Exploring the Effect of Using an Oral Appliance to Reduce Movement Dysfunction in an Individual with Parkinson Disease: A Single-Subject Design Study as originally seen in Journal of Neurologic Physical Therapy
This one’s hot off the press in 2017’s first quarter’s issue of JNPT.
In wanders a patient into the clinic and he goes, “Hey, I heard something about wearing a mouth guard that might help with my Parkinson. Do you know anything about that?” Cue research! I just love this single-subject design idea that I first heard about at IV Step last summer. How many times has a patient said something like that to you? I’ve heard it a lot. If I know something on the topic, I’ll tell them, and if not, I hit the books and find out! In this case there wasn’t much in the books of even minimal quality, so the amazing therapists said, “Hey, let’s put something out there!” And so they did…
They got a custom made “oral appliance originally designed for TMJ dysfunction.” Later on they mentioned that basically, it puts an extra 3mm on the resting space between the front teeth. Then they did a bunch of movement tests– four square step test, serpentine test (walking figure of 8 through 4 cones) and tandem gait– while on a motion analysis machine. Also included was a grip strength test. They did the tests first without the mouth guard, then with the mouth guard and then again without the mouth guard. Then they also did a self-perceived questionnaire (PDQ-39) of general health in Parkinson and another self-report on 0-10 scale specific to this study before using the device and then after he had been wearing it daily for a month.
What they found that was positive was “modest task-specific improvements in speed of movement, […] postural stability, […] upright posture, […] accuracy of whole body movement trajectory in space and strength in his more impaired [arm].” The self-report questionnaire and scale had a positive effect in the patient’s perception in emotional well-being, communication, stigma, ease of movement within the community, ease of movement while performing activities of daily living (ADL), and standing balance while performing ADL.
What they didn’t find was why this seems to work. The hypothesis is that it works by resetting the firing rate of the trigeminal nerve (a branch of which can get irritated with stress, trauma, jaw clenching and teeth grinding) which in turn projects into the reticular formation of the brain which plays a role in balance by influencing postural reflexes/righting reactions, conscious movements and maintenance of resting muscle tone. To me that sounds a little …
But what do I know. If it works for someone, who really cares about the mechanism? Ok, ok, I do, because I’m a neuro nerd like that.
Obviously much more research needs to be done into not only that mechanism, but also to find what populations this works best in. Maybe this works for other balance impaired folk too? Maybe it doesn’t? Maybe it only works in Parkinson? Maybe it only works for this guy? Also we need to find the optimum dosing. What happens if the space is increased to 4mm? Or reduced to 2mm? Do you really have to wear it all day or would say just wearing it at night be enough? A cheaper alternative would be nice to find too. I went looking on Amazon at a few general teeth guards wondering if maybe something that wasn’t custom would work. The folk on there were saying that a custom guard can cost upwards of $600-700 dollars! I know my patients can’t afford that. So that would be nice to know too.
Interesting line of thought anyway. When I saw that title on the cover, I was immediately intrigued and dismissive at the same time. So I had to investigate and bring y’all along for the ride!