Targeted botox delivery shows promise for treating jaw disorder

Temporomandibular disorder (TMD) limits jaw function and is so painful that it lessens the quality of life. Botulinum toxin-also known as botox-is emerging as an effective treatment option, but there are concerns about side effects, like muscle dysfunction. Eungyung Kim and Yu Shin Kim, from the University of Texas Health Science Center at San Antonio, led a study using a mouse model of TMD to explore the possibility of using botox as a treatment. 

In their JNeurosci paper, the researchers discovered that injecting botox directly into the male mouse temporomandibular joint (TMJ) instead of surrounding muscle tissue reduced TMD-related pain without causing side effects. More specifically, hypersensitivity and pain from TMD were mitigated without impairing general movement abilities and feeding behavior. The researchers also found that the botox injections they delivered reduced TMD-related neural activity. On a molecular level, mice that received botox injections into the TMJ had less expression of proteins that promote pain. 

While sex differences remain unexplored, according to the authors, this work suggests it may be possible to overcome botox side effects by avoiding muscle tissue and injecting the toxin directly into the TMJ.