Use of Botulinum Toxin (Botox) in the Management of Masseter Muscle Hypertrophy: A Simplified Technique

Sir: The purpose of this study was to investigate the changes in the masseter muscle after injection of botulinum toxin type A (Botox; Allergan, Inc., Irvine, Calif.) clinically, and to formulate a simple technique for administration of the drug to achieve optimal results. A total of five patients with unilateral or bilateral masseter muscle hypertrophy were treated at the Department of Oral and Maxillofacial Surgery at Nair Hospital Dental College, Mumbai, India. The outcome was noted clinically (standardized photography) and ultrasonographically. Excellent results were obtained, with satisfactory regression of the hypertrophied muscle with intramuscular injection of botulinum toxin. Recurrence was noted in one case for which reinjection was given. No side effects were noted. Given below is a simplified technique that has shown promising results. The drug used for injection was Botox, which is available as a freeze-dried powder ready for reconstitution with sterile 0.9% normal saline. Each vial contains 100 units of toxin. The toxin was reconstituted with 2.0 ml of saline to obtain a concentration of 50 U/ml. With the use of a tuberculin syringe (1-ml syringe with a 27-gauge, 0.5-inch needle), 40 units of botulinum toxin was injected at three different sites of the affected muscle in divided doses. The first injection was given into the site of maximal swelling seen on clenching. The other two points form a triangle, with the apex at point A. The other two points, B and C, signify the areas of hypertrophy but are less prominent as compared with point A (Fig. 1). It is very important to deposit the toxin within the muscle; superficial injections are to be avoided. This is done very easily by going bone deep and retrieving the needle, aspirating, and then injecting. After injections, the patients are advised to massage the muscles regularly for the subsequent 48 hours so that the toxin can spread evenly throughout the muscle mass.Fig. 1.: The site of injection with botulinum toxin in masseter muscle hypertrophy.Excellent results were seen after the follow-up period of 6 months, which were noted clinically (Fig. 2) and ultrasonographically (Table 1).Fig. 2.: Pretreatment (left) and posttreatment (right) photographs of the patient. Note the excellent results at the end of 6 months.Table 1: Thickness of the Masseter Muscle (mm): Results Obtained on Ultrasound Study at the End of the Follow-Up PeriodUnfortunately, Botox has a very short shelf life. Once the toxin is reconstituted, it has to be used within 4 hours.1 Regardless of the above-mentioned issue, it is always advisable to use the toxin freshly prepared. The toxin, without reconstitution, can be stored at a temperature of 4°C for a period of 1 year. Contraindications for use of botulinum toxin are hypersensitivity to the drug, localized infection or inflammation, diseases of the neuromuscular system, and coagulopathy.2 Thus, it can be safely concluded that botulinum toxin has a definite role in the management of masseter muscle hypertrophy that can be performed on an outpatient basis, thus avoiding the morbidity associated with surgical correction of this deformity. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article. PATIENT CONSENT The patient provided written consent for the use of his images. Neelam Noel Andrade, M.D.S. Gaurav Shekhar Deshpande, M.D.S. Nair Hospital Dental College Mumbai, India