A systematic review of the use of Botulinum toxin type A with subpectoral breast implants

Onabotulinum toxin injections for shoulder and chest wall muscle pain in breast cancer survivors: retrospective study - preliminary report

OBJECTIVES

The primary objective of this retrospective review is to describe patient-reported improvement in muscular pain after initial treatment with onabotulinum toxin. A secondary objective was to determine other physiatry (physical medicine & rehabilitation (PM&R)) interventions ordered.

METHODS

Preliminary retrospective review of physiatry interventions for 47 patients referred by breast radiation oncology to PM&R at a tertiary referral-based academic cancer centre clinic from 1 January 2018 to 31 December 2021 for muscular shoulder/chest wall pain.

RESULTS

Patients were most commonly diagnosed with muscle spasm 27/47 (58%), lymphedema 21/47 (45%), myalgia/myofascial pain 16/47 (34%), radiation fibrosis 14/47 (30%), fatigue/deconditioning 13/47 (28%), neurological impairment 11/47 (23%) and joint pathology 3/47 (6%). The top three physiatric interventions were home exercise programme education (17/47, 36%), botulinum toxin injection (17/47, 36%) and physical or occupational therapy referral (15/47, 32%). Patients who had muscle spasms documented were more likely to have botulinum toxin recommended by physiatry (24/24) compared with those with questionable spasms (4/7) and those without spasms(0/16) (p=0.0005). 17/28 (60.7%) received botulinum toxin injection, and a total of 35 injections were performed during the study period. 94% (16/17) of patients who received botulinum toxin injection voiced improvement in pain after injection.

CONCLUSION

Botulinum toxin injections may play a role in the treatment of muscle spasm-related pain in breast cancer survivors. Additional blinded controlled research on the effectiveness of botulinum toxin injection after breast cancer treatment with spastic muscular shoulder/chest wall pain is needed.

The Impact of Botulinum Toxin Injection on the Outcomes of Breast Surgeries: A Systematic Review and Meta-Analysis

BACKGROUND

Breast surgeries aim to restore the natural appearance of the breasts with acceptable functional and cosmetic outcomes. However, these surgical procedures may be associated with considerable adverse events. The present systematic review and meta-analysis was designed to reveal the functional and aesthetic outcomes of botulinum toxins (BTX) injection in patients subjected to breast surgeries.

METHODS

A literature review was performed up to 21 September 2022. All clinical studies included patients older than 18 years old and treated with BTX injection for breast surgeries were included.

RESULTS

The present study included 12 articles, encompassing 496 patients. The average dosage of BTX injection ranged from 20 to 100 units. Injecting BTX significantly reduced the mean post-operative opioid analgesics usage (SMD -1.577; 95% -2.087, -1.067; P < 0.001) and the risk of severe animation deformity (RR 12.37; 95% 1.76, 86.66; P = 0.01). There was a statistically significant higher mean expansion volume per visit in the BTX injection group (SMD 1.166; 95% 0.313, 2.018; P = 0.007). There was no statistically significant impact of BTX injection on the risk of surgical site infection (RR 0.59; 95% 0.15, 2.34; P = 0.45) and seroma (RR 0.51; 95% 0.03, 10.15; P = 0.66).

CONCLUSIONS

The present study revealed the potential benefits of BTX injection in breast surgeries. This included reduced post-operative analgesics, as well as the risk of severe animation deformity. This was accomplished with increased expansion volume per visit and a similar risk of BTX injection-related complications.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Analgesic Efficacy of Pectoral Nerve Blocks in Implant-Based Mammoplasty: A Systematic Review and Meta-Analysis

OBJECTIVE

To evaluate the analgesic effect of pectoral nerve block in implant-based mammoplasty.

METHODS

EMbase, PubMed, Web of science, MEDLINE, CNKI, Wanfang Database, VIP and other databases were searched from establishment to February 2022 by computer to collect randomized controlled trials which applied pectoral nerve block in implant-based mammoplasty, and meta-analysis was conducted after data extraction and quality evaluation of the literature meeting the inclusion criteria.

RESULTS

A total of 336 patients in seven RCT studies were included in this study. Pectoral nerve block has a significant effect on postoperative analgesia in patients with implant-based mammoplasty with 1h VAS score significantly reduced in the resting state (MD=-1.85, 95%CI: -2.64~-1.07, P<0.00001); VAS score was significantly decreased 4-6 hours after operation (MD=-1.51, 95%CI: -2.47~-0.55, P=0.002); postoperative opioid consumption was reduced (SMD=-1.37, 95%CI: -2.51~-0.24, P=0.02) in PECS block group; and the incidence of postoperative nausea and vomiting in the PECS block group was significantly lower (RR: 0.30, 95 %CI: 0.19-0.38, P<0.00001).

CONCLUSIONS

The application of PECS block in submuscular implant-based mammoplasty can effectively reduce the degree of acute postoperative pain, opioid consumption and the incidence of postoperative nausea and vomiting, indicating its broad prospects in clinical application.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The botulinum neurotoxin for pain control after breast reconstruction: neural distribution of the pectoralis major muscle

INTRODUCTION

The use of the botulinum neurotoxin injection is a growing area of research and clinical activity, with a focus on its role in facilitating postoperative pain management after reconstructive breast surgery. The study aimed to find out the standard injection points for botulinum neurotoxin injection by revealing the intramuscular nerve arborization of the pectoralis major.

METHODS

Sihler's technique was conducted on the pectoralis major muscles (16 cadaveric specimens). The intramuscular nerve arborization was documented relative to the inferior border of the clavicle bone and lateral border of the sternum.

RESULTS

After the staining, the pectoralis major was divided into fifths transversely from the inferior border of the clavicle and vertically into fifths from the lateral border of the sternum. Intramuscular nerve arborization of the pectoralis major muscle was the largest in the middle sections of the muscle belly.

DISCUSSION

The results indicate that botulinum neurotoxin should be applied to the pectoralis major in certain regions. The regions of major arborization are optimal as the most effective and most reliable points for injecting botulinum neurotoxin.

Mechanisms of action of fascial plane blocks: a narrative review

BACKGROUND

Fascial plane blocks (FPBs) target the space between two fasciae, rather than discrete peripheral nerves. Despite their popularity, their mechanisms of action remain controversial, particularly for erector spinae plane and quadratus lumborum blocks.

OBJECTIVES

This narrative review describes the scientific evidence underpinning proposed mechanisms of action, highlights existing knowledge gaps, and discusses implications for clinical practice and research.

FINDINGS

There are currently two plausible mechanisms of analgesia. The first is a local effect on nociceptors and neurons within the plane itself or within adjacent muscle and tissue compartments. Dispersion of local anesthetic occurs through bulk flow and diffusion, and the resulting conduction block is dictated by the mass of local anesthetic reaching these targets. The extent of spread, analgesia, and cutaneous sensory loss is variable and imperfectly correlated. Explanations include anatomical variation, factors governing fluid dispersion, and local anesthetic pharmacodynamics. The second is vascular absorption of local anesthetic and a systemic analgesic effect at distant sites. Direct evidence is presently lacking but preliminary data indicate that FPBs can produce transient elevations in plasma concentrations similar to intravenous lidocaine infusion. The relative contributions of these local and systemic effects remain uncertain.

CONCLUSION

Our current understanding of FPB mechanisms supports their demonstrated analgesic efficacy, but also highlights the unpredictability and variability that result from myriad factors at play. Potential strategies to improve efficacy include accurate deposition close to targets of interest, injections of sufficient volume to encourage physical spread by bulk flow, and manipulation of concentration to promote diffusion.

Application of Botulinum Neurotoxin Injections in TRAM Flap for Breast Reconstruction: Intramuscular Neural Arborization of the Rectus Abdominis Muscle

Breast reconstruction after mastectomy is commonly performed using transverse rectus abdominis myocutaneous (TRAM) flap. Previous studies have demonstrated that botulinum neurotoxin injections in TRAM flap surgeries lower the risk of necrosis and allow further expansion of arterial cross-sectional diameters. The study was designed to determine the ideal injection points for botulinum neurotoxin injection by exploring the arborization patterns of the intramuscular nerves of the rectus abdominis muscle. A modified Sihler's method was performed on 16 rectus abdominis muscle specimens. Arborization of the intramuscular nerves was determined based on the most prominent point of the xyphoid process to the pubic crest. All 16 rectus abdominis muscle specimens were divided into four muscle bellies by the tendinous portion. The arborized portions of the muscles were located on the 5-15%, 25-35%, 45-55%, and 70-80% sections of the 1st, 2nd, 3rd, and 4th muscle bellies, respectively. The tendinous portion was located at the 15-20%, 35-40%, 55-60%, and 90-100% sections. These results suggest that botulinum neurotoxin injections into the rectus abdominis muscles should be performed in specific sections.

Botulinum Toxin A in Tissue Expander Breast Reconstruction: A Double-blinded Randomized Controlled Trial

Subpectoral tissue expander breast reconstruction is often associated with muscle spasms, pain, and discomfort during tissue expansion. In this study, we hypothesized that an intraoperative injection of botulinum toxin A (BTX-A) in the pectoralis major muscle reduces the pain associated with tissue expansion and improves women's physical well-being.

Methods

Between May 2012 and May 2017, women undergoing immediate subpectoral tissue expander breast reconstruction were randomized to administer 100 units of BTX-A or a placebo injection. A numeric pain intensity scale and the physical well-being scale of the BREAST-Q: Reconstruction Module were used to test our hypothesis. Data on postoperative oral narcotic consumption were not collected.

Results

Of the 131 women included in the analysis, 48% were randomized to placebo and 52% to BTX-A. The preoperative median pain intensity score was 0 [interquartile range (IQR), 0-1], and the median preoperative BREAST-Q score was 91 (IQR, 81-100). The median slopes for the change in pain intensity scores from baseline throughout tissue expansion for those randomized to placebo and BTX-A were -0.01 (IQR, -0.02 to 0.00) and -0.01 (IQR, -0.02 to 0.00), respectively (P = 0.55). The median slopes for the change in BREAST-Q scores from baseline throughout tissue expansion for those randomized to placebo and BTX-A were 0.04 (IQR, -0.17 to 0.14) and 0.02 (IQR, -0.06 to 0.13), respectively (P = 0.89).

Conclusion

In this study, we found that an intraoperative intramuscular injection of 100 units of BTX-A in the pectoralis major muscle did not reduce postoperative pain and patient-reported physical well-being when compared with placebo.

Optimizing non-opioid pain control after implant-based breast reconstruction: a review of the literature and proposed pain control algorithm

Despite the intense focus on the opioid epidemic and its known association with surgical procedures, there is a paucity of evidence-based literature on pain management in implant-based breast reconstruction (IBR). Herein, we present an updated review of the literature aimed at identifying pain treatment protocols to minimize narcotic use and its associated potential addiction in IBR. A comprehensive review of the published English literature was conducted using Ovid Medline/PubMed Database without timeframe limitations. The inclusion criteria of selected articles presented in this review included studies reporting objective outcomes of pain modulation (preoperatively, intraoperatively and postoperatively) in IBR. Articles for inclusion were stratified based on intervention. A total of 219 articles were identified in the initial search query, with 23 studies meeting the inclusion criteria. Pain optimization interventions in IBR are herein summarized and analyzed based on the reported outcomes of each respective study. There is a substantial need for evidence-based guidelines in the plastic surgery literature for pain optimization without the use of opioids. While this review of studies to date investigates potential solutions, we hope this area of study continues to be a top priority for plastic surgeons to allow for optimized post-operative care for patients following IBR.

Latest Trends in Subpectoral Breast Reconstruction

There has been a shift in recent years toward a growing popularity of implant-based breast reconstruction, especially in the setting of increased frequency of concurrent contralateral prophylactic mastectomy. Advancements in implant safety and technology have also allowed for an expanding implant reconstruction practice across the country. The traditional approach is immediate two-stage implant reconstruction with placement of a tissue expander within a subpectoral pocket. The introduction of acellular dermal matrix has revolutionized implant-based breast reconstruction, allowing surgeons the opportunity to minimize morbidity while maximizing aesthetic outcomes. There have also been advances in the management of postoperative pain control as well as secondary revision surgery.

The effectiveness of Botulinum Toxin A for treatment of upper limb impairments and dysfunctions in breast cancer survivors: A randomised controlled trial

OBJECTIVE

To examine the effectiveness of a single Botulinum Toxin A (BTX-A) infiltration in the pectoralis major muscle, in addition to a standard physical therapy (PT) programme on upper limb impairments and dysfunctions after breast cancer treatment.

METHODS

Fifty breast cancer patients with persistent pain 3 months after finishing treatment participated in a double-blinded randomised controlled trial. The intervention group received a single BTX-A infiltration. The control group received a placebo (saline) infiltration. Within one week after the infiltration, all patients attended an individual PT programme (12 sessions) during the first 3 months. Outcome parameters were active shoulder range of motion, upper limb strength, scapular statics and shoulder function. Measures were taken before the intervention, at 1, 3 (i.e. after the intervention) and 6 months follow-up.

RESULTS

No differences between groups were found for all outcome parameters over the course of 6 months. However, overall beneficial effects of the PT for active forward flexion shoulder range of motion and shoulder function were found in both groups.

CONCLUSION

A single Botulinum Toxin A (BTX-A) infiltration in the pectoralis major muscle, in addition to a PT programme cannot be recommended to treat upper limb impairments and dysfunctions after breast cancer treatment.

Tissue expanders; review of indications, results and outcome during 15 years' experience

BACKGROUND

Tissue expanders (TE) are frequently used worldwide. In this study we surveyed outcome of our patients retrospectively during 15 years.

MATERIALS AND METHODS

We had 1105 patients for whom 3059 TEs have been used. Demographic data, age, sex, indications, type of tissue expander devices, volume of devices, site of scar and site TE insertion, our technique for tissue expander insertion and flap design, complications and outcome were gathered. A complete and through technical points and tips will be discussed.

RESULTS

In 91% of patients overexpansion was done. (Expansion ratio=2.1-4.5). Re-expansion has been done in about 12% of patients. Complications were perforation of skin of pocket (11%) or exposure, infection (6%), dehiscence of the wound (1.5%), perforation of the port or disconnection of the tubes (2.1%), expansion of the scar itself (1%), saggy flap (3%), dog ear (5%), lack of adhesions of flap to its new site (4%).

OUTCOME

In 93% of the patients we could totally remove the scar. Around 9.1% of our patients had two sessions of expansion in the same area and 2.9% had three sessions of expansion. 51% of our patients were highly satisfied and 42% were satisfied of the results of expansion.

CONCLUSION

Our patients were satisfied with the results. In 12% cases we have done re-expansion. Re-expansion is possible as long as you have enough thickness of dermis in the skin. More than 50% of our patients were optimistic for 2nd or 3rd session of re-expansion.

Botulinum Toxin A Plays an Important Role in the Placement of Implants Deep Within the Pectoralis Major Muscle for Mammaplasty: A Systematic Review and Meta-analysis

BACKGROUND

Breast prosthesis implants have been safely and efficiently used in the plastic surgery department. With the increasing demand for aesthetics, these silicon implants were not only used in breast augmentation surgery but also in breast reconstruction after mastectomy. Nevertheless, breast prosthesis implantation brings a lot of complications, such as: postoperative chronic pain, capsule contracture, prosthesis displacement and prosthesis rupture and infection in severe cases. From the year 1998, botulinum toxin A (BTX-A), a neurotoxin, has been reported to be effective for pain control, capsule contracture lessening, expander enlargement and so on. However, those articles included all kinds of study types: randomized, double-blinded controlled trial (RCT), nonrandomized trial, retrospective analysis and case series, besides the outcomes were varied. To clarify how BTX-A acts at the mammaplasty field, we made this systematic review and meta-analysis.

PURPOSE

To review how BTX-A acts in the field of mammaplasty as well as discuss the relative mechanisms of BTX-A and the related research progress.

METHODS

We searched Pubmed, Embase, Cochrane, Web of science, Clinical trials, Wanfang Database and VIP from inception until March 2018 for papers reporting the use of BTX-A in the breast surgery using implants deep within the pectoralis major muscle. System review, viewpoints and case reports were excluded.

RESULTS

Ten articles met the criteria for inclusion including six prospective controlled (2 RCT; 4 other trails), three retrospective cohorts and one case series. These studies were all about patients using BTX-A during or after breast surgery with expanders or prostheses. A total of 682 patients were enrolled, 543 (79.61%) accepted BTX-A injection, 185 underwent mastectomies with immediate reconstruction, 13 with delayed reconstruction, 295 mastectomies with either immediate or delayed reconstruction and 189 with breast augmentation using silicone prostheses. The study time ranging from 4 months to 13 years, 15 patients (2.76%) received BTX-A injection more than two times, 9.2% received less than 75 U BTX-A, 34.3% 75-100 U, 0.18% 250 U, and in 56.4% the dosage was not stated. No complications associated with BTX-A were mentioned, almost all the studies reported efficacy for pain control. Other assessments included increased speed of expander enlargement and volume were mentioned in four papers, two articles analyzed the visual analogue scores, three suggested relief of capsular contracture, two reported lower narcotic use, three mentioned shorter hospital stays and one proved lowering the rate of unplanned expander. It seems all the studies demonstrate the valid usage of BTX-A, but the quality of this evidence still under the line.

CONCLUSION

We could try to use BTX-A as a new method in the field of mammaplasty. There are so many advantages such as postoperative pain relief, reducing the hospital stay, and increasing operation success rate, but rigorous methodological evidence is still lacking. A lot of studies were retrospective, only two studies used the RCT method. Therefore, to obtain strong evidence to clarify the usage of BTX-A, more randomized double-blinded controlled trials will be required, meanwhile the mechanism study adds to the evidence.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these evidence-based medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Effectiveness of Botulinum Toxin A for Persistent Upper Limb Pain After Breast Cancer Treatment: A Double-Blinded Randomized Controlled Trial

OBJECTIVE

To investigate the effect of a single botulinum toxin A (BTX-A) infiltration in the pectoralis major muscle in addition to a standard physical therapy program for treatment of persistent upper limb pain in breast cancer survivors.

DESIGN

Double-blinded (patient and assessor) randomized controlled trial.

SETTING

A university hospital.

PARTICIPANTS

Breast cancer patients (N=50) with pain.

INTERVENTION

The intervention group received a single BTX-A infiltration. The control group received a placebo (saline) infiltration. Within 1 week after the infiltration, all patients attended an individual physical therapy program (12 sessions) during the first 3 months and a home exercise program up to 6 months after infiltration.

MAIN OUTCOME MEASURES

The primary outcome was change in pain intensity at the upper limb (visual analog scale, 0-100) after 3 months. Secondary outcomes were prevalence rate of pain, pressure hypersensitivity, pain quality, shoulder function, and quality of life. Measures were taken before the intervention and at 1, 3, and 6 months' follow-up.

RESULTS

No significant difference in change in pain intensity after 3 months was found (mean difference in change, 3/100; 95% confidence interval [CI], -13 to 19). From baseline up to 6 months, a significantly different change in upper limb pain intensity was found between groups in favor of the intervention group (mean difference in change, 16/100; 95% CI, 1-31).

CONCLUSIONS

A single BTX-A infiltration in combination with an individual physical therapy program significantly decreased pain intensity at the upper limb in breast cancer survivors up to 6 months. However, the effect size was not clinically relevant, and no other beneficial effects were found.

Acrylamide inhibits nerve sprouting induced by botulinum toxin type A

Botulinum toxin type A is a potent muscle relaxant that blocks the transmission and release of acetylcholine at the neuromuscular junction. Intramuscular injection of botulinum toxin type A has served as an effective and safe therapy for strabismus and focal dystonia. However, muscular weakness is temporary and after 3–4 months, muscle strength usually recovers because functional recovery is mediated by nerve sprouting and reconstruction of the neuromuscular junction. Acrylamide may produce neurotoxic substances that cause retrograde necrotizing neuropathy and inhibit nerve sprouting caused by botulinum toxin type A. This study investigated whether acrylamide inhibits nerve sprouting after intramuscular injection of botulinum toxin type A. A tibial nerve sprouting model was established through local injection of botulinum toxin type A into the right gastrocnemius muscle of Sprague-Dawley rats. Following intramuscular injection, rats were given intraperitoneal injection of 3% acrylamide every 3 days for 21 days. Nerve sprouting appeared 2 weeks after intramuscular injection of botulinum toxin type A and single-fiber electromyography revealed abnormal conduction at the neuromuscular junction 1 week after intramuscular injection of botulinum toxin type A. Following intraperitoneal injection of acrylamide, the peak muscle fiber density decreased. Electromyography jitter value were restored to normal levels 6 weeks after injection. This indicates that the maximal decrease in fiber density and the time at which functional conduction of neuromuscular junction was restored were delayed. Additionally, the increase in tibial nerve fibers was reduced. Acrylamide inhibits nerve sprouting caused by botulinum toxin type A and may be used to prolong the clinical dosage of botulinum toxin type A.

Botulinum toxin A, brain and pain

Botulinum neurotoxin type A (BoNT/A) is one of the most potent toxins known and a potential biological threat. At the same time, it is among the most widely used therapeutic proteins used yearly by millions of people, especially for cosmetic purposes. Currently, its clinical use in certain types of pain is increasing, and its long-term duration of effects represents a special clinical value. Efficacy of BoNT/A in different types of pain has been found in numerous clinical trials and case reports, as well as in animal pain models. However, sites and mechanisms of BoNT/A actions involved in nociception are a matter of controversy. In analogy with well known neuroparalytic effects in peripheral cholinergic synapses, presently dominant opinion is that BoNT/A exerts pain reduction by inhibiting peripheral neurotransmitter/inflammatory mediator release from sensory nerves. On the other hand, growing number of behavioral and immunohistochemical studies demonstrated the requirement of axonal transport for BoNT/A's antinociceptive action. In addition, toxin's enzymatic activity in central sensory regions was clearly identified after its peripheral application. Apart from general pharmacology, this review summarizes the clinical and experimental evidence for BoNT/A antinociceptive activity and compares the data in favor of peripheral vs. central site and mechanism of action. Based on literature review and published results from our laboratory we propose that the hypothesis of peripheral site of BoNT/A action is not sufficient to explain the experimental data collected up to now.