Efficacy of Botulinum Toxin in Treating Asian Indian Patients with Masseter Hypertrophy: A 4-Year Follow-Up Study.

[BACKGROUND] Asian Indians usually have wide lower faces because of masseter hypertrophy. The authors evaluated the efficacy of botulinum toxin type A in long-term management of bilateral masseter hypertrophy in Asian Indian patients.

[METHODS] Fifty patients were enrolled in the study and injected with 30 U of botulinum toxin type A to each side of the face, at baseline. Based on masseter muscle thickness and response to the injections, 25 patients underwent a second injection session at week 12, and the other 25 patients underwent additional third sessions, at week 24 after the first injection, respectively. Standardized photography and ultrasonography were performed to assess facial contour and masseter muscle thickness at baseline and at 1-, 2-, 3-, and 4-year follow-ups. A p value < 0.05 was considered statistically significant.

[RESULTS] The authors observed 12 percent (p < 0.0001) average masseter muscle size reduction at week 12. The maximum reduction (26.6 percent; p < 0.0001) was observed at week 24 for the patients who received two injections and maintained an average 24.43 percent (p < 0.0001) reduction until follow-up at year 4. Patients who received three injections exhibited very high reduction (42.52 percent; p < 0.0001) of masseter volume at week 36 and maintained an average 40.64 percent (p < 0.0001) reduced volume until year 4.

[CONCLUSIONS] Botulinum toxin type A treatment is effective for long-term management of bilateral masseter hypertrophy. Doses repeated at 12-week intervals accentuate masseter volume reduction and also help maintain reduced masseter volume for 4-year follow-up, with satisfactory facial contour.