How Do I Inject Botulinum Toxin Into the Lateral and Medial Pterygoid Muscles?

Abstract

View Supplementary Video. Oromandibular dystonia is a focal dystonia that manifests as involuntary masticatory and/or tongue muscle contractions. Jaw opening, jaw deviation, and jaw protrusion types of oromamdibular dystonia are caused by involuntary contraction of the lateral pterygoid muscles. The medial pterygoid can be very hyperactive in jaw closing dystonia as a result of the so-called “whack-a-mole phenomenon,” after repeated botulinum toxin injections into the masseter and temporalis muscles. The more accurately the botulinum toxin is injected into the muscles, the more likely the improvement in the patient's symptoms, and the lower the risk of complications, such as hematoma or arterial bleeding. Both pterygoid muscles can be accessed by intra- and extraoral routes. Safe and correct injection of botulinum toxin into both pterygoid muscles is described in this video. With understanding of the anatomy of the muscles, indications for injection, and technique of needle placement, injection of botulinum toxin into the lateral and medial pterygoid muscles is safe and effective for oromandibular dystonia.