Effects of Manual Therapy in Somatic Tinnitus Patients Associated with Cervicogenic and Temporomandibular Dysfunction Domain: Systematic Review and Meta Analysis of Randomised Controlled Trials

Abstract

Despite manual therapy has been used as an effective treatment but there is limited of literature emphasizing its role to improve quality of life and pain pressure threshold in patients with somatic tinnitus. In this Meta analysis we compared the effects of manual therapy on quality of life and pain pressure threshold in the patients with somatic tinnitus associated with cervicogenic and temporomandibular dysfunction domain. We systematically searched different databases such as Pubmed, Google Scholar and Scopus to find out the relevant studies compairing the effects of manual therapy with quality of life and pain pressure threshold. Two independent reviewers performed quality check and data extraction. We analyzed the data using RevMan ver. 5.4 software. Total three randomised controlled trials were included in this study. Manual Therapy proven to be effective in improving quality of life as well pain pressure threshold in somatic tinnitus patients. {ORs 0.80; 95% Confidence Interval (95%CI), P = 0.97}. Further clinical trials are needed to explore manual therapy as an effective intervention.

Introduction

Tinnitus refers to the false perception of the sound in the absence of any external auditory stimuli [1]. The phantom sound can be characterized as ringing, buzzing, pulsating or clicking sensation [2]. Tinnitus affects 20.7–24.2% of the general population and 10–15% of the adult population which hampers the quality of life of the patients [3–5]. It can be continuous or sporadic which can be present in unilateral or bilateral ears or situated centrally in the head [6]. Tinnitus can be classified into Subjective and objective. One of the types of subjective tinnitus is Somatic tinnitus [2].

Somatic or somato-sensory tinnitus attributes to the disorders of cervical spine or temporo-mandibular region [3] which can modulate the pitch and loudness in tinnitus patients [7]. Its prevalence is 36–43% of the Belgian population along with subjective tinnitus patients [3]. Somatogenic disorders turn out to be highly prevalent in tinnitus patients [7]. Prevalence of Cervicogenic somatic tinnitus is 43% [4] and Temporomandibular Disorders is 64% in patients with chronic tinnitus [3] which is more common in patients with dental pulpagia [7].

Michiels et al. [8] has conducted a systematic review in 2016 to investigate the evidences regarding the treatment of physical therapy in subjective tinnitus patients. They searched the online databases upto March 2016 and only included Randomized Controlled trials and Quasi Experimental designs in their review. They concluded that all included studies showed positive effects of physical therapy and recommended future reviews which should be on larger and higher quality studies. The next study was conducted in 2019 by Lynn Kinne et al. [2] in which they observed the effect of manual therapy techniques in somatic tinnitus patients. They included eight studies in their review and concluded that manual therapy has an effective role in treating somatic tinnitus.

To best of authors’ knowledge there is no previous study which has performed Meta analysis in order to find out the efficacy of manual therapy in treating somatic tinnitus associated with both the domains that is Cervicogenic and Temporomandibular Dysfunction. Therefore, the objective of this study is to find out the strong evidence on the effect of manual therapy on pain pressure threshold and Quality of life in Cervicogenic somatic tinnitus patients and Temporomandibular Dysfunction (TMD) associated somatic tinnitus patients.

Materials and Methods

This Systematic Review and Meta Analysis has written according to the PRISMA Guidelines (Preferred reporting items for Systematic Reviews and Meta Analysis) [9]. This review has also been registered in the PROSPERO (International Prospective Register of Systematic Reviews). Registration Number: CRD42020196819.

This Systematic Review and Meta Analysis is a part of larger project entitled “Effect of manual therapy in somatic tinnitus patients associated with Cervicogenic and Temporomandibular Dysfunction domain: Systematic review and Meta analysis of Randomised controlled trials.” The objectives of this study are (1) to find out the efficacy of manual therapy in Cervicogenic Somatic tinnitus patients. (2) To find out the efficacy of manual therapy in TMD associated somatic tinnitus patients.

Data Sources Search Terms and Strategy

This study had based on systematic searches which had been carried out in multiple databases such as Pubmed, Scopus and Google Scholar. The included articles were published or accepted for publication till May 2020. All the searched terms are mentioned in Table 1. Systematic searches were performed from the possible combination of the three categories of key words. All the references were inspected of the included reviews and randomised controlled trials to discover any potentially eligible studies. All the published randomised controlled trials and systematic reviews on the effect of manual therapy in patients with somatic tinnitus are included in this study. The search strategy has been done in such a way to lessen the possibility of selection and detection bias. Search results were transferred to the end note and all the replicates were excluded. Manual screening was there of included studies so as to identify other related studies.

Table 1.

Search terms used in literature search

Category 1	Category 2	Category 3
Tinnitus	Musculoskeletal manipulations	Quality of life
Somatic tinnitus	Manipulations therapy	HRQOL
	Manual therapies	Life quality
Tinnitus, subjective	Therapy, manipulations	Pain threshold
		Pressure

Inclusion and Exclusion Criteria

In this review eligible studies has selected who has been performed manual therapy for the treatment of Cervicogenic Somatic Tinnitus or Temporomandibular Dysfunction associated somatic tinnitus in somatic tinnitus patients. Studies with Randomised Controlled trials are included in this study. Case reports, Case series, Qualitative interview studies are excluded. For Meta analytical part of this study the included studies has provide the relationship of manual therapy and somatic tinnitus and also provided adequate information with effect size to be calculated of this relationship. Studies lacking of this information has not been included in this Meta analysis.This Meta analysis included only those articles which are published in English language or can be translated into English language and this study has only included published RCTs or the RCTs which had been accepted for publication. Conference Abstracts, Dissertations and grey literature are not included. Initially, appropriate articles have selected on the basis of title and abstracts and then the full text description of the particular articles has inspected and assessed according to the methodological quality.

The primary researcher managed the search strategy and eliminates all the replicates by using Endnote X7. According to the inclusion and exclusion criteria the other two researchers assessed the included articles independently. Any differences in the outlook were resoluted through discussion or by consulting the third researcher. This procedure has been performed to reduce the biasness while including or excluding relevant studies. All the researchers conducted the process of data extraction independently by using data extraction sheet. According to the Lipsey and Wilson [10] the form has assessed about manual therapy, somatic tinnitus, participant’s characteristics, quality of life, pain pressure threshold, study characteristics or other appropriate variables.

Assessment of Methodological Quality (Risk of Bias)

To reduce the risk of biasness all the researchers performed the search independently. The Quality of each RCT was assessed by PEDro Scale [11] and Downs and Black Checklist [12]. Methodological quality scores of PEDro were given as: 9–10 (high quality, low risk of bias); 6–8 (acceptable quality, moderate risk of bias); 3–5 (low quality, high risk of bias); 0–2 (unacceptable, reject). Table 3 demonstrates the methodological quality of the included studies. We had included three randomised controlled trials in this review although the minimum studies can be two to conduct a meta analysis [13] Cochrane Risk of Bias Assessment Tool was also followed to evaluate the risk of bias in the integrated studies [14] Grades were referred as high, low and unclear risk.

Table 3.

Assessment of methodological quality

Study	1	2	3	4	5	6	7	8	9	10	11	Score
Bonaconsa et al. [16]	Yes	Yes	No	Yes	No	No	No	Yes	No	Yes	No	4/10
Delgado et al. [17]	Yes	Yes	Yes	Yes	No	Yes	No	Yes	Yes	Yes	No	7/10
Michiels et al. [6, 8]	Yes	Yes	Yes	No	No	No	Yes	Yes	Yes	No	Yes	6/10

Statistical Analysis

Data Analysis was performed by calculating the Odds ratio (ORs), relative risk (95% confidence interval) and estimating p value of the interventions for quality of life and pain pressure threshold. Random-effect model was used to calculate odd ratio (Ors) to connect the studies which used the different scales and calculated the same results. Inverse variance approach was used through this model, results in the distribution of true effect sizes which will further provide more balance in weight adjustments. All the statistical analysis was performed by the Cochrane Collaboration, RevMan v.5.4 software [15].

Heterogeneity between the studies was calculated by Cochran’s Q-statistics. Heterogeneity will be statistically significant if the P value comes to be < 0.05 or I² was > 50%. Precautions were taken in terms of event rates and risk ratios (RR) with 95% CI.

Results

Description of Studies

Records identified through the search of different databases includes total of 396 articles. 1 article was identified through the additional records. After removing duplicates 296 articles remained. Further screening of the article based on titles, abstracts and selection criteria 6 articles were assessed for qualitative synthesis from which 3 articles were excluded and 3 articles left for inclusion in the review [6, 16, 17] PRISMA flow diagram (Fig. 1) demonstrates the screening and selection of the included studies. Table 2 demonstrates the description of the included studies. All the included 3 Randomised controlled trials were published in the last 10 years that is from 2010 to 2020. Somatic tinnitus patients attributed due to cervical spine or temporomandibular dysfunction included in all the studies. A total of 70 participants obtained manual therapy as an intervention and 69 patients were either in control group or received any other treatment. All the studies opted for parallel group design and involve both males and females in their studies. The outcomes used in all the studies were Tinnitus Handicap Inventory or Tinnitus functional index to evaluate quality of life, pain pressure threshold, and visual analogue scale as a primary outcome measure.

Fig. 1.

PRISMA (2009) flow chart

Table 2.

Summary of included studies

References	Study design/aims	Participants	Intervention	Outcome measures	Findings(p values) OR others as given	Conclusion
Bonaconsa et al. [16]	Randomised Controlled Trial/ To evaluate somatic components to tinnitus and to find out effects of two physical therapy treatment	40 Somatic tinnitus patients. Osteopathic manipulation (N = 20) Transcutaneous Dynamic electrical stimulation (N = 20)	Osteopathic manipulations and Transcutaneous Dynamic electrical stimulation. (once a week for 2 months)	Audiogram,THI questionnaire, Posturography, VAS	THI (P < 0.0375), VAS (P < 0.06)	Manipulation therapy has positive effects on somatic tinnitus patients
Delgado et al. [17]	Randomized, parallel group, multicenter clinical trial/ To find out the effects of cervico-mandibular manual therapies on TMD attributed somatic tinnitus	61 Somatic tinnitus patients attributed due to TMD. Manual Therapy + Exercise + Education (N = 31) Exercise + Education (N = 30)	Manual therapy, Exercise and Postural Education (6 treatment sessions)	TMD pain, tinnitus severity, THI, CF-PDI, SF-12, BDI-II, PPT, ROM	THI(P = 0.707), PPT: Masseters(P = 0.643), Temporalis(0.863), TMJ(0.646)	Cervicomandibular manual therapies with exercise and education has better outcome than exercise and education alone
Michiels et al. [6, 8]	Delayed start randomized controlled trial/ To find out the effects of multimodel cervical physical therapy in cervicogenic somatic tinnitus patients	38 Somatic tinnitus Patients attributed due to cervical spine. Immediate Start Therapy group (N = 19), Delayed start Therapy Group (N = 19)	Multimodal Cervical Physical Therapy(Exercises for deep neck flexors + Self mobilizing Exercises) (12 sessions)	TFI,NBQ,VASand AST	TFI Decreased by 16.9 points (SD:26.6)	Cervical physical therapy has positive results on the tinnitus patients with neck complaints

THI Tinnitus Handicap Inventory, VAS Visual Analogue Scale; TMD = Temporomandibular Dysfunction; CF-PDI = Craniofacial Pain and Disability Inventory; SF-12 = 12 item short form health survey; BDI-II = Back Depression Inventory; PPT = Pain pressure threshold; ROM = Range of motion; NBQ = Neck Bournemouth Questionnaire; AST = Adapted Spurling Test

Evidence of Quality and Risk of Bias in the Included Study

Table 3 demonstrates the assessment of methodological quality of the included studies. Two studies were of acceptable quality and having moderate risk of bias and one study was having low risk of bias. Two studies have used allocation concealment and blinding in order to prevent performance and detection bias. Figure 2 demonstrates the risk of bias graph in the included study.

Fig. 2.

Risk of bias graph: presented percentage across each included study of authors’ judgment about each risk of bias item

Intervention

Table 2 summarizes information of intervention including types, duration, frequency and intensity. The effect of manual therapy on quality of life and pain pressure threshold was assessed by all three articles. All the studies provide manual therapy as an intervention for experimental group. Manual therapies are osteopathic manipulation, manual therapy, exercise, multimodal cervical physical therapy.

Manual Therapy and Quality of Life

All the three RCTs were included to find out the comparison between manual therapy and quality of life. (ORs 0.80; 95% Confidence Interval (95%CI), P = 0.97). Figure 3 demonstrates forest plot showing comparison of manual therapy and quality of life.

Fig. 3.

Forest plot showing comparison of manual therapy and quality of life

Manual Therapy and Pain Pressure Threshold

All the three RCTs were included to find out the comparison between manual therapy and pain pressure threshold. (ORs 0.80; 95% Confidence Interval (95%CI), P = 0.97). Figure 4 demonstrates forest plot showing comparison of manual therapy and pain pressure threshold.

Fig. 4.

Forest plot showing comparison between manual therapy and pain pressure threshold

Discussion

To best of the authors’ knowledge this is the first Meta analysis performed to find out the efficacy of manual therapy on pain pressure threshold and quality of life in somatic tinnitus patients. This review consists of only three studies to fulfil the inclusion criteria and to include only randomised controlled trials.

Three studies were analyzed in this study to find out the comparison between manual therapy and quality of life and manual therapy and pain pressure threshold in somatic tinnitus patients.

Recent systematic review was performed in 2019 by Lynn Kinne et al. [2] to find out the effects of manual therapy in somatic tinnitus patients. They include eight articles in their study which consists of three randomized controlled trials, two non randomized studies and three case reports. They concluded manual therapy as an effective intervention to treat somatic tinnitus patients.

Bonaconsa et al. [16] performed randomised controlled trial to find out the effects of physical therapy treatment on the somatic components of tinnitus. Twenty somatic tinnitus patients received osteopathic manipulations and twenty somatic tinnitus patients received transcutaneous dynamic electrical stimulation. Outcome measures were audiogram, THI Questionnaire, VAS and Posturography. All the outcome measures were improved in experimental group. They concluded manipulation therapy as a significant intervention to treat somatic tinnitus patients (P < 0.05).

Delgado et al. [17] performed randomized parallel group multicenter clinical trial to find out the effects of cervicomandibular manual therapies on patients with TMD associated somatic tinnitus. They included sixty one somatic tinnitus patients in which thirty one patients received combination of manual therapy, exercise and education and other thirty patients received only exercise and education. They concluded combination of manual therapy, exercise and education has significant results (P < 0.05) to treat somatic tinnitus patients associated with temporomandibular dysfunction.

Michiels et al. [6, 8] conducted randomised controlled trials to find out the effects of multimodal cervical physical therapy in treating somatic tinnitus associated with cervical spine. They provide 12 treatment sessions of multimodal cervical physical therapy to the immediate physical therapy and delayed physical therapy group. They had seen significant improvement (p < 0.05) in immediate physical therapy group and concluded multimodal cervical physical therapy as an effective intervention to treat somatic tinnitus patients associated with cervical spine.

Limitations

Only three studies were included in this review on which conclusion is based due to lack of published randomized controlled trials. The literature search was limited to few databases from last ten years and studies were limited to only English language. Therefore, there is a possibility of missing the articles which are published in other languages. The review includes the patients on somatic tinnitus only.

Strength of this review are only two reviewers perform the selection of studies and data extraction process. For quality check of the studies specific criterion scale has been used. Lastly, this is the first Meta analysis performed on the present topic.

Conclusion

Manual therapy has significant results on quality of life and pain pressure threshold. Further clinical trials are needed to explore manual therapy as an intervention to treat somatic tinnitus patients.