the Effect of Orofacial Treatment on Tinnitus as Part of a Multidisciplinary Program
Possible advantages of orofacial physical treatment can be expected in a chronic tinnitus population referred to tertiary care
No clinically relevant reduction but the results approach the minimal clinically relevant threshold
Future studies may use a more sensitive questionnaire to examine the effects of orofacial physical therapy treatment
Introduction
We all have experienced tinnitus at some point in time, probably after hearing loud noises or when returning home from a loud event. Tinnitus may have many causes although and can be influenced by altered somatosensory input from the cervical spine and temporomandibular area. The presence of connecting fibers between the jaw and the neck with the dorsal cochlear nucleus explains the relationship. Altered somatosensory input from the jaw encompasses dysfunction of the temporomandibular joint and muscles and oral parafunctional habits like bruxism. According to prevalence studies, tinnitus occurs in 30-64% of patients with temporomandibular disorders. Earlier studies showed positive effects of orofacial physical therapy treatment on tinnitus complaints but were often characterized by a high risk of bias. Therefore, this study conducted a randomized controlled trial and aimed to minimize the risk of bias.
Methods
A randomized controlled trial with a delayed treatment design was conducted. Patients with moderate to severe chronic subjective tinnitus, characterized by a Tinnitus Functional Index score (TFI) between 25 and 90 that was stable for at least 3 months, were recruited from a tertiary tinnitus clinic. Additionally, patients also had to have a temporomandibular disorder or show oral parafunctional habits.
All patients received advice and information concerning their tinnitus prior to any other treatment. The orofacial physical therapy treatment consisted of massage of the masticatory muscles; stretching exercises; relaxation therapy, counseling regarding mouth habit reversal, bruxism, sleep hygiene, lifestyle advice, and biofeedback. If patients were grinding their teeth, an occlusal splint was provided. Mobilizations and exercises of the cervical spine were added if patients had coexisting cervical spine problems.
Patients were randomly assigned to the early or delayed orofacial treatment group. Patients in the early group started physiotherapy from weeks 0-9, while the delayed group started with a wait-and-see approach during the same period and initiated the orofacial physical therapy treatment from weeks 9-18. That timeframe was the follow-up period of the early physiotherapy group. Weeks 18-27 served as the follow-up for the delayed physiotherapy group. A maximum of 18 sessions were allowed during the 9-week timeframe.
The primary outcome measure was the change in the Tinnitus Questionnaire (TQ). This is a validated questionnaire of 52 questions that are answered on a 3-point scale, ranging from ‘true’ (scoring 0), ‘partly true’ (scoring 1), to ‘not true’ (scoring 2). The total score ranges between 0 and 84, with higher scores indicating higher tinnitus annoyance. The total score can be used to classify individuals into 4 categories of tinnitus-related distress: Degree 1 (slight) 0 to 30 points, degree 2 (mediocre) between 31 and 46 points, degree 3 (severe) between 47 and 59 points, and degree 4 (extremely severe) between 60 and 84 points.
Results
A total of 80 patients were included and were equally randomized to the early or delayed orofacial physical therapy treatment group. At baseline, both groups were comparable in clinical and demographic characteristics. During the first 9 weeks, a decrease of -4.1 points in the TQ was observed in the early group, while the delayed group had a decrease of -0.2 points. This between-group difference was not statistically significant, nor clinically meaningful. When the delayed group received orofacial physical therapy treatment during weeks 9-18, a similar non-relevant decrease of 6 points was measured. After the follow-up, a decrease of -2 points in the early group and -1.2 points in the delayed group was observed.
So it appears that no significant, nor clinically relevant group differences were observed between the early and delayed groups on the primary outcome measure. The within-group analysis showed significant decreases between baseline and after having received orofacial treatment and after follow-up in both groups. Here the differences were significant, but not clinically relevant because the decrease remained smaller than the minimally clinically relevant change of 8.72 points. In total, 34% of patients reached a clinically relevant improvement in the TQ after treatment and 46% after follow-up.
Questions and thoughts
This trial showed significant decreases in tinnitus annoyance after orofacial physical therapy treatment (as can be seen from the within-group analysis), however, this reduction in the primary outcome measure did not reach the clinically meaningful threshold.
The between-group analysis is less relevant as in both groups the same treatment was administered. Using the wait-and-see period in the delayed group was a way to minimize the risk of bias by creating a control group as it was considered inappropriate to not offer treatment to those individuals in this tertiary clinical setting. Another advantage of this approach is that it allows us to get an idea of the effects of the natural evolution of the condition. As the recruited patients were referred to a tertiary clinic and had stable tinnitus complaints for at least 3 months, it could have been assumed not many benefits would have been seen after the wait-and-see period in the delayed group. It is thus interesting to see that indeed, these patients did not achieve improvements during 9 weeks of waiting for treatment.
Both groups showed significant decreases in tinnitus annoyance after receiving orofacial treatment and that effect continued even after the follow-up. The total decrease however did not reach the clinically meaningful threshold of 8.72 points but this may be partially explained by the fact that at baseline the mean tinnitus annoyance was mediocre (37 in the early group and 34 in the delayed group) and by the fact that the questionnaire consisted of questions rated on a three-point scale what may mean that this scale is less sensitive to smaller changes in tinnitus annoyance. The secondary outcome Tinnitus Functional Index (TFI), where questions regarding tinnitus severity are rated on an 11-point Likert scale showed significant and clinically relevant improvements in both groups. Although this study was not powered to detect differences in the TFI, the significance of the clinically meaningful reduction in the TFI and the correlation between the TFI and TQ may indicate a possible clinical benefit.
If a primary outcome fails, there are some questions that one may ask when trying to evaluate the clinical relevance of the study’s findings.
There is some indication of potential benefit as reductions on the TQ was significant and approached the threshold of the clinically meaningful difference. The TQ as the primary outcome seems appropriate but may have been not sensitive enough to detect changes, compared to the TFI. Yet both questionnaires are correlated well and a meaningful reduction in the latter was observed. Considering the population, it should be noted that these were patients with stable tinnitus complaints referred to tertiary care and that 9 weeks of administering the orofacial physical therapy treatment may have been just a little too short.
So to answer some of these questions, yes, there is an indication of potential benefit and secondary outcomes reveal positive findings in an appropriate population where the dosage of the therapy may have been a little too low
Somewhat less clear is the effect of the orofacial physical therapy treatment alone as this trial also prescribed occlusal splints for those grinding their teeth and administered cervical spine treatment for those with coexisting spinal complaints. Therefore, as the orofacial therapy was not examined very strictly, we cannot exclude that the observed effects are truly attributable to the orofacial physical therapy treatment alone.
Talk nerdy to me
The good aspects of this trial included the fact that it was registered and used a sample size calculation before the study procedures were initiated. The minimal clinically relevant difference of 8.72 points was considered in the sample size calculation. Missing data were analyzed by an intention-to-treat approach. The fact that randomization was kept concealed and that the treating therapist was unaware of the groups patients belonged to was according to the rules of art.
Take home messages
Orofacial physical therapy treatment has potential benefits in reducing tinnitus complaints in patients referred to tertiary care. The effects are possibly influenced by cervical spine treatment and occlusal splints. Although no clinically meaningful reduction was achieved, the trial results can be important considering the chronic population, which may be more therapy-resistant. Also, the primary outcome chosen may not have been the most sensitive one to register smaller changes. Further research should examine if clinically meaningful reductions can be achieved in these chronic patients when the treatment is administered for a little longer than 9 weeks or when a more sensitive questionnaire is used.
References
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