Treatment of Chronic Tension-Type Headache with Botulinum Toxin: A Double-Blind, Placebo-Controlled Clinical Trial

The effectiveness of botulinum toxin for chronic tension-type headache prophylaxis: A systematic review and meta-analysis

BACKGROUND

A systematic and meta-analysis was conducted to examine the evidence of the effects of botulinum toxin A on chronic tension-type headache.

METHODS

Cochrane, Embase, Ovid, ProQuest, PubMed, Scopus, Web-of-Science databases, and ClinicallTrials.gov registry were systematically searched for studies examining the effects of botulinum toxin A on tension-type headaches. The records were screened by two independent reviewers using pre-determined eligibility criteria. DerSimonian Liard random-effects meta-analyses were performed using the 'meta' package (5.2-0) in R (4.2.0). Risk of bias and quality of evidence were assessed using the Cochrane Collaboration's Tool RoB 2 and Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Clinical significance was determined using pre-defined minimal clinically important differences.

RESULTS

Eleven controlled trials were included (390 botulinum toxin A, 297 controls). Botulinum toxin A was associated with significant improvements in standardized headache intensity (-0.502 standard deviations [-0.945, -0.058]), headache frequency (-2.830 days/month [-4.082, -1.578]), daily headache duration (-0.965 [-1.860, -0.069]) and the frequency of acute pain medication use (-2.200 days/month [-3.485, -0.915]) vs controls. Botulinum toxin A-associated improvements exceeded minimal clinically important differences for headache intensity, frequency, and acute pain medication use. A 79% (28%, 150%) greater response rate was observed for botulinum toxin A vs controls in improving chronic tension-type headache. Treatment of eight chronic tension-type headache patients was sufficient to elicit a therapeutic response in one patient.

CONCLUSIONS

Corroborating the current mechanistic evidence, our meta-analysis supports the utility of botulinum toxin A for managing chronic tension-type headaches. However, due to limitations in the quality of evidence, adequately-powered high-quality controlled trials examining the effects of Botulinum toxin A on chronic tension-type headache are warranted.

REGISTRATION

Protocol preregistered in PROSPERO International Prospective Register of Systematic Reviews (CRD42020178616).

Ultrasound-guided five-point injection of botulinum toxin for patients with trapezius hypertrophy

OBJECTIVES

Our study aimed to explore the clinical therapeutic effects of ultrasound-guided five-point injection of botulinum toxin type A for patients with trapezius hypertrophy.

METHODS

Twenty female patients diagnosed with trapezius hypertrophy were enrolled in this study. The thicknesses of the trapezius muscle were measured by using the ultrasound scanner to locate the thickest point of trapezius, followed by labelling the other four points around the first point. Botulinum toxin type A was injected bilaterally (50 IU/side, 5 points/side) in the trapezius muscle of these patients. The surgery effects were evaluated by thicknesses of the trapezius muscle, intramuscular needle electromyographic and electroneurographic examinations, appearance changes and patients' satisfactions.

RESULTS

Statistically significant differences in thicknesses of the trapezius muscle were observed at 4 weeks (p < 0.001), 12 weeks (p < 0.001), 20 weeks (p < 0.001), 28 weeks (p = 0.011), 36 weeks (p = 0.022), and 44 weeks (p = 0.032) after surgery. The latencies of trapezius muscle became longer at 12 weeks after surgery (left: 2.40 ms, right: 2.53 ms vs. left: 1.75 ms, right: 2.00 ms). Electroneurographic results showed amplitude reduction of compound muscle action potentials (CMAPs) at 12 weeks after surgery (left: 1.91 uV, right: 3.10 uV vs. left: 15.00 uV, right: 15.40 uV). Obvious appearance changes were revealed at 12 weeks after surgery. All of 80% patients were very satisfied, 15% patients were relatively satisfied, and 5% patients were not satisfied with the surgery.

CONCLUSION

Ultrasound-guided five-point injection of botulinum toxin type A might be effective for patients with trapezius hypertrophy.

Beyond chronic migraine: a systematic review and expert opinion on the off-label use of botulinum neurotoxin type-A in other primary headache disorders

Introduction: Botulinum neurotoxin type-A (BoNTA) is licensed for the treatment of chronic migraine (CM), but it has been tested off-label as a therapeutic choice in other primary headaches (PHs). We aimed to provide a systematic review and expert opinion on BoNTA use in PHs, beyond CM.Areas covered: After providing an overview on PHs and mechanism of BoNTA action, we report the results of a systematic review, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations, of BoNTA therapeutic trials in PHs beyond CM. Studies and results were reviewed and discussed, and levels of evidence were graded. We also collected data on relevant ongoing trials.Expert opinion: Although there are contradictory findings on PHs other than CM, BoNTA may represent a therapeutic option for patients who do not respond to conventional prophylactic treatments. Based on limited available evidence, BoNTA may be considered in refractory tension-type headache, trigeminal autonomic cephalalgias, primary stabbing headache, nummular headache, hypnic headache, and new daily persistent headache, after the primary nature of cephalalgia has been documented and other drugs have failed. Experienced physicians in BoNTA treatment are required to guide the therapeutic protocol for each patient to optimize good and safe outcomes.

Endogenous melatonin levels and therapeutic use of exogenous melatonin in tension type headache: A systematic review

BACKGROUND-PURPOSE

A bidirectional relationship appears to connect tension-type headache (TTH) and circadian dysregulation. The present systematic review examined the published evidence for melatonin (MT) supplementation in the prophylaxis of TTH. Initially, we reviewed case-control studies investigating nocturnal MT or 6-sulphatoxymelatonin (aMT6s, a urine-discarded metabolite) in TTH individuals and healthy controls (HC). Secondly, we reviewed studies appraising the use of MT in the prevention of TTH.

METHODS

The search strategy involved MEDLINE EMBASE, CENTRAL, PsycINFO, trial registries, Google Scholar and OpenGrey. Case-control studies were appraised according to the Newcastle-Ottawa-Scale, whereas randomised controlled trials were assessed based on the risk-of-bias Cochrane tool. Infrequent, as well as frequent, episodic, and chronic TTH patients were evaluated separately in children and adults.

RESULTS

Our search strategy yielded two case-control studies. One (high-quality) did not reveal any difference in morning salivary MT concentration between children with frequent episodic TTH and HC. The second (moderate-quality) was indicative of a disturbed nocturnal secretion pattern in adults with chronic TTH. For the second part, five uncontrolled studies were retrieved. In total, 94 adults with chronic TTH were assessed and results were suggestive of a beneficial effect of MT on headache frequency, intensity, induced disability, and induced analgesic consumption. However, the uncontrolled-unblinded designs may have induced an important placebo effect. Non-adult populations and frequent TTH were substantially understudied.

CONCLUSIONS

There are not enough studies to designate the role of MT in the prevention of TTH. Given the disease's background, additional relevant research is warranted for chronic TTH.

The efficacy of botulinum toxin A treatment for tension-type or cervicogenic headache: a systematic review and meta-analysis of randomized, placebo-controlled trials

OBJECTIVES

The pathogeneses of chronic tension-type headache (CTTH) and cervicogenic headache (CEH) are not well established. Peripheral activation or sensitization of myofascial nociceptors is suggested as a potential mechanism and injections of botulinum toxin (BONTA) have thus been used in the treatment for both headache conditions. BONTA inhibits the release of acetylcholine at the neuromuscular junction and inhibits contraction of skeletal muscles. If the pain is precipitated by increased tone in cervical muscles, local injections of BONTA could represent a prophylactic measure. However, the treatment is still controversial, and a thorough assessment of the current evidence is required. This review aims to assess the evidence of BONTA injection as a prophylactic treatment for CTTH and CEH by reviewing and examining the quality of placebo-controlled, randomized trials.

METHODS

Data sources: we searched in the following databases: PubMed (including Medline), Embase, Cochrane Central register of Controlled Trials, Cinahl, Amed, SCOPUS and Google Scholar including other repository sources. Both MeSH and free keywords were used in conducting the systematic search in the databases. The search covered publications from the root of the databases to November 2020.

STUDY ELIGIBILITY CRITERIA

The review included RCTs, comparing single treatment of BONTA with placebo on patients with CTTH or CEH above 18 years of age, by measuring pain severity/relief or headache frequency.

DATA EXTRACTION

The following data were extracted: year of publication, country, setting, trial design, number of participants, injection procedure, BONTA dosages, and clinical outcome measures.

STUDY APPRAISAL

To assess validity and quality, and risk of bias, the Oxford Pain Validity Scale, Modified Jadad Scale, last version of Cochrane Collaboration's tool for assessing risk of bias (RoB 2), and the CONSORT 2010 Checklist were used. The trials were assessed, and quality scored independently by two of the reviewers. A quantitative synthesis and meta-analyses of headache frequency and intensity were performed.

RESULTS

We extracted 16 trials, 12 on prophylactic BONTA treatment for CTTH and four on CEH. Of these 12 trials (8 on CTTH and 4 on CEH) were included in the quantitative synthesis. A majority of the trials found no significant difference on the primary outcome measure when BONTA treatment was compared with placebo. Three "positive" trials, reporting significant difference in favor of BONTA treatment, but two of these were hampered by low validity and quality scores and high risk of bias.

CONCLUSIONS

There is no clear clinical evidence supporting prophylactic treatment with BONTA for CTTH or CEH.

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.

The Expanding Therapeutic Utility of Botulinum Neurotoxins

Botulinum neurotoxin (BoNT) is a major therapeutic agent that is licensed in neurological indications, such as dystonia and spasticity. The BoNT family, which is produced in nature by clostridial bacteria, comprises several pharmacologically distinct proteins with distinct properties. In this review, we present an overview of the current therapeutic landscape and explore the diversity of BoNT proteins as future therapeutics. In recent years, novel indications have emerged in the fields of pain, migraine, overactive bladder, osteoarthritis, and wound healing. The study of biological effects distal to the injection site could provide future opportunities for disease-tailored BoNT therapies. However, there are some challenges in the pharmaceutical development of BoNTs, such as liquid and slow-release BoNT formulations; and, transdermal, transurothelial, and transepithelial delivery. Innovative approaches in the areas of formulation and delivery, together with highly sensitive analytical tools, will be key for the success of next generation BoNT clinical products.

Botulinum toxin: A review of the mode of action in migraine

Botulinum toxin serotype A (BoNT/A) was originally used in neurology for the treatment of dystonia and blepharospasms, but is now clinically used worldwide for the treatment of chronic migraine. Still, the possible mode of action of BoNT/A in migraine is not fully known. However, the mode of action of BoNT/A has been investigated in experimental pain as well as migraine models, which may elucidate the underlying mechanisms in migraine. The aim of this study was to review studies on the possible mode of action of BoNT/A in relation to chronic migraine treatment. Observations suggest that the mode of action of BoNT/A may not be limited to the injection site, but also includes anatomically connected sites due to axonal transport. The mechanisms behind the effect of BoNT/A in chronic migraine may also include modulation of neurotransmitter release, changes in surface expression of receptors and cytokines as well as enhancement of opioidergic transmission. Clinical and experimental studies with botulinum toxin in the last decade have advanced our understanding of headache and other pain states. More research into botulinum toxin as treatment for headache is warranted as it can be an attractive alternative for patients who do not respond positively to other drugs.

Rhinogenic and nonrhinogenic headaches

PURPOSE OF REVIEW

To review the present knowledge and the recent publications on the cause, characteristics, course and treatment of chronic and recurring facial pain and headaches. Facial pain is amongst the commonest complaints in ear, nose and throat clinics. Recent articles have presented important evidence-based approach to this common problem.

RECENT FINDINGS

Recent publications in the fields of otolaryngology and neurology have better defined the differences between rhinogenic and nonrhinogenic facial pain, and place this symptom in the context of rhinosinusitis. Although chronic facial pain has conventionally been considered to be due to sinusitis because of anatomical proximity, there is increasing evidence to support the contrary. Published literature has identified that only 16-20% of patients with sinusitis (purulent or with polyposis) confirmed by nasal endoscopy actually declared symptoms of facial pain. More pertinently, surgical series have shown that up to 40% of patients had persistent postoperative facial pain despite resolution of sinusitis on nasal endoscopy and computed tomography (CT). Rhinogenic pain is generally unilateral, severe, located on the same side and related to rhinogenic symptoms, and almost always accompanied by endoscopic and CT abnormalities. Incidental CT mucosal disease can be noted in 30% of asymptomatic patients.

SUMMARY

Traditionally, facial pain has often been considered to be caused by chronic rhinosinusitis. Increasing evidence has shown that the commonest cause for chronic facial pain is of nonrhinogenic origin. As otorhinolaryngologists, we deal with facial pain on a daily basis and therefore need to be aware of the different causes for this common symptom.

Botulinum Toxin Type a as a Therapeutic Agent against Headache and Related Disorders

Botulinum neurotoxin A (BoNT/A) is a toxin produced by the naturally-occurring Clostridium botulinum that causes botulism. The potential of BoNT/A as a useful medical intervention was discovered by scientists developing a vaccine to protect against botulism. They found that, when injected into a muscle, BoNT/A causes a flaccid paralysis. Following this discovery, BoNT/A has been used for many years in the treatment of conditions of pathological muscle hyperactivity, like dystonias and spasticities. In parallel, the toxin has become a “glamour” drug due to its power to ward off facial wrinkles, particularly frontal, due to the activity of the mimic muscles. After the discovery that the drug also appeared to have a preventive effect on headache, scientists spent many efforts to study the potentially-therapeutic action of BoNT/A against pain. BoNT/A is effective at reducing pain in a number of disease states, including cervical dystonia, neuropathic pain, lower back pain, spasticity, myofascial pain and bladder pain. In 2010, regulatory approval for the treatment of chronic migraine with BoNT/A was given, notwithstanding the fact that the mechanism of action is still not completely elucidated. In the present review, we summarize experimental evidence that may help to clarify the mechanisms of action of BoNT/A in relation to the alleviation of headache pain, with particular emphasis on preclinical studies, both in animals and humans. Moreover, we summarize the latest clinical trials that show evidence on headache conditions that may obtain benefits from therapy with BoNT/A.

Efficacy of regular sauna bathing for chronic tension-type headache: a randomized controlled study

OBJECTIVE

Chronic tension-type headache (CTTH) is a chronic syndrome characterized by frequent headache occurring more than 15 days per month. The intensity and duration of headache pain can be very distressing and disabling on an individuals' well-being. The purpose of this study was to examine the applicability of sauna bathing as a new method of treatment for reducing pain in patients with CTTH.

METHODS

Thirty-seven people who fulfilled the International Headache Society criteria for CTTH were randomly assigned into two groups. The control group (n=20) received advice and education while the intervention group (n=17) received the same advice and attended a sauna regularly for 8 weeks. Reductions in subjective pain were determined using the numerical pain rating scale (NPRS). Disturbance in sleep, depression as assessed by Beckman Disability Index (BDI), and Headache Disability Index (HDI) were measured.

RESULTS

Mean change in headache intensity significantly differed between the sauna and control group by 1.27 (95% confidence interval, 0.48-2.07; F=10.17; df=1, 117; p=0.002). There was no statistically significant change in duration of headache or improvement in sleep, depression, or HDI between the sauna and control groups.

CONCLUSION

Regular sauna bathing is a simple, self-directed treatment that is effective for reducing headache pain intensity in CTTH.

Botulinum toxin type a for cephalic cutaneous allodynia in chronic migraine: a randomized, double-blinded, placebo-controlled trial

Cephalic allodynia (CA) can be observed in 50-70% of patients with chronic migraine (CM). The aim of this trial was to assess the efficacy of botulinum toxin type A (Botx-A) in the treatment of CA associated with CM. In this placebo-controlled trial, patients were randomized either into Botx-A or 0.9% saline injections and efficacy measures were assessed every 4 weeks for 3 months. Efficacy endpoints were number of migraine episodes associated with CA, changes from baseline in visual analogical scale scores for pain (VAS) and frequency of common analgesics use for migraine. A total of 38 subjects were randomized to saline (n=18) or Botx-A (n=20). There were no significant differences in baseline between active intervention or placebo groups regarding mean age, number of headache episodes [mean 12.1 (9.22) and 17.00 (9.69) respectively; P=0.12], pain severity as measured by the VAS or frequency of analgesic use for headache episodes. Efficacy analysis showed that Botx-A injections led to an important decrease from baseline in the mean migraine episodes associated with CA after 12 weeks (5.20 versus 11.17; P=0.01). Also, VAS scores and frequency of analgesics use for headache were significantly reduced in the Botx-A group. This study suggests that Botx-A injections are superior to saline in the treatment of CA associated with CM, with mild self limited side effects.

OnabotulinumtoxinA for the treatment of headache

Botulinum toxin, a potent muscle relaxant, has been found to have analgesic effects in patients with various pain syndromes. Both in vitro and in vivo studies showed the ability of the toxin to block the release of pain neurotransmitters, such as substance P, glutamate, and calcitonin gene-related peptide. The effect of the toxin, and specifically of one of its serotypes, botulinum neurotoxin type A, on headaches, has been extensively studied. This serotype is available in the United States in 3 forms, including as onabotulinumtoxinA. Data from clinical trials confirmed the efficacy, safety, and tolerability of onabotulinumtoxinA in the prophylactic treatment of chronic migraine, the most severe and debilitating type of migraine, in adults. The drug was approved by the Food and Drug Administration for this indication in 2010. The drug was not found to be effective for episodic migraine or tension-type headache. Noncontrolled studies suggest the efficacy of the toxin for headache associated with craniocervical dystonia. Proper injection technique and appropriate patient selection are essential for achieving positive results after treatment with onabotulinumtoxinA. The recommended injection paradigm combines a fixed site/fixed dose and follow the pain approaches, with the toxin injected to multiple sites of the head and neck, at a total dose of 155U-195U. The treatment is given at intervals of 12 weeks on average. The efficacy of onabotulinumtoxinA for some headaches, its long duration of action, and its favorable adverse effect profile make it a viable treatment option for the appropriate headache patients. The drug may be particularly suitable for patients who cannot tolerate, or are not compliant with, the daily intake of oral headache preventive drugs.

Headache direction and aura predict migraine responsiveness to rimabotulinumtoxin B

OBJECTIVE

To report a retrospective analysis of patients with migraine headaches treated with rimabotulinumtoxin B as preventive treatment, investigating an association between clinical responsiveness with migraine directionality and migrainous aura.

BACKGROUND

The Phase III Research Evaluating Migraine Prophylaxis Therapy studies demonstrated onabotulinumtoxin A is effective in the preventive management of chronic migraine headaches. Jakubowski et al reported greater response to onabotulinumtoxin A in migraine patients reporting inward-directed head pain (imploding or ocular) compared with outward-directed head pain (exploding), suggesting subpopulations of patients may be better candidates for its use. No correlation was found between those reporting migrainous aura and onabotulinumtoxin A responsiveness.

METHODS

One hundred twenty-eight migraine patients were identified who had received rimabotulinumtoxin B injections over an average of 22 months, or 7 injection cycles. Migraine directionality was reported as inward directed (imploding, n = 72), eye centered (ocular, n = 28), outward directed (exploding, n = 16), and mixed (n = 12).

RESULTS

One hundred two out of one hundred twenty-eight patients (80%) improved; of these, 58 (57%) demonstrated a >75% reduction in monthly headache frequency (">75%-responders"), 76% of which noted sustained benefits >12 months with repeated injections every 10-12 weeks. Those reporting ocular- and imploding-directed headaches were significantly more likely to be >75%-responders, compared with exploding- and mixed-directed headaches (P < .0025). Patients with ocular-directed headaches were most likely to be sustained >75%-responders. Patients reporting migrainous aura were more likely to be >75%-responders (P = .0007). Those reporting exploding- and mixed-directed headaches were more likely to be nonresponders (P < .0001).

CONCLUSIONS

Reported migraine directionality and presence of migrainous aura predict migraine headache responsiveness to rimabotulinumtoxin B injections.

Treatment of refractory pain with botulinum toxins--an evidence-based review

OBJECTIVES

To provide updated information on the role of botulinum toxins in the treatment of refractory pain based on prospective, randomized, double-blind, placebo-controlled studies. DESIGN OF THE REVIEW: Class I and class II articles were searched online through PubMed (1966 to the end of January 2011) and OvidSP including ahead-of-print manuscripts.

RESULTS

Level A evidence (two or more class I studies-established efficacy): pain of cervical dystonia, chronic migraine, and chronic lateral epicondylitis. Level B evidence (one class I or two class II studies-probably effective and recommended): post-herpetic neuralgia, post-traumatic neuralgia, pain of plantar fasciitis, piriformis syndrome, and pain in total knee arthroplasty. Level C evidence (one class II study-possibly effective, may be used at discretion of clinician): allodynia of diabetic neuropathy, chronic low back pain, painful knee osteoarthritis, anterior knee pain with vastus lateralis imbalance, pelvic pain, post-operative pain in children with cerebral palsy after adductor hip release surgery, post-operative pain after mastectomy, and sphincter spasms and pain after hemorrhoidectomy. Level U evidence (efficacy not proven due to diverse class I and II results): myofascial pain syndrome and chronic daily headaches. Studies in episodic migraine and tension headaches have shown treatment failure (level A-negative).

CONCLUSION

Evidence-based data indicate that administration of botulinum toxin in several human conditions can alleviate refractory pain. The problems with some study designs and toxin dosage are critically reviewed.

Botulinum toxin type-A in the prophylactic treatment of medication-overuse headache: a multicenter, double-blind, randomized, placebo-controlled, parallel group study

Medication-overuse headache (MOH) represents a severely disabling condition, with a low response to prophylactic treatments. Recently, consistent evidences have emerged in favor of botulinum toxin type-A (onabotulinum toxin A) as prophylactic treatment in chronic migraine. In a 12-week double-blind, parallel group, placebo-controlled study, we tested the efficacy and safety of onabotulinum toxin A as prophylactic treatment for MOH. A total of 68 patients were randomized (1:1) to onabotulinum toxin A (n = 33) or placebo (n = 35) treatment and received 16 intramuscular injections. The primary efficacy end point was mean change from baseline in the frequency of headache days for the 28-day period ending with week 12. No significant differences between onabotulinum toxin A and placebo treatment were detected in the primary (headache days) end point (12.0 vs. 15.9; p = 0.81). A significant reduction was recorded in the secondary end point, mean acute pain drug consumption at 12 weeks in onabotulinum toxin A-treated patients when compared with those with placebo (12.1 vs. 18.0; p = 0.03). When we considered the subgroup of patients with pericranial muscle tenderness, we recorded a significant improvement in those treated with onabotulinum toxin A compared to placebo treated in both primary (headache days) and secondary end points (acute pain drug consumption, days with drug consumption), as well as in pain intensity and disability measures (HIT-6 and MIDAS) at 12 weeks. Onabotulinum toxin A was safe and well tolerated, with few treatment-related adverse events. Few subjects discontinued due to adverse events. Our data identified the presence of pericranial muscle tenderness as predictor of response to onabotulinum toxin A in patients with complicated form of migraine such as MOH, the presence of pericranial muscle tenderness and support it as prophylactic treatment in these patients.

The role of botulinum toxin in management of pain: an evidence-based review

PURPOSE OF REVIEW

In the present review we discuss the role of botulinum neurotoxins (BoNTs) in the management of different pain conditions, with evidence-based data on the toxins' efficacy on pain and its mechanisms.

RECENT FINDINGS

Experimental in-vitro studies have reported promising results of a novel recombinant chimera of BoNT A and E that inhibits the calcitonin gene-related peptide exocytosis from brainstem sensory neurons. Animal studies in neuropathic pain rat models have reported an analgesic effect of BoNT A given after the neuropathic procedure and a bilateral antinociceptive effect to the unilateral noxious stimuli. There is a growing body of evidence that BoNTs are effective in myofascial pain syndrome, neuropathic pain, and joint pain. The pre-existing evidence that BoNTs are ineffective in migraine or other headache disorders has not yet been challenged. In other pain syndromes, studies published in the last review year have not contributed significantly in either demonstrating or invalidating the research that has so far proved inconclusive.

SUMMARY

The role of BoNTs in management of pain is not yet well established. Larger studies in neuropathic pain, joint pain, and myofascial pain syndrome are needed to fully ascertain the role for BoNT therapy in those areas.

Re-engineering clostridial neurotoxins for the treatment of chronic pain: current status and future prospects

Clostridial neurotoxins from the botulinum neurotoxin (BoNT) family are protein complexes, derived from the bacterium Clostridium botulinum, which potently inhibit acetylcholine release and result in a reversible blockade of the neuromuscular junction. This feature led to the clinical development of BoNT-A for a number of neuromuscular disorders. BoNT-A toxins are commercially available as three different preparations: Dysport/Azzalure, Botox/Vistabel, and Xeomin/Bocouture. Although BoNT-A preparations have not yet been approved for the treatment of pain, a substantial body of preclinical and clinical evidence shows that BoNT-A is effective in treating a number of different types of pain. It is thought to exert an analgesic effect both via muscle-relaxant properties and also directly, via inhibition of nociceptive neuropeptides. This review explores the mechanistic basis of this analgesic effect, summarizing current knowledge of the structure-function relationship of BoNT and discussing effects on both motor and pain neurons. For a complete picture of the analgesic properties of BoNT-A, clinical evidence of efficacy in myofascial pain and neuropathic pain is considered in tandem with a mechanistic rationale for activity. Patients experiencing chronic pain are clear candidates for treatment with a modified clostridial endopeptidase that would provide enduring inhibition of neurotransmitter release. A strong preclinical evidence base underpins the concept that re-engineering of BoNT could be used to enhance the analgesic potential of this neurotoxin, and it is hoped that the first clinical studies examining re-engineered BoNT-A will confirm this potential.

Botulinum neurotoxin in the treatment of headache disorders

Botulinum neurotoxin (BoNT) has been in clinical use for the treatment of headaches for over 15 years. Recent double-blind placebo-controlled trials have confirmed the efficacy of BoNT type A (onabtoulinumtoxinA, Botox) in the treatment of chronic migraine. The efficacy of BoNT in the treatment of episodic migraine headaches, cluster headaches, and chronic tension-type headache (TTH) has not been examined in large controlled trials. Presumed mechanisms of action of BoNT in headache disorders are the reduction of afferent input induced by muscle relaxation and inhibition of the release of neurotransmitters, such as glutamate and calcitonin gene-related peptide, from peripheral sensory nerve terminals. Over 20 years of extensive clinical experience has established a remarkable safety for BoNT, particularly type A and specifically Botox or onabotulinumtoxinA, which has been used much longer and more widely than any other form or serotype of BoNT. Because BoNT is a biological product, the safety and efficacy of one BoNT formulation cannot be extrapolated to a different one, even of the same serotype.

Pharmacotherapy and Lifestyle Interventions for Tension-Type Headaches

The objective of this review was to evaluate the efficacy of pharmacotherapy and lifestyle interventions for tension-type headaches. Literature was obtained through a MEDLINE (1966 to April 2008) search and a bibliographic review of published articles. Key terms searched included tension-type headaches, chronic tension-type headaches, pharmacotherapy, and lifestyle therapy. The search was further limited to the English language. Tension-type headaches are the most common and least studied primary headache disorder. These headaches are characterized by mild to moderate bilateral pain that is described as dull, aching, and bandlike. Episodic tension-type headaches may be treated with mild analgesics such as nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen; although treatment should be individualized, data suggest that NSAIDs may be considered first line. Chronic and frequent episodic tension-type headaches often require prophylactic therapy. Although tricyclic antidepressants are considered the drugs of choice for chronic tension-type headaches, preliminary trials with venlafaxine, mirtazapine, tizanidine, and topiramate have shown promise. Lifestyle interventions such as physical therapy, behavioral therapy, and acupuncture are often employed, despite the lack of sound clinical evidence to support their use. Preliminary data support the combination of a tricyclic antidepressant and behavioral therapy for chronic tension-type headache.

Is botulinum toxin useful in treating headache? No

The discrepancy between the widespread use of botulinum neurotoxin (BoNT) in managing headache and the supporting clinical evidence is unprecedented. No substance seems to have inspired more physicians and patients to undertake spirited treatment attempts. Tremendous treatment success in small, uncontrolled clinical trials has been repeatedly reported, but no substance that has been studied to an equal extent has so utterly failed to provide proof of effect in controlled clinical trials. Nevertheless, even though most randomized, controlled clinical trials have not met their defined primary outcome criterion, BoNT is still considered a promising treatment alternative for primary headache disorders. Experimental approaches to the pathophysiologic impact of BoNT on the perception of pain have been equally unsuccessful. Although most studies have been unable to find a direct antinociceptive effect in humans, some researchers continue to seek specific injection sites or injection techniques that may promise more successful results. Others look for a positive effect by narrowing the indications for BoNT to more homogenous symptoms or special patient subgroups. The results of randomized, controlled studies involving a total of 3552 patients indicate that BoNT injection is probably ineffective for patients with migraine and chronic tension-type headache regardless of injection site, dosage, or injection regimen, and there is insufficient evidence to draw a conclusion about its effectiveness for the treatment of chronic daily headache or subforms. The lack of direct experimental or clinical trial evidence that BoNT has a direct antinociceptive effect in humans must be addressed before more trials are conducted, involving even more patients. Additional pathophysiologically oriented research is also needed to unravel the mechanisms of action of BoNT in human pain perception or, alternatively, to bring it all down to the placebo effect.

Is botulinum toxin useful in treating headache? Yes

Recent scientific data support an effect of botulinum neurotoxin (BoNT) on pain and headache. BoNT was shown to affect the release of neurotransmitters that are important in pain transmission and in migraine pathogenesis. Data from both animal and clinical studies suggest that the toxin may have an analgesic effect that is independent from its effect on muscle tone. The high tolerability and long duration of action of the drug make it appealing as a potential prophylactic treatment for headache patients. Results of controlled trials on the efficacy of BoNT in the treatment of episodic migraine (EM) are mostly negative, although some subgroups of patients (eg, those with high attack frequency) may respond to the drug. Studies of patients with chronic daily headache have been inconclusive, although (as with the EM studies) specific subgroups of patients appear to benefit from the drug. BoNT is probably ineffective for the treatment of chronic tension-type headache. There are anecdotal reports on a positive effect of BoNT in patients with other types of headache (eg, nummular headache). Factors that may affect the response of patients to BoNT include headache characteristics, disease duration, the use of concurrent preventive medications, and the presence or absence of medication overuse. The authors' clinical experience shows that some headache patients benefit significantly from BoNT treatment. The challenge for future studies is to identify those patients who will best respond to the drug.

Botulinum neurotoxins in the treatment of refractory pain

The proper management of pain is a critical issue in the practice of medicine. Despite the availability of a large number of analgesic medications, management of pain that is refractory to conventional treatments remains a challenge for both clinicians and surgeons. Botulinum neurotoxin (BoNT) has recently emerged as a potential novel approach to control pain. Animal studies have revealed a number of mechanisms by which BoNTs can influence and alleviate chronic pain, including inhibition of pain peptide release from nerve terminals and sensory ganglia, anti-inflammatory and antiglutaminergic effects, reduction of sympathetic neural discharge, and inhibition of muscle spindle discharge. In humans, prospective, placebo-controlled, double-blind studies have also provided evidence for effectiveness of BoNT therapy in a number of painful disorders. These include cervical dystonia, pelvic pain, low back pain, plantar fasciitis, postsurgical painful spasms, myofascial pain syndromes, migraine, and chronic daily headaches. Long-term studies on cervical dystonia and low back pain have demonstrated safety and sustained efficacy after repeated injections. This Review focuses on the analgesic effects of BoNT and the mechanisms of its pain control as revealed by animal models, and provides evidence-based data on the efficacy of BoNT therapy in various pain syndromes in humans.

Botulinum toxin: could it be an effective treatment for chronic tension-type headache?

Several clinical trials suggest that botulinum toxin type-A (BTX-A) may be an effective treatment option for patients with chronic tension-type headache (CTTH); however, controversy remains as to how the botulinum toxin optimally should be used for treating headache and which patient's profile fits this treatment. The objective of this study was to evaluate the efficacy and tolerability of BTX-A for the prophylactic treatment of CCTH in Egyptian patients. This was a randomized, single-blind, placebo-controlled study of BTX-A for the treatment of patients aged 25-50 years old with CCTH. Following a 30-day screening, headache parameters and severity assessed by the standard visual analogue scale (VAS), and the 25-item Henry Ford Hospital Headache Disability Inventory (HDI) were recorded as a baseline. Then, injection was done with either BTX-A or with saline by a combination of two methods for detecting injection sites (the fixed-site approach and follow-the-pain approach). Our study showed significant improvement after 1 month of BTX-A injection regarding headache days/month, severity measured by VAS and HDI in headache severity. There was significant reduction of prophylactic medications, and there were minor complications, but these reversed spontaneously without further treatment. BTX-A was an effective and well-tolerated prophylactic treatment in Egyptian patients with CCTH.

Botulinum toxin A injection into corrugator muscle for frontally localised chronic daily headache or chronic tension-type headache

Objective:

To describe our results with botulinum toxin type A injection for headache in carefully selected patients, and to present the rationale behind this therapy.

Setting:

Tertiary referral centre.

Patients and methods:

This article describes a case series of 10 consecutive patients with frontally localised headache, whose pain worsened when pressure was applied at the orbital rim near the supratrochlear nerve. The patients received a local anaesthetic nerve block with Xylocaine 2 per cent at this site. If this reduced the pain, they were then offered treatment with botulinum toxin.

Intervention:

Injection with 12.5 IU of botulinum toxin A into the corrugator supercilii muscle on both sides (a total of 25 IU).

Main outcome measure:

Pain severity scoring by the patients, ranging from zero (no pain) to 10 (severe pain) on a verbal scale.

Results:

Following injection, all patients had less pain for approximately two months. This treatment did not appear to have lasting side effects.

Conclusion:

Xylocaine injection is a good predictor of the effectiveness of botulinum toxin injection into the corrugator muscle as treatment of frontally localised headache. We hypothesise that this pain is caused by entrapment of the supratrochlearis nerve in the corrugator muscle. Furthermore, we found botulinum toxin injection to be a safe and effective means of achieving pain relief in this patient group.

Pericranial injection of botulinum toxin type A (Dysport) for tension-type headache - a multicentre, double-blind, randomized, placebo-controlled study

Increasingly, botulinum type A toxin is used to influence pathologically increased muscle activity in conditions such as dystonia and spasticity. Studies have also assessed its efficacy in tension-type headache, where muscle tenderness may be increased. We undertook a prospective, multicentre, randomized, double-blind, placebo-controlled trial. Patients received injections of Dysport (total dose of 420 or 210 units) or saline placebo in 18 sites on the head and neck. Of 125 patients treated, 118 were included in the intention-to-treat dataset. No significant differences between each verum group and placebo were seen for the primary efficacy parameter - change in the number of headache-free days at 4-8 weeks after injection compared with 4 weeks before injection. The groups receiving 420 or 210 units of Dysport experienced 2.60 and 2.87 more headache-free days respectively, compared with 1.93 more headache-free days for the placebo group (P = 0.66 versus 420 units; P = 0.52 versus 210 units). Treatment with 420 units of Dysport was associated with significant improvements compared with placebo for two secondary efficacy parameters: mean change in headache duration from baseline to weeks 8-12 (P < 0.05) and improved global physician and patient assessment scores (P < 0.05). Further studies should address the possible value of multiple injections with extended observation periods, dose optimization, and whether duration of headache history and number of previous treatments are predictors of patient response.

Tension-type headache: current research and clinical management

Tension-type headache (TTH) is the most common form of headache, and chronic tension-type headache (CTTH) is one of the most neglected and difficult types of headache to treat. The pathogenesis of TTH is multifactorial and varies between forms and individuals. Peripheral mechanisms (myofascial nociception) and central mechanisms (sensitisation and inadequate endogenous pain control) are intermingled: the former predominate in infrequent and frequent TTH, whereas the latter predominate in CTTH. Acute therapy is effective for episodes of TTH, whereas preventive treatment--which is indicated for frequent and chronic TTH--is, on average, not effective. For most patients with CTTH, the combination of drug therapies and non-drug therapies (such as relaxation and stress management techniques or physical therapies) is recommended. There is clearly an urgent need to improve the management of patients who are disabled by headache. This Review summarises the present knowledge on TTH and discusses some of its more problematic features.