Carpal Tunnel Release With Ultrasound Guidance: Intermediate-Term Clinical Outcomes and Magnetic Resonance Imaging Findings

Abstract

Purpose: The purpose of this study was to report intermediate-term outcomes following carpal tunnel release using ultrasound guidance and wide-awake local anesthesia no tourniquet, including a subset of patients with preoperative and postoperative magnetic resonance imaging (MRI).

Methods: In this observational study, patients with carpal tunnel syndrome were treated with carpal tunnel release using ultrasound guidance and wide-awake local anesthesia no tourniquet in a procedure room at a single center. Main outcomes were complications; return to activity and work at 2 weeks; Quick Disabilities of the Arm, Shoulder, and Hand and Boston Carpal Tunnel Questionnaire scores through 6 months; and postoperative morphological changes of the transverse carpal ligament, median nerve, and carpal tunnel evaluated using MRI.

Results: No complications were reported among 65 patients (68% women, 96 wrists). By 2 weeks, 97% of patients returned to normal activity and 100% returned to work. Statistically significant improvements in Boston Carpal Tunnel Questionnaire symptom severity scale, Boston Carpal Tunnel Questionnaire functional status scale, and Quick Disabilities of the Arm, Shoulder, and Hand scores occurred by the 2-week follow-up interval and persisted at 6 months (all P < .001). Pre- and postoperative MRI scans were available for 13 patients (17 wrists) at the 3-month mean follow-up. Complete transverse carpal ligament transection was documented in all wrists. Key MRI findings included a 22% increase in carpal tunnel cross-sectional area at the hamate (P < .001), a 52% increase in median nerve cross-sectional area at the hamate (P < .001), an 18% reduction in median nerve signal intensity (P = .002), a 38% reduction in the flattening ratio of the median nerve at the hamate (P < .001), a 33% reduction in the flattening ratio of the median nerve at the pisiform (P < .001), a 20% reduction in the flattening ratio of the carpal tunnel at the hamate (P < .001), and a palmar shift of the median nerve relative to the hamate in all cases.

Conclusions: Carpal tunnel release using ultrasound guidance using wide-awake local anesthesia no tourniquet in a procedure room setting was safe, effective, and resulted in morphological changes that were consistent with carpal tunnel decompression as demonstrated by MRI.

Type of study/level of evidence: Therapeutic IV.

Keywords: CTR-US; Carpal tunnel release; Carpal tunnel syndrome; Magnetic resonance imaging; WALANT.

Figure 1

Change in BCTQ-SSS and BCTQ-FSS score over 6 months following CTR-US. Plotted data are mean and 95% confidence interval. Asterisk denotes P < .001 for change compared to baseline using a Bonferroni-adjusted linear mixed model.

Figure 2

Change in QuickDASH score over 6 months following CTR-US. Plotted data are mean and 95% confidence interval. Asterisk denotes P < .001 for change compared to baseline using a Bonferroni-adjusted linear mixed model.

Figure 3

A Preoperative T2 weighted axial MRI at the hamate (H) level shows the cross-sectional area of median nerve (white outline) with the transverse carpal ligament intact (arrow). B 3-months postoperative T2 weighted axial image at the hamate level shows an increase in the cross-sectional area of median nerve (white outline) and a gap in the transected transverse carpal ligament (white line). Dashed line and arrow in images A and B show a palmar shift of median nerve reported as the difference in postoperative distance measured from the palmer aspect of the carpals (dashed line) and the center of the median nerve (dashed arrow).

Figure 4

A Preoperative T2 weighted axial MRI at the hamate (H) level shows the cross-sectional area of carpal tunnel (yellow shading). B 4-months postoperative T2 weighted axial image at the hamate level shows an increase in the cross-sectional area of the carpal tunnel (yellow shading).