A practical guide to botulinum neurotoxin treatment of shoulder spasticity 1: Anatomy, physiology, and goal setting

Abstract

Botulinum neurotoxin type A (BoNT-A) is a first-line treatment option for post-stroke spasticity, reducing pain and involuntary movements and helping to restore function. BoNT-A is frequently injected into the arm, wrist, hand and/or finger muscles, but less often into the shoulder muscles, despite clinical trials demonstrating improvements in pain and function after shoulder BoNT-A injection. In part 1 of this two-part practical guide, we present an experts' consensus on the use of BoNT-A injections in the multi-pattern treatment of shoulder spasticity to increase awareness of shoulder muscle injection with BoNT-A, alongside the more commonly injected upper limb muscles. Expert consensus was obtained from five European experts with a cumulative experience of more than 100 years of BoNT-A use in post-stroke spasticity. A patient-centered approach was proposed by the expert consensus: to identify which activities are limited by the spastic shoulder and consider treating the muscles that are involved in hindering those activities. Two patterns of shoulder spasticity were identified: for Pattern A (adduction, elevation, flexion and internal rotation of the shoulder), the expert panel recommended injecting the pectoralis major, teres major and subscapularis muscles; in most cases injecting only the pectoralis major and the teres major is sufficient for the first injection cycle; for Pattern B (abduction or adduction, extension and internal rotation of the shoulder), the panel recommended injecting the posterior part of the deltoid, the teres major and the latissimus dorsi in most cases. It is important to consider the local guidelines and product labels, as well as discussions within the multidisciplinary, multiprofessional team when deciding to inject shoulder muscles with BoNT-A. The choice of shoulder muscles for BoNT-A injection can be based on spastic pattern, but ideally should also firstly consider the functional limitation and patient expectations in order to establish better patient-centered treatment goals. These recommendations will be of benefit for clinicians who may not be experienced in evaluating and treating spastic shoulders.

Canadian Physicians’ Use of Intramuscular Botulinum Toxin Injections for Shoulder Spasticity: A National Cross-Sectional Survey

“…A recent 2022 expert consensus by Jacinto et al adapted the five post-stroke spasticity patterns into two shoulder spasticity patterns: “A” (adduction, elevation, flexion and internal rotation of shoulder) with the presence of elevation and flexion, vs. extension in Pattern “B” (abduction or adduction, extension and internal rotation of the shoulder. It is notable that Jacinto et al’s expert panel made further suggestions to define patterns [ 8 ].…”

“…While the literature often focuses on the pectoralis major and subscapularis, there are many muscles implicated in shoulder spasticity including the deltoid, trapezius, teres major and minor, pectoralis major, subscapularis, supra- and infra- spinatus, coracobrachialis, latissimus dorsi and the long head of the biceps and triceps brachii muscles [ 8 ]. The choice of muscles to inject is largely due to personal bias or experience.…”

“…A 2022 European consensus identified the expert groups’ preferences. This included the teres major and deltoid muscles as frequent targets in addition to the commonly studied subscapularis and pectoralis major muscles [ 8 ].…”

A practical guide to botulinum neurotoxin treatment of teres major muscle in shoulder spasticity: Intramuscular neural distribution of teres major muscle in cadaver model

“…Shoulder spasticity can affect adduction, elevation, flexion, and internal rotation of the shoulder; abduction only; or adduction, extension, and internal rotation of the shoulder. 1 To treat spasticity for an adducted shoulder, injections are typically administered to the pectoralis major, teres major, and subscapularis muscle. In most cases, it is sufficient to inject only the pectoralis major and teres major as the primary treatment.…”

“…In recent years, botulinum neurotoxin has been shown to be safe and effective in reducing muscle tone for focal spasticity of the upper limb and in improving active upper limb function. 1 Shoulder muscles have been included in clinical trials of botulinum toxin for upper limb spasticity and have demonstrated improvements. [2][3][4][5][6][7][8] Injection with botulinum toxin has been shown to improve shoulder function and reduce pain in an observational study of chronic poststroke spasticity.…”