Comparison of the Effect of Out-of-plane and In-plane Injection Approaches on Injection Pain and Functionality in Patients with Carpal Tunnel Syndrome Undergoing Ultrasound-guided Injection: A Patient- and Assessor-blinded Randomized Study

Abstract

ObjectivesThe aims were i) to compare the out-of-plane (OP) and in-plane (IP) approaches for carpal tunnel syndrome (CTS) in terms of pain during injection and post injection adverse effects, and ii) to investigate whether these approaches led to any difference in terms of pain/numbness, symptom severity, functionality, and median nerve cross-sectional area and to examine the relationship of these parameters with the pain during injection. DesignPatient/assessor blinded randomized study SettingHospital outpatient clinic. ParticipantsFifty patients with mild to moderate CTS. InterventionsThe participants were randomized into OP and IP (both n = 25) ultrasound-guided injection groups. Main outcome measuresEach patient reported the pain felt during the injection at 1 h thereafter, and also any adverse effects at 4 weeks after injection. Before and 4 weeks after injection, patients used a visual analog scale to indicate pain/numbness; symptom severity and functionality were assessed using the Boston Carpal Tunnel Syndrome Questionnaire. The cross-sectional area of the median nerve was also obtained. ResultsThe average pain during injection was 2.64±0.82 in the IP group and 1.96±0.86 in the OP group (p=0.017). Post-injection adverse effects were similar between the two groups (p<0.05). After injection, the percentage change in symptom severity was 49.8±11.8 in the IP group and 40.6±11.5 in the OP group (p=0.008). In the IP group, day pre-injection pain/numbness, night pain/numbness percentage change scores, and symptom severity percentage change scores were moderately correlated with the pain during injection (r=0.439, 0.469, and 0.429, respectively). ConclusionsIP injection caused greater pain during injection compared to OP injection and led to greater reduction in symptom severity at 1 month after injection. In that group, injection pain was associated with the baseline day pain score, change in night pain score, and change in symptom severity score.