A proposal for safe and efficient botulinum toxin injection points of the temporal muscle in sleep bruxism

Abstract

Botulinum toxins(BoNT-A), purified exotoxins of Clostridium botulinum, have long been used for numerous neuromuscular disorders caused by muscular overactivation. Nowadays, the clinical indications for BoNT-A are constantly growing, ranging from the treatment of overactive skeletal musclesuch as bruxism, to the management of painful disorders such as migraines. The injection points on patients with bruxism aregenerally on the temporal region. For clinical applications on the temporal area, clinicians and investigatorsinject different anatomical regions. Optimizing the protocol for clinical use of BoNT-A is likely to improve the outcomes of therapy and is necessary in order to improve convenience for its use.In this study, we suggest a safe and efficient BoNT-A injection points, and generate a topographic map of considerable anatomic structures of the temporal region by dividing the temporalis muscle into 9 compartments. 19 sides of temporalis muscle from 10 Korean cadavers were used in this study. The superficial temporal artery(STA), middle temporal vein(MTV), temporalis tendon and the temporalis musclewere studied. The relationship among the 3 components of the 9 total compartments,which were established using the reference line and the anterior, superior, and posterior boundaries of the temporalis muscle.The shape of temporalis muscle above the zygomatic arch was rectangular with rounded upper right and left corners. The distance from the anterior temporalis margin to the posterior margin was the width of the temporalis rectangle and the distance from reference line to the superior temporalis margin was the height, so that the mean ratio of widthtoheight was 5:4. With the results from this study, we set an outline of the temporalis muscle.We recommend Am, Muand Pmas injection sites forBoNT –A on temporal region because there sites allow us to avoid large blood vessels and tendon, which improve the safety and efficacy of the injection. Further studies on the temporalis muscle’s thickness and distribution of motor nerve ending might explore even more accurate injection points.