Idiosyncratic adverse reactions to intramuscular botulinum toxin type A injection

Mild Allergic Reactions after Botulinum Toxin Injection: A Case Series and Literature Review

Background

Botulinum toxin type A (BTA) is becoming more and more prevalent as an injection agent in cosmetic surgery. However, there is an increasing amount of cases reporting unexpected adverse reactions related to BTA injection. BTA can invoke many kinds of hypersensitive reactions, some of which can be delayed-type or even fatal; hence, it is of crucial importance to pay close attention to atypical and early symptoms that may indicate the presence of BTA allergy in patients.

Methods

In this study, we reported three cases of mild and unexpected BTA-related hypersensitive reaction with a symptom of nonpruritic erythema on the chest that happened after BTA treatment of upper facial wrinkles and proposed several suggestions based on our practical experience and literature review.

Results

Two patients' symptoms were alleviated spontaneously, and one patient's were alleviated after taking oral corticosteroid. According to our literature review, we believe that these incidences indicate a kind of unreported allergic reaction relevant to botulinum toxin.

Conclusions

We suggest clinicians consider warily patients' subsequent BTA injection schedule if any suspicious reaction occurs after treatment. We suggest that patients who experience nonpruritic erythema after botulinum toxin injection should suspend subsequent injection plans for at least 3 months to prevent more severe consequences.

The impact of SARS-Cov-2 infection on the periocular injection pain and hypersensitive reaction to botulinum toxin type A: results from clinical questionnaires

Background

The COVID-19 pandemic has brought about significant changes in the medical field, yet the use of botulinum toxin type A has remained uninterrupted. Plastic surgeons must carefully consider the timing of administering botulinum toxin type A to patients who have recovered from COVID-19.

Methods

A questionnaire survey was conducted among patients who had contracted and recovered from SARS-CoV-2 within a month. The survey aimed to investigate various indicators in patients who had received botulinum toxin A injections at the same site before and after their infection, including pain scores and allergic reactions and the occurrence of complications.

Results

The pain scores of patients who contracted SARS-CoV-2 infection between 14-21 days post-infection exhibited significant variation from previous injections. However, patients who contracted the infection between 22-28 days post-infection did not exhibit significant variation from previous injections. Furthermore, the incidence of allergic reactions and complications following botulinum toxin injection within one month after contracting the infection did not significantly differ from that observed prior to infection.

Conclusion

Administering botulinum toxin type A three weeks after COVID-19 recovery is a justifiable and comparatively secure approach.

Long-term efficacy and safety of a new botulinum toxin type A preparation in mouse gastrocnemius muscle

A new type A botulinum toxin (BoNT/A) preparation, JTM201 (NCBI chromosomal DNA ID: CP046450), has been developed, which comprises 900-kDa complexed toxin purified from Clostridium botulinum (strain: NCTC13319), but its safety and efficacy have not yet been evaluated. The purpose of this study was to evaluate the long-term efficacy and safety of JTM201 at different concentrations in comparison to another commercially available BoNT/A product, Botox® (onabotulinumtoxin A, ONA), using a mouse model. The LD₅₀ of JTM201 was similar to that of ONA, but the intrinsic activity of JTM201 was higher than that of ONA. Functional recovery of the nerves and muscles in SKH-1 mice after administration of the two BoNT/A preparations (JTM201 and ONA) to the right gastrocnemius muscle was observed over 24 weeks. In addition, JTM201 did not induce any skin or muscle inflammatory response in 24 weeks. Paralysis induced by neurotransmitter blockade after JTM201 administration was comparable to that of ONA treatment. Both muscle weight and volume decreased in a concentration-dependent manner following JTM201 or ONA toxin injection until week 4. Reduced muscle fiber size due to atrophy and consequent fibrosis were detected following injection of JTM201 or ONA. Moreover, we assessed the extent of diffusion of JTM201 or ONA to the tibialis anterior and quadriceps femoris muscles, demonstrating limited diffusion to off-target muscles. In conclusion, JTM201 demonstrated long-term efficacy and safety equivalent to those of ONA based on compound muscle action potential, muscle volume, and histology analyses. These data suggest that JTM201 is a new BoNT/A formulation with safety and efficacy comparable to those of ONA.

In silico mutagenesis: decreasing the immunogenicity of botulinum toxin type A

Botulinum toxin serotype A is a prominent therapeutic enzyme, for both clinical and cosmetic uses. Since this protein is produced by bacteria, it exhibits an allergenic effect when subjected to human therapy. Protein mutagenesis is one method to improve the characteristics of protein. However, in silico study is needed to give suggestion of which amino acid should be mutated. Hence, a lot of money and time can be saved. This study initially screened which residue of the Botulinum toxin serotype A is B-cell epitopes both linearly and conformationally. By overlapping the B-cell epitopes with the excluded conserve sequence, seven residues were allowed to be mutated. There were two proposed muteins showing a reduction in the antigenicity probability: ΔE147, E510F, T1062F, ΔE1080, N1089M and ΔQ1090; and ΔE147, E510F, T1062F, E1080W, N1089M and ΔQ1090. Molecular dynamics simulation of the 3D proposed muteins indicated an increase of flexibility in both muteins compared to that in the native protein. Both muteins have lower antigenicity. In addition, they are similar in structure, stability and functionality compared to the native protein.

Delayed Hypersensitivity Reaction to OnabotulinumtoxinA

http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)2330-1619/homepage/mdc312575-sup-v001.htm.

Injectable and topical neurotoxins in dermatology: Indications, adverse events, and controversies

The use of neuromodulators for therapeutic and cosmetic indications has proven to be remarkably safe. While aesthetic and functional adverse events are uncommon, each anatomic region has its own set of risks of which the physician and patient must be aware before treatment. The therapeutic usages of botulinum toxins now include multiple specialties and multiple indications. New aesthetic indications have also developed, and there has been an increased utilization of combination therapies to combat the effects of global aging. In the second article in this continuing medical education series, we review the prevention and treatment of adverse events, therapeutic and novel aesthetic indications, controversies, and a brief overview of combination therapies.

[Management and prevention of adverse events in esthetic interventions]

BACKGROUND

Esthetic interventions are an integral part of today's dermatology. A plethora of novel agents and techniques is currently being launched on the market accompanied by a variety of side effects.

METHOD

We summarize the most common adverse events of fillers, laser treatments, and injection of botulinum toxin and present feasible means of prevention and management.

RESULTS

The profile of adverse events is more favorable in temporary fillers such as hyaluronic acid than in permanent ones. The most common filler-related adverse events include changes of skin color and unspecific swelling. Neural and vascular dysfunctions are observed less frequently, but may result in severe tissue necrosis or loss of vision. Undesirable events of laser treatments largely depend on the applied modality, localization, and indication. Local effects comprise erythema, swelling, crusting, blister formation, and weeping in extreme cases. The formation of laser-induced scarring is more likely to occur in lasers with high energies. Most adverse events of botulinum toxin are mild and transient. Pain and redness around the sites of injection are common. However, a poor injection technique and injection of too many units can trigger major motoric impairment with ptosis and dysarthria.

CONCLUSION

Excellent results can be achieved with esthetic interventions. To guarantee a maximum amount of safety and to minimize risks it is of paramount importance to work with clear indications and respect contraindications. It is important to recognize early adverse events to achieve satisfactory results and avoid severe complications.

Report of Allergic Reaction After Application of Botulinum Toxin

Botulinum toxin is a widely used treatment with satisfactory results, and it is relatively safe in the doses used for cosmetic procedures. The authors report a case of allergic reaction to Chinese botulinum toxin serotype A (CBTX-A). Although this is a rare adverse event, it is nonetheless clinically relevant to healthcare professionals. A 44-year-old woman presented to the authors' hospital complaining of dynamic wrinkles. CBTX-A was used to treat her. Minutes after application, she developed urticarial plaques proximal to the injection site. The patient had an allergic reaction, as documented by a positive skin test, which was controlled by the administration of antihistamines and systemic corticosteroids. This report is intended to guide healthcare professionals faced with this type of adverse event regarding how to proceed without hindering the delivery and effectiveness of the treatment. When performed by a qualified health professional, this treatment brings excellent results in the vast majority of cases.

LEVEL OF EVIDENCE

5 Risk.

Single-fiber electromyography analysis of botulinum toxin diffusion in patients with fatigue and pseudobotulism

OBJECTIVE

To characterize electromyographic abnormalities according to symptoms (asymptomatic, fatigue, pseudobotulism) reported 1 month after botulinum toxin injection.

DESIGN

Retrospective, single-center study comparing single-fiber electromyography (SFEMG) in the extensor digitorum communis (EDC) or orbicularis oculi (OO) muscles.

SETTING

Hospital.

PARTICIPANTS

Four groups of adults treated for spasticity or neurologic bladder hyperactivity (N=55): control group (asymptomatic patients: n=17), fatigue group (unusual fatigue with no weakness: n=15), pseudobotulism group (muscle weakness and/or visual disturbance: n=20), and botulism group (from intensive care unit of the same hospital: n=3).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Mean jitter, percentage of pathologic fibers, and percentage of blocked fibers were compared between groups.

RESULTS

SFEMG was abnormal for 17.6% of control patients and 75% of patients in the pseudobotulism group. There were no differences between the control and fatigue groups. Mean jitter, percentage of pathologic fibers, and percentage of blocked fibers of the EDC muscle were significantly higher in the pseudobotulism group than in the fatigue and control groups. There were no differences between groups for the OO muscle. The SFEMG results in the botulism group were qualitatively similar to those of the pseudobotulism group.

CONCLUSIONS

SFEMG of the EDC muscle confirmed diffusion of the toxin into muscles distant from the injection site in the pseudobotulism group. SFEMG in the OO muscle is not useful for the diagnosis of diffusion. No major signs of diffusion of botulinum toxin type A were found away from the injection site in patients with fatigue but no motor weakness. Such fatigue may be related to other mechanisms.

Botulinum toxins: mechanisms of action, antinociception and clinical applications

Botulinum toxin (BoNT) is a potent neurotoxin that is produced by the gram-positive, spore-forming, anaerobic bacterium, Clostridum botulinum. There are 7 known immunologically distinct serotypes of BoNT: types A, B, C1, D, E, F, and G. Clostridum neurotoxins are produced as a single inactive polypeptide chain of 150kDa, which is cleaved by tissue proteinases into an active di-chain molecule: a heavy chain (H) of ∼100 kDa and a light chain (L) of ∼50 kDa held together by a single disulfide bond. Each serotype demonstrates its own varied mechanisms of action and duration of effect. The heavy chain of each BoNT serotype binds to its specific neuronal ecto-acceptor, whereby, membrane translocation and endocytosis by intracellular synaptic vesicles occurs. The light chain acts to cleave SNAP-25, which inhibits synaptic exocytosis, and therefore, disables neural transmission. The action of BoNT to block the release of acetylcholine botulinum toxin at the neuromuscular junction is best understood, however, most experts acknowledge that this effect alone appears inadequate to explain the entirety of the neurotoxin's apparent analgesic activity. Consequently, scientific and clinical evidence has emerged that suggests multiple antinociceptive mechanisms for botulinum toxins in a variety of painful disorders, including: chronic musculoskeletal, neurological, pelvic, perineal, osteoarticular, and some headache conditions.

Abo-, inco-, ona-, and rima-botulinum toxins in clinical therapy: a primer

Botulinum neurotoxin (BoNT) is an acetylcholine release inhibitor and a neuromuscular-blocking agent used for the treatment of a variety of medical and cosmetic indications. Currently, in the United States, there are four BoNT formulations licensed for use: abobotulinumtoxinA, incobotulinumtoxinA, onabotulinumtoxinA, and rimabotulinumtoxinB. These revised name designations were established to reinforce the understanding that each BoNT product has an individual potency and is not interchangeable with any other BoNT product. The therapeutic use of BoNTs is expanding and new formulations are on the horizon. This article is a primer that describes distinctions among currently available, licensed BoNT formulations. Toxin pharmacology, product characteristics, storage, handling, preparation, and dosages will be reviewed. In addition, issues related to dose equivalency ratios, immunogenicity, potency, and toxin spread will be discussed. Therapeutic indications and safety are discussed briefly. Knowledge of the available and licensed BoNT formulations and the ability to make distinctions in toxin pharmacology, product characteristics, and indications are vital for product selection, preparation, drug information, avoidance of drug errors, quality assurance, and patient safety.

Complications of minimally invasive cosmetic procedures: prevention and management

Over the past decade, facial rejuvenation procedures to circumvent traditional surgery have become increasingly popular. Office-based, minimally invasive procedures can promote a youthful appearance with minimal downtime and low risk of complications. Injectable botulinum toxin (BoNT), soft-tissue fillers, and chemical peels are among the most popular non-invasive rejuvenation procedures, and each has unique applications for improving facial aesthetics. Despite the simplicity and reliability of office-based procedures, complications can occur even with an astute and experienced injector. The goal of any procedure is to perform it properly and safely; thus, early recognition of complications when they do occur is paramount in dictating prevention of long-term sequelae. The most common complications from BoNT and soft-tissue filler injection are bruising, erythema and pain. With chemical peels, it is not uncommon to have erythema, irritation and burning. Fortunately, these side effects are normally transient and have simple remedies. More serious complications include muscle paralysis from BoNT, granuloma formation from soft-tissue filler placement and scarring from chemical peels. Thankfully, these complications are rare and can be avoided with excellent procedure technique, knowledge of facial anatomy, proper patient selection, and appropriate pre- and post-skin care. This article reviews complications of office-based, minimally invasive procedures, with emphasis on prevention and management. Practitioners providing these treatments should be well versed in this subject matter in order to deliver the highest quality care.

Pilot study evaluating the safety of intradetrusor injections of botulinum toxin type A: investigation of generalized spread using single-fiber EMG

AIMS

Intradetrusor botulinum toxin type-A injections are a novel therapy for treatment of neurogenic overactive bladder resistant to parasympatholytic treatment. In rare cases, however, it may be associated with generalized muscle weakness. Single-fiber electromyographic (SFEMG) analysis of neuromuscular jitter (NJ) was used to study OnabotulinumtoxinA (BOTOX®) migration to striated muscle.

METHODS

This study comprised a prospective, single-center investigation of 21 spinal cord injured patients receiving intradetrusor OnabotulinumtoxinA. Clinical tolerance was assessed through muscle testing and para-clinical tolerance by systematic analysis of NJ in muscles distant from the bladder.

RESULTS

Twenty-one patients (13 males, 8 females) received one intradetrusor injection of 300  U OnabotulinumtoxinA. Mean age was 42.1  ±  14.4 and mean number of injections prior to study inclusion was 2.6  ± 1.7. Clinical and para-clinical assessments were performed on average 26 days  ±  8 days post-OnabotulinumtoxinA injection. Seven patients had abnormal NJ results on SFEMG, but no patient had evidence of blocking. Four patients complained of tiredness (one with NJ abnormalities).

CONCLUSIONS

Patients showed good tolerance to intradetrusor OnabotulinumtoxinA injections. Tiredness was not associated with generalized muscle weakness since testing remained unchanged and NMJ was normal in three of four patients. NJ analysis was abnormal in 7 of 21 patients, but this was not considered serious and there was no evidence of muscle fiber block. These results support the safety of bladder injections of OnabotulinumtoxinA and suggest that, although migration of OnabotulinumtoxinA to other muscle groups may impair NJ function in a minority of patients, this does not correlate with symptoms of tiredness or muscle weakness.

Systemic weakness after therapeutic injections of botulinum toxin a: a case series and review of the literature

The use of intramuscular injections of Botulinum neurotoxin A (BoNT-A) is common in the treatment of hypertonicity and movement disorders. Although most side effects are mild, systemic effects, manifested by generalized weakness distant from the site of injection, have been reported. Previously reported occurrences are discussed, and 3 new cases of patients, who developed systemic weakness after administration of BoNT-A (Botox), despite having tolerated similar injections on several previous occasions, are presented. A review of the literature and reported cases indicate that risk of developing systemic effects does not seem to be related to dose based on body weight. It may be more likely that risk for systemic effects is related to total injection dose and injection frequency. The results of our 3 patients would indicate that injections of greater than 600 units of Botox with follow-up injections occurring every 3 months may lead to an increased risk. We would recommend careful consideration of reinjection frequency if injections of greater than 600 units of Botox are given. Reduction in systemic side effects may occur if reinjection frequency occurs in intervals of 4 months or greater in these individuals.

Botulinum toxin in facial rejuvenation: an update

Since its initial approval by the US Food and Drug Administration (FDA) 20 years ago for the treatment of strabismus, hemifacial spasm, and blepharospasm in adults, botulinum toxin (BTX) has become one of the most frequently requested products in cosmetic rejuvenation around the world. After years of clinical success and consistent safety in the upper face, the use of BTX has expanded and evolved to include increasingly complicated indications. In the hands of adept injectors, the focus has shifted from the treatment of individual dynamic rhytides to shaping, contouring, and sculpting, alone or in combination with other cosmetic procedures, to enhance the aesthetic appearance of the face. Although recent reports have questioned the safety of BTX, 25 years of therapeutic and over 20 years of cosmetic use has demonstrated an impressive record of safety and efficacy when used appropriately by experienced injectors.

Botulinum toxin type B (Myobloc, NeuroBloc): a new choice in cervical dystonia

Botulinum toxin has dramatically improved the treatment of cervical dystonia. Prior to the use of botulinum toxin for many neurologic disorders, patients had few effective therapeutic options. Botulinum toxin type B (Myobloc, NeuroBloc) is a new antigenically distinct botulinum toxin with a unique structure and mechanism of action. Preclinical studies have demonstrated that im. injections of botulinum toxin type B effectively induce a dose-dependent paralysis. Controlled clinical trials have shown that it is safe and effective in alleviating symptoms associated with cervical dystonia. Given its efficacy and safety profile, the clinical use of type B toxin is anticipated to expand into other therapeutic areas.

Undesirable distant effects following botulinum toxin type a injection

OBJECTIVES

To study the incidence of clinical signs linked to botulinum toxin type A (BoNTA) spread from the injection site.

METHODS

Single-center, retrospective, cohort study. All patients who received BoNTA injections for spasticity treatment were assessed 1 month postinjection. Adverse effects indicative of BoNTA treatment were systematically sought. Any patient with adverse effects possibly due to BoNTA spread underwent further clinical examination and single-fiber electromyography. One patient underwent neuromuscular biopsy.

RESULTS

Between January and September 2005, 266 BoNTA injection sessions (187 patients) were performed (233 BOTOX, 33 Dysport). Five patients presented with clinical signs of toxin spread. Four of these underwent single-fiber electromyography, which showed increased jitter. Neuromuscular biopsy detected signs of recent denervation without signs of reinnervation.

CONCLUSIONS

Diffusion diagnosis of BoNTA from the injection site depends on clinical, temporal, and electromyographic factors. Clinical expression of spread varies widely, with mechanisms remaining largely unknown, and further prospective, randomized clinical trials are required.

Skin reactions after intramuscular injection of Botulinum toxin A: a rare side effect

The use of Botulinum toxin as a treatment for dystonia and other neurological conditions has been rapidly increasing over the past decade. In general, idiosyncratic adverse reactions to repeated injections of Botulinum toxin seem to be rare and were described in only a few recent reports. We present two cases of substantial skin reactions, one with systemic involvement, after intramuscular application of Botulinum toxin A. The possible role of immunologic factors and other mechanisms such as intolerance and pseudoallergic reaction are discussed. We would like to alert the clinician to this rare, but occasionally serious side effect that may be underestimated.

Complications of Botulinum Toxin Type A

Introduced over 30 years ago for the treatment of strabismus and blepharospasm, botulinum toxin type A (BTX-A) now has established uses for various therapeutic and cosmetic purposes. Although remarkably safe and effective, BTX-A is a potent toxin. Complications can occur, particularly when used by the inexperienced injectors. Through knowledge of its mechanism of action and effect and careful attention to dosing and technique can minimize the risk of more serious adverse events.

Botulinum toxin A for myofascial trigger point injection: a qualitative systematic review

Botulinum toxin injection is used to treat various pain conditions including muscle spasticity, dystonia, headache and myofascial pain. Results are conflicting regarding the use of Botulinum toxin for trigger point injection in terms of improvement in pain. The aim of this study was to carry out a systematic review to assess the evidence for efficacy of Botulinum toxin A (BTA) compared with placebo for myofascial trigger point injection. Electronic databases on Medline, Cochrane Library, Scopus, CINAHL were queried using key words such as "botulinum toxin", "myofascial pain", "trigger point", "chronic pain" and "musculoskeletal pain". Relevant published randomized controlled trials that described the use of BTA as injection therapy for trigger points were considered for inclusion. The five-item 0-16 point Oxford Pain Validity Scale (OPVS) was used as a selection criteria for suitable clinical trials. Trials were also assessed based on quality using the Oxford Rating Scale. Data extracted from qualified trials included outcome measures such as pain intensity and pain pressure threshold. All studies were ranked according to the OPVS and the authors' conclusions were compared. Five clinical trials met the inclusion criteria. One trial concluded that BTA was effective, and four concluded that it was not effective for reducing pain arising from trigger points. OPVS scores ranged from 8 to 14 with the negative studies corresponding with higher validity scores. The current evidence does not support the use of BTA injection in trigger points for myofascial pain. The data is limited and clinically heterogeneous.

Managing adverse events associated with botulinum toxin type A: a focus on cosmetic procedures

Botulinum toxin A (BTXA) has become a widely used drug in cosmetic dermatology, not only to treat focal hyperhidrosis but also hyperkinetic facial lines, platysma bands, décolleté bands, and other skin features. The spectrum of possible adverse effects of BTXA is broad but fortunately those that have been observed with cosmetic use of this product are generally mild and transient. The major tools for preventing adverse effects from BTXA are knowledge and skill. Use of correct injection techniques is mandatory since most unwanted effects are caused by incorrect technique. Knowledge of the target structures, e.g. the facial and extrafacial muscles, allows physicians to select the optimal dose, time and technique. The most common adverse effects are pain and hematoma. In the periocular region, lid and brow ptosis are important adverse effects. Adverse effects such as pain, hematoma, ecchymosis, and bruising may also occur in the upper and lower face and at extrafacial sites. Other possible adverse effects seen in other indications that the user of BTXA in cosmetic dermatology should be wary of include induction headaches and possible interaction with concomitant medications. Induction of neutralizing antibodies due to cosmetic BTXA treatment has not been observed. This article also outlines recommendations regarding use of BTXA. Of these, the most important for avoiding most unwanted adverse effects are the proper techniques of dilution, storage, and injection, as well as the careful exclusion of patients with any contraindications. Pain, hematoma, ecchymosis, and bruising can be prevented by cooling the skin before and after BTXA injection. Upper lid ptosis may be partly corrected using apraclonidine or phenylephrine eyedrops. If simple rules relating to the indications for and application of BTXA are followed, this is a safe and effective drug in cosmetic dermatology.

[Botulinum toxin and medical liability: is the patient sufficiently informed?]

INTRODUCTION

The use of botulinum toxin injection therapy is soaring significantly today, with an ever-wider field of applications despite well-known side effects of the treatment. This article aims at analysing the medicolegal practices of practitioners who use this therapy, especially the information given to patients and finding a common practice for providing that information.

METHODS

We sent a questionnaire to 340 practitioners who might use the therapy (physiatrists, neurologists, ophthalmologists, ENT specialists, plastic surgeons) working in hospitals and in physical therapy and rehabilitation centres in France. Besides mentioning the possible side effects of the therapy, the questionnaire focused on how such information was transmitted before the injection.

RESULTS

Data collection and analysis were performed by use of a spreadsheet software programme. A total of 124 questionnaires were analysed. We did not analyse the items dealing with side effects. Sixty-five percent of the responders said they did not seek statutory authorisation for injections. Only 31% provided written, detailed information and 12% required a signed consent form. Complaints were rare, approximately 12%, were written or verbal, and were always dismissed.

DISCUSSION

Side effects after botulinum toxin injection are clearly described in the medical literature. Therefore, it is of utmost importance for this product to be used therapeutically and only by experienced therapists who will carefully respect the product's standard rules of use and inform their patients to the best of their ability. Issuing a detailed letter of information describing all the side effects seems necessary. We suggest a model information letter such as that provided to the patients in our facility.

CONCLUSION

Botulinum toxin is a very worthwhile product for numerous abnormalities but has side effects, often brief, at the site of the injection. Therefore it is our duty to inform patients effectively.

Botulinum toxins in pain management

BTs are a useful treatment in refractory MPS and have shown promise in various superficial neuropathic pain syndromes. Presumably BTs work by breaking the spasm/pain cycle, giving the patient a "window of opportunity" for traditional conservative measures to have a greater beneficial impact, but several studies suggest that a direct antinociceptive effect distinct from any reduction in muscle spasm may be at play. The major benefit of BTs compared with standard therapies is duration of response. BTs cannot be considered a "first line" treatment for any pain application; however, in refractory cases in which nothing else has helped, BTs may offer the patient and physician a chance for improvement and perhaps even cure.

The basic science of botulinum toxin

Understanding the basic science of botulinum toxin should serve as a fundamental first step for clinical therapy. This article endeavors to cover many aspects of basic research that also have clinical import. The two principal toxins of the clostridial family, Clostridium tetani and C botulinum, are described in detail. The five clinical manifestations of botulism poisoning are also outlined, and structural aspects and the mechanism of action of botulinum toxin are then presented. Finally, the immunologic and pharmacologic principles that define the various serotypes of botulinum toxin are set forth.

The Cosmetic Use of Botulinum Toxin

The approach to facial rejuvenation continues to evolve. For decades, the primary focus on rejuvenation has centered on modalities such as skin care, skin resurfacing, soft-tissue augmentation, and surgical intervention. A better understanding of the physiologic changes that occur with facial aging lends itself to new approaches and techniques that are mindful of the causes. As animation has shown to be a significant contributor to both the appearance of facial lines and soft-tissue malposition, there has been recent interest in chemodenervating agents and their applications in the field of facial rejuvenation. These agents, by and large, efface rhytides by selective and precise focal paralysis of the underlying facial musculature and, therefore, reduce or eliminate the prominence of the overlying rhytides. In addition, chemodenervation can serve as an adjunct for facial rejuvenation because of its influence on facial soft-tissue position and shape. Botulinum toxin, derived from Clostridium botulinum, is the most widely used agent; therefore, this new modality, its applications in cosmetic plastic surgery, and its applications to other areas will be discussed.

Botulinum toxin in pain management of soft tissue syndromes

Botulinum toxin is approved for the treatment of muscle overactivity associated with several disorders, such as dystonias. However, control of muscle spasm often results in pain relief as well. Effective relief of pain associated with myofascial pain syndrome provides a model for the use of botulinum toxin to relieve pain associated with other types of soft-tissue syndromes, such as fibromyalgia. Although the mechanisms that trigger the pain in these syndromes vary, recent data suggest that a central neuroplastic mechanism may contribute to many complex pain syndromes. Botulinum toxin therapy may be particularly useful in soft-tissue syndromes that are refractory to traditional treatment with physical therapy, electrical muscle stimulation, and other approaches. Although not used as first-line therapy for pain relief, botulinum toxin may decrease pain long enough for patients to resume more conservative therapy. A primary benefit of treatment with botulinum toxin is its long duration of action. Several studies have demonstrated the efficacy of botulinum toxin types A and B in treating several neuropathic pain disorders. Proper patient selection, injection technique, and dosing are critical to obtaining the best outcomes in managing pain with botulinum toxin. Additional study is needed to better characterize its use for the treatment of pain.

Achalasia: a review of therapeutic options and outcomes

Advances in achalasia has led to the development of new therapeutic options. This review will focus on methodology and outcomes of two established techniques; pneumatic dilation and surgical myotomy; and one new technique, LES injection of botulinum A toxin.

Treatment of achalasia with botulinum A toxin

Achalasia is an idiopathic neuromuscular disorder of the esophagus which is associated with absence of esophageal peristalsis and incomplete relaxation of a normal or raised lower esophageal sphincter (LES). Dysphagia is the most commonly associated symptom. Conventional therapeutic approaches are directed to reducing LES pressure and include orally-administered smooth muscle relaxants, forceful sphincter dilation with balloon dilators, and open or laparoscopic-assisted myotomy of the LES. Pharmacologic therapies have a low success rate. Forceful dilation has a perforation complication rate of 2% to 5%, and myotomies may precipitate significant gastroesophageal reflux, a complication minimized when a partial fundal wrap is employed simultaneously. In recent years, botulinum toxin, utilized widely as a striated muscle relaxant in managing blepharospasm, anal sphincter spasm, and muscle spasm complicating CVAs, and in smoothening facial wrinkles, has been extended to the management of achalasia on the basis that it impairs smooth muscle responsiveness to acetylcholine. Eighty units of Botox (botulinum toxin) are injected directly into the endoscopically (endoscopic ultrasound techniques may facilitate localization) located LES region (20 units into each of 4 quadrants). Symptom relief lasting 6 months on average is experienced in more than 65% of treated patients, and the complication rate is negligible. This therapeutic option is reserved for patients too ill to undergo any surgical procedure and is most effective when the lower esophageal region is hypertonic.

Polyradiculoneuritis after botulinum toxin therapy for cervical dystonia

A 40-year-old man with cervical dystonia developed an acute inflammatory demyelinating polyradiculoneuritis after botulinum toxin type A treatment. Some cases of idiopathic brachial plexopathy and polyradiculoneuritis have been reported to date. Although a causal relationship is not firmly established, the clinical temporal profile suggests a pathogenic relationship. In patients with cervical dystonia, further use of type A botulinum toxin should be considered contraindicated, and the use of another type of botulinum toxin should be taken into consideration.