Effects of botulinum toxin type A on bilateral masseteric hypertrophy evaluated with computed tomographic measurement.

BACKGROUND A paucity of reports exist on the use of botulinum toxin type A injections as an alternative noninvasive treatment for masseteric hypertrophy. OBJECTIVE To evaluate the effects of botulinum toxin type A on masseteric hypertrophy using computed tomography. METHODS Percutaneous intramuscular injections of botulinum toxin type A of 30 U per side was carried out in 11 subjects with masseteric hypertrophy. The changes in the masseteric muscle volume before and 12 weeks after injection were evaluated using computed tomography. The changes in the lower facial contours on the photographs were evaluated as excellent, good, fair, and no changes. RESULTS Nine of the 11 subjects showed a mean reduction of approximately 22% in the masseteric muscle volume. The maximum reduction was 35.4% (range, 8.1% to 35.4%). Nine subjects showed aesthetically good results with a grade of good or excellent at 12 weeks after treatment. CONCLUSION Botulinum toxin injections are a noninvasive alternative method for treating masseteric hypertrophy.