Ultrasound (US) Changes in the Median Nerve Cross-Sectional Area After Microinvasive US-Guided Carpal Tunnel Release

Advances in Imaging of Compressive Neuropathies

Ultrasound and magnetic resonance neurography are useful modalities to aid in the assessment of compressive neuropathies, although they are still limited in their resolution of nerve microstructure and their capacity to monitor postoperative nerve recovery. Optical coherence tomography, a preclinical imaging modality, is promising in its ability to better identify structural and potential physiologic changes to peripheral nerves, but requires additional testing and research prior to widespread clinical implementation. Further advances in nerve imaging may elucidate the ability to visualize the zone of nerve injury intraoperatively, monitor the progression of nerve regeneration, and localize problems during nerve recovery.

Office-Based Carpal Tunnel Release With Ultrasound Guidance: 6-month Outcomes From the Multicenter ROBUST Trial

Purpose

The purpose of this study was to determine the safety and effectiveness of office-based carpal tunnel release with ultrasound guidance (CTR-US).

Methods

In this prospective multicenter observational study, patients were treated with CTR-US in an office setting. Outcomes were time to resume normal daily activities, time to return to work, Boston Carpal Tunnel Questionnaire Symptom Severity Scale and Functional Status Scale scores, Michigan Hand Questionnaire, Numeric Pain Scale, EuroQoL-5 Dimension 5-Level score, procedure satisfaction, and adverse events over 6 months.

Results

A total of 149 participants (226 hands) from seven centers underwent office-based CTR-US. The mean age was 58 years, 52% were women, and 68% were employed. The mean incision length was 5 mm, 52% had simultaneous bilateral procedures, and wide-awake local anesthesia no tourniquet was used in all cases. All procedures were completed as planned, with no conversions to open repair and mean intraoperative pain severity of 1.6 ± 1.5. The median time to resume normal activities was 2 days (interquartile range: 1-4 days) and return to work was 4 days (interquartile range: 1-5 days). Over 6 months, Boston Carpal Tunnel Questionnaire Symptom Severity Scale decreased by a mean of 1.7 points, Boston Carpal Tunnel Questionnaire Functional Status Scale decreased by 1.1 points, Michigan Hand Questionnaire Global score increased by 35 points, Numeric Pain Scale decreased by 3.7 points, and EuroQoL-5 Dimension 5-Level score increased by 0.11 points. At 6 months, 94% reported procedure satisfaction. Unilateral and simultaneous bilateral procedures were similarly effective. There was one (0.4%) adverse event, a nerve contusion treated with neurolysis and nerve wrap where the patient fully regained normal function within 7 weeks. There were no revisions for persistent or recurrent carpal tunnel syndrome symptoms.

Conclusions

Office-based CTR-US, performed either unilaterally or as simultaneous bilateral procedures, is well tolerated with a low complication rate and associated with rapid recovery, sustained improvement in symptoms and function, and high procedure satisfaction.

Type of study/level of evidence

Therapeutic III.

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

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.

Ultrasound-Guided Interventions for Carpal Tunnel Syndrome: A Systematic Review and Meta-Analyses

Carpal tunnel syndrome (CTS) is the most common peripheral entrapment, and recently, ultrasound-guided perineural injection (UPIT) and percutaneous flexor retinaculum release (UPCTR) have been utilized to treat CTS. However, no systematic review or meta-analysis has included both intervention types of ultrasound-guided interventions for CTS. Therefore, we performed this review using four databases (i.e., PubMed, EMBASE, Scopus, and Cochrane) to evaluate the quality of evidence, effectiveness, and safety of the published studies on ultrasound-guided interventions in CTS. Among sixty studies selected for systemic review, 20 randomized treatment comparison or controlled studies were included in six meta-analyses. Steroid UPIT with ultrasound guidance outperformed that with landmark guidance. UPIT with higher-dose steroids outperformed that with lower-dose steroids. UPIT with 5% dextrose in water (D5W) outperformed control injection and hydrodissection with high-volume D5W was superior to that with low-volume D5W. UPIT with platelet-rich plasma outperformed various control treatments. UPCTR outperformed open surgery in terms of symptom improvement but not functional improvement. No serious adverse events were reported in the studies reviewed. The findings suggest that both UPIT and UPCTR may provide clinically important benefits and appear safe. Further treatment comparison studies are required to determine comparative therapeutic efficacy.

Ultrasound-guided percutaneous carpal tunnel release: A systematic review

OBJECTIVE

Carpal tunnel syndrome (CTS) is the most common peripheral entrapment mononeuropathy. The purpose of this systematic review is to evaluate the reported clinical effectiveness and safety of ultrasound-guided percutaneous carpal tunnel release (USCTR) for the treatment of CTS.

LITERATURE SURVEY

PubMed, EMBASE, and ScienceDirect databases were queried from database inception to February 20, 2021, to identify clinical studies on USCTR.

METHODOLOGY

Two reviewers independently completed title, abstract, and full-text screening, and they extracted data in duplicate for analysis. Procedure techniques, outcome measures, and complications were descriptively analyzed.

SYNTHESIS

Eighty-seven studies were eligible for screening. Twenty studies (three randomized controlled trials, three prospective cohort studies, and 14 case series) met inclusion criteria, with a total of 1772 USCTR cases. The overall level of evidence was very low, with seven studies with at least moderate risk of bias. Thirteen studies exceeded the minimal clinically important difference (MCID) for the Boston Carpal Tunnel Questionnaire Symptom Severity Scale (BCTQ-SS) and Boston Carpal Tunnel Questionnaire Functional Status Scale (BCTQ-FS), and six studies exceeded the MCID for the Quick Disabilities of Arm, Shoulder & Hand (QDASH). Five studies reported statistically significant improvement in these functional outcome measures as early as the first week post-procedure. A major complication occurred in one patient who developed suspected compartment syndrome, and minor complications were reported in 24 patients.

CONCLUSIONS

Based on very low level of evidence, early studies suggest that USCTR may be an effective treatment for CTS, with potential for short post-procedure recovery times.

[Trifid median nerve. A rare anatomical variant in sonographic evaluation of carpal tunnel]

The ultrasound study for the diagnosis of carpal tunnel syndrome can reveal different anatomical variants. A rare variant is the presence of a trifid median nerve. The visualization of this anatomical variant may be of importance in the surgical planning of carpal tunnel syndrome. Fifty-two-year-old male, with a clinic compatible with bilateral carpal tunnel syndrome. In the ultrasound examination, a bifid median nerve appears as a finding in the right wrist and a trifid median nerve in the left wrist as anatomical variants. It is important to distinguish a trifid median nerve from a persistent median artery at the level of the carpal tunnel, much more frequent than the first. For this, the ultrasound visualization of the study area using the Doppler function is essential.

Ultrasound Cross-Sectional Area of the Median Nerve Is Not a Predictor of Patient Reported Outcomes After Carpal Tunnel Release

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.

Future Considerations in the Diagnosis and Treatment of Compressive Neuropathies of the Upper Extremity

Compressive neuropathies of the upper extremity are among the most common conditions seen by hand surgeons. The diagnoses of carpal tunnel syndrome and cubital tunnel syndrome have traditionally been made by a combination of history, physical examination, and electrodiagnostic testing. However, findings can be nonspecific and electrodiagnostic testing is invasive for the patient. The diagnosis of compressive neuropathies continues to evolve as technology advances, and newer diagnostic modalities predominantly focus on preoperative diagnostic imaging with ultrasound and magnetic resonance imaging/neurography. With the advent of cheaper, faster, and less invasive imaging, the future may bring a paradigm shift away from electrophysiology as the gold standard for the preoperative diagnosis of compressive neuropathies. Intraoperative imaging of nerve health is an emerging concept that warrants further investigation, whereas postoperative imaging of nerve recovery with ultrasound and magnetic resonance imaging currently has a limited role because of nonspecific findings and potential for misinterpretation. Advances in surgical treatment of compressive neuropathies appear to center around the use of imaging for less invasive neurolysis techniques and other adjunctive treatments with nerve decompression. The management of failed peripheral nerve decompressions and recurrent compressive neuropathies remains challenging.

Long-term Clinical Results of Carpal Tunnel Release Using Ultrasound Guidance

BACKGROUND

The purpose of this study was to determine the long-term safety and efficacy of carpal tunnel release (CTR) using ultrasound guidance in a group of patients treated by a single physician.

METHODS

The study group consisted of 76 consecutive CTRs performed on 47 patients between June 2017 and April 2019 for whom 1-year follow-up was available. All procedures were performed by the same operator using a single CTR technique. Outcomes included complications; Boston Carpal Tunnel Questionnaire symptom severity (BCTQ-SSS) and functional status (BCTQ-FSS) scores; Quick Disabilities of the Arm, Shoulder, and Hand (QDASH) scores; and a 5-point global satisfaction score (4 = satisfied, 5 = very satisfied).

RESULTS

The 47 patients included 27 females and 20 males (ages 31-91 years). Twenty-five patients (50 hands) had simultaneous bilateral CTRs, 4 patients (8 hands) had staged bilateral CTRs, and 18 patients had unilateral CTRs. No complications occurred. Statistically and clinically significant reductions in BCTQ-SSS, BCTQ-FSS, and QDASH scores occurred by 1 to 2 weeks post-CTR and persisted at 1-year (mean 1-year changes vs. pre-CTR -2.11, -1.70, and -44.99, respectively; P < .001 for all). The mean global satisfaction score at 1-year was 4.63.

CONCLUSIONS

CTR using ultrasound (US) guidance is a safe and effective procedure that produces statistically and clinically significant improvements within 1 to 2 weeks postprocedure that persist to 1 year. Furthermore, simultaneous bilateral CTRs using US guidance are feasible and may be advantageous for patients who are candidates for bilateral CTR.

Relationship Between Morphological Change of Median Nerve and Clinical Outcome Before and After Open Carpal Tunnel Release: Ultrasonographic 1-Year Follow-up After Operation

Background: The aims of this study were 2-fold: (1) to assess the morphological change of the median nerve in patients with carpal tunnel syndrome (CTS) preoperatively and at 6 and 12 months postoperatively; and (2) to analyze correlation between the changes in ultrasonographic findings and the changes in clinical findings after surgical decompression. Methods: Of the 28 patients with CTS, 34 wrists were treated with open carpal tunnel release. We evaluated them using the Boston questionnaire, Japanese Society for Surgery of the Hand Version of the Quick Disability of the Arm, Shoulder, and Hand questionnaire, nerve conduction study (NCS), and ultrasound preoperatively and at 6 and 12 months postoperatively. We measured the cross-sectional area (CSA) of the median nerve at the level of the proximal inlet of the carpal tunnel (CSAc) and more proximally at the level of the distal radioulnar joint (CSAd). Paired t tests and repeated measures analysis of variance of ranks were used to identify changes over time. The Spearman correlation coefficient by rank test was used for the analysis of the relation between the amount of change of CSA and the patient-rated questionnaire score and NCS findings. Results: Findings for CSAc, CSAd, and NCS and patient-rated outcomes at 6 and 12 months postoperatively were significantly lower than their preoperative values. However, no significant correlation was found between the postoperative changes in CSAc, CSAd, and clinical variables obtained preoperatively and postoperatively. Conclusions: Evaluation of sonographic imaging might not be helpful for assessing clinical conditions in patients with CTS after surgical decompression.

MRI of carpal tunnel syndrome: before and after carpal tunnel release

Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome. Magnetic resonance imaging (MRI) is increasingly used to diagnose CTS, exclude secondary causes of CTS, and investigate patients with persistent symptoms after carpal tunnel release. Median nerve compression may also be either subclinical in the early stages or present with atypical symptoms. Radiologists are therefore not infrequently the first to alert clinicians as to the possibly of subclinical or atypical CTS. This review shows the normal and abnormal appearances of the carpal tunnel before and after CTR.

Ultrasonography Findings of the Carpal Tunnel after Endoscopic Carpal Tunnel Release for Carpal Tunnel Syndrome

Objective

To investigate changes in the median nerve, retinaculum, and carpal tunnel on ultrasound after successful endoscopic carpal tunnel release (ECTR).

Materials and Methods

This prospective study involved 37 wrists in 35 patients (5 male, 30 female; mean age ± standard deviation [SD], 56.9 ± 6.7 years) with primary carpal tunnel syndrome (CTS). An in-house developed scoring system (0–3) was used to gauge the clinical improvement after ECTR. Ultrasound was performed before ECTR, and at 1, 3, and 12 months post-ECTR. Changes in the median nerve, flexor retinaculum, and carpal tunnel morphology on ultrasound after ECTR were analyzed. Ultrasound parameters for different clinical improvement groups were compared.

Results

All patients improved clinically after ECTR. The average clinical improvement score ± SD at 12 months post-ECTR was 2.2 ± 0.7. The median nerve cross-sectional area proximal and distal to the tunnel decreased at all time intervals post-ECTR but remained swollen compared to normal values. Serial changes in the median nerve caliber and retinacular bowing after ECTR were more pronounced at the tunnel outlet than at the tunnel inlet. The flexor retinaculum had reformed in 25 (68%) of 37 wrists after 12 months.

Conclusion

Postoperative changes in median nerve and retinaculum parameters were most pronounced at the tunnel outlet. Even in patients with clinical improvement after ECTR, nearly all ultrasound parameters remain abnormal at one year post-ECTR. These ultrasound parameters should not necessarily be relied upon to diagnose persistent CTS after ECTR.

Comparison of short- and long-axis nerve hydrodissection for carpal tunnel syndrome: A prospective randomized, single-blind trial

Background: This study is to compare the efficacy of short-axis hydrodissection with long-axis hydrodissection for patients with mild-to-moderate carpal tunnel syndrome (CTS). Methods: Forty-seven patients with mild-to-moderate CTS were enrolled in a prospective, randomized, single-blinded, controlled trial (6 months follow-up). With ultrasound guidance, patients in both groups (short-axis or long-axis groups) were injected with normal saline (5 mL per session). Assessments were performed before and 2 weeks after the injection, as well as at 1, 3, and 6 months post-intervention. The primary outcome measure was the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) score and secondary outcomes included the cross-sectional area of the median nerve and electrophysiological studies. Results: Forty-four patients (21 wrists in the short-axis group and 23 wrists in the long-axis group) completed the study. Compared with the baseline, both groups showed improved BCTQ and cross-sectional area at all follow-up assessments (p<0.05). The short-axis group was not more effective except significant improvements in BCTQ-severity and BCTQ-function 1 month post-injection compared to the long-axis group (p = 0.031 and p = 0.023, respectively). Conclusions: Both short- and long-axis hydrodissection were effective for patients with mild-to-moderate CTS and the short-axis approach was not more effective than long-axis injection. Further studies with larger sample sizes, multiple injections, and larger injection volume are encouraged in the future.

MRI of the Carpal Tunnel 3 and 12 Months After Endoscopic Carpal Tunnel Release

OBJECTIVE. The purpose of this study was to study changes in the median nerve, retinaculum, and carpal tunnel on MRI after successful endoscopic carpal tunnel release (ECTR). SUBJECTS AND METHODS. In this prospective study, 35 wrists in 32 patients (five men, 27 women; mean age, 56.7 ± 6.8 [SD] years) with nerve conduction test-confirmed primary carpal tunnel syndrome were evaluated from May 2013 to September 2016. Clinical scores ranging from 0 to 4 (no improvement to symptoms completely resolved) and MRI morphologic features of median nerve and carpal tunnel were evaluated at baseline and 3 and 12 months after ECTR. The paired t test was used to compare MRI parameters before and after ECTR and their relationships to clinical improvement scores. RESULTS. All patients' conditions improved after ECTR with mean clinical improvement scores of 2.94 ± 1.0 at 3 months and 3.49 ± 0.56 at 12 months. Although median nerve swelling did decrease proximally, the nerve remained swollen (> 15 mm²) and flattened in all areas, even 12 months after ECTR. Additional changes occurred in median nerve caliber-change ratio, relative signal intensity, and carpal tunnel cross-sectional area. A retinacular gap was present in 33 (94%) wrists 3 months and six (17%) wrists 12 months after ECTR, and increased retinacular bowing persisted. CONCLUSION. After ECTR, undue swelling and flattening of the median nerve persist as long as 12 months after surgery, even in patients with a good surgical outcome. One should be wary of using these MRI findings as signs of persistent neural compression. The retinaculum reforms in most patients within 12 months of surgery but with a more bowed configuration.

Minimally Invasive Ultrasound-Guided Carpal Tunnel Release Improves Long-Term Clinical Outcomes in Carpal Tunnel Syndrome

BACKGROUND. Ultrasound guidance allows performance of carpal tunnel release with smaller incisions and quicker recovery than traditional open or endoscopic surgery. OBJECTIVE. The purpose of this study was to evaluate the long-term effectiveness of ultrasound-guided carpal tunnel release in improving function and discomfort in patients with carpal tunnel syndrome. METHODS. Retrospective review was conducted of 61 ultrasound-guided carpal tunnel release procedures performed on 46 patients (15 bilateral procedures) with clinically diagnosed carpal tunnel syndrome. The procedures were performed with a single-use transection device and local anesthesia at an outpatient radiology office. Patients answered three questionnaires (Quick Disabilities of the Arm, Shoulder, and Hand [QDASH] and two parts of the Boston Carpal Tunnel Syndrome Questionnaire-the symptom severity [BCTSQ-SS] and functional status [BCTSQ-FS] scales) to assess the function of and discomfort in the affected wrist immediately before and 2 weeks and at least 1 year after the procedure. Higher scores indicated increasing disability. Patients also answered a global satisfaction question at follow-up. Preprocedure and postprocedure scores were compared by paired Wilcoxon signed rank tests. RESULTS. The 46 patients (25 women, 21 men; mean age, 60.6 years; range, 21-80 years) had median preprocedure scores of 45.4 for QDASH, 3.2 for BCTSQ-SS, and 2.5 for BCTSQ-FS. The median scores 2 weeks after the procedure were 22.5 for QDASH, 1.7 for BCTSQ-SS, and 1.9 for BCTSQ-FS. All scores decreased (p < .001) from preprocedure scores and surpassed reference standards for clinically important difference in scores. Follow-up questionnaires obtained for 90% (55/61) of wrists a median of 1.7 years (range, 1.0-2.8 years) after the procedure showed further declines (p < .001) in median scores: 2.3 for QDASH, 1.2 for BCTSQ-SS, and 1.1 for BCTSQ-FS. At long-term follow-up evaluation, 96% (52/54) of wrists had lower QDASH and 98% (53/54) had lower BCTSQ (average of BCTSQ-SS and BCTSQ-FS) scores compared with the preprocedure scores. Among the patients who participated in the survey, 93% (37/40) were satisfied or very satisfied with the long-term outcomes. No immediately postoperative complications occurred. Two patients needed surgical intervention 8 and 10 days after surgery, one for infection after injury and one for posttraumatic compartment syndrome. CONCLUSION. Ultrasound-guided carpal tunnel release quickly improves hand function and reduces hand discomfort; improvement persists beyond 1 year. CLINICAL IMPACT. Ultrasound-guided carpal tunnel release may be a safe, effective, and less invasive alternative to traditional surgery.