What is the role of botulinum toxin (BTX) injection for the treatment of shoulder pain following a stroke?

Updated: Jun 19, 2018
  • Author: Anthony H Wheeler, MD; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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Answer

Answer

BTX has been studied for use in shoulder pain following stroke. A small, double-blind, 2-parallel group, randomized controlled trial showed a beneficial effect on shoulder pain following injection of BTX-A into the subscapularis muscle in patients who had experienced a stroke and who had spastic hemiplegia. [82]

To assess the effects of BTX-A on hemiplegic shoulder pain associated with spasticity, a double-blind, randomized controlled trial looked at a one-time injection of BTX-A (500 Speywood U) into the pectoralis major and biceps brachii on the hemiplegic side. [83] VAS of shoulder pain, shoulder adductor and elbow flexor tone using the Ashworth scale, and passive range of shoulder abduction were assessed as outcomes. Only 17 patients were enrolled, 8 in the BTX-A group and 9 in the placebo group. Negative findings in this study include the small sample size and the presence of causes of shoulder pain not related to spasticity, which could have confounded outcome.

A double-blind, randomized controlled trial was performed to determine the efficacy of BTX-A for treatment of shoulder pain in patients with spasticity after stroke. [84] Two cases dropped out (6.5%) of 31 patients enrolled from an acute-care hospital in Spain. Fourteen subjects were treated with infiltration of 500 U of BTX-A compared with 15 who received placebo in the pectoralis major muscle of the paretic side. Patients were assessed using a VAS for pain. A significant reduction in pain was considered when the VAS score was below 33.3 mm or less than half the initial score. At 6 months, patients treated with BTX-A showed significantly greater improvement in pain than placebo from the first week postinfiltration. Patients with shoulder pain from spasticity treated with BTX-A infiltration into the pectoralis major muscle on the paretic side had a higher likelihood of pain relief, ranging between 2.43-3.11-fold.

A randomized, double-blind, placebo-controlled study of the effect of BTX-A injections into the subscapular muscle was performed in 22 stroke patients with spastic hemiplegia, substantial shoulder pain, and reduced external rotation of the humerus. [85] Twenty-one of twenty-two patients completed the study. No significant changes in pain or external rotation were noted as a result of BTX-A administration. Therefore, application of BTX-A into the subscapular muscle for reduction of shoulder pain and improvement of humeral external rotation in spastic hemiplegia did not appear to be clinically efficacious.

A prospective, double-blind, randomized controlled trial was conducted to compare the effects of BTX-A and triamcinolone acetonide (TA) on shoulder pain and arm function in 29 patients who had experienced hemiplegic stroke with pain duration of 24 months or less and numeric rating scale of 6 out of 10 or more. [86] Patients were randomized into 2 groups: a group that received intramuscular injections of BTX-A 100 U (total) during one session to the infraspinatus, pectoralis, and subscapularis muscles in conjunction with intra-articular injections of NS into the painful joint and a comparison group that received an intra-articular injection of TA (40 mg) and an intramuscular injection of NS to the same muscles. Results from this study suggest that injection of BTX-A into selected muscles of the shoulder girdle might provide more pain relief and range of motion improvement than intra-articular TA in patients with hemiplegic shoulder pain.

A Cochrane systematic review was performed to determine the efficacy and safety of BTX compared with placebo or other treatment options for shoulder pain. [87] Using well-known standard search strategies, 6 randomized controlled trials comparing BTX with placebo or active treatment in 164 patients with shoulder pain were evaluated. Participants in 5 of the trials with poststroke shoulder pain received a single intramuscular injection of BTX that significantly reduced pain at 3-6 months postinjection when compared with placebo; shoulder external rotation was increased following one month, but not at 3-6 months.

Shoulder abduction, external rotation and spasticity did not differ between groups, nor did the number of adverse events. Only one trial with arthritis-related shoulder pain showed that BTX reduced shoulder pain severity and disability with a reduction in the Shoulder Pain and Disability Index score compared with placebo. The authors suggest that the results of their review should be interpreted with caution due to the small number of studies, small sample sizes, and the outcome targeted ranges of motion when compared with placebo in patients with shoulder pain due to spastic hemiplegia or arthritis. Pain relief in poststroke study patients primarily relates to study limitations and interpretation, rather than to any research-proven clinical phenomenon.


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