Masseter muscle reduction procedure with radiofrequency coagulation

Mechanism and clinical use of botulinum neurotoxin in head and facial region

PURPOSE

Botulinum neurotoxin (BoNT) is a biological toxin produced by Clostridium botulinum. BoNT is a potent toxin extensively used in therapeutic interventions. This review provides an updated overview of the mechanisms of action and clinical applications of BoNT in head and facial region.

STUDY SELECTION

MEDLINE/PubMed searches were conducted using the terms "botulinum neurotoxin" and "dentistry" along with a combination of other related terms. In addition, studies were manually selected from reference lists of the selected articles.

RESULTS

The Food and Drug Administration in the United States initially approved BoNT to treat strabismus, blepharospasm, and hemifacial spasms. The use of BoNT in dermatology and cosmetics has been widely established and has created a revolution in these fields. Over the years, its applications in various medical specialties have expanded widely. Owing to its safety, efficacy, and long duration of action, it is well-accepted by patients. BoNT/A and BoNT/B are widely used in clinical practice. Several off-label uses of BoNT in the dental fraternity have yielded promising results. We have elaborated on the speculated mechanism of action, dosage, effective sites of injection, and adverse effects of each therapeutic application. The various clinical indications for BoNT include bruxism, myofascial pain, temporomandibular joint dislocation, hemifacial pain, orofacial dystonia, facial paralysis, chronic migraine, and trigeminal neuralgia.

CONCLUSIONS

BoNT is a safe treatment that can be used effectively, provided that the clinician has adequate knowledge regarding the mechanism, injection techniques, and local and systemic side effects and that it is administered cautiously and purposefully.

Masticatory muscle tendon-aponeurosis hyperplasia that was initially misdiagnosed for polymyositis: a case report and review of the literature

BACKGROUND

Masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) is a relatively newly identified clinical condition that manifests as trismus with a square-shaped mandible. Herein, we report a case of MMATH that was initially misdiagnosed for polymyositis due to trismus and simultaneous lower limb pain, with literature review.

CASE PRESENTATION

A 30-year-old woman had a history of lower limb pain after exertion for 2 years. Initial physical examination had been performed at the Department of General Medicine in our hospital. There was also redness in the hands and fingers. Although polymyositis was suspected, it was denied. The patient visited our department for right maxillary wisdom tooth extraction. Clinical examination revealed that the patient had a square-shaped mandible. The maximal mouth opening was 22 mm. There was no temporomandibular joint pain at the time of opening. Furthermore, there was awareness of clenching while working. Panoramic radiography revealed developed square mandibular angles with flattened condyles. Computed tomography showed enlarged masseter muscles with high-density areas around the anterior and lateral fascia. Magnetic resonance imaging also showed thickened tendons and aponeuroses on the anterior surface and inside bilateral masseter muscles. Finally, the patient was diagnosed with MMTAH. Bilateral aponeurectomy of the masseter muscles with coronoidectomy and masseter muscle myotomy was performed under general anesthesia. The maximum opening during surgery was 48 mm. Mouth opening training was started on day 3 after surgery. Histopathological examination of the surgical specimen showed that the muscle fibers were enlarged to 60 μm. Immunohistochemistry testing for calcineurin, which was associated with muscle hypertrophy due to overload in some case reports, showed positive results. Twelve months after surgery, the mouth self-opening and forced opening were over 35 mm and 44 mm, respectively.

CONCLUSIONS

Herein, we report a case of MMATH. Lower limb pain due to prolonged standing at work and overload due to clenching were considered risk factors for symptoms onset of MMATH.

Efficacy of botulinum toxin in masseter muscle hypertrophy for lower face contouring

BACKGROUND

Masseter muscle hypertrophy (MMH) usually presents with cosmetic concerns as it may lead to widening of the lower face. Apart from the traditional surgical approaches, botulinum toxin type A (BTA) injection is a non-invasive treatment option available. There are no standard guidelines for this procedure.

OBJECTIVES

To study the efficacy of botulinumtoxin A in MMH for lower face contouring.

METHODOLOGY

The Cochrane Library, PubMed/MEDLINE, Google-scholar, Science-Direct database, and ResearchGate from inception until September 2021 were searched using the keywords "botulinumtoxin type A," "masseter muscle hypertrophy," "lower face contouring," and "masseter botox." All available retrospective and prospective studies, case-series, case-reports, and expert reviews were included with an emphasis on efficacy of BTA in MMH and units injected into the muscle, points of placement, adverse events, and the duration of its effect. Reference lists of the resultant articles, as well as relevant reviews, were also searched.

RESULT

40 articles were shortlisted for the review, of which 14 studies with sample-size ≥10 in accordance with the study requirements were summarized in a tabular form for analysis and easy comparison and reference.

CONCLUSION

BTA injection is a non-invasive, safe, and effective treatment for MMH. The optimum number of BTA units could not be ascertained due to wide variability in the studies as well as ethnicity of patients and extent or some measurement of MMH. The points of placement of injection should be well within the boundaries of the masseter muscle. The maximum effect of BTA after a single injection session is usually seen in ~3 months, and the duration may last for 6-12 months. Multiple injection sessions may be required to maintain a long-term effect. Injection technique and total number of injection units of neuromodulator must be individualized for each patient.

New Management in Bilateral Masseter Muscle Hypertrophy

Bilateral masseter muscle hypertrophy is an alteration in shape and thickness of the masseter muscles that can modify the width of the lower face causing aesthetic and functional problems. A 21-year-old man was referred to the Department of Maxillofacial Surgery at the Civil Hospital in Brescia by his dentist for an evaluation of his facial appearance with a square-face type. To reduce the undesirable facial appearance, a surgical intraoral approach was performed; the procedure includes the bilateral dissection of the masseter muscle, partial lipectomy, and the ostectomy of the mandibular angle assisted by a surgical guide built on a stereolithographic model. The patient was satisfied with the functional and aesthetic outcomes of both the profile and the frontal views. There was no evidence of complication at a 1-year follow-up. This new method yields optimal aesthetic results with an enhanced outline of the lower face.

Three-dimensional CT might be a potential evaluation modality in correction of asymmetrical masseter muscle hypertrophy by botulinum toxin injection

For correction of this asymmetrical hypertrophy, botulinum toxin type A (BTxA) injection is one of convenient treatment modalities. Unfortunately, physical examination of masseter muscle is not enough to estimate the exact volume of muscle hypertrophy difference. Two Koreans, male and female, of bilateral masseter hypertrophy with asymmetricity were evaluated. BTxA (NABOTA(®), Daewoong, Co. Ltd., Seoul, Korea) was injected at master muscle site with total 50 U (25 U at each side) and volume change was evaluated with three-dimensional (3D) CT image analysis. Maximum reduction of masseter hypertrophy was recognized at 2-month follow-up and reduced muscle size started to restore after 3 months. Mean reduction of masseter muscle volume was 36% compared with baseline. More hypertrophied side of masseter muscle presented 42% of volume reduction at 2-month follow-up but less hypertrophied side of masseter muscle showed 30% of volume shrinkage. In conclusion, 3D CT image analysis might be the exact evaluation tool for correction of asymmetrical masseter hypertrophy by botulinum toxin injection.

Botulinum toxin: The Midas touch

Botulinum Toxin (BT) is a natural molecule produced during growth and autolysis of bacterium called Clostridium botulinum. Use of BT for cosmetic purposes has gained popularity over past two decades, and recently, other therapeutic uses of BT has been extensively studied. BT is considered as a minimally invasive agent that can be used in the treatment of various orofacial disorders and improving the quality of life in such patients. The objective of this article is to review the nature, mechanism of action of BT, and its application in various head and neck diseases.

A modified surgical method of lower-face recontouring

BACKGROUND

In general, the width of the lower face is determined by four parts: the mandible, the masseter muscle, the buccal fat pad, and the subcutaneous fat. In this article, we introduce a modified surgical method to reshape the outline of round faces that have no significant overgrowth or eversion of the lower jawbone.

METHOD

The procedure includes dissection of the masseter muscle and partial lipectomy of the buccal fat pad through the same intraoral small incision.

RESULTS

The patients were satisfied with the aesthetic outcome of both the profile and frontal view. Follow-up of more than 6 months shows no prospective complications.

CONCLUSION

This method yields an optimal aesthetic result in patients who have a round face without significant overgrowth or eversion of the lower jawbone.

LEVEL OF EVIDENCE IV

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

Botulinum toxin type A combined with cervical spine manual therapy for masseteric hypertrophy in a patient with Alzheimer-type dementia: a case report

OBJECTIVE

The purpose of this case study is to present the findings of combining botulinum toxin type A (BoNT-A) and cervical spine manual therapy to address masseter muscle spasticity in a patient with Alzheimer-type dementia.

CASE REPORT

A 78-year-old woman with bilateral spasticity of the masseteric regions for 2 years was referred for physiotherapy. She had trismus and bruxism, and could neither close nor open her mouth normally; thus, she was unable to be fed orally in a normal manner.

INTERVENTION AND OUTCOME

The patient underwent combined treatment with BoNT-A and cervical spine manual therapy. A medical physician (neurologist) performed the BoNT-A injections into 2 points at the center of the lower third of the masseter muscle. A physical therapist performed manual therapy interventions targeted at the cervical spine. Manual therapy started the day after the BoNT-A injection and continued for 5 sessions per week for a total period of 2 weeks. Clinical outcomes were measured including spasticity (Modified Ashworth Scale), functionality (Barthel Index), and jaw opening. Outcomes were conducted at baseline, 2 weeks after treatment, and at 2-month follow-up session after finishing the treatment. The patient improved in all of the outcomes at the end of treatment, and these results were maintained during the follow-up. After treatment, the patient was able to feed with minimal caregiver dependency because oral feeding was possible.

CONCLUSION

The patient in this study responded positively to a combination of BoNT-A and manual therapy, resulting in decreased masseter muscles spasticity and improved trismus and bruxism.

Management of bilateral masseter muscle hypertrophy

Masseter muscle hypertrophy is characterized by unilateral or bilateral enlargement of the masseter muscles affecting both females and males after puberty. Limitations on mouth opening, swollen cheek, and also tension in the region of the hypertrophied muscle are symptoms reported. Also, masseter hypertrophy can cause aesthetic and functional problems. A 40-year old woman was referred to our clinic with the chief complaint of facial appearance with square-face type. To eliminate undesirable facial appearance, surgical intraoral approach compromising reduction of deep masseter muscle with monocortical and bicortical ostectomy of the angle of the mandible was performed. The patient was satisfied with both functional outcomes and aesthetic outcomes on both facial profile and frontal view. No complication was seen intraoperatively and postoperatively after a 12-month follow-up period. This treatment modality would be suggested to gain optimal aesthetic results especially in a square face from the lateral profile.

Excessive gastrocnemius fibrosis developed after radiofrequency-induced cosmetic volume reduction

Cosmetic shaping of the lower leg is becoming increasingly popular. The use of radiofrequency therapy in cosmetic medicine also is growing. To date, no serious complications have been reported after the use of cosmetic radiofrequency therapy. This report describes a patient who presented at the author's clinic with a disabling ankle plantarflexion contracture in both calves that developed during a period of 18 months after cosmetic radiofrequency volume reduction. This reduction, performed at another clinic, involved applying a bipolar electrode with a mean power of 35 W at each of approximately 100 spots for 2 to 4 s. On each calf, 15 kJ was applied in a crisscross fashion. Magnetic resonance imaging and muscle biopsy indicated excessive gastrocnemius fibrosis. The patient was treated using botulinum toxin injections followed by serial castings and intensive physiotherapy. After treatment, the patient was able to walk with less difficulty and showed no tiptoeing. This appears to be the first report of serious muscle contracture after cosmetic radiofrequency volume reduction requiring extensive rehabilitation management.

Electromyographic activity of the masseter muscle after radiofrequency therapy in an animal model

PURPOSE

The purpose of this study was to examine changes in the electromyographic (EMG) activity of the masseter muscle after radiofrequency therapy (RF).

METHODS

Twelve rabbits were used in this study: four in each group according to the number of RF applications. Preoperative EMG in the masseter muscle was used as the control. EMG was recorded at 1, 2, 3, and 4 weeks after RF in each rabbit. The recorded data were analyzed in terms of voltage and frequency, and changes in recorded variables were compared among the groups. The relative activity in peak voltage, root mean square of the action potential, area of voltage, and area of frequency were investigated.

RESULTS

When compared to preoperative values, the variables at 3 or 4 weeks after RF application were significantly different in the single and quadruple therapy groups (P<0.05). There was no significant difference in the other groups (P>0.05). When the samples were regrouped as two groups like small number of application group (one or two point) and large number of application group (three or four points), the area of voltage and the area of frequency were significantly different between the groups at 4 weeks (P<0.05).

CONCLUSIONS

Masseter muscle activity after RF was significantly decreased compared to its preoperative state. The decreased activity was related to the number of applications and time elapsed after RF.