Introduction
Tinnitus is the perception of hearing sound in the absence of any external stimulus and can sound like a buzzing, roaring, hissing or clicking sound. It comprises two components: the perception of sound and the emotional reaction towards it. There have been attempts toward trying to understand tinnitus pathophysiology and provide specialised treatments to individuals with tinnitus.Reference Langguth, Kreuzer, Kleinjung and De Ridder1,Reference Fuller, Haider, Kikidis, Lapira, Mazurek and Norena2 Audiological treatment options include hearing aids, cochlear implants, tinnitus retraining therapy, sound devices, biofeedback, counselling and tinnitus maskers.Reference Henry, Zaugg and Schechter3 The most commonly used psychological therapies for tinnitus management included cognitive behaviour therapy, internet-delivered cognitive behaviour therapy and tinnitus education.Reference Thompson, Hall, Walker and Hoare4
The clinical practice guidelines for tinnitus have recommended against the use of pharmacological options, medicinal plants, dietary supplements and transcranial magnetic stimulation for tinnitus management.Reference Tunkel, Bauer, Sun, Rosenfeld, Chandrasekhar and Cunningham5 A recent systematic review on the effect of mindfulness-based intervention on tinnitus concluded that a decrease in tinnitus was noted among moderate-to-high quality studies. However, long-term effectiveness is uncertain and needs further exploration.Reference Rademaker, Stegeman, Ho-Kang-You, Stokroos and Smit6 There have been several treatment options explored for tinnitus management. No single curative treatment has been found so far for tinnitus, and most are aimed at ameliorating the impact rather than curing tinnitus.Reference McFerran, Stockdale, Holme, Large and Baguley7
There is growing interest and evidence towards the effectiveness of yoga in improving physical and mental health. Yoga involves several mental, physical and spiritual practices that help to bring good health and balance. It is often depicted metaphorically as a tree comprising eight aspects or limbs including: physical postures (asana), concentration (dharana), meditation (dhyana), ethics (niyama), breath control (pranayama), control of senses (pratyahara), universal ethics (yama) and bliss (samadhi).Reference Iyengar8 Yoga helps in enhanced muscular strength and flexibility, improved respiratory and cardiovascular function, reduced stress, depression, anxiety, better sleep and enhanced overall wellbeing and quality of life of an individual.Reference Kim9,Reference Woodyard10 Recent systematic reviews on the effect of yoga and meditation as an adjunct therapy have shown promising effects on reducing stress,Reference Wang and Szabo11 hypertension,Reference Tyagi and Cohen12,Reference Wu, Johnson, Acabchuk, Chen, Lewis and Livingston13 post-traumatic stress disorder, anxiety and depression.Reference Nguyen-Feng, Clark and Butler14
To date, there has been no systematic review of the literature on the effect of yoga and meditation on tinnitus. Thus, the present systematic review was planned to explore the published literature on the application of yoga and meditation on tinnitus.
Materials and methods
This systematic review was carried out and reported according to quality standards in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (‘PRISMA’) checklist.Reference Moher, Liberati, Tetzlaff and Altman15 A systematic search was carried out to identify the eligible studies exploring the effect of yoga on tinnitus. The eligible studies published up to June 2020 were included. PubMed, Scopus and Cochrane Library electronic databases were searched using suitable keywords and Boolean operators. The Population, Intervention, Comparator and Outcomes (‘PICO’) model was used in analysis.Reference McKenzie, Brennan, Ryan, Thomson, Johnston, Thomas, Higgins, Thomas, Chandler, Cumpston, Li and Page16 The Population, Intervention, Comparator and Outcomes search terms for the present review were as follows: population, individual with tinnitus; intervention, yoga or meditation; comparator, no comparison group; and outcome, change in tinnitus.
Only articles published in the English language were included. The exclusion criteria were: case reports, case series, letter to the editor and mindfulness-related intervention studies. Both the authors independently carried out the screening process. The relevant searches across the databases were gathered using Mendeley reference management software, and duplicates were removed. The authors sorted the articles based on inclusion and exclusion criteria, and any disparity was discussed and resolved.
The data from the included study were extracted using a pre-designed extraction sheet. The information that was extracted from the studies were: author and year of publication, country, study design, number of participants, age and gender, type of tinnitus, duration of tinnitus, objective of the included study, yoga and meditation related details, duration of yoga and meditation practice, and instrument used to measure the outcome and the results. The mixed methods appraisal tool (2018 version) was used for quality appraisal of the included studies.Reference Hong, Pluye, Fàbregues, Bartlett, Boardman and Cargo17 As per the procedural requirements, the mixed methods appraisal tool was independently administered by both the reviewers and compiled.
Results
A total of 142 studies were obtained, which were merged using reference management Mendeley desktop software, and 36 duplicates were removed. After the title and abstract screening based on inclusion and exclusion criteria, five studies were included. Figure 1 illustrates the schematic representation of the study selection process, and Table 1 displays the characteristics of studies included in the present review.
Fig. 1. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (‘PRISMA’) flowchart explaining the steps followed in review.
Table 1. Characteristics of included studies
Summary of study findings
The five studies in the review were conducted in different countries: Germany, India, the UK, Turkey and Poland. One study was a randomised controlled trial whereas the remaining studies used different observational study designs. All the included studies used validated questionnaires for studying outcomes on tinnitus following yoga and meditation. The type and duration of yoga and meditation varied across the studies. The duration varied from 5 to 120 minutes for 8 to 12 weeks. The quality appraisal of included studies was performed using the mixed methods appraisal tool (2018 version) as shown in Tables 2 and 3.The discussion is based on the different types of yoga and meditation and their effects observed across the different tinnitus outcome measures.
Table 2. Quality appraisal of included studies using the Mixed Methods Appraisal tool (2018)
Table 3. Quality appraisal of included studies using the Mixed Methods Appraisal tool (2018)
Discussion
The present systematic review aimed to explore the published literature on the application of yoga and meditation on tinnitus. Three electronic databases were searched to overcome publication bias and provide as many studies as possible. Both authors independently screened the studies at three levels to overcome reviewer bias. Five studies were found suitable and included in the review.
The studies included different types of yoga such as Hatha yoga,Reference Kröner-Herwig, Hebing, van Rijn-Kalkmann, Frenzel, Schilkowsky and Esser18 Brahmari pranayama,Reference Pandey, Mahato and Navale19 yoga and pranayama,Reference Köksoy, Eti, Karataş and Vayisoglu21 and Ashtanga yoga,Reference Niedziałek, Raj-Koziak, Milner, Wolak, Ganc and Wójcik22 while one study used relaxation therapy.Reference Arif, Sadlier, Kumar, James and Tahir20 Hatha yogaReference Kröner-Herwig, Hebing, van Rijn-Kalkmann, Frenzel, Schilkowsky and Esser18 comprises yoga exercises for fostering relaxation through breathing exercises and body postures (asanas). Brahmari pranayamaReference Pandey, Mahato and Navale19 involves pressing the tragus to occlude the external auditory meatus with the thumbs. The middle finger and index fingers are placed above the eyebrows while the ring and little finger are placed over closed eyelids. A deep breath is taken, and then a humming sound similar to a bee is made while releasing the breath while closing the mouth.
The yoga exercise routine used by Köksoy et al.Reference Köksoy, Eti, Karataş and Vayisoglu21 involved warm-up exercises, yoga postures and breathing exercises (pranayama) ending with meditation and relaxation. Ashtanga yogaReference Niedziałek, Raj-Koziak, Milner, Wolak, Ganc and Wójcik22 practices involved focus on the diaphragm and stretching muscles in the head, back, neck, torso, limbs and pelvis. These practices were aimed at improving blood circulation and reducing tension. The Hatha yoga, yoga and pranayama, and Ashtanga yoga were all taught and practised under the guidance of a qualified yoga instructor. Arif et al.Reference Arif, Sadlier, Kumar, James and Tahir20 conducted relaxation therapy across five sessions. The first session involved exploration and explanation. The second session involved mental skill development focusing on relaxation and visualisation. The third session was on cue controlled relaxation focusing on breathing. The next session was differential relaxation focusing more on relaxation while performing everyday activities. The final session involved rapid relaxation application.
Brahmari pranayamaReference Pandey, Mahato and Navale19 helped to reduce the irritability, anxiety and depression associated with tinnitus. The authors concluded that this positive change could be a result of inducing the parasympathetic system, with the humming acting as a source of self-generated noise and by acting as a relaxation technique. Kuppusamy et al.Reference Kuppusamy, Kamaldeen, Pitani, Amaldas and Shanmugam23 systematically reviewed several studies to conclude the encouraging effect of Brahmari pranayama on several physiological systems. Brahmari pranayama thus seems to be a low cost and quick technique that could be useful for individuals with tinnitus. Yoga and pranayamaReference Köksoy, Eti, Karataş and Vayisoglu21 helped in reducing the tinnitus handicap scores and reduced stress and tinnitus severity, and this is indicative of the usefulness of yoga in this population. After a 12-week course of Ashtanga yoga,Reference Niedziałek, Raj-Koziak, Milner, Wolak, Ganc and Wójcik22 there was improvement seen in terms of control over tinnitus, sleep, intrusiveness of tinnitus and quality of life. Niedziałek et al.Reference Niedziałek, Raj-Koziak, Milner, Wolak, Ganc and Wójcik22 also carried out magnetic resonance imaging studies and noted significant changes in the thickness of the right anterior circular sulcus of the insula and an increase of white matter volume in the right paracentral area following yoga. A reduction in the grey matter in the subparietal sulcus was also noted, which is indicative of a higher degree of emotional calming after the yoga training. These changes could also lead to an overall improvement in the patients’ perceptions towards their tinnitus. Out of the four studies exploring the effect of yoga on tinnitus, only one study did not support the effectiveness of yoga. Kröner-Herwig et al.Reference Kröner-Herwig, Hebing, van Rijn-Kalkmann, Frenzel, Schilkowsky and Esser18 compared yoga and tinnitus coping training. They concluded that patients treated with tinnitus coping training had higher satisfaction compared with yoga because tinnitus coping training gave the patient a feeling of more control over the symptoms of tinnitus. Arif et al.Reference Arif, Sadlier, Kumar, James and Tahir20 explored the effect of mindfulness meditation and relaxation therapy on various tinnitus outcomes. After relaxation therapy, improvement was noted for outcome measures such as distress, interference with activities, distress severity, avoidance, anxiety and depression associated with tinnitus.
• Yoga, as a physical, mental and spiritual practice, has a positive effect on tinnitus
• The present review highlights the usefulness of yoga in individuals with chronic tinnitus
• The combination of yoga along with the regular ontological and audiological treatment option can lead to better prognosis
Limitations and future recommendations
Studies published in English language and peer-reviewed journals only were considered for inclusion. Grey literature, unpublished work and articles in non-peer reviewed journals would have been missed out. Most of the included studies lacked a strong methodology and study design and included a limited number of participants. There is a need to have more randomised controlled trials in this area to evidence the effect of yoga on tinnitus empirically. Furthermore, the outcome measures used in the studies were mainly questionnaire-based, which could have an investigator or participant bias.
Conclusion
In order to have successful management of tinnitus, it is important to recommend options that help patients to overcome the symptoms. The findings of the present review highlighted the limited yet growing evidence towards the application of yoga in tinnitus management. Based on this, yoga and meditation could be included in the supportive treatment options that are made available for individuals with tinnitus.
Competing interests
None declared
