Botulinum Toxin Type A (BOTOX ® ) for the Prophylactic Treatment of Chronic Daily Headache: A Randomized, Double‐Blind, Placebo‐Controlled Trial

Botulinum Toxin Injections for Psychiatric Disorders: A Systematic Review of the Clinical Trial Landscape

Botulinum toxin type A (BONT-A) has shown promise in improving the mood-related symptoms of psychiatric disorders by targeting muscles linked to the expression of negative emotions. We conducted a systematic review of past and ongoing efficacy trials of BONT-A therapy for psychiatric disorders to identify relevant trends in the field and discuss the refinement of therapeutic techniques. A comprehensive search for published clinical trials using BONT-A injections for psychiatric disorders was performed on 4 May 2023 through OVID databases (MEDLINE, Embase, APA PsycINFO). Unpublished clinical trials were searched through the ClinicalTrials.gov and International Clinical Trial Registry Platform public registries. The risk of bias was assessed using the JBI Critical Appraisal tools for use in systematic reviews. We identified 21 studies (17 published, 4 unpublished clinical trials) involving 471 patients. The studies focused on evaluating the efficacy of BONT-A for major depressive, borderline personality, social anxiety, and bipolar disorders. BONT-A was most commonly injected into the glabellar area, with an average dose ranging between 37.75 U and 44.5 U in published studies and between 32.7 U and 41.3 U in unpublished trials. The results indicated significant symptom reductions across all the studied psychiatric conditions, with mild adverse effects. Thus, BONT-A appears to be safe and well-tolerated for psychiatric disorders of negative affectivity. However, despite the clinical focus, there was a noted shortage of biomarker-related assessments. Future studies should focus on pursuing mechanistic explorations of BONT-A effects at the neurobiological level.

Comparative retention and effectiveness of migraine preventive treatments: A nationwide registry-based cohort study

BACKGROUND AND PURPOSE

Little is known about the comparative effects of migraine preventive drugs. We aimed to estimate treatment retention and effectiveness of migraine preventive drugs in a nationwide registry-based cohort study in Norway between 2010 and 2020.

METHODS

We assessed retention, defined as the number of uninterrupted treatment days, and effectiveness, defined as the reduction in filled triptan prescriptions during four 90-day periods after the first preventive prescription, compared to a 90-day baseline period. We compared retention and efficacy for different drugs against beta blockers. Comparative retention was estimated with hazard ratios (HRs), adjusted for covariates, using Cox regression, and effectiveness as odds ratios (ORs) using logistic regression, with propensity-weighted adjustment for covariates.

RESULTS

We identified 104,072 migraine patients, 81,890 of whom were female (78.69%) and whose mean (standard deviation) age was 44.60 (15.61) years. Compared to beta blockers, botulinum toxin (HR 0.43, 95% confidence interval [CI] 0.42-0.44) and calcitonin gene-related peptide pathway antibodies (CGRPabs; HR 0.63, 95% CI 0.59-0.66) were the least likely to be discontinued, while clonidine (HR 2.95, 95% CI 2.88-3.02) and topiramate (HR 1.34, 95% CI 1.31-1.37) were the most likely to be discontinued. Patients on simvastatin, CGRPabs, and amitriptyline were more likely to achieve a clinically significant reduction in triptan use during the first 90 days of treatment, with propensity score-adjusted ORs of 1.28 (95% CI 1.19-1.38), 1.23 (95% CI 0.79-1.90), and 1.13 (95% CI 1.08-1.17), respectively.

CONCLUSIONS

We found a favorable effect of CGRPabs, amitriptyline, and simvastatin compared with beta blockers, while topiramate and clonidine were associated with poorer outcomes.

Functional outcomes between headache surgery and targeted botox injections: A prospective multicenter pilot study

Introduction

Chronic migraine headaches (MH) are a principal cause of disability worldwide. This study evaluated and compared functional outcomes after peripheral trigger point deactivation surgery or botulinum neurotoxin A (BTA) treatment in patients with MH.

Methods

A long-term, multicenter, and prospective study was performed. Patients with chronic migraine were recruited at the Ohio State University and Massachusetts General Hospital and included in each treatment group according to their preference (BTA or surgery). Assessment tools including the Migraine Headache Index (MHI), Migraine Disability Assessment Questionnaire (MIDAS) total, MIDAS A, MIDAS B, Migraine Work and Productivity Loss Questionnaire-question 7 (MWPLQ7), and Migraine-Specific Quality of Life Questionnaire (MSQ) version 2.1 were used to evaluate functional outcomes. Patients were evaluated prior to treatment and at 1, 2, and 2.5 years after treatment.

Results

A total of 44 patients were included in the study (surgery=33, BTA=11). Patients treated surgically showed statistically significant improvement in headache intensity as measured on MIDAS B (p = 0.0464) and reduced disability as measured on MWPLQ7 (p = 0.0120) compared to those treated with BTA injection. No statistical difference between groups was found for the remaining functional outcomes. Mean scores significantly improved over time independently of treatment for MHI, MIDAS total, MIDAS A, MIDAS B, and MWPLQ 7 (p<0.05). However, no difference in mean scores over time was observed for MSQ.

Conclusions

Headache surgery and targeted BTA injections are both effective means of addressing peripheral trigger sites causing headache pain. However, lower pain intensity and work-related disabilities were found in the surgical group.

Neutralizing Antibody Formation with OnabotulinumtoxinA (BOTOX®) Treatment from Global Registration Studies across Multiple Indications: A Meta-Analysis

Though the formation of neutralizing antibodies (NAbs) during treatment with botulinum neurotoxin is rare, their presence may nonetheless affect the biological activity of botulinum toxin and negatively impact clinical response. The goal of this updated meta-analysis was to evaluate and characterize the rate of NAb formation using an expanded dataset composed of 33 prospective placebo-controlled and open-label clinical trials with nearly 30,000 longitudinal subject records prior to and following onabotulinumtoxinA treatment in 10 therapeutic and aesthetic indications. Total onabotulinumtoxinA doses per treatment ranged from 10 U to 600 U administered in ≤15 treatment cycles. The NAb formation at baseline and post-treatment was tested and examined for impact on clinical safety and efficacy. Overall, 27 of the 5876 evaluable subjects (0.5%) developed NAbs after onabotulinumtoxinA treatment. At study exit, 16 of the 5876 subjects (0.3%) remained NAb positive. Due to the low incidence of NAb formation, no clear relationship was discernable between positive NAb results and gender, indication, dose level, dosing interval, treatment cycles, or the site of injection. Only five subjects who developed NAbs post-treatment were considered secondary nonresponders. Subjects who developed NAbs revealed no other evidence of immunological reactions or clinical disorders. This comprehensive meta-analysis confirms the low NAb formation rate following onabotulinumtoxinA treatment across multiple indications, and its limited clinical impact on treatment safety and efficacy.

Rimegepant for the treatment of migraine

Migraine is a common form of primary headache, affecting up to 1 in every 6 Americans. The pathophysiology is an intricate interplay of genetic factors and environmental influence and is still being elucidated in ongoing studies. The trigeminovascular system is now known to have a significant role in the initiation of migraines, including the release of pain mediators such as CGRP and substance P. Traditional treatment of migraine is usually divided into acute and preventive treatment. Acute therapy includes non-specific therapy, such as NSAIDs and other analgesics, which may provide relief in mild to moderate migraines. 5-HT1 agonists may provide relief in severe migraine, but are not universally effective and carry a significant side-effect profile with frequent redosing requirement. Prophylactic therapy may reduce the occurrence of acute migraine attacks in selected patients, but does not completely eliminate it. More recently, CGRP antagonism has been studied and shown to be effective in both abortion and prevention of migraine. Novel medications, targeting CGRP, divide into CGRP antibodies and receptor antagonists (gepants). Rimegepant, a second-generation gepant, has shown efficacy in several clinical trials in treating acute migraine. Ongoing trials are also evaluating its role in migraine prophylaxis, and results are promising. It is also generally safer for use than existing options, does not appear to increase the chance of developing chronic migraines, and carries a very tolerable side effects profile. It is a part of a growing arsenal in migraine treatment, and may present the silver bullet for treatment of this disease.

The efficacy of botulinum toxin type-A for intractable chronic migraine patients with no pain-free time

AIM

This is a retrospective report of the efficacy of botulinum toxin-A, Botox^® (Allergan), in intractable chronic migraine patients non-responsive to previous pharmacological management and with largely no pain-free time, including those with new onset daily persistent headache.

METHODS

Thirty-three patients, all with severe Headache Impact Test (HIT)-6 scores at baseline, received 3-monthly injections of Botox^® as per Phase III REsearch Evaluating Migraine Prophylaxis Therapy (PRE-EMPT) protocol over a maximum 33-month period. Response criteria were a sustained reduction of HIT-6 scores below 60.

RESULTS

Four patients had headache on at least 20 days a month; the remaining patients had daily headache with no pain-free time, including nine patients with new onset persistent migraine. There was a significant reduction in HIT-6 scores following Botox^® therapy (x̅ = -5.45, p = 0.000920). Twenty-one percent of the cohort exhibited a sustained reduction in HIT-6 scores below 60. The number of headache days and pain-free time did not change in five of the six responders, but disability improved. There was no difference between patients with episodic migraine evolving to chronic as opposed to those with chronic migraine from onset.

CONCLUSION

This report suggests that Botox^® treatment is efficacious in intractable chronic migraine without pain-free time. The HIT-6 is a reliable and practical parameter to assess disability in this patient group. Use of such validated parameters should be considered with greater weight in future International Classification of Headache Disorders (ICHD) guidelines for controlled clinical trials.

Placebo response with subcutaneous injections in calcitonin gene-related peptide receptor monoclonal antibody migraine preventative trials – A systematic review and meta-analysis

Background:

The majority of CGRP monoclonal antibodies for migraine prevention are administered subcutaneously. Therefore, we attempted to calculate the pooled placebo response with subcutaneous placebo injections in this systematic review and meta-analysis.

Methods:

We identified 16 randomized controlled trials that met our inclusion and exclusion criteria through a comprehensive search in five electronic databases (PubMed Central, EMBASE, MEDLINE, Cochrane library and clinicaltrials.gov ). The risk of bias was assessed for all included studies. Random effects model was used to calculate pooled mean monthly migraine days and 50% response rates.

Results:

A total of 4240 subjects were included from 16 studies in this meta-analysis. The pooled mean monthly migraine day reduction with subcutaneous placebo injections was 2.15 (95% CI: 1.60–2.69). The pooled proportion of patients achieving a 50% reduction in mean monthly headache days was 26% (95% CI: 20%–31%). Placebo response accounted for more than 50% of therapeutic gain in our study.

Conclusion:

A substantial placebo response was noted with subcutaneous injections in migraine CGRP monoclonal antibody clinical trials. This meta-analysis may serve as a reference point to calculate sample size in clinical trials using subcutaneous interventions for migraine prevention. We registered our study at PROSPERO (CRD42020185300).

OnabotulinumtoxinA for the prophylactic treatment of headaches in adult patients with chronic migraine: a safety evaluation

Introduction: Existing oral prophylaxis for chronic migraine (CM) are often ineffective or poorly tolerated. OnabotulinumtoxinA (onabotA) is approved for headache prophylaxis in CM and ameliorates headaches in patients refractory to multiple preventatives.Areas covered: We appraise evidence regarding action mechanisms, pharmacodynamics, and pharmacokinetics of onabotA in CM prophylaxis. We critically evaluate salient clinical and real-world studies demonstrating its efficacy in improving multiple aspects of CM. We discuss onabotA safety, tolerability, and adverse events (AEs) for CM prophylaxis from clinical trials, post-authorization studies and meta-analyses, including novel pregnancy safety data and comparisons with oral prophylactics. We explore areas of future interest, particularly onabotA safety and efficacy in the context of novel antibody-based prophylaxis.Expert opinion: Clinical and real-world evidence demonstrate onabotA safety, tolerability and efficacy for CM prophylaxis. Most AEs are mild/moderate and self-limiting, with few serious AEs and no treatment-related deaths. Common AEs include neck pain, ptosis, muscle weakness, and stiffness. Modifying existing responder-criteria enables more patients to benefit from onabotA. OnabotA shows superior safety and efficacy to oral preventatives, and appears safe in pregnancy. Future pregnancy-risk register will clarify pregnancy and lactation safety further. Future research comparing onabotA safety and efficacy with newly emergent antibody-based prophylaxis is keenly awaited.

Experience of Botulinum Toxin A Injections for Chronic Migraine Headaches in a Pediatric Chronic Pain Clinic

OBJECTIVES

Prevalence of chronic migraine in children can reach 7.7%, causing decreased school performance, difficulty with extracurricular activities (including sports, theater, or music), and changes in sleep and mood. Many studies confirm that botulinum toxin type A injections effectively alleviate chronic migraines in adults; however, the literature regarding children is sparse. This study aims to analyze the safety and effectiveness of botulinum type A injections in a group of pediatric patients diagnosed with chronic migraines in a pediatric pain clinic.

METHODS

In this retrospective (2013-2018) study, the effects of botulinum toxin type A injections were analyzed using data from 65 pediatric patients diagnosed with chronic migraines. The study group ranged from 11 to 18 years of age. A pediatric pain management physician administered the botulinum using the Phase 3 Research Evaluating Migraine Prophylaxis Therapy program protocol and followed the pain pattern. Dosages, tolerance, and side effects were measured.

RESULTS

In this study, 74% of the patients tried more than 6 medications before the injections. There was a decrease in the visual analog scale score of 5.2 ± 2.2 points upon 6-week follow-up. The mean amount of medication used was 173.2 ± 35 units, and patients received an average of 2.8 ± 1.1 units/kg. Adverse events include one patient who developed dizziness and another who had low-grade fevers with enlarged cervical lymph nodes; both resolved within few minutes.

CONCLUSIONS

This study supports the use of botulinum type A for chronic migraines in pediatric patients. Multicentered, randomized studies with larger population are needed to evaluate the long-term safety and efficacy of this therapy.

Botulinum Toxin in the Treatment of Headache

Botulinum toxin type A has been used in the treatment of chronic migraine for over a decade and has become established as a well-tolerated option for the preventive therapy of chronic migraine. Ongoing research is gradually shedding light on its mechanism of action in migraine prevention. Given that its mechanism of action is quite different from that of the new monoclonal antibodies directed against calcitonin gene-related peptide (CGRP) or its receptor, it is unlikely to be displaced to any major extent by them. Both will likely remain as important tools for patients with chronic migraine and the clinicians assisting them. New types of botulinum toxin selective for sensory pain neurons may well be discovered or produced by recombinant DNA techniques in the coming decade, and this may greatly enhance its therapeutic usefulness. This review summarizes the evolution of botulinum toxin use in headache management over the past several decades and its role in the preventive treatment of chronic migraine and other headache disorders.

OnabotulinumtoxinA injection in the treatment of chronic migraine

The earliest descriptions of botulism were in the early 19th century, and was reported by the German physician Justinus Kerner. The term "botulism" was derived from the Latin word botulus, indicating its original association with sausages. It took another 150 years or so to come into clinical use. The first clinical application was strabismus, and was developed by the American ophthalmologist Alan B. Scott, whose effort led to the pharmaceutical product known as onabotulinumtoxinA today. The therapeutic benefit in migraine was an incidental finding in a report by the American plastic surgeon William J. Binder, which inspired a series of clinical studies in headache disorders. The doses and injection techniques in the earlier reports were variable, so were the results. It was until the Phase III REsearch Evaluating Migraine Prophylaxis Therapy (PREEMPT) 1 and 2 studies when its efficacy and safety, as well as the indication, i.e., chronic migraine (CM), were ascertained. Even though there were criticisms regarding the heterogeneities in the results between the PREEMPT 1 and 2 studies, the data on efficacy endpoints and safety were generally consistent, which were subsequently confirmed by the open-label extension of the PREEMPT 1 and 2 studies, and three open-label studies, namely the Chronic Migraine OnabotulinuMtoxinA Prolonged Efficacy open Label (COMPEL), the REal-life use of botulinum toxin for the symptomatic treatment of adults with chronic migraine, measuring healthcare resource utilization, and Patient-reported OutcomeS observed in practice (REPOSE) studies, and the CM Post-Authorization Safety Study (CM PASS) studies. On the other hand, the results were challenged by the Chronification and Reversibility of Migraine (CHARM) study, which involved CM patients with medication overuse. It was concluded that the clinical improvement was attributed to early withdrawal of the overused acute medications, rather than onabotulinumtoxinA injections. However, fundamental differences in the patient profile and methodology between the CHARM and PREEMPT studies existed, and cautious should be exercised when interpreting and comparing the results. According to the practical guidelines and reimbursement regulations in many countries, its use is limited to CM patients, and is reserved for those who fail at least 2-3 preventive medications, due to either lack of efficacy or intolerability. Cessation of treatment is recommended in patients who do not respond to 2-3 injection cycles, or in patients whose headache frequency has dropped to <10-15 days a month. Even in the era of calcitonin-gene-related peptide monoclonal antibodies, onabotulinumtoxinA injection remains a treatment option of reasonable cost-effectiveness in carefully selected patients.

An Evidence-Based Review of Fremanezumab for the Treatment of Migraine

Migraine headache is a common, chronic, debilitating disease with a complex etiology. Current therapy for migraine headache comprises either treatments targeting acute migraine pain or prophylactic therapy aimed at increasing the length of time between migraine episodes. Recent evidence suggests that calcium gene-related peptide (CGRP) is a critical component in the pathogenesis of migraines. Fremanezumab, a monoclonal antibody against CGRP, was recently approved by the Food and Drug Administration (FDA) after multiple studies showed that it was well-tolerated, safe, and effective in the treatment of migraines. Further research is needed to elucidate the long-term effects of fremanezumab and CGRP-antagonists in general, and additional data is required in less healthy patients to estimate its effects in these populations and potentially increase the eligible group of recipients. This is a comprehensive review of the current literature on the efficacy and safety of fremanezumab for the treatment of chronic migraine. In this review we provide an update on the epidemiology, pathogenesis, diagnosis, and current treatment of migraine, and summarize the evidence for fremanezumab as a treatment for migraine.

Modifications to the PREEMPT Protocol for OnabotulinumtoxinA Injections for Chronic Migraine in Clinical Practice

OBJECTIVE

To assess the PREEMPT protocol modifications that have developed in clinical practice over time.

BACKGROUND

The United States Food and Drug Administration approved the 155-unit fixed-dose, fixed-site PREEMPT protocol of onabotulinumtoxinA (BoNT-A) injections for migraine prevention 9 years ago.

METHODS

This is an anonymous survey with free text response options of Headache Medicine clinicians.

RESULTS

Out of the 878 contacted Headache Medicine clinicians, 182 (20.7%) completed the survey. Of the 182 respondents, 141 (77.5%) reported that they did not always follow the PREEMPT protocol. Of the 182 respondents, 128 (70%) changed the number of injections, 115 (63%) changed the total units of BoNT-A injected, 105 (57.7%) altered the location of injection sites (58%); 101 (55.5%) do not aspirate to ensure the absence of blood return; 22 (12.1%) changed the dilution; and 4 (2.2%) added lidocaine. The main reported reasons for changes in number, dose, and location of injections included adapting to the patients' pain, anatomy, and preferences.

CONCLUSIONS

The wide inter- and intra-personal variations in BoNT-A injections for chronic migraine prevention seen in this survey raise concerns about the standardization of the procedure and suggest that an advisory protocol containing more evidence and discussion of the reasoning behind the recommendations might be more helpful than the current prescriptive protocol.

The Use of Botulinum Toxin in the Management of Headache Disorders

Tremendous progress has been made in the past decades for the treatment of headache disorders. Chronic migraine is the most disabling type of headache and requires the use of acute and preventive medications, many of which are associated with adverse events that limit patient adherence. Botulinum toxin (BoNT) serotype A, a neurotoxin derived from certain strains of Clostridium, disrupts neuropeptide secretion and receptor translocation related to trigeminal nociception, thereby preventing pain sensitization through peripheral and possibly central mechanisms. Ever since the first randomized controlled trial on onabotulinumtoxinA (onabotA) for migraine was published two decades ago, onabotA has been the only BoNT formulation approved for use in the prevention of chronic migraine. Superior tolerability and efficacy have been demonstrated on multiple migraine endpoints in many controlled trials and real-life studies. OnabotA is a safe and efficacious treatment for chronic migraine and possibly high-frequency episodic migraine. Further research is still needed to understand its mechanism of action to fully develop its therapeutic potential.

Wearing Off Effect of OnabotulinumtoxinA Near the End of Treatment Cycle for Chronic Migraine: A 4-Year Clinical Experience

INTRODUCTION

The injection interval for onabotulinumtoxinA (BoNTA) in the management of chronic migraine (CM) is 12 weeks (78-84 days). The aim of this study was to review patient-reported wearing off effect (WOE) of the therapeutic benefit of BoNTA near the end of the treatment cycle. We intended to describe the demographics of patients at baseline and compare groups of patients with multiple episodes of WOE.

METHODS

We conducted a retrospective review of patients with CM who received uninterrupted BoNTA therapy from January 2014 to March 2018. The data from patient-reported WOE (worsening headache variables and neck pain) that occurred during the 4 weeks (28 days) prior to the scheduled re-injection of BoNTA for treatment cycles with injection interval ≤13 weeks and without obvious confounding factors were reviewed.

RESULTS

We identified 98 eligible patients and analyzed 471 treatment cycles. Forty-three unique patients reported at least 1 occurrence of WOE. About 24/43 patients reported 1 WOE event and 19/43 patients reported ≥2 WOE events. Between the 2 groups, anxiety disorder and opioid use for headache were statistically significantly different. In the former group, the median interquartile range (IQR) dose of BoNTA was 165 (155, 175) units and the median IQR duration of the antinociceptive effect of BoNTA was 66.5 (63, 71.5) days. In the latter group, the median IQR dose of BoNTA was 167 (155, 173.3) units and the median IQR duration of the antinociceptive effect of BoNTA was 65.3 (62.5, 68.8) days. Up to 32% of these patients reported an increase in the use of abortive therapies to manage the symptoms of WOE.

DISCUSSION

The primary goal of BoNTA in the treatment of CM is to mitigate the development of central sensitization. Since the 12-week injection paradigm may not provide sustained antinociceptive effect in all patients, it may account for the failure of response to BoNTA. Repeated occurrences of the WOE can potentially lead to medication overuse and impact quality of life.

Efficacy of Botulinum Toxin Type A in Trigeminal Neuralgia in a South Asian Cohort

Introduction:

The antinociceptive effect of botulinum toxin-A (BTX-A) in trigeminal neuralgia (TN) has been described. We evaluated effects of BTX-A in relieving pain in patients with refractory TN at National Hospital of Sri Lanka.

Materials and Methods:

Pain in patients with TN was assessed using a visual analog from 0 to 10. Three months after commencement of drug therapy with ≥2 drugs including one first-line drug (carbamazepine/oxcarbazepine), pain scores were re-assessed. Twenty-two patients who did not report improvement of ≥50% at 90 days’ posttreatment were recruited. They were given adjunct BTX-A directly to the trigger point (if identified) or intradermal. Pain scores were assessed at 10, 20, 30, 60, and 90 days’ posttreatment.

Results:

There was a statistically significant improvement in mean pain scores at 10, 20, 30, 60, and 90 days’ posttreatment (5.59 [standard deviation (SD) = 2.7], 5.68 [SD = 2.6], 5.27 [SD = 3.2], 4.77 [SD = 3.7], and 5.32 [SD = 4.0]) compared to pre-BTX-A treatment (7.14, SD = 2.2). Percentage reduction in mean pain score ranged from 20.4% to 33.1%. Maximum response was at day 60 post-BTX-A (50% had ≥50% reduction in pain). No significant difference was found in response with higher doses and injection strategy.

Conclusion:

Consistent statistically significant reductions in pain scores at the aforesaid intervals compared to pretreatment means that there is a place for BTX in refractory TN.

Botulinum Toxin a Valuable Prophylactic Agent for Migraines and a Possible Future Option for the Prevention of Hormonal Variations-Triggered Migraines

BACKGROUND

In 1989, Botulinum toxin (BoNT) was accepted by the FDA for the management of some ophthalmic disorders. Although it was initially considered a lethal toxin, in recent times, Botulinum toxin A (BoNT-A), which is the more used serotype, has expanded to cover different clinical conditions, primarily characterized by neuropathic pain, including migraines and headaches. Evidence suggests that migraines are influenced by hormonal factors, particularly by estrogen levels, but very few studies have investigated the prevalence and management strategies for migraines according to the hormonal status. The effects of several therapeutic regimens on migraines have been investigated, but the medications used varied widely in proven efficacies and mechanisms of action. BoNT-A is increasingly used in the management of migraine and several placebo-controlled trials of episodic and chronic migraine are currently underway. This paper is a review of the recently published data concerning the administration of BoNT-A in the prevention of chronic migraines. Considering the lack of population-based studies about the effectiveness of BoNT-A in the alleviation of premenstrual and perimenopausal migraines, this study proposes a new perspective of the therapeutic approach of migraine syndrome associated with menopausal transition and the premenstrual period.

METHODS

We selected the reviewed papers from CrossRef, PubMed, Medline, and GoogleScholar, and a total of 21 studies met our inclusion criteria.

RESULTS

To date, no specific preventive measures have been recommended for menopausal women with migraines. BoNT-A often reduces the frequency and intensity of migraine attacks per month; the treatment is well tolerated and does not exhibit a significantly higher rate of treatment-related side effects. No population-based studies were conducted in order to highlight the role of BoNT-A in menopause-related migraines, neither in menstrual migraines.

CONCLUSION

There is a need for further research in order to quantify the real burden of menstrual and perimenopausal migraines and to clarify if BoNT-A could be used in the treatment of refractory postmenopausal and premenstrual migraines.

OnabotulinumtoxinA in Migraine and Other Headaches: Review and Update

PURPOSE OF THE REVIEW

The role of onabotulinumtoxinA in headache management was serendipitously found over a decade ago and approved for chronic migraine in 2010 based on pivotal studies. The purpose of this review is to highlight the impact on headache and other health parameters which is critically reviewed, as well as the putative mechanisms of action.

RECENT FINDINGS

OnabotulinumtoxinA is effective in migraine, not only headache frequency and pain intensity but also other health parameters including quality of life. Tolerability is high and benefit/cost analysis is favorable. It should be considered off-label in refractory trigeminal neuralgia and post-herpetic neuralgia but further research in these areas. Ongoing investigation of onabotulinumtoxinA in cluster headache is too preliminary for recommendation of use but promising. Recent and future developments in other headache disorders are discussed. OnabotulinumtoxinA has been approved for migraine almost a decade ago and been proven beneficial not only on headache parameters but other health outcomes. Its role as adjuvant is being studied and emerging in other headache syndromes.

Botulinum Toxin versus Placebo: A Meta-Analysis of Prophylactic Treatment for Migraine

BACKGROUND

The purpose of this study was to assess the efficacy of botulinum toxin in reducing the frequency of migraine headaches.

METHODS

The MEDLINE, Embase, and Cochrane Library databases were searched to identify randomized, double-blind, placebo-controlled trials that compared patients receiving botulinum toxin versus placebo injections in the head and neck muscles, for the preventive treatment of migraine. The primary outcome was change in the number of headache episodes per month from baseline to 3 months.

RESULTS

There were 17 studies including a total of 3646 patients. Overall analysis reported a tendency in favor of botulinum toxin over placebo at 3 months, with a mean difference in the change of migraine frequency of -0.23 (95 percent CI, -0.47 to 0.02; p = 0.08). The reduction in frequency of chronic migraines was significant, with a mean differential change of -1.56 (95 percent CI, -3.05 to -0.07; p = 0.04). Analysis of chronic migraine frequency was also significant after 2 months. The findings also highlighted an improvement of the patient's quality of life at 3 months in the botulinum toxin group (p < 0.00001). Further adverse events were traced in the botulinum toxin type A group with a statistically significant risk ratio of 1.32 (p = 0.002).

CONCLUSIONS

This meta-analysis reveals that botulinum toxin type A injections are superior to placebo for chronic migraines after 3 months of therapy. For the first time, a real benefit in patient quality of life is demonstrated with only few and mild adverse events.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, II.

Entrapment Neuropathy: A Concept for Pathogenesis and Treatment of Headaches-A Narrative Review

Entrapment neuropathy is a known cause of neurological disorders. In the head and neck area, this pathophysiological mechanism could be a trigger for headache. Over the last few decades, injection of botulinum toxin type A in the muscles that are causing the compression as well as surgical decompression have proved to be effective treatment methods worldwide for large numbers of patients with daily headaches. In particular the entrapment of the supraorbital nerves in the glabellar musculature and the occipital nerves in the neck musculature are triggers for headache disorders for which many patients are still seeking an effective treatment. This article reviews the literature and aims to bring the concept of neural entrapment to the attention of a wider audience. By doing so, we hope to give more exposure to an effective and relatively safe headache treatment.

Anatomical Look Into OnabotulinumtoxinA Injection for Chronic Migraine Headache

BACKGROUND AND OBJECTIVES

While existing studies about onabotulinumtoxinA for chronic migraines have focused on injection location and appropriate dosing, little consideration has been given to patient body habitus and its potential impact on efficacy. We hypothesized that with increasing patient body mass index (BMI) there would be more subcutaneous fat separating targeted muscle groups from the skin surface, such that standard 0.5-inch needles used in existing protocols may not allow intramuscular injection. This may have implications for treatment planning.

METHODS

Anatomically normal computed tomography scans of the head, neck, and face were randomly selected. Subjects were stratified into 4 groups based on BMI, with 30 patients in each group. Four standardized locations were chosen to obtain measurements from the skin surface to the underlying muscle fascia, including (1) frontalis, (2) temporalis, (3) semispinalis capitis, and (4) trapezius.

RESULTS

Median depth for the temporalis was 12.65 mm (Q1 = 9.32 mm, Q3 = 15.08 mm) for the BMI greater than 35 kg/m group. Median depth for the semispinalis capitis was 13.77 mm (Q1 = 10.3 mm, Q3 = 15.7 mm) for the BMI 30 to 35 kg/m group, and 14.75 mm (Q1 = 11.00, Q3 = 17.00 mm) for the BMI greater than 35 kg/m group. Median depth for the trapezius was 13.95 mm (Q1 = 10.18 mm, Q3 = 19.00 mm) for the BMI greater than 35 kg/m group. These medians exceeded the length of the standard 0.5-inch (12.-mm) needle used in existing protocols.

CONCLUSIONS

Our study demonstrates that with increasing BMI there is a greater distance between the skin surface and the muscle fascia of muscles that are targeted for injection in standard chronic migraine botulinum toxin injection protocols. Because of this, patient body habitus may be an important factor in injection technique.

Guideline on the use of onabotulinumtoxinA in chronic migraine: a consensus statement from the European Headache Federation

OnabotulinumtoxinA is being increasingly used in the management of chronic migraine (CM). Treatment with onabotulinumtoxinA poses challenges compared with traditional therapy with orally administered preventatives. The European Headache Federation identified an expert group that was asked to develop the present guideline to provide recommendations for the use of onabotulinumtoxinA in CM. The expert group recommend onabotulinumtoxinA as an effective and well-tolerated treatment of CM. Patients should preferably have tried two to three other migraine prophylactics before start of onabotulinumtoxinA. Patients with medication overuse should be withdrawn from the overused medication before initiation of onabotulinumtoxinA if feasible, if not onabotulinumtoxinA can be initiated from the start or before withdrawal. OnabotulinumtoxinA should be administered according to the PREEMPT injection protocol, i.e. injecting 155 U–195 U to 31–39 sites every 12-weeks. We recommend that patients are defined as non-responders, if they have less than 30% reduction in headache days per month during treatment with onabotulinumtoxinA. However other factors such as headache intensity, disability and patient preferences should also be considered when evaluating response. Treatment should be stopped, if the patient does not respond to the first two to three treatment cycles. Response to continued treatment with onabotulinumtoxinA should be evaluated by comparing the 4 weeks before with the 4 weeks after each treatment cycle. It is recommended that treatment is stopped in patients with a reduction to less than 10 headache days per month for 3 months and that patients are re-evaluated 4–5 months after stopping onabotulinumtoxinA to make sure that the patient has not returned to CM. Questions regarding efficacy and tolerability of onabotulinumtoxinA could be answered on the basis of scientific evidence. The other recommendations were mainly based on expert opinion. Future research on the treatment of CM with onabotulinumtoxinA may further improve the management of this highly disabling disorder.

Botulinum toxins for the prevention of migraine in adults

BACKGROUND

Migraine occurs in around 15% of adults and is ranked as the seventh most disabling disease amongst all diseases globally. Despite the available treatments many people suffer prolonged and frequent attacks which have a major impact on their quality of life. Chronic migraine is defined as 15 or more days of headache per month, at least eight of those days being migraine. People with episodic migraine have fewer than 15 headache days per month. Botulinum toxin type A has been licensed in some countries for chronic migraine treatment, due to the results of just two trials.

OBJECTIVES

To assess the effects of botulinum toxins versus placebo or active treatment for the prevention or reduction in frequency of chronic or episodic migraine in adults.

SEARCH METHODS

We searched CENTRAL, MEDLINE & MEDLINE in Process, Embase, ClinicalTrials.gov and World Health Organization International Clinical Trials Registry (to December 2017). We examined reference lists and carried out citation searches on key publications. We sent correspondence to major manufacturers of botulinum toxin.

SELECTION CRITERIA

Randomised, double-blind, controlled trials of botulinum toxin (any sero-type) injections into the head and neck for prophylaxis of chronic or episodic migraine in adults. Eligible comparators were placebo, alternative prophylactic agent or different dose of botulinum toxin.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials and extracted data. For continuous outcomes we used mean change data when available. For dichotomous data we calculated risk ratios (RRs). We used data from the 12-week post-treatment follow-up time point. We assessed the evidence using GRADE and created two 'Summary of findings' tables.

MAIN RESULTS

Description of trialsWe found 90 articles describing 28 trials (4190 participants), which were eligible for inclusion. The longest treatment duration was three rounds of injections with three months between treatments, so we could not analyse long-term effects. For the primary analyses, we pooled data from both chronic and episodic participant populations. Where possible, we also separated data into chronic migraine, episodic migraine and 'mixed group' classification subgroups. Most trials (21 out of 28) were small (fewer than 50 participants per trial arm). The risk of bias for included trials was low or unclear across most domains, with some trials reporting a high risk of bias for incomplete outcome data and selective outcome reporting.Botulinum toxin versus placeboTwenty-three trials compared botulinum toxin with placebo. Botulinum toxin may reduce the number of migraine days per month in the chronic migraine population by 3.1 days (95% confidence interval (CI) -4.7 to -1.4, 4 trials, 1497 participants, low-quality evidence). This was reduced to -2 days (95% CI -2.8 to -1.1, 2 trials, 1384 participants; moderate-quality evidence) when we removed small trials.A single trial of people with episodic migraine (N = 418) showed no difference between groups for this outcome measure (P = 0.49).In the chronic migraine population, botulinum toxin reduces the number of headache days per month by 1.9 days (95% CI -2.7 to -1.0, 2 trials, 1384 participants, high-quality evidence). We did not find evidence of a difference in the number of migraine attacks for both chronic and episodic migraine participants (6 trials, N = 2004, P = 0.30, low-quality evidence). For the population of both chronic and episodic migraine participants a reduction in severity of migraine rated during clinical visits, on a 10 cm visual analogue scale (VAS) of 3.3 cm (95% CI -4.2 to -2.5, very low-quality evidence) in favour of botulinum toxin treatment came from four small trials (N = 209); better reporting of this outcome measure from the additional eight trials that recorded it may have improved our confidence in the pooled estimate. Global assessment and quality-of-life measures were poorly reported and it was not possible to carry out statistical analysis of these outcome measures. Analysis of adverse events showed an increase in the risk ratio with treatment with botulinum toxin over placebo 30% (RR 1.28, 95% CI 1.12 to 1.47, moderate-quality evidence). For every 100 participants 60 experienced an adverse event in the botulinum toxin group compared with 47 in the placebo group.Botulinum toxin versus other prophylactic agentThree trials studied comparisons with alternative oral prophylactic medications. Meta-analyses were not possible for number of migraine days, number of headache days or number of migraine attacks due to insufficient data, but individually trials reported no differences between groups for a variety of efficacy measures in the population of both chronic and episodic migraine participants. The global impression of disease measured using Migraine Disability Assessment (MIDAS) scores were reported from two trials that showed no difference between groups. Compared with oral treatments, botulinum toxin showed no between-group difference in the risk of adverse events (2 trials, N = 114, very low-quality evidence). The relative risk reduction (RRR) for withdrawing from botulinum toxin due to adverse events compared with the alternative prophylactic agent was 72% (P = 0.02, 2 trials, N = 119).Dosing trialsThere were insufficient data available for the comparison of different doses.Quality of the evidenceThe quality of the evidence assessed using GRADE methods was varied but mostly very low; the quality of the evidence for the placebo and active control comparisons was low and very low, respectively for the primary outcome measure. Small trial size, high risk of bias and unexplained heterogeneity were common reasons for downgrading the quality of the evidence.

AUTHORS' CONCLUSIONS

In chronic migraine, botulinum toxin type A may reduce the number of migraine days per month by 2 days compared with placebo treatment. Non-serious adverse events were probably experienced by 60/100 participants in the treated group compared with 47/100 in the placebo group. For people with episodic migraine, we remain uncertain whether or not this treatment is effective because the quality of this limited evidence is very low. Better reporting of outcome measures in published trials would provide a more complete evidence base on which to draw conclusions.

Current Prophylactic Medications for Migraine and Their Potential Mechanisms of Action

A relatively high number of different medications is currently used for migraine prevention in clinical practice. Although these compounds were initially developed for other indications and differ in their mechanisms of action, some general themes can be identified from the mechanisms at play. Efficacious preventive drugs seem to either suppress excitatory nervous signaling via sodium and/or calcium receptors, facilitate GABAergic inhibition, reduce neuronal sensitization, block cortical spreading depression and/or reduce circulating levels of CGRP. We here review such mechanisms for the different compounds.

Onabotulinum toxin A in the treatment of chronic migraine: patient selection and special considerations

Discovered by serendipity, onabotulinum toxin A (BoNT-A) is the only US Food and Drug Administration-approved treatment for the prevention of chronic migraine (CM), one of the most disabling and burdensome human conditions. Its efficacy, safety and tolerability, proved by the largest and longest migraine therapeutic trial (the Phase III Research Evaluating Migraine Prophylaxis Therapy program [PREEMPT]), have been replicated by various real-life studies also in the presence of medication overuse. The benefit of BoNT-A prophylaxis is likely due to its ability to counteract peripheral and central nociceptive sensitization through reversible chemical denervation of pericranial sensitive afferents. Its efficacy increases considerably over time during long-term treatments, significantly varying among patients. The present review focuses on the state-of-the art of current knowledge on putative instrumental, biochemical and clinical predictors of BoNT-A responsiveness, outlining the need for a thorough characterization of the full phenotypic migraine picture when trying to predict good responders. Available evidence suggests that disentangling the BoNT-A responsiveness puzzle requires 1) a reappraisal of easy-obtainable clinical details (eg, site and quality of pain, presence of cranial autonomic symptoms), 2) a proper stratification of patients with CM according to their headache frequency, 3) the evaluation of potential synergistic effects of concomitant prophylaxis/treatment and 4) a detailed assessment of modifiable risk factors evolution during treatment.

Botulinum toxin for chronic migraine: Clinical trials and technical aspects

OnabotulinumtoxinA has been approved for the prophylaxis of chronic migraine following the demonstration of efficacy in two large controlled trials. Data collected from pragmatic studies in the real-life setting have contributed important additional information useful for the management of this group of extremely disabled and challenging patients. The main findings from these studies are presented and discussed.

Botulinum toxin in the management of chronic migraine: clinical evidence and experience

Chronic migraine (CM) is a severely disabling neurological condition characterized by episodes of pulsating unilateral or bilateral headache. The United States Food and Drug Administration (FDA) approved onabotulinumtoxinA (Botox®) for the prophylactic treatment of CM in 2010. It has been shown that onabotulinumtoxinA is effective in the reduction of headache frequency and severity in patients with CM. Treatment is well tolerated by the patients. This review reports on the history of botulinum neurotoxin (BoNT) in CM and presents the current clinical evidence for the use of onabotulinumtoxinA in the treatment of CM.

Risk Factors for and Management of Medication-Overuse Headache

PURPOSE OF THE REVIEW

This review focuses on patients with migraine who frequently use acute medications.

RECENT FINDINGS

Chronic migraine and medication-overuse headache are common in the general population and often coexist. According to new diagnostic criteria, both diagnoses can be made for an individual patient. Evidence is slowly emerging on the most appropriate management approach for both disorders.

SUMMARY

Although the relationship of the primary headache disorder and the pattern of overuse varies, medication-overuse headache is a secondary disorder attributable to the overuse of acute medications. While distinguishing chronic migraine and medication-overuse headache may not always be possible, treatment approaches are similar for the two disorders.

Comparison of the effectiveness of repeated injections of onabotulinum toxin A for refractory idiopathic detrusor overactivity: analysis of an open label extension of a randomized trial (the RELAX study)

AIMS

To assess effects of repeat treatment with onabotulinumtoxin A (onaBoNT-A) in women with refractory idiopathic detrusor overactivity (DO).

METHODS

Analysis of an open-label extension study of a large randomized placebo controlled trial of onaBoNT-A. Participants had been randomized to receive 200 IU onaBoNTA or placebo and were offered up to two further onaBoNTA injections over a 5-year period. For this analysis, the primary outcome was duration of treatment effect by patient-reported symptom return. Weibull proportional hazards regression models were fitted in a Bayesian framework to estimate missing times. Multivariable hazard regression analysis (hazard ratio, 95% credible intervals (HR, 95% CrI) compared repeated injections adjusting for differences in baseline symptom severity. Secondary outcomes included inter-injection interval, incontinence, urgency, and voiding episodes 6 weeks after injection.

RESULTS

Four hundred and forty-two active injections were administered: 228 patients had one, 155 had two, and 59 had three injections. Time to symptom return for injection number 1 and 2 was 84 (95%CI: 63, 112) and 180 (95%CI: 135, 223) days, respectively. Median inter-injection intervals for receiving second and third injection were 266 days (range: 130, 1400) and 372 days (range: 134, 1283). No statistically significant differences in symptom outcomes or time to symptom return (HR 0.88, 95% CrI 0.37, 2.07 for injection 2, HR 0.33, 95% CrI 0.09, 1.03 for injection 3) were observed.

CONCLUSIONS

Repeated onaBoNT-A injections have consistent efficacy and duration of action. There appears to be long-term placebo effects in both groups of randomized patients, with implications for open-label extension studies.

The use of onabotulinum toxin A (Botox(®)) in the treatment of chronic migraine at the Parma Headache Centre: a prospective observational study

Chronic migraine is a debilitating headache, whose treatment is often complicated by the concomitant overuse of symptomatic medication and by the poor efficacy of standard prophylactic treatments. The PREEMPT studies have demonstrated the efficacy and tolerability of onabotulinum toxin A (Botox(®)) in the treatment of this headache type. Data about its use in clinical practice are still scarce. Our study evaluated all subjects with chronic migraine who were treated with onabotulinum toxin A between February 2014 and November 2015 at the Parma Headache Centre. Botox was injected according to the PREEMPT paradigm every 3 months. The data about variations in the number of headache days and in symptomatic medication intake before and after the Botox injections were collected from the patients' headache diaries. The study also evaluated tolerability to treatment, disability, and depressive symptoms. Of the 52 treated subjects, 14 received Botox treatment for at least 9 months and showed a significant decrease in the median number of headache days (from 19 to 14.5, p = 0.011) and in the median number of days of symptomatic medications intake and symptomatic drugs. Overall, the treatment was well tolerated. The average MIDAS and BDI-II scores after 9 months were reduced, though not significantly. The treatment with Botox proved effective and well tolerated in our clinical practice. Further studies on larger patient samples will help shed light on the persistence of the drug's effect at long term and identify the predictive factors of response to treatment.

Diagnosis and Management of Childhood Headache

Headache is one of the most common chief complaints seen in the pediatrician's office. Oftentimes, identifying the etiology of headache and differentiating primary and secondary causes can present a diagnostic conundrum. Understanding the most common causes of primary and secondary headache is vital to making a correct diagnosis. Here we review the typical presentations of the most common primary headache disorders and the approach to evaluation of the pediatric patient presenting with headache. Diagnostic workup, including the key features to elicit on physical examination, when to order head imaging, and the use of other ancillary tests, is discussed. Current treatment modalities and their indications are reviewed. We will also describe some of the new, emerging therapies that may alter the way we manage headache in the pediatric population. Headache can, at times, be a frustrating symptom seen in the pediatrician's office, but here we hope to better elucidate the approach to evaluation, management, and treatment as well as provide some hope in regards to more effective upcoming therapies.

Effect of OnabotulinumtoxinA Injection on Depression in Chronic Migraine

OBJECTIVE

The current study retrospectively evaluated patient reported outcomes (PROs) collected before and after at least 2 sessions of onabotulinumtoxinA (onabot) injections for chronic migraine. Depression was assessed by the Patient Health Questionnaire-9.

METHOD

Chronic migraineurs receiving onabot were identified. In addition to the Patient Health Questionnaire-9 (PHQ9), the European Quality of Life (QOL), 5-Dimension (EQ-5D) (QOL), Headache Impact Test (HIT6), and Pain Disability Index (PDI) were reviewed across ≥2 consecutive onabot injections for 6-12 months. Paired t-tests on patient's questionnaire scores before and after treatment were performed. Analysis of the PHQ9 was restricted to patients with pretreatment scores ≥ 10 (moderate to severe depression). Change in PHQ9 was the primary outcome, and other PROs were also evaluated.

RESULTS

Four hundred twenty-nine patients met the inclusion criteria, and data were gathered from 2010 to 2014. Average age was 45 years, with 85.5% female, and 92.1% Caucasian. There were 127 patients with PHQ9 scores ≥10 at baseline. Their PHQ9 scores improved from 14.4 (high-moderate) pre-onabot to 11.3 (low-moderate) post-onabot (P <.0001, 95% CI = -4.2 to -2.1); PDI improved from 4.3 to 3.8 (P = .0078, 95% CI = -0.7 to -0.1); EQ-5D improved from 0.74 to 0.77 (P = .0078; 95%CI = 0.01 to 0.04); HIT6 improved from 63.3 to 60.5 (P <.0001, 95%CI = -3.4 to -2.2). For comparison, in the PREEMPT onabot regulatory trials, HIT6 changed from 66 to 61.2 after 5 onabot injections at 24 weeks, P < .001.

CONCLUSION

Onabot injections in chronic migraine patients statistically improved depression scores in patients beginning with at least moderate depression and improved scores in headache and quality of life. Onabot injections also decreased impact of headache on daily life.

OnabotulinumtoxinA for trigeminal neuralgia: a review of the available data

Trigeminal neuralgia (TN) patients may develop side effects from centrally acting drugs, have contraindications for neurosurgical procedures, or experience relapse during conventional therapies. OnabotulinumtoxinA (BoNT/A) has been reported to be effective for TN, although this finding has been challenged. An overview of the available evidence based on a narrative/qualitative analysis of the literature is presented. About 90% of patients who receive BoNT/A show an improvement, a higher figure than that reported for the placebo effect of BoNT/A for other headaches. Tolerability of BoNT/A is good, and its few side-effects are transient. The articles reviewed were mainly case reports, case series and open-label trials; however, randomized controlled trials have endorsed the efficacy of BoNT/A for TN. This evidence, together with a better understanding of the analgesic mechanisms of BoNT/A and its proven efficacy in treating other pain syndromes, supports the use of this toxin as a therapeutic option for TN.

Update on Medication-Overuse Headache and Its Treatment

OPINION STATEMENT

Medication-overuse headache-i.e., a too-frequent consumption of acute headache medications leading to increased headache frequency and reduced effectiveness of acute and preventive treatments-is a serious medical condition whose pathophysiology still remains incompletely known, which is reflected into a lack of mechanism-based treatments. The first mandatory step in the therapeutic strategy remains withdrawal of the abused drug, preferably abrupt, in concomitance with a detoxification pharmacological regimen to lessen withdrawal symptoms. Intravenous hydration, antiemetics, corticosteroids (prednisone), tranquilizers (benzodiazepine), neuroleptics, and rescue medication (another analgesic than the overused) should be delivered in various combinations, on an inpatient (hospitalization and day hospital) basis or outpatient basis, depending on the characteristics of the specific patient and type of overuse. Inpatient withdrawal should be preferred in barbiturate and opioid overuse, in concomitant depression, or, in general, in patients who have difficulty in stopping the overused medication as outpatients. In contrast, in overuse limited to simple analgesics in highly motivated patients, without high levels of depression and/or anxiety, home detoxification should be chosen. Re-prophylaxis should immediately follow detoxification, ideally with local injections of onabotulinumtoxinA every 3 months or topiramate orally for at least 3 months. Adequate information to patients about the risks of a too-frequent consumption of symptomatic headache medications is essential and should constantly parallel treatment to help preventing relapse after detoxification and re-prophylaxis.

OnabotulinumtoxinA for chronic migraine: a critical appraisal

Chronic migraine (CM) is a severe disabling condition with a few available evidence-based management options. OnabotulinumtoxinA (onaBoNTA) is approved for use in a number of disorders. Its benefits and potential use in migraine were observed incidentally while treating patients cosmetically for wrinkles. The mechanism of action of onaBoNTA in CM is not fully understood, but there is evidence that this involves axonal transport via sensory fibers. The Phase III REsearch Evaluating Migraine Prophylaxis Therapy trials have established the efficacy as well as the long-term safety and tolerability of onaBoNTA in CM. This review will discuss the evidence behind its use in this setting.

Therapeutic use of botulinum toxin in migraine: mechanisms of action

Migraine pain represents sensations arising from the activation of trigeminal afferents, which innervate the meningeal vasculature and project to the trigeminal nucleus caudalis (TNC). Pain secondary to meningeal input is referred to extracranial regions innervated by somatic afferents that project to homologous regions in the TNC. Such viscerosomatic convergence accounts for referral of migraine pain arising from meningeal afferents to particular extracranial dermatomes. Botulinum toxins (BoNTs) delivered into extracranial dermatomes are effective in and approved for treating chronic migraine pain. Aside from their well-described effect upon motor endplates, BoNTs are also taken up in local afferent nerve terminals where they cleave soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins, and prevent local terminal release. However, a local extracranial effect of BoNT cannot account for allthe effects of BoNT upon migraine. We now know that peripherally delivered BoNTs are taken up in sensory afferents and transported to cleave SNARE proteins in the ganglion and TNC, prevent evoked afferent release and downstream activation. Such effects upon somatic input (as from the face) likewise would not alone account for block of input from converging meningeal afferents. This current work suggests that BoNTs may undergo transcytosis to cleave SNAREs in second-order neurons or in adjacent afferent terminals. Finally, while SNAREs mediate exocytotic release, they are also involved in transport of channels and receptors involved in facilitated pain states. The role of such post-synaptic effects of BoNT action in migraine remains to be determined.

Botulinum toxin A: a new option for treatment of chronic migraine with medication overuse

The application of Botulinum toxin for several pathological conditions has been largely debated in the last decades and its use has been definitively consolidated for disorders related to increased muscle tone and hyperidrosis. Botulinum neurotoxin (BoNT-A) is a potent toxin produced by an anaerobic bacterium, Clostridium botulinum, which presents several pharmacological proprieties, but also different and serious contraindications. As chronic migraine (CM) is commonly reported as a serious and debilitating condition and a big challenge from the therapeutic point of view, in the last decades, after isolated observations, BoNT-A has been applied as preventive treatment for CM patients and, after randomized and rigorous studies, it has been accepted among the most effective pharmacological treatments for these problematic patients. In the present report, a group of patients suffering from CM with medication overuse was treated with BoNT-A to verify its efficacy for CM. The results confirmed the efficacy of BoNT-A when used at the dosage of 155 UI, according with the PREEMPT study protocol. Although these results are preliminary, in a limited group of patients, they led to intense efforts to enforce the use of BoNT-A for CM and to assess its clinical applicability.