A cadaveric analysis of the efficacy of blind injections into lateral pterygoid muscle.

[BACKGROUND] Temporomandibular disorders (TMDs) are among the most common causes of orofacial pain. Hyperactivity of the lateral pterygoid muscle (LPM) is associated with the pathological mechanisms associated with TMD. Botulinum toxin-A (BTX) injections into the LPM can be used as a treatment for TMD. However, a lack of clinical standardisation for this procedure can lead to adverse outcomes, especially when using anatomical landmark-based approaches.

[MATERIALS AND METHODS] To better understand the precision of extraoral landmark- based LPM BTX injections, a maxillofacial surgeon injected 1.5 mL of 0.25% methylene blue dye into the LPM of five cadavers. Needle location, dye spread, and disrupted structures were then examined through cadaveric dissection.

[RESULTS] Landmark-based LPM BTX approaches resulted in poor outcomes in accuracy (0%) and a 40% incidence of neurovascular disruption, including the facial plexus, superficial temporal artery and superficial temporal vein.

[CONCLUSIONS] Randomised controlled trials have highlighted the risks associated with extraoral botulinum toxin injections for TMD symptomatic relief. This report demonstrates the low accuracy rate and high neurovascular risk that accompany blind LPM injections, and highlights the need for safe treatment protocols in TMD, in particular guided image-based diagnostics and procedures.