Botulinum Toxin Useful for Treating Masseteric Muscle Hypertrophy

Injections of botulinum toxin (BoNT) for the treatment of mandibular swelling due to masseteric muscle hypertrophy (MMH) have proved an effective therapy, according to a new study.

Researchers at the second University of Naples (Italy) reported on a small case series that involved two men and three women ranging in age from 46 to 56 years. All but one of the patients had bilateral hypertrophy of the masseter, and three of the patients had evidence of tooth grinding. The botulinum toxin (BoNT type A) was injected into the thickest portion of the hypertrophied muscle, as determined by palpation. The results showed that all of the patients experienced a marked improvement in their condition. One of the patients experienced a relapse, but was successfully treated with repeat injections. Satisfactory results were obtained 20 days, on average, after injection. The study was published in the November 2008 issue of The Journal of Craniofacial Surgery.


"The results of this study suggest that the use of botulinum toxin type A for contouring of the lower face can be established as a simple, predictable, alternative facial contouring procedure,” concluded lead author Raffaele Rauso, M.D., and colleagues of the department of head and neck pathology.

Botulinum toxin is a neurotoxic protein produced by the bacterium Clostridium botulinum, and is the most toxic protein known. Despite this, it is used in many parts of the world to treat muscle spasms and as a cosmetic treatment, since injecting muscles with minute quantities of BoNT decreases muscle activity by blocking the release of acetylcholine at the neuromuscular junction. This renders the muscle unable to contract for a period 3 to 4 months. The application of BoNT extends over many different indications, including strabismus, blepharospasm, hemifacial spasm, and others.

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