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J Oral Maxillofac Surg70:1243-1245, 2012

Use of Botulinum Toxin A for Treatmentof Myofascial Pain and Dysfunction

Heshaam M. Fallah, DDS, MD,* and Shama Currimbhoy, DDS†

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Since its introduction in 1992, the Research Diagnos-tic Criteria for Temporomandibular Disorders (RDC/TMD) has been used to classify patients with TMDbased on physical diagnosis (Axis I) and pain-relateddisability and psychological status (Axis II).1 This sys-em has allowed the standardization of diagnosticriteria for TMDs and has been validated for researchnd clinical use.2 Myofascial pain is the first group of

disorders under the physical diagnosis axis of theRDC/TMD and is defined by 3 main criteria: report ofpain at rest or during function, pain on palpation at 3 ormore defined sites, and at least 1 palpable painful sitehaving the same laterality as the patient’s perception ofpain. Myofascial pain is further subclassified in relationto the limitation of mouth opening. A recent meta-analysis of the epidemiology of Axis I found thatmyofascial pain affects almost half of patients present-ing for TMD treatment.3 Despite the widespread prev-alence of myofascial pain disorders, no universal treat-ment approach has been determined.

Botulinum toxin A (Botox), a neurotoxin isolatedfrom Clostridium botulinum, has been used for thetreatment of a wide spectrum of conditions involvingmuscular spasm and hyperactivity, including but notlimited to: blepharospasm, strabismus, cervical dysto-nia, upper limb spasticity, and, most recently, bladderincontinence. The established mechanism of the ac-tion of Botox is the inhibition of acetylcholine releasefrom the motor nerve endings resulting in a locallydecreased muscle contraction. Perhaps the most com-mon use for Botox is the treatment of dynamic gla-bellar lines (aka frown lines). Millions of patientsundergo this procedure every year. It is in this groupof patients that the analgesic effect of Botox was first

Received from the Kaiser Permanente Oakland Medical Center,

Oakland, CA.

*Associate Surgeon. Kiaser Permanente Oakland Medical Center.

†Private Practice, Sacramento, CA. Former Resident; Department

of Oral and Maxillofacial Surgery, Highland General Hospital, Oak-

land, CA.

Address correspondence and reprint requests to Dr Fallah: Kai-

ser Permanente Oakland Medical Center, 280 West MacArthur

Boulevard, Oakland, CA 94611; e-mail: heshaam.m.fallah@kp.org

© 2012 American Association of Oral and Maxillofacial Surgeons

278-2391/12/7005-0$36.00/0

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documented by Binder et al.4 In their cohort of 116atients, 10 had migraine headaches. At the end of thereatment window, 70% of the headache group re-orted an improvement or resolution of migraineymptoms. Further evidence has suggested that thenalgesic effects of Botox are mediated through thenhibition of the release of substance P and glutamate,

hich occurs at a lower concentration than that nec-ssary to produce muscle weakness.5,6

Although the pathophysiology of myofascial painremains uncertain, multiple neurologic, myogenous,and psychological theories have been postulated.Among the most accepted theories is that myofascialpain originates from hyperactive skeletal muscleband(s), aka trigger point(s), which evoke a referredpain pattern from central convergence and facilita-tion.7 Such trigger points can result from directrauma, strain, overuse, or repetitive microtrauma.8

Many treatment modalities have been advocated toarrest, stabilize, or reverse this muscle hyperactivity,ranging from conservative therapies such as heat,physical therapy, and splint therapy to more invasivemeasures such as oral medications, direct muscle in-jections, or dry needling. Although all of these haveshown some degree of success, all have potential com-plications. Splint therapy, for example, with an orthoticbite appliance has been advocated for the treatment ofbruxism and facial pain related to muscle hyperactivity.The bite appliance is thought to facilitate neuromus-cular balance by eliminating occlusal interferences,resulting in a change in mechanical input to the peri-odontal proprioceptive fibers and thus the afferents inthe jaw-closing muscles of mastication.9,10 Althoughthe effectiveness of oral appliances remains debat-able, potential serious side effects have been reported,including increased muscle activity, an increased loadon the temporomandibular joint, and the supereruptionof teeth.11-13 Furthermore, the variability in applianceesign may contribute to the inconsistent success ratend development of complications.

Several studies have investigated the use of Botoxor the treatment of myofascial pain, with positivendings. Acquadro and Borodic14 reported improvedyofascial pain and tension headache symptoms after

ust 2 injections 4 weeks apart in the trapezius andplenius capitis. Freund et al15 found a statisticallyignificant improvement in pain, tenderness, func-

ion, and mouth opening in a cohort of 46 patients

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1244 BOTOX FOR MYOFASCIAL PAIN AND DYSFUNCTION

with an 8-week follow-up. Lalli et al,16 in a random-ized double-blinded clinical trial of 20 patients, re-ported a statistically significant improvement in pal-pable muscle spasms with Botox compared with localanesthetic as measured by the visual analog scale.Similarly, Porta17 compared the effects of Botox withthose of a local anesthetic/steroid injection in a single-blinded study of 40 patients with myofascial pain andreported a statistically significant improvement after60 days in the Botox group. Von Lindern et al,18 in aingle-blinded placebo-controlled study, reported aignificant pain decrease after Botox injections in 90atients with chronic facial pain. In a double-blindedlacebo-controlled randomized clinical trial, Kurtoglut al19 reported that, despite some return of musclectivity, there was a statistically significant longer-asting improvement in pain and psychological statusfter Botox injections compared with placebo salinenjections.

Some clinical trials, however, have failed to find aenefit of Botox injections for patients with myofas-ial pain. Nixdorf et al,20 in a group of 15 patients,ound no statistical improvement in myofascial pain inesponse to Botox injections. However, it is worthoting that with a 33% dropout rate, only 10 patientsompleted the study. This decreased the statisticalower of the study to below the target stated by the

nvestigators to detect clinically significant change.urthermore, although the masseter and temporalisuscles were injected, the injection sites were

tandardized and not correlated with patient symp-oms. In a randomized clinical trial of 21 patients,rnberg et al21 concluded there was no clinicallyelevant efficacy for Botox in the treatment of myo-ascial pain. This study was limited by a small sample,nd the injections were limited to the masseter muscles,hich were not correlated with patient symptoms. Pain

nvolving the temporalis muscles was not addressed,hich may have affected the patients’ assessmentf pain, a primary outcome measurement of thistudy. Despite these shortcomings, there was a 30%ain decrease in the treatment group comparedith the control.Conducting randomized clinical trials is essential to

stablishing a therapeutic effect. Unfortunately, fewuch studies have been performed using Botox toreat myofascial pain in the maxillofacial region.22

Among the problems with current studies are themethodologically diversity in experimental designs,small samples, and variability of injection sites. Thesefactors contribute to the paucity of high-quality dataavailable on the efficacy of Botox for the treatment ofmyofascial pain dysfunction in the maxillofacial re-gion. Although there is strong anecdotal evidencesupporting the use of Botox, many clinical trials have

fallen short of producing conclusive results.

In conclusion, myofascial pain disorder remains acomplex multifactorial condition that likely wouldbenefit from a variety of treatments if targeted tospecific etiologies. Conventional treatments, such asbite appliances, are not always effective and cancause complications. Botox may not be a first-linetherapy for myofascial pain, but it is a useful alterna-tive or adjunctive treatment if conservative measuresfail to produce satisfactory results.

As stated by Janal et al,23 “it would be a shame ifconclusions drawn from insufficiently powered clini-cal trials were responsible for limiting future researchon treatments that may benefit some TMD sufferers.”The best data on the use of Botox for the treatment ofmyofascial pain disorder have yet to arrive, so staytuned!

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