# Ultrasound-guided botulinum toxin type A for shoulder pain: a meta-analysis of randomized controlled trials

## TL;DR

This study finds that ultrasound-guided botulinum toxin A injections can significantly reduce shoulder pain and improve movement and function.

## Contribution

The study provides a meta-analysis of randomized trials showing the effectiveness of ultrasound-guided botulinum toxin A for shoulder pain.

## Key findings

- Ultrasound-guided botulinum toxin A significantly reduces shoulder pain (SMD = -1.1).
- Improves upper extremity function and shoulder range of motion in flexion and external rotation.
- Mild improvements observed in shoulder abduction and quality of life measures.

## Abstract

Shoulder pain is a very common symptom. A number of studies have demonstrated that botulinum toxin type A is effective in relieving shoulder pain. Therefore, this systematic review and meta-analysis aimed to synthesize scientific evidence and quantify the combined effects of ultrasound-guided botulinum toxin type A on shoulder pain.

A comprehensive literature search was conducted in databases such as PubMed, Embase, Scopus, Cochrane Central Register of Controlled Trials (CENTRAL), China National Knowledge Information Database (CNKI), Wanfang database, and VIP database (VIP) using the keywords "ultrasound", "Botulinum toxin type A", and "shoulder pain". Two reviewers independently reviewed the studies, extracted data from eligible studies, and assessed the risk of bias. A random-effects model was used to calculate the standardized mean difference (SMD) and 95% confidence interval (CI) for Visual Analog Scale (VAS), Upper Extremity Fugl-Meyer Assessment (UEFMA), Range of Motion (ROM), Modified Barthel Index (MBI). Funnel plots and sensitivity analyses were also employed to evaluate the four outcome indicators above.

Out of retrieved 854 records, ten studies (involving 533 patients) were finally included. Pooled analysis showed that ultrasound-guided botulinum toxin type A was associated with large improvements in shoulder pain (SMD = -1.1; 95% CI -1.47 to -0.73; P < 0.001), UEFMA score (SMD = 1.43; 95% CI 0.49 to 2.37; P = 0.003), ROM of shoulder flexion (SMD = 1.28; 95% CI 0.63 to 1.93; P < 0.001) and external rotation (SMD = 1.66; 95%CI, 0.83 to 2.48; P < 0.001). Mild improvements were observed in ROM of shoulder abduction (SMD = 0.8; 95%CI 0.18 to 1.43; P = 0.01) and MBI score (SMD = 1.33; 95% CI 0.22 to 2.43; P = 0.02).

Our meta-analysis has shown ultrasound-guided BoNT-A injections have potential benefits for reducing shoulder pain and improving upper limb function, range of motion, and quality of life. However, these findings should be interpreted cautiously due to small sample size, measured differences, substantial heterogeneity and possible publication bias. More high-quality studies with large sample size are needed to assess long-term efficacy, strengthening the evidence that ultrasound-guided BoNT-A facilitates the reduction of shoulder pain.

The online version contains supplementary material available at 10.1186/s12891-025-09347-8.