Background: Current illustrations of the carpal tunnel vary greatly. The relative positions of the components such as the median nerve and flexor pollicis longus (FPL) tendon seem often arbitrarily chosen. The purpose of this study was to determine the locations of the median nerve and FPL in the carpal tunnel using ultrasound (US) and to determine whether the position of the median nerve changes in carpal tunnel syndrome (CTS). Method: Patients with and without CTS underwent US examination of the wrist. A 4 × 10 grid was fitted to each saved cross-sectional image. The center points of the median nerve and FPL were identified, and their horizontal and vertical coordinates were recorded. Results: The median nerve was identified in 115 wrists (average x = 0.70, y = 0.82), and FPL was identified in 90 wrists (average x = 0.86, y = 0.59). A scatter plot was created by stacking all US images to demonstrate the average positions of the median nerve and FPL. There were 97 wrists without CTS (No CTS) and 17 wrists with CTS. There was a significant difference in the vertical position of the median nerve between No CTS and CTS wrists ( P = .0006). Conclusions: The locations of the median nerve and FPL within the carpal tunnel were determined using US of 115 wrists, and a heat map was created to illustrate these locations. The median nerve was found to be more superficial in the setting of CTS.

Background: Although increased cross-sectional area of the median nerve on ultrasound has been associated with carpal tunnel syndrome, there has been little research examining outlier cases with exceedingly large nerves. The purpose of this study was to identify factors associated with these “mega” nerves, and to determine whether these nerves carry with them increased severity of disease. Methods: Patients who presented to clinic with upper extremity paresthesias over a 4-year period were included in this study. Two groups were created: mega nerves (cross-sectional area >2 SD above average), and nonmega nerves. Statistical analysis was performed to compare demographics, symptom scores, and nerve conduction studies (NCS). Significant variables were then compared between patients with mega nerves and those with ultrasound positive nerves (≥10 mm2), which did not reach mega size (normal nerves were excluded). Results: The cohort included 425 median nerves with 25 mega nerves. The groups differed significantly in diabetes status, body mass index (BMI), Boston Carpal Tunnel Questionnaire (BCTQ) Symptom Severity Scale scores, and NCS results. When compared only with ultrasound positive but nonmega nerves, mega nerves were still associated with diabetes, higher BMI, and worse NCS results. Conclusions: Diabetes, BMI, NCS results, and BCTQ Symptom Severity Scale scores are associated with mega nerves. However, BCTQ scores do not differ between mega nerves and other ultrasound positive nerves. In patients with obesity or diabetes, outlier ultrasound measurements may not correlate with worsened clinical symptoms, even in the setting of more significantly altered NCS results.

Background: The purpose of this study was to evaluate the relationship between cross sectional area (CSA) of the median nerve on ultrasound (US) with pre- and postoperative Boston Carpal Tunnel Questionnaire (BCTQ) scores. We hypothesize that there is a positive correlation between CSA and the ΔBCTQ after carpal tunnel release (CTR). Methods: This was a single center study. During a 6-year period (2014-2020), CSA of the median nerve on US and BCTQ scores were collected prospectively for patients presenting with the chief complaint of numbness and tingling in the upper extremity. Patients who underwent CTR and presented for their 6-week follow-up had repeat measurements of the CSA and BCTQ. These patients were included in this study. Patients were then divided into ultrasound positive (CSA ≥ 10) and ultrasound negative (CSA < 10) groups. These groups were compared on the basis of demographics, preoperative BCTQ scores, postoperative BCTQ scores, and 6-week ΔBCTQ score. Results: US-positive and-negative groups did not differ significantly in their preoperative BCTQ, postoperative BCTQ, or ΔBCTQ scores. Both groups did, however, experience significant improvement when comparing preoperative to postoperative BCTQ scores within their respective US group. Conclusion: Regardless of the preoperative CSA of the median nerve, patients who underwent CTR experienced a significant improvement in their BCTQ results. US-positive patients experienced no greater improvement than US-negative patients. These results would suggest that US is not a good predictor of subjective surgical outcome measures such as the BCTQ.

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.