The Effect of Botulinum Toxin Injection into the Common Extensor Tendon in Patients with Chronic Lateral Epicondylitis: A Randomized Trial

Botulinum toxin in the rehabilitation of painful syndromes: multiperspective literature analysis, lexical analysis and systematic review of randomized controlled trials

Pain represents a common symptom of several diseases and is often associated with a reduction in rehabilitation outcomes and recovery. The effectiveness of pain alleviation by botulinum toxin has been recently demonstrated. We searched in PubMed the papers about this topic published in the last ten years, and we selected clinical trials, guidelines, meta-analyses, reviews, and systematic reviews. We used different approaches: multiperspective presentation, lexical evaluation, and systematic review. The systematic review was only performed for the randomized controlled trials. We predominantly found reviews and trials about the rehabilitation of stroke/brain injury and epicondylitis. The most common outcome measures were pain, function, and spasticity. Among the common words, pain was the most frequent and the terms were grouped into different families, especially concerning the outcomes. Rehabilitation showed a relatively low frequency. Finally, the systematic review showed moderate-low levels of bias which confirms the effectiveness of botulinum toxin for pain treatment. The current literature about botulinum toxin is wide and globally diffuse but with some limitations in study strategies and clearness in the formal presentation. The evidence justifies the use of botulinum toxin in treating pain in different diseases.

Botulinum Toxin in Chronic Lateral Epicondylitis, from Tendon to Muscle Approach-A Review

BACKGROUND

Chronic lateral epicondylitis challenges the therapeutical approach; underlying mechanisms are incompletely understood; neuropathic pain and central and peripheral sensitization may explain the fact that botulinum toxin has been found to play a role in pain and function management.

METHODS

We searched the literature for MeSH terms: lateral epicondylitis or synonyms and botulinum toxin.

RESULTS

We found 14 papers containing trials on botulinum toxin injection into the tendon or into the extensor muscles (specifically, extensor carpi radialis brevis and extensor communis digitorum). We followed the administration pathways, doses, timing, and side effects.

CONCLUSIONS

With a chronic course, the focus of the therapy shifts from the afflicted tendon to the inserting muscles, as muscle contracture may create a vicious loop to perpetuate and aggravate the disease. Doses, timing, and side effects are discussed.

Clinical efficacy of botulinum toxin in lateral elbow tendinopathy: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Botulinum toxin injections for lateral elbow tendinopathy have been used as an alternative therapeutic option. However, few studies have quantitatively summarized the effect of botulinum toxin as well as its clinical significance. We aimed to evaluate the clinical efficacy (based on pain and grip strength) and adverse events of botulinum toxin on lateral elbow tendinopathy.

PATIENTS AND METHODS

The MEDLINE, EMBASE, Web of Science, and Scopus databases were searched until March 2023 for randomized controlled trials reporting the effects of botulinum toxin injections on lateral elbow tendinopathy. A random- or fixed-effects model (depending of inter-study variability) and generic inverse variance method were used to pool quantitative data from outcomes. The risk of bias was assessed with the Cochrane Risk of Bias 2.0 tool.

RESULTS

A total of 8 clinical trials recruiting 438 subjects were included for meta-analysis. Pooled analysis revealed that botulinum toxin significantly reduced pain (mean difference [MD] -0.95, 95% CI [-1.63, -0.26], p=0.007) but it was not clinically relevant. No significant effect was detected for grip strength (MD-0.62kg, 95% CI [-2.25, 1.02], p=0.46) or in the risk for adverse events (odds ratio [OR] 0.41, 95% CI [0.05, 3.56], p=0.42) between botulinum toxin injection and control interventions.

DISCUSSION

The use of botulinum toxin reached greater pain relief than control interventions and normal saline after a period of 12 to 24 weeks. However, changes in pain relief did not reach clinical significance. The studies that had the greatest reduction in pain used higher doses of botulinum toxin (60 U). Additionally, differences in grip strength and adverse events did not reach statistical or clinical importance. A subanalysis indicated that botulinum toxin outperformed corticosteroid injections in terms of improving grip strength. Botulinum toxin only causes local and minimal side effects such as irritation, ecchymosis, and paralysis.

LEVEL OF EVIDENCE

I.

Effectiveness of different doses of botulinum neurotoxin in lateral epicondylalgia: A network meta-analysis

BACKGROUND

Previous studies have investigated the role of botulinum neurotoxin (BoNT) in lateral epicondylalgia, with controversial results. We hypothesized that BoNT would be effective and safe for the treatment of lateral epicondylalgia.

OBJECTIVE

To investigate the effectiveness and safety of different doses of BoNT in participants with lateral epicondylalgia.

METHODS

PubMed, Embase, and Cochrane Library were searched up to August 27, 2022, for randomized controlled trials (RCTs) of BoNT treatment for epicondylalgia. The Cochrane risk of bias tool was used for quality assessment. A network meta-analysis and a trial sequential analysis (TSA) were conducted on pain, grip strength and adverse events. Meta-regression was applied for high heterogeneity comparisons.

RESULTS

We included 8 RCTs consisting of 448 participants. Four studies scored low risk of bias in all categories, whereas the other 4 studies had unclear risk only in the selection bias category. The network meta-analysis and TSA revealed that corticosteroid (standardized mean difference [SMD]: -1.32, 95% CI: -2.13; -0.50), high-dose BoNT (SMD -1.32, -2.04; -0.61), and low-dose BoNT (SMD -0.52, -0.93; -0.10), relieved pain significantly better than placebo for up to 7 to 10 weeks. High-dose BoNT demonstrated a significantly greater reduction in pain than low-dose BoNT for up to 7 to 10 weeks (SMD -0.81, -1.39; -0.22). Finally, after low-dose BoNT, younger participants (p = 0.023) and women (p = 0.012) showed more pain decrease than older individuals and men at 2 to 6 weeks. As for grip strength and adverse events, only grip strength after low-dose BoNT versus placebo (SMD -0.49, -0.88; -0.10) and corticosteroid (SMD -1.36, -2.15; -0.57) at 2 to 6 weeks reached significance after threshold adjustment in TSA.

CONCLUSIONS

Our meta-analysis confirmed the effectiveness of low-dose BoNT in the reduction of pain for lateral epicondylalgia. Further conclusions cannot be drawn due to insufficient available data.

Lateral Epicondylitis: Critical Analysis Review of Current Nonoperative Treatments

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Lateral epicondylitis (LE) or tennis elbow is a common cause of elbow pain in the general population, especially women in the fourth and fifth decades of life who participate in repetitive forceful movements involving the wrist and forearm.

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The pathogenesis of this overuse injury is believed to start from an overload event leading to a microtear in or near the origin of the extensor carpi radialis brevis that is subsequently prone to additional injury and structural weakness over time.

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Treatment of LE often begins with a wide variety of nonoperative modalities including rest, nonsteroidal anti-inflammatory drugs, bracing, and physical therapy. For recalcitrant symptoms, additional nonoperative therapies are implemented; however, there remains a lack of comparative efficacy between these adjunct treatments.

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In this article, we examine the available literature regarding nonoperative management of LE and provide supplementary insight into the effectiveness of current modalities.

Efficacy of Botulinum Toxin in Treating Lateral Epicondylitis-Does Injection Location Matter?: A Systematic Review

OBJECTIVE

Clinical trials assessing the efficacy of botulinum toxin in treating recalcitrant lateral epicondylitis have demonstrated varied results and differed greatly in methodology. The objective of this systematic review was to demonstrate injection location as a significant contributor to outcome heterogeneity.

DESIGN

Two reviewers independently conducted a systematic review using Scopus, Embase, and PubMed for randomized controlled trials assessing botulinum toxin in the treatment of lateral epicondylitis. After applying inclusion/exclusion criteria to abstracts and reviewing the full-text articles, seven studies were found representing six separate injection locations. Reduction in visual analog scale pain and change in grip strength were the principal outcomes of interest.

RESULTS

The largest reduction in pain was seen in injection at 1/3 of the length of the forearm from the lateral epicondyle at 16-wk follow-up, whereas the smallest reduction was seen at 12-wk follow-up after injection at the 0-cm mark. Differences were also identified in grip strength, although all studies reported return to baseline strength by weeks 12-18.

CONCLUSIONS

This study demonstrates injection location as a potential source of heterogeneity. This clinical question warrants further evaluation with direct comparison of outcomes at different injection locations while controlling for dosage, toxin type, and ultrasound/electromyographic guidance.