OBJECTIVE: To review the literature and assess the comparative effectiveness of ultrasound-guided versus landmark-guided local corticosteroid injections in patients with carpal tunnel syndrome (CTS).
DATA SOURCES: Cochrane Central Register of Controlled Trials, MEDLINE (PubMed), Embase (Ovid), and Web of Science (from inception to February 1, 2017).
STUDY SELECTION: Randomized controlled trials (RCTs) comparing ultrasound-guided injection with landmark-guided injection in patients with CTS were included.
DATA EXTRACTION: Two authors independently screened abstracts and full texts. The outcomes of interest were Symptom Severity Scale (SSS) and Functional Status Scale (FSS) scores of the Boston Carpal Tunnel Questionnaire and 4 electrodiagnostic parameters, including compound muscle action potential (CMAP), sensory nerve action potential (SNAP), distal motor latency (DML), and distal sensory latency (DSL).
DATA SYNTHESIS: Overall, 569 abstracts were retrieved and checked for eligibility; finally, 3 RCTs were included (181 injected hands). Pooled analysis showed that ultrasound-guided injection was more effective in SSS improvement (mean difference [MD], -.46; 95% confidence interval [CI], -.59 to -.32; P<.00001), whereas no significant difference was observed between the 2 methods in terms of the FSS (MD, -.25; 95% CI, -.56 to .05; P=.10). There were also no statistically significant differences in improvements of CMAP (MD, 1.54; 95% CI, 0.01 to 3.07; P=.05), SNAP (MD, -0.02; 95% CI, -6.27 to 6.23; P>.99), DML (MD, .05; 95% CI, -.30 to .39; P=.80), or DSL (MD, .00; 95% CI, -.65 to .65; P>.99).
CONCLUSIONS: This review suggested that ultrasound-guided injection was more effective than landmark-guided injection in symptom severity improvement in patients with CTS; however, no significant differences were observed in functional status or electrodiagnostic improvements between the 2 methods.
A meta-analysis of three studies compared using landmarks to ultrasound for carpal tunnel injections suggests that symptoms were improved but there was no difference in objective outcomes. Since the rationale for US guided injection is avoidance of complications (injury to median nerve, radial artery, ulnar neurovascular bundle) it may be that the symptom severity score was lower in landmark patients due to inadvertent nerve impact rather than improved effect on the carpal tunnel. It may suggest that if US is available, it should be used but need not be a prerequisite for treatment.
This makes logical sense and may reduce the cost of this procedure if landmarks can be used, as well.