ULTRASONOGRAPHIC EVALUATION OF THE MASSETER MUSCLE BEFORE AND AFTER BOTULINUM TOXIN INJECTION IN PATIENTS WITH BRUXISM

Abstract

<h3>Background</h3> Bruxism is defined as a diurnal or nocturnal parafunctional activity of the masticatory muscles, with a prevalence of 20% and an impact of life quality. It is characterized by the compression and/or grinding of the teeth without purpose. In cases where conventional therapies are insufficient, botulinum toxin type A can be used as an alternative therapeutic treatment for patients who present masticatory muscle hyperfunction. <h3>Objective(s)</h3> The purpose of this case series was to assess the masseter muscles before and after injection of botulinum toxin type A by using ultrasonography. <h3>Study Design</h3> Ethical approval and patient consent were obtained. Botulinum toxin injection was performed on 4 patients with bruxism. Masseter muscles on both sides were assessed before and 1 month after injection by using ACUSON S 2000 (Siemens, Munich, Germany) with a 9-18 MHz linear probe. Maximum width, height, and volume measurements of the masseter muscles were obtained, along with elastography and virtual touch IQ elastography measurements in both rest and contraction positions. <h3>Results</h3> Measurements obtained from the patients before and after injection at rest position showed a decrease of 10% and 3% in masseter muscle width and volume, respectively. Measurements obtained from the masseter muscles before and after injection at contraction position again showed a decrease of 20% and 3% in muscle width and volume, respectively. According to virtual touch IQ elastography values, approximately 20% reduction was found at both positions. However, we were unable to reveal any constant variation before and after injection at both positions in consideration of height and elastography. <h3>Discussion/Conclusions</h3> Certain measurements of the masseter muscle with ultrasonography before and after botulinum type A injection in patients with bruxism may provide useful information in the follow-up process. Further research is essential, with more patients evaluated at different follow-up intervals.