nerve conduction velocity of the median nerve were established by both methods using a standardized technique.

Electrodiagnostic, Sonographic, and Clinical Features of Carpal Tunnel Syndrome with Bifid Median Nerve

Purpose

A bifid median nerve (BMN) is not a rare variant. This study aimed to investigate the features of carpal tunnel syndrome (CTS) accompanied by BMN.

Patients and Methods

In this retrospective study, we defined a BMN group as CTS with BMN and a non-bifid median nerve (NMN) group as CTS without BMN. All hands were assigned to four severity grades according to the findings of electrodiagnosis (EDx): very mild, mild, moderate, and severe. The cross-sectional area (CSA) of the median nerve, palmar bowing of the flexor retinaculum, and persistent median artery (PMA) were assessed by ultrasonography. Numerical pain rating scale (NRS) and symptom duration were assessed as clinical variables.

Results

Sixty-four hands (57 patients) and 442 hands (341 patients) were enrolled in the BMN and the NMN groups, respectively. BMN was prevalent in 12.6% of all CTS hands. The distribution of EDx severity grade was milder in the BMN group than in the NMN group (P<0.001). The CSA of the BMN group was 16.2±4.1 mm², slightly larger than 15.1±4.2 mm² in the NMN group (P=0.056). The BMN group showed higher NRS than the NMN group (5.5±1.5 and 4.4±1.7, respectively; P<0.001). In the subgroup analysis, NRS was significantly higher in the BMN group than in the NMN group at all EDx severity grades. In the BMN group, the PMA group showed greater EDx severity (P=0.037) and higher NRS (6.0 and 5.0, respectively; P=0.012) than the non-PMA group. The radial side branch's CSA was larger than that of the ulnar side branch (10.0 mm² and 6.0 mm², respectively; P<0.001).

Conclusion

CTS with BMN presented more severe symptoms and relatively milder EDx severity. When assessing the severity of CTS with BMN, the clinical symptoms should primarily be considered, as well as we should complementarily evaluate the EDx and ultrasonography.

Carpal Tunnel Decompression Surgery Outcome and Effect of Diabetes

OBJECTIVE

The benefits of carpal tunnel decompressive surgery (CTDS) among diabetic patients with carpal tunnel syndrome (CTS) were previously investigated through comparing the outcome before and after CTDS, and in comparison to nondiabetic CTS. We sought to investigate if diabetes mitigates the benefits of CTDS compared to not receiving CTDS.

METHODS

In this retrospective study, we compared the risk of reporting any unfavorable outcomes among CTS patients (diabetic and nondiabetic) who underwent CTDS versus no CTDS after controlling for diabetes. We also compared the risk of reporting any unfavorable outcomes (waking up at night, pain during the day or during daily activities, or hand weakness) among diabetic CTS patients who underwent CTDS versus no CTDS after controlling for severity.

RESULTS

We included 207 patients; of these, 105 patients had CTDS and 102 did not. There were 60 diabetic and 147 nondiabetic patients. The risk of any unfavorable outcomes was reduced by CTDS from 83.3 to 66.6%, with an odds ratio (OR), after controlling for diabetes, of 0.39 (95% confidence interval [CI] 0.20-0.78). Among diabetic patients, there was no difference between the CTDS and non-CTDS groups in the risk of reporting any unfavorable outcomes; however, after adjustment for severity, the risk of hand weakness was less with CTDS, with an OR of 0.13 (95% CI 0.02-0.86).

CONCLUSION

Diabetes did not mitigate the benefits of CTDS. CTDS may prevent hand weakness among diabetic CTS patients.

Diagnostic Value of the Second Lumbrical-Interosseous Distal Motor Latency Comparison Test in Severe Carpal Tunnel Syndrome

Objective

To examine the usefulness of the second lumbrical-interosseous (2L-INT) distal motor latency (DML) comparison test in localizing median neuropathy to the wrist in patients with absent median sensory and motor response in routine nerve conduction studies.

Methods

Electrodiagnostic results from 1,705 hands of patients with carpal tunnel syndrome (CTS) symptoms were reviewed retrospectively. All subjects were evaluated using routine nerve conduction studies: median sensory conduction recorded from digits 1 to 4, motor conduction from the abductor pollicis brevis muscle, and the 2L-INT DML comparison test.

Results

Four hundred and one hands from a total of 1,705 were classified as having severe CTS. Among the severe CTS group, 56 hands (14.0%) showed absent median sensory and motor response in a routine nerve conduction study, and, of those hands, 42 (75.0%) showed an abnormal 2L-INT response.

Conclusion

The 2L-INT DML comparison test proved to be a valuable electrodiagnostic technique in localizing median mononeuropathy at the wrist, even in the most severe CTS patients.