Unique Transligamentous Variant of the Recurrent Motor Branch of the Median Nerve.

This case report presents a 72-year-old female with a unique anatomical variation of the median nerve recurrent motor branch that has not been described in the literature. During her open carpal tunnel release, the recurrent motor branch was found to divide from the median nerve within the carpal tunnel, pierce the proximal aspect of the transverse carpal ligament in a transligamentous fashion, and then immediately divide into one branch that pierced the thenar muscles and another branch that traveled superficial to the transverse carpal ligament before piercing the thenar muscles more distal. This variation in anatomy stresses the importance of thoughtful incision design and direct visualization of all structures during carpal tunnel release.

Comparison of median nerve area measurement between MRI and electromyography in patients diagnosed with carpal tunnel syndrome.

BACKGROUND: Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy that occurs when the median nerve is compressed within the carpal tunnel. Electromyography (EMG) is accepted as the most frequently used and important diagnostic method for CTS. Recently, magnetic resonance imaging (MRI) has begun to be used in CTS patients to directly visualize the median nerve and examine the changes occurring in the nerve structure. OBJECTIVES: In this study, the area of the median nerve was measured at various levels in the wrist in patients with CTS using MRI, examining its relationship with signal increase, and comparing this to results obtained with EMG. MATERIAL AND METHODS: Overall, 35 patients diagnosed with CTS were included in the study. Patients with normal-mild and moderate-severe EMG tests were included in the study; wrist MRI was taken to investigate the area/mm2 of the median nerve at various levels and whether there was an increase in signal. Thenar muscles included in the imaging were also evaluated. RESULTS: Of the 35 patients included in the study, 24 were women (68.6%) and 11 were men (31.4%). Measurements of the average median nerve area measured in mm2 at the distal radioulnar junction (DRUJ) and the median nerve area measured in mm2 at the hamate bone level were obtained, showing that DRUJ and hamate bone distance measurements were higher in patients with positive EMG. Electromyography findings were also significantly positive in patients with increased signal. CONCLUSIONS: In some cases, the diagnosis of CTS can be easily made with history and physical examination or employing confirmatory tests such as EMG, which is considered the gold standard. Magnetic resonsnace imaging can be used as an alternative method for imaging the median nerve in patients with CTS. In our study, EMG findings were also significantly positive in patients with increased signal on MRI, making it a preferable method, especially in soft tissue-related pathological cases.

The recovery and independence of elbow flexion and forearm supination after Oberlin II transfer in brachial plexus injuries: a long term follows up study.

PURPOSE: The Oberlin II double fascicular nerve transfer has been evaluated extensively for objective outcomes for elbow flexion in brachial plexus injuries (BPI). However, there is limited information available on the recovery pattern of supination and patient-reported activity in the long-term. Our study aimed to assess the functional results with a minimum of five years of follow-up. METHODS: We evaluated patients with a minimum of five years after the Oberlin II procedure for post-traumatic BPI. They were evaluated using MRC grading, range of active movements, QuickDASH score and activity to check elbow flexion and forearm supination independent of finger and wrist flexion. RESULTS: 18 out of 26 patients responded with a mean follow-up of 79.4 months (range: 61-98). 16 (88.9%) (p < 0.000) patients recovered to achieve active elbow flexion and forearm supination of either MRC grade 3 power or more. The average range of active elbow flexion was 113.9° (range: 0-140°) and active supination was 67.8° (0-90°). Patients who achieved grade 3 flexion or higher were found to regain supination after a delay. The recovery continues even after two years of surgery. The mean QuickDASH score was 21.8 (range: 2.3-63.6). There's a significant inverse correlation between QuickDASH with both flexion and supination (p < .001 and < 0.05). 15 patients (83.3%) could demonstrate a dissociation of elbow and forearm movements from digital and wrist movements. CONCLUSION: Our study demonstrated reliable functional results with independent elbow flexion, forearm supination and acceptable patient-reported outcomes for Oberlin II procedure in BPI.

Potential misinformation in websites on carpal tunnel syndrome.

Objective: We sought to evaluate the potential reinforcement of misconceptions in websites discussing carpal tunnel syndrome (CTS). Methods: After removing all cookies to limit personalization, we entered "carpal tunnel syndrome" into five search engines and collected the first 50 results displayed for each search. For each of the 105 unique websites, we recorded publication date, author background, and number of views. The prevalence of potential reinforcement and/or reorientation of misconceptions for each website was then scored using a rubric based on our interpretation of the best current evidence regarding CTS. The informational quality of websites was graded with the DISCERN instrument, a validated tool for assessing online health information. Results: Every website contained at least one potentially misleading statement in our opinion. The most common misconceptions reference "excessive motion" and "inflammation." Greater potential reinforcement of misinformation about CTS was associated with fewer page views and lower informational quality scores. Conclusions: Keeping in mind that this analysis is based on our interpretation of current best evidence, potential misinformation on websites addressing CTS is common and has the potential to increase symptom intensity and magnitude of incapability via reinforcement of unhelpful thoughts regarding symptoms. Innovation: The prevalence of patient-directed health information that can increase discomfort and incapability by reinforcing common unhelpful thoughts supports the need for innovations in how we develop, oversee, and evolve healthy online material.

The association of bariatric surgery and carpal tunnel syndrome: A propensity score-matched cohort study.

OBJECTIVES: To test the hypothesis that weight loss following bariatric surgery is associated with a reduced risk of developing carpal tunnel syndrome (CTS) compared with obese patients who do not undergo bariatric surgery. METHODS: We performed a cohort study using data from the Swedish nationwide healthcare registries. Patients aged 18-79 years who underwent bariatric surgery from 2006 to 2019 were propensity score (PS)-matched to up to 2 obese bariatric surgery-free patients ("unexposed patients"). Cox proportional hazard regression was used to calculate hazard ratios (HR) with 95% confidence intervals (CIs) to compare the incidence of CTS among bariatric surgery patients to obese unexposed patients both overall and divided by subgroups of age, sex, bariatric surgery type, and duration of follow-up. RESULTS: In total, 40,619 bariatric surgery patients were PS-matched to 63,540 obese unexposed patients who did not undergo surgery. Bariatric surgery was not associated overall with CTS (HR 0.98, 95% CI 0.91-1.05). There was a 23% decreased risk of CTS incidence observed within >1-3 years after bariatric surgery (HR 0.77, 95% CI 0.68-0.88). Decreased CTS risks were observed among bariatric surgery patients aged 18-34 years (HR 0.87, 95% CI 0.74-1.01) and those who underwent sleeve gastrectomy (HR 0.81, 95% CI 0.63-1.03), but these risks did not reach significance level compared with obese unexposed patients. However, there was a 20% increased CTS risk after 6 years (HR 1.20, 95% CI 1.05-1.36). CONCLUSION: Our results suggest that marked weight does not have a lasting impact on the reduction of CTS incidence.

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.

Comparison of Functionality Level, Disability and Quality of Life in Subjects with Peripheral Nerve Repair in the Upper Extremity.

Background: Peripheral nerve damage is a very important factor in patients' quality of life and functionality for various reasons. We aimed to compare the functionality level, disability and quality of life in subjects with peripheral nerve repair in the upper extremity. Methods: This cross-sectional study was conducted on patients with nerve injuries in 2019. Among those patients, Eighty-five were selected as the sample. The instruments used in this study included the health-related quality of life standard questionnaire (SF-36), and the disability of the arm, shoulder and hand questionnaire (DASH-38). Data were analyzed by SPSS software version 22 and one-way ANOVA and Kruskal-Wallis statistical tests. Results: Results of the Kruskal-Wallis test showed that the disability score in the groups of patients was not significant. In addition, according to the results of the one-way ANOVA test, the quality of life score was not significant among the patient groups. Conclusion: Considering that peripheral nerve damage has a significant impact on patients' quality of life and functionality, apart from more research on the subject, it is necessary to provide support for patients to improve their quality of life.

Association of Anthropometry With Nerve Conduction Parameters of Median Nerve: A Cross-Sectional Study in a North Indian Medical University Hospital.

Background Nerve conduction studies ease the understanding of the various pathologies of the peripheral nervous system. It helps physicians to delineate between the two principal types of peripheral etiologies: axonal degeneration and demyelination. An increase in weight in the form of excessive fat deposition or obesity could have a worrisome effect on nerve conduction. So, to find the association of various anthropometric parameters (age, gender, height, weight, waist-hip ratio and body mass index) with motor and sensory median nerve conduction parameters (latency, amplitude and velocity) this cross-sectional study was conducted. Materials and method A total of 87 subjects were taken and their height, weight, waist-hip ratio and body mass index were measured using standard techniques. Motor and sensory nerve conduction parameters were measured on an electromyography machine. Data was stored, tabulated and analyzed. Results The average height of male and female subjects ± SD was 1.699 ± 0.072 m and 1.589 ± 0.067 m respectively. The average weight of male and female subjects ± SD was 64.089 ± 11.497 kg and 52.949 ± 8.404 kg, respectively. The average BMI of normal, underweight and overweight subjects ± SD was 21.668 ± 2.048 kg/m2, 17.074 ± 0.794 kg/m2 and 26.595 ± 0.915 kg/m2 respectively. Weight showed a significant (p = 0.0025) correlation with the latency of motor median nerve conduction. Waist-hip ratio showed a significant (p = 0.042 and p = 0.036) correlation with motor median nerve conduction velocity in both male and female subjects, respectively. BMI in the overweight category showed a significant (p = 0.0156 and p = 0.0290) correlation with latency and amplitude of motor median nerve conduction study, respectively. Conclusions This study exemplifies that an increase in BMI of our body can affect nerve conduction. This could serve as a preliminary study to assess the effect of obesity on peripheral nerve conduction, especially in the Indian population.

Diagnostic meta-analysis of the efficacy of ultrasonography for diagnosing carpal tunnel syndrome: A comparison between Asian and non-Asian populations.

BACKGROUND: Ultrasonography is used to diagnose carpal tunnel syndrome (CTS) according to various criteria. This diagnostic meta-analysis aimed to evaluate the efficacy of ultrasonography for diagnosing CTS, focusing on the cross-sectional area (CSA) of the median nerve (MN) at the inlet of the carpal tunnel and regional variations in diagnostic thresholds between Asian and non-Asian populations. METHODS: A comprehensive literature search was conducted using PubMed, Embase, and the Cochrane Library. The risk of bias was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2). Patient demographic data, diagnostic "gold standards", CSA cutoff values, and diagnostic results were extracted. Meta-analysis was performed to determine the sensitivity, specificity, and optimal CSA cutoff values. RESULTS: For the 25 included studies, a combined sensitivity of 88% and specificity of 84% for CSA measurements at the carpal tunnel inlet were obtained. The Asian group had a sensitivity of 84% and specificity of 86%, while the non-Asian group had a sensitivity of 91% and specificity of 82%. The mean CSA in the Asian group was significantly lower than that in the non-Asian group (12.93 mm2 and 14.77 mm2, respectively; p = 0.042). For the Asian group, the summary receiver operating characteristic curve had an area under the curve (AUC) of 0.92 with an optimal cutoff of 10.5 mm2; for the non-Asian group, an AUC of 0.94 was obtained with a cutoff of 11.5 mm2. CONCLUSION: Ultrasonography is a reliable diagnostic method for CTS, with distinct optimal cutoff values observed between Asian and non-Asian populations. Therefore, population-specific diagnostic criteria for CTS are recommended.

Radial and median nerves distal peripheral tension after reverse shoulder arthroplasty: a cadaveric study.

Background: Peripheral nerve injury is a recognized complication after reverse shoulder arthroplasty (RSA) that has mainly been studied at the level of the brachial plexus and its proximal branches. However, the impact of RSA on distal peripheral nerves and the influence of elbow and wrist position is not known. This cadaveric study aimed to analyze the effect of RSA implantation and upper limb position on tension in the distal median and radial nerves. The hypothesis was that RSA increased distal nerve tension, which could be further affected by elbow and wrist position. Methods: 12 upper limbs in 9 full fresh-frozen cadavers were dissected. Nerve tension was measured in the median nerve at the level of the proximal arm, elbow, and distal forearm, and in the radial nerve at the level of the elbow, using a customized three-point tensiometer. Measurements were carried out before and after RSA implantation, using a semi-inlay implant (Medacta, Castel San Pietro, Switzerland). Two different configurations were tested, using the smallest and largest available implant sizes. Three upper-limb key positions were considered (plexus at risk, plexus relief, and neutral), from which the effect of elbow and wrist position was further tested. Results: RSA implantation significantly increased median and radial nerve tension throughout the upper limb. The distal nerve segments were particularly dependent on elbow and wrist position. The plexus at risk position induced the most tension in all nerve segments, especially with the large implant configuration. On the other hand, the plexus relief position induced the least amount of tension. Flexing the elbow was the most efficient way to decrease nerve tension in all tested nerve segments and key positions. Wrist flexion significantly decreased nerve tension in the median nerve, whereas wrist extension decreased tension in the radial nerve. Conclusion: RSA significantly increases tension in the median and radial nerves and makes them more susceptible to wrist and elbow positioning. The mechanism behind distal peripheral neuropathy after RSA may thus result from increased compression of tensioned nerves against anatomical fulcrums rather than nerve elongation alone. Elbow flexion was the most effective way to decrease nerve tension, while elbow extension should be avoided when implanting the humeral component. Further studies are needed to assess the ulnar nerve.

Cords of the Brachial Plexus and Their Branches Positioned Laterally to the Axillary Artery.

The brachial plexus, which supplies the upper limb, extends from the interscalene triangle in the root of the neck to the axilla and is closely related to the subclavian and axillary arteries. Variations in the formation, branching pattern, and relations are profound, and it is generally stated that variant anatomy of the plexus appears to be a rule rather than an exception. In previous studies, it was hypothesized that the anomalous development of the subclavian-axillary stem and the persistence of intersegmental arteries could induce variations in the plexus. In this study, all three cords of the brachial plexus (lateral, medial, and posterior) and their terminal branches are consistently found lateral to the third part of the axillary artery. Most of the studies reported variation in one or the other cord or its branches, but very few studies have reported about all cords lateral to the brachial plexus. The brachial plexus variations are usually also associated with the variations in the branches of the axillary artery, but in this study, no such variation is noted in the branches of the axillary artery. These differences impact the methods of surgery and the application of regional anesthesia. For successful outcomes, it is important to know how neurovascular relationships work, such as where the cords are in relation to the axillary artery. We report an interesting case of all cords and their branches positioned lateral to the axillary artery in the axilla in an adult male cadaver.

Effect of cervical contralateral lateral flexion on the median nerve and fascia at the wrist - Cadaveric study.

BACKGROUND: Neurodynamic tests are an essential aspect of the physical examination of the patient when suspicion of neural involvement exists. A manoeuvre that is hypothesised to move nerves differentially relative to other structures (structural differentiation) has been proposed as a necessary part of neurodynamic testing for differential diagnosis. However, although the specificity of structural differentiation for peripheral nerve over muscle has been demonstrated in some body regions, no study has tested specificity of nerve movement relative to fascia. OBJECTIVES: The aim of this study was to measure the effect of the cervical contralateral lateral flexion (CCLF) as an structural differentiation manoeuvre for the median nerve compared to fascia (superficial and deep) at the wrist during the upper limb neurodynamic test 1 (ULNT1). DESIGN: A cross-sectional study was performed in 5 fresh frozen cadavers. METHODS: Excursion and strain in the fascia (superficial and deep) and the median nerve were measured at the wrist with structural differentiation during the ULNT1. KINOVEA software was used to measure kinematic parameters. RESULTS: CCLF resulted in significant proximal excursion in the median nerve (p < 0.001*) but not in the strain. CCLF neither produced changes in strain nor excursion in the superficial and deep fascia (p > 0.05). CONCLUSION: This study showed that CCLF produced significant differential excursion in the median nerve at the wrist compared to the local superficial and deep fascia during the ULNT1. The data support CCLF in mechanical differentiation between nerve and fascia in this area in diagnosis of local sources of wrist pain.

Alternative treatment of carpal tunnel syndrome with ultrasound-guided median nerve hydrodissection in the emergency department.

Hydrodissection is becoming increasingly recognized as a treatment for nerve entrapment syndromes in the orthopedic and rehabilitation world. Carpal Tunnel Syndrome (CTS) is the most prevalent nerve entrapment neuropathy, characterized by compression of the median nerve as it passes through the carpal tunnel. Initial management includes NSAIDs and wrist splints, but surgical intervention is often necessary when these measures fail. Ultrasound-guided hydrodissection of the median nerve is both safe and effective and presents a minimally invasive option when first-line treatments fail to provide adequate symptom relief. This case report demonstrates the potential for an alternative approach to analgesia in the Emergency Department (ED) for patients presenting with pain related to CTS. Here we discuss a case of a 26-year-old female presenting with CTS symptoms and her successful treatment with ultrasound-guided hydrodissection in the ED.

Bilateral median nerve stimulation and High-Frequency Oscillations unveil interhemispheric inhibition of primary sensory cortex.

OBJECTIVE: This study aimed at investigating the effect of median nerve stimulation on ipsilateral cortical potentials evoked by contralateral median nerve electrical stimulation. METHODS: We recorded somatosensory-evoked potentials (SEPs) from the left parietal cortex in 15 right-handed, healthy subjects. We administered bilateral median nerve stimulation, with the ipsilateral stimulation preceding the stimulation on the contralateral by intervals of 5, 10, 20, or 40 ms. We adjusted these intervals based on each individual's N20 latency. As a measure of S1 excitability, the amplitude of the N20 and the area of the High Frequency Oscillation (HFO) burst were analyzed for each condition. RESULTS: The results revealed significant inhibition of N20 amplitude by ipsilateral median nerve stimulation at interstimulus intervals (ISIs) between 5 and 40 ms. Late HFO burst was suppressed at short ISIs of 5 and 10 ms, pointing to a transcallosal inhibitory effect on S1 intracortical circuits. CONCLUSIONS: Findings suggest interhemispheric interaction between the primary somatosensory areas, supporting the existence of transcallosal transfer of tactile information. SIGNIFICANCE: This study provides valuable insights into the interhemispheric connections between primary sensory areas and underscore the potential role of interhemispheric interactions in somatosensory processing.

Comparison of Fibrin Glue With Conventional Suturing in Peripheral Nerve Repairs: A Study of Sensory and Motor Outcomes.

BACKGROUND: Nerve injuries have traditionally been repaired with sutures, and this method is considered the gold standard technique in the management of nerve injuries. However, fibrin glue has recently become a promising tool for repairing nerve injuries and has advantages including ease of usability, atraumatic application technique, and decreased co-optation time of the nerves. This study aims to clinically evaluate the efficacy of nerve repair with fibrin glue compared with the usual suture technique in terms of sensory and motor outcomes. METHODS: A total of 80 patients were included in the study; 50 patients underwent primary nerve repair, and 30 patients underwent Oberlin's repair. These subsets were randomly divided into two groups in which the nerves were repaired with microsutures in one group and fibrin glue in the other group. RESULTS: In the comparison of fibrin glue with microsutures, there were no significant differences between the two groups in the 2-point discrimination (2PD) test, Semmes-Weinstein test, motor function, and Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire scores. However, the co-optation times were significantly shorter with fibrin glue than with microsutures. CONCLUSION: Based on our findings, nerve repair with fibrin glue is as effective as microsutures in terms of sensory and motor recovery and has added advantages of ease of usability and shorter repair times. Therefore, fibrin glue may be an effective alternative to sutures in nerve repair.

T2 magnetic resonance imaging mapping and morphology of the median nerve before and after surgery in carpal tunnel syndrome.

INTRODUCTION/AIMS: T2 magnetic resonance imaging (MRI) mapping has been applied to carpal tunnel syndrome (CTS) for quantitative assessment of the median nerve. However, quantitative changes in the median nerve before and after surgery using T2 MRI mapping remain unclear. We aimed to investigate whether pathological changes could be identified by pre- and postoperative T2 MRI mapping of the median nerve in CTS patients after open carpal tunnel release. METHODS: This was a prospective study that measured median nerve T2 and cross-sectional area (CSA) values at the distal carpal tunnel, hamate bone, proximal carpal tunnel, and forearm levels pre- and postoperatively. Associations between T2, CSA, and nerve conduction latency were also evaluated. RESULTS: A total of 36 patients with CTS (mean age, 64.5 ± 11.7 years) who underwent surgery were studied. The mean preoperative T2 values significantly decreased from 56.3 to 46.9 ms at the proximal carpal tunnel levels (p = .001), and from 52.4 to 48.7 ms at the hamate levels postoperatively (p = .04). Although there was a moderate association between preoperative T2 values at the distal carpal tunnel levels and distal motor latency values (r = -.46), other T2 values at all four carpal tunnel levels were not significantly associated with CSA or nerve conduction latency pre- or postoperatively. DISCUSSION: T2 MRI mapping of the carpal tunnel suggested a decrease in nerve edema after surgery. T2 MRI mapping provides quantitative information on the median nerve before and after surgery.

Ultrasound Cross-Sectional Area in Median Nerve Axonal Loss and Demyelination in Carpal Tunnel Syndrome.

Introduction: Ultrasound is an effective diagnostic tool for carpal tunnel syndrome (CTS). However, it is unclear how ultrasound correlates with axonal loss and/or demyelination on electrodiagnostic studies (EDS). The objective of this study is to determine whether ultrasound cross-sectional area (CSA) of the median nerve varies between patients with axonal loss or demyelination. Methods: A retrospective review was completed of patients who presented to an orthopaedic hand clinic with numbness/paresthesias over a 6-year period. Demographics, CTS symptoms scale 6 (CTS-6) scores, Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) scores, EDS results, and ultrasound results were collected. Median neuropathies were graded as normal, demyelination, or axonal loss using EDS reports. The data were analyzed with chi-square and t-tests. Results: In all, 383 hands were included (92 axonal loss, 182 demyelination only, and 108 neither). The average patient age was 52.2 and the average body mass index (BMI) was 31.7. The group consisted of 70.7% females, and 23.2% had diabetes. Patients with either axonal loss or demyelination had larger CSA and higher CTS-6 and BCTQ scores than patients with negative EDS. Patients with axonal loss also had larger CSA and higher CTS-6 and BCTQ scores than patients with demyelination only. The rates of positive ultrasound results between axonal loss and demyelination groups did not differ until the ultrasound cutoff was increased from 10 to 12 mm2. Conclusion: Rates of positive ultrasound results (CSA ≥ 10 mm2) do not differ between wrists with axonal loss or demyelination alone. Therefore, the character of carpal tunnel neuropathy does not affect ultrasound's diagnostic ability. Additionally, CSA increases as wrists develop axonal loss, and an increased ultrasound cutoff of 12 mm2 is correlated with this pathology.

Diabetes Increases Median Nerve Cross-Sectional Area but Not Disease Severity in Patients with Carpal Tunnel Syndrome.

Background: Ultrasonography (US) is a useful diagnostic modality for diagnosis of carpal tunnel syndrome (CTS). Diabetes mellitus is increasingly prevalent and is a risk factor for CTS. Given the increasing use of US in the diagnosis of CTS, our goal was to evaluate the influence of diabetes on CTS severity and the cross-sectional area (CSA) of the median nerve in patients with CTS. Methods: Patients with clinically diagnosed CTS were seen in the outpatient setting from October 2014 to February 2021. Median nerve CSA and patient reported severity measures were obtained: Boston Carpal Tunnel Syndrome Questionnaire (BCTSQ) and CTS-6. For patients with diabetes, additional parameters were collected including most recent A1c, insulin pharmacotherapy, and polypharmacy. Results: Ninety-nine patients (122 nerves) without diabetes and 55 patients (82 nerves) with diabetes were recruited for the study. Patients in the diabetes group were more obese and older and had a significantly increased median nerve CSA compared with patients without diabetes. Obesity was associated with higher median nerve CSA in all patients but not in patients with diabetes. There was no difference in disease severity in patients with and without diabetes as reported by BCTSQ or CTS-6 scores. In patients with diabetes, there was significantly decreased median nerve CSA with A1c of 6.5 or higher and a trend to decreased CSA with polypharmacy. There was no influence of insulin therapy on median nerve CSA. Conclusion: Diabetes is associated with higher median nerve CSA in patients with CTS of similar disease severity. The increased median nerve CSA in patients with diabetes may be reflective of diabetes-related microvascular changes. Interestingly, the trend to decreased median nerve CSA in patients with suboptimal diabetic control (A1c ≥ 6.5) may suggest eventual degenerative changes to the median nerve. In summary, clinicians should be cautious with interpreting a larger median nerve CSA as more severe CTS in patients with diabetes. Level of Evidence: Level 3 Diagnostic.