Biting down on an oral orthotic device may suppress tics in patients with Tourette Syndrome.
Tourette Syndrome is a neurological disorder characterized by repetitive and involuntary movements or sounds called tics. Simple motor tics can present as eye movements, grimacing, herd jerks, or shoulder shrugs. Simple vocal tics include throat-clearing, coughing, sniffing, barking, and grunting noises.
Although not life-threatening, people who suffer from Tourette Syndrome may experience psychosocial distress contributing to anxiety, depression, and low self-esteem. As there is no cure for this condition, pharmacological, behavioural, and surgical treatments are available to manage tic severity. Nonetheless, the efficacy of these interventions can vary and no therapy can fully eliminate the tics. Research into novel therapeutic approaches has generated interest in the use of orthodontic devices for Tourette Syndrome. In dentistry, oral splints are worn in the mouth to ease muscle tension and stabilise the jaw in temporo-mandibular joint (TMJ) disorders. Initial findings in patients with both TMJ disorder and tic disorder showed an improvement in tic symptoms that warranted further study.
Researchers at Osaka University tackled precisely this question, looking at twenty-two patients with Tourette Syndrome. Subjective severity of motor and phonic tics was recorded on a Tic Symptom Self-Report before and after the application of an oral splint.
“Biting down on the device immediately improved both motor and vocal tics in 10 of the 14 children and 6 of the 8 adults that participated in the study,” said Jumpei Murakami, co-first author of the study. Motor tic severity saw a 30% reduction while phonic tic severity dropped 43%.
“What’s more,” according to Murakami, “these effects were long-lasting. Long-term improvements in motor tics after more than 100 days were especially evident in patients who were younger when their tics first started.”
The results were published in the journal Movement Disorders.
Researchers speculate that the act of biting down may represent a ‘sensory trick’, voluntary motions, such as touching of the face, that alleviate the involuntary movements. Sensory tricks are known to relieve symptoms of tics and spasms in other movement disorders like dystonia.
“Considering previous findings on sensory tricks in patients with cervical dystonia, it seems possible that the oral splint modulates proprioceptive, or ‘touch’ signals,” explains Yoshihisa Tachibana, co-first author of the study. “These ‘touch’ signals might be modified by the muscles involved in jaw-closing before being relayed to the brain.”
For now, the therapeutic promise of an oral splint for Tourette Syndrome must be validated by larger-scale studies to confirm clinical effect and investigate its underlying mechanism.
Written by Cheryl Xia, HBMSc
- Murakami, J. et al. Oral splint ameliorates tic symptoms in patients with tourette syndrome. Mov Disord mds.27819 (2019). doi:10.1002/mds.27819
- Saori Obayashi. An oral splint that can reduce Tourette syndrome tics. EurekAlert! (2019).