The behavioural treatment of muscle tension voice disorders: A systematic review.

International Journal of Speech-Language Pathology

ISSN: 1754-9507 (Print) 1754-9515 (Online) Journal homepage: http://www.tandfonline.com/loi/iasl20

The behavioural treatment of muscle tension voice disorders: A systematic review Clare Eastwood, Catherine Madill & Patricia Mccabe To cite this article: Clare Eastwood, Catherine Madill & Patricia Mccabe (2015) The behavioural treatment of muscle tension voice disorders: A systematic review, International Journal of Speech-Language Pathology, 17:3, 287-303, DOI: 10.3109/17549507.2015.1024169 To link to this article: http://dx.doi.org/10.3109/17549507.2015.1024169

View supplementary material

Published online: 08 May 2015.

Submit your article to this journal

Article views: 241

View related articles

View Crossmark data

Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=iasl20 Download by: [Australian National University]

Date: 05 November 2015, At: 19:07

International Journal of Speech-Language Pathology, 2015; 17(3): 287–303

The behavioural treatment of muscle tension voice disorders: A systematic review Clare Eastwood, Catherine Madill & Patricia Mccabe

Downloaded by [Australian National University] at 19:07 05 November 2015

The Voice Research Laboratory, Discipline of Speech Pathology, The University of Sydney, Sydney, Australia

Abstract Purpose: A systematic review of behavioural intervention for the treatment of adults with muscle tension voice disorders (MTVD). Method: A search of 12 electronic databases and reference lists for studies published between the years 1990–2014 was conducted using the PRISMA guidelines. Inclusion and exclusion criteria included type of publication, participant characteristics, intervention, outcome measures and report of outcomes. Methodological quality rating scales and confidence in diagnostic scale supported the literature evaluation. Result: Seven papers met the inclusion criteria. Significant improvement on at least one outcome measure was reported for all studies. Effect sizes were small-to-large. Methodological qualities of research were varied. No study explicitly reported treatment fidelity and cumulative intervention intensity could only be calculated for two out of seven studies. Outcome measures were used inconsistently and less than half of the measures had reported reliability values. Confidence in the accuracy of subject diagnosis on average was rated as low. Specific “active ingredients” for therapeutic change were not identified. Conclusion: Voice therapy for the treatment of MTVD is associated with positive treatment outcomes; however, there is an obvious need for systematic and high quality research designs to expand the evidence base for the behavioural treatment of MTVD.

Keywords: Intervention, systematic review, voice disorder

Introduction Muscle Tension Voice Disorder (MTVD), as defined by Baker, Oates, Leeson, Woodford, and Bond (2014), is a functional voice disorder that is differentiated from voice disorders of psychogenic and organic aetiology. The presence of MTVD may adversely affect quality-of-life in occupational, social, communicational and psychological domains (Ma & Yiu, 2001; Smith, Verdolini, Gray, Nichols, Lemke, Barkmeier, et al., 1996) and can place considerable economic burden on society (Roy, Merrill, Gray, & Smith, 2005). For these reasons, it is essential that Speech-Language Pathologists (SLPs) are able to make appropriate intervention decisions when treating people with MTVD so that management is efficient and efficacious. Behavioural voice therapy Behavioural voice therapy is defined in this study as any method of treatment that aims to improve vocal

function by modifying client behaviour. In clinical practice, SLPs who implement behavioural voice therapy are able to choose between direct and indirect approaches (Carding, 2000), a variety of individual voice therapy techniques and voice programs (Chan, McCabe, & Madill, 2013), as well as a range of pedagogic strategies (Mathieson, 2001). It has been reported that SLPs base their choices on a variety of themes including clinician experience, patient-centred factors and the evidence-base available (Chan et al., 2013). In consideration of one or a number of these themes, the first decision a therapist will make is whether the individual client would likely benefit most from indirect or direct therapy. Indirect voice therapy refers to treatment that does not directly focus on changing the mechanical function of the larynx (e.g. vocal hygiene, anti-reflux measures), while direct voice therapy aims to modify the mechanical functioning to allow for the development of optimal voice production (e.g. voice exercises) (Carding, Horsley, & Docherty, 1998).

Correspondence: Clare Eastwood, The Voice Research Laboratory, Discipline of Speech Pathology, The University of Sydney, Sydney, Australia. Email: clare. [email protected] ISSN 1754-9507 print/ISSN 1754-9515 online © 2015 The Speech Pathology Association of Australia Limited Published by Informa UK, Ltd. DOI: 10.3109/17549507.2015.1024169


288 C. Eastwood et al. Next, the clinician will decide whether to use a voice therapy technique, a voice therapy program or a combination. Techniques here refer to individual voice exercises (direct therapy) such as yawn-sigh (Boone & McFarlane, 1993) or, for example, use of amplification and ideal vocal hygiene (indirect therapy). Conversely, therapy programs are a set of exercises that follow a systematic and prescribed progression and might involve indirect or direct therapy in isolation or in combination. Examples of therapy programs include the Accent method (Thyme & Frøkjær-Jensen, 2001) and Lessac-Madsen Resonant Voice Therapy (LMVRT) (Verdolini, 2008). The clinical use of a combination of direct and indirect voice therapy techniques and/or programs, referred to as eclectic therapy (Joffe & Pring, 2008), is reported to be in common use (Chan et al., 2013; Gartner-Schmidt, Roth, Zullo, & Rosen, 2013). Eclectic therapy involves tailoring intervention to meet the needs of the individual clients (Chan et al., 2013). Finally, if direct voice therapy is selected as part of the intervention design, the SLP must also decide what pedagogic strategies will facilitate client learning for optimal laryngeal function. As outlined by Mathieson (2001), pedagogic strategies include modifying the vocal behaviour (explanation, modelling, imitation, generation/attempts at target behaviour and generalization), feedback/biofeedback, imagery, negative practice and awareness of perceptual differences. External evidence and systematic reviews An important framework from which to base clinical decisions is evidence-based practice (EBP). EBP, or more recently termed E3BP (Dollaghan, 2007), is defined as the judicious application of three sources of information to decision-making: best available external evidence (scientific research), best available internal evidence (clinical factors) and client preferences. The design of the present study, a systematic review, provides the highest level of external evidence from which to recommend evidence-based practice (Coleman, Norris, Weson, Grimmer-Somers, Hillier, Merlin, et al., 2009). According to the E3PB framework, it is important to integrate the highest quality external evidence into the clinical decision-making process (Dollaghan, 2007). Systematic reviews are used to appraise and synthesize a number of studies, often with the aim of recommending clinical practice guidelines (Schlosser, Wendt, & Sigafoos, 2007). Thus, systematic reviews can provide strong scientific support for intervention methods. This support might (a) demonstrate that intervention has a positive effect, (b) substantiate that one/some interventions are more effective than another and (c) verify the active ingredients (how and

why a treatment is effective) (Kaderavek & Justice, 2010). Considerations for appraising the behavioural voice therapy literature In evaluating the scientific evidence for treatment of MTVD, there are a number of important considerations. First, it is essential that treatment studies clearly define and accurately diagnose the target population in order to correctly interpret therapy effects (Murray, McCabe, & Ballard, 2014). Second, consideration of the methodological design and the quality of design is recommended (Schlosser et al., 2007), as merely labelling the type of design (e.g. Randomized Controlled Trial–RCT) does not account for a study’s validity. For example, if a RCT has poor allocation concealment and no blinding, exaggeration of the treatment effects might result (Schulz, Chalmers, Hayes, & Altman, 1995). An appraisal of the individual studies should also assess treatment fidelity (Hinckley & Douglas, 2013); that is, the degree to which an intervention has been reliably administered in correspondence to its prototype (Moncher & Prinz, 1991). Failure to report fidelity risks both the internal and external validity of a study (O’Donnell, 2008; Zvoch, 2012). Finally, the accuracy and reproducibility of a study’s results depends on the reliability of the outcome measures used. An examination of the reliability of outcome is, therefore, important when analysing the effects of treatments in a systematic review. Systematic reviews and behavioural voice therapy Previous systematic reviews which examined the effects of voice therapy generally reported positive treatment effects (e.g. Maryn, De Bodt, & Van Cauwenberge, 2006; Ruotsalainen, Sellman, Lehto, Jauhiainen, & Verbeek, 2007; Ruotsalainen, Sellman, Lehto, & Verbeek, 2008; Speyer, 2008; Ziegler, Gillespie, & Verdolini Abbott, 2010). However, these reviews have a number of methodological limitations including, for example, lack of reporting of appraisal of the diagnostic methods used, as well as of treatment fidelity and reliability of data extraction (Maryn et al., 2006; Ruotsalainen et al., 2007, 2008; Speyer, 2008; Ziegler et al., 2010). Furthermore, previous systematic reviews represent appraisal of the literature regarding the effects of behavioural therapy in different populations of interest ranging from functional voice disorders (Ruotsalainen et al., 2007, 2008) to voice disorders in general (Maryn et al., 2006; Speyer, 2008) and voice disorders among teachers (Ziegler et al., 2010). As populations with dissimilar types of voice problems respond differently to treatment (Fischer, Gutenbrunner, & Ptok, 2009), it is important to conduct systematic reviews with a specific focus on intervention for people with MTVD.

Systematic review of voice treatment 289


Purpose of the current study

Inclusion criteria

This study is a systematic review of behavioural voice intervention specifically focused on the population of MTVD. It’s purpose is to provide a broad view of voice therapy methods used in the treatment of MTVD and their effectiveness in order to guide SLP practice and expose gaps in the literature for future research. The study aims to answer the following research questions:

Criterion 1: Type of publication. 1a: Study design. All types of experimental treatment studies were included in the review, as were case series. Case reports and case studies without experimental control were excluded. Studies that only included subjects that were retrospectively deemed as having a successful response to therapy such as selection of successful cases from a database were also excluded (for example see Roy, Nissen, Dromey, & Sapir, 2009, p. 126).

1. Is voice therapy effective for treating MTVD? 2. Is one or more methods of therapy more effective than another for the management of MTVD? 3. If positive effects are shown, what are the active ingredients of the voice therapy?

Method In order to answer these questions a systematic review was conducted. Figure 1 shows a flow chart adapted from PRISMA (Moher, Liberati, Tetzlaff, & Altman, 2009) reporting the processes of the review.

1b: Place of publication. Originally, studies that were peer reviewed and published in a journal were included. Given potential publication bias as a result of this restriction, peer reviewed conference proceedings and approved masters or doctorate research theses were later also considered for inclusion. Research theses were regarded as “peer reviewed” in the general sense that they undergo a review process by experts in the field; however, limitations of the review process including that examinations are frequently not blinded are acknowledged. 1c: Language. Publications written in all languages were considered during the initial database searches; however, only English language documents were

Records identified through database searching on 11 and 24 May 2013 (n = 19861)

Records identified through updated database searching on 26 Feb 2014 (n = 1341)

Records after duplicates removed (n =11793)

Records after duplicates removed (n =478)

Additional records identified through reference lists (n = 70)

Additional records identified through reference lists (n = 0)

Records screened (n = 11863)

Records excluded (n = 12069)

Full-text articles assessed for eligibility (n = 272)

Studies included in analysis (n = 7)

Records screened (n = 478)

Full-text articles excluded (n = 265) 20 failed criterion 1a 64 failed criterion 1b 26 failed criterion 1c 23 failed criterion 2a 132 failed criterion 2b 0 failed criterion 3 0 failed criterion 4 0 failed criterion 5

Figure 1. PRISMA 2009 flow diagram (Moher et al., 2009).

290 C. Eastwood et al. ultimately considered eligible for analysis due to the first author’s (CE) restriction to English as an only language.


Criterion 2: Participant characteristics. 2a: Age. The physiological properties of the layered structure of the lamina propria are still in development up until the age of 16 years (Ishii, Yamashita, Akita, & Hirose, 2000). As physiological properties of the vocal folds impact on laryngeal functioning (Li, Heris, & Mongeau, 2013), studies were only considered if all participants were at least 16 years of age. 2b: Description of voice disorder. Participants within the studies had to have MTVD as defined by the Diagnostic Classification System for Voice Disorders (Baker, Ben-Tovim, Butcher, Esterman, & McLaughlin, 2007). This meant that studies had to provide an explicit report of an absence of psychogenic and organic voice disorder unless the definition of MTVD reported in the study (or from relevant citations) separated MTVD from a psychogenic and organic classification or if the aetiology was described as compensatory to a past organic or acute pathology. Studies were also included if participants were diagnosed with dysphonia or symptoms of voice disorder without the reported presence of an organic and psychogenic voice disorder, as defined by Baker et al. (2007). Also included were studies that explicitly reported participants diagnosed with phonotraumatic lesions as a result of habitual laryngeal dysfunction. This explicit report was considered essential because lesions, for example, vocal nodules and polyps, can be caused by either habitual laryngeal dysfunction or underlying diseases such as reflux (Hocevar-boltezar, Radšel, & Zlargi, 1997; Kuhn, Toohill, Ulualp, Kulpa, Hofmann, Arndorfer, et al., 1998). Studies were excluded if the participants exhibited any of the following: psychogenic voice disorder; spasmodic dysphonia; puberphonia/mutational falsetto; gender dysphoria; structural voice disorder not associated with phonotrauma, e.g. papilloma, laryngeal web, acid reflux, chemicals, inhalants, presbyphonia (Martins, Gonçalvez, Pessin, & Branco, 2014); laryngeal injuries; neurologic voice disorder, e.g. vocal fold paresis, spasmodic dysphonia; other neurologic disorders causing weakness or in-coordination of the laryngeal muscles, e.g. Parkinson’s disease, amyotrophic lateral sclerosis or essential tremor; health conditions that can affect voice or therapy progress, e.g. hearing impairment, laryngeal carcinoma; or other systemic conditions affecting laryngeal function. This strict criterion was considered essential because, while terminologies used to describe voice disorders in the literature including MTVD are often used interchangeably they are not always synonymous (Baker, 2008). Hence, the criterion was important to establish a high degree of

confidence in results that reflected treatment effects on the intended population. Criterion 3: Intervention. Studies with any type of behavioural voice therapy were considered for inclusion. Laryngeal massage therapies were also considered as they are clinically used by SLPs to treat voice disorders (Chan et al., 2013). Studies that included medical (e.g. pharmaceuticals, acupuncture, Chinese medicine) or surgical treatment conditions used alone or in combination with behavioural methods were not included. Prevention studies were also excluded. Criterion 4: Outcome measures. Studies with any type of outcome measure relating to the “voice” were considered. This included patient reported measures (e.g. voice-related quality-of-life, voice handicap, voice symptoms), subjective measures (e.g. judgements on vocal quality, laryngeal image, spectrographic ratings) or objective measures (e.g. results generated via technology such as parameters from acoustic, aerodynamic, electroglottographic tools). Criterion 5: Reporting of outcomes. Only studies with quantitative analysis of at least one outcome measure were included. Search methods Electronic database searches. A systematic literature search was conducted using 12 electronic databases: CINHAL, Communication Sciences and Disorders Dome, ERIC, Medline, International Index to Performing Arts, International Index to Music Periodicals, Linguistics and Language Behaviour Abstracts, PsychInfo, Scopus, SpeechBITE, PubMed and the Web of Science. Searches used a combination of key words as well as MeSH and CINHAL terms (see Appendix A for the Medline search strategy as an example to be found online at http://informahealthcare.com/doi/ abs/10.3109/17549507.2015.1024169). There were no language limits applied to the searches; however, dates prior to 1990 were excluded and limits including peer review, scholarly journal, article/article in press and review were applied. These searches were completed by the first author (CE) within a single 24-hour period on 11 May 2013. The Medline database was selected and re-searched to ascertain reliability of the searches. Intra-reliability was completed on 11 May 2013. Inter-reliability between the first author and an independent SLP was completed on 24 May 2013. Both intra- and inter-rater reliability were 100%. A search was also conducted and completed on 24 May 2013 to retrieve conference proceedings and research theses. The previously mentioned search strategies were repeated in each database; however,

the limits “peer review, scholarly journal and article/ article in press” were not applied. Instead, limits to conference proceedings and dissertations were applied. The same method of intra- and inter-rater reliability completed for the article searches above was performed and completed on 24 May 2013. Intra- and inter-rater reliability were both 100%.


Reference list search. The reference lists of all articles and dissertations deemed relevant on an initial screening process (see below) were viewed by the first author (CE) to locate any documents not previously retrieved from the electronic database searches. Update on searches. The electronic and the reference list searches were repeated on 26 February 2014 to find articles, conference proceedings and theses published after 24 May 2013. Selection of eligible documents Screening and detailed evaluation. All references from the three database searches (11 May 2013, 24 May 2013 and 26 February 2014) and reference list searches were imported to EndNote X6. This program was used to remove duplicates and screen for relevant references. Based on the title, abstract and key word screen, the first author (CE) removed studies that met any exclusion criterion. A final year undergraduate SLP student completing an honours research project in the area of voice was recruited to repeat 20% of the screening process to assess reliability. The student participated in a 10-minute training session with the first author (CE), who explained the screening procedure. Written instructions and the selection criteria were also given to the student to use throughout the screening process. Reliability of the screening was 100%. Full text copies of all relevant articles identified through the electronic searches and reference lists were obtained and a more detailed evaluation completed. The first author (CE) applied the inclusion/ exclusion criteria to each study and removed those that did not meet all inclusion criteria or met an exclusion criterion. A random 20% selection of the documents was assessed by an independent and fully qualified SLP. The ratings of inclusion and exclusion from this selection were compared between the first author (CE) and the independent SLP. Inter-rater reliability was 96%. In order to rule out the possibility that disagreements were due to errors in reading rather than a true disagreement about whether a study met or did not meet the inclusion/exclusion criteria, both authors re-read and re-rated the articles that did not have comparable ratings. Inter-rater reliability after the second reading was 100%.


Data extraction and analysis Data of interest. Key data of interest were extracted by the first author (CE). Participant characteristics (description of voice disorder, severity of dysphonia, gender and age); outcome measures (type of measure and reliability ratings), results of treatment (p-values and effect sizes) and reliability of outcomes were extracted directly from included studies. For single case experimental designs (SCEDs), results of treatment were only extracted for outcome measures with repeated observations throughout phases. Probability values and effect sizes for group designs were only extracted for statistically significant data. When effect sizes were not reported within the article, they were calculated from other reported statistical values (e.g. mean, standard deviation). Authors were contacted for further information when inadequate statistical data were reported within the original papers to calculate the effects. For SCEDs, results and effect sizes were extracted or calculated (effect size only) if an article reported an improvement of behaviour from a baseline to treatment phase or follow-up phase. Classification of MTVD. Using definitions described by Baker et al. (2007), participants in the included studies were classified into either MTD type I, MTD type II or a mixed MTVD group based on the descriptions included in the papers. Confidence in diagnosis. There is a wide variety of measures available for voice measurement, but currently no standard method of voice evaluation (Roy, Barkmeier-Kraemer, Eadie, Sivasankar, Mehta, Paul, et al., 2013). While there is no standardized method of evaluation, the American Academy of Otolaryngology–Head and Neck Surgery guidelines suggest that the following should be included in evaluation: (a) patient history, (b) identification of a voice symptom by the patient or clinician and (c) visualization of the larynx (Schwartz, Cohen, Dailey, Rosenfeld, Deutsch, Gillespie, et al., 2009). In order to diagnose disorders that are functional, methods to visualize the larynx must allow inspection of vocal fold vibration such as that obtained through stroboscopy (Schwartz et al., 2009) and high speed imaging (Sataloff, Hawkshaw, Divi, & Heman-Ackah, 2007). Psychological assessment has also been suggested to be important when exploring factors contributing to the aetiology of a voice disorder (Baker, 2008). A 5-point rating scale (0  no confidence to 4  high confidence) was developed by the present study’s authors based on the above information and the rating scale used by Murray, McCabe, and Ballard (2014). Because the scale was developed specifically for the confidence in diagnosis of participants with MTVD, testing of the scale for reliability was completed on one of the studies that met the inclusion criteria of the review. This was

292 C. Eastwood et al.


completed by two qualified SLPs independent from the current study, who each rated the same article. Inter-rater reliability between the SLPs was 100%. The first author (CE) then used the scale to rate the confidence in the diagnosis of participants within each study included in the review. The rating scale and instructions are shown in Appendix B to be found online at http://informahealthcare.com/doi/ abs/10.3109/17549507.2015.1024169. Level of evidence and methodological quality. Within Australia the level of evidence hierarchy in common use is that described by the Australian National Health and Medical Research Council (NHMRC) (see Coleman et al., 2009, p. 6). This hierarchy consists of four levels and was used in the present study to rate systematic reviews, randomized-controlled trials (RCTs), non-controlled trials (NRCTs) and case series. For SCEDs, the five-level evidence hierarchy described by Logan, Hickman, Harris, and Heriza (2008, p. 100) was used. All ratings of the level of evidence were completed by the first author (CE). The methodological quality of each study was rated using a number of scales depending on the study’s design. Ratings of RCTs and NRCTs were obtained from the speechBITE database (see http:// speechbite.com/). Ratings of methodological quality on this database are published only after two trained independent raters have reached a consensus rating on a paper (Murray, Power, Togher, McCabe, Munro, & Smith, 2013) using the PEDro-P scale. The PEDro-P scale (see www.psychbite.com/docs/ The_PEDro-P_Scale.pdf) is a reliable, 11-item scale that assesses the validity of a study’s findings and whether it reports adequate statistics for interpretation (Murray et al., 2013). Item 1 relates to the external validity of a study; however, it is not included in the final quality rating score (Murray et al., 2013). Case series were not rated for their design quality as they are considered to have questionable reliability and low empirical value (Perdices, Schultz, Tate, McDonald, Togher, Savage, et al., 2006; Togher, Schultz, Tate, McDonald, Perdices, Smith, et al., 2009). The methodological quality of SCEDs was rated using the SCED scale (Tate, Mcdonald, Perdices, Togher, Schultz, & Savage e, 2008). The authors of the present study acknowledge that a revised version of the SCED scale called the RoBiN-T scale (Tate, Perdices, Rosenkoetter, Wakim, Godbee, Togher, et al., 2013) has been developed; however, this scale has not yet been published. The SCED scale is a reliable and valid scale that consists of 11 items, with items 2–11 contributing to the methodological quality score (Tate et al., 2008) (see http://www.psycbite.com/docs/The_SCED_Scale.pdf). Analogous to SpeechBITE PEDro-P ratings, SCED papers were rated by two raters who reached a consensus score. The ratings were completed by the first author

(CE) and an independent, qualified SLP trained in the use of the SCED scale. The ratings between the SLP and first author (CE) were compared for reliability. Initial comparisons yielded an inter-rater reliability of 91%. In order to rule out the possibility that disagreements were due to errors in reading rather than true disagreements about whether a SCED item had been met or not, both authors reread and re-rated the articles that had conflicting ratings. Inter-rater reliability after the second reading was 100%. Treatment fidelity. Given the importance of treatment fidelity for making accurate interpretations of treatment results, this element was added to the methodological quality ratings of all RCTs, NRCTs and SCEDs. The first author rated whether each of the studies provided a measure of treatment fidelity or not by binary choice. A study was given a rating of “yes” if it reported that treatment fidelity was measured and a rating “no” if there was no such report. Available voice therapy types. Each study’s treatment method was classified according to its characteristics. The characteristics included (a) category of therapy (indirect vs direct vs combined; Carding et al., 1998), (b) type of therapy (single or mixed use of techniques and/or programs) and (c) approach to therapy (individualized vs controlled). Individualized treatment was defined as any treatment method in which techniques were selected to meet the client’s and/or the clinician’s needs, whereas controlled treatment was defined as treating all participants with the same therapeutic method. The pedagogic strategies used in each treatment that were directly reported within the study’s text were also identified. Pedagogic strategies of interest were those outlined by Mathieson (2001, pp. 486– 495) and comprised modifying the vocal behaviour (explanation, modelling, imitation and generalization), feedback/biofeedback, imagery, negative practice and awareness of perceptual differences. The number of practice attempts at generating the target behaviour was analysed separately in the present review as part of intervention intensity (see below). In addition, for those studies that reported controlled treatment, the studies or treatment manuals cited for the direct techniques or programs used were retrieved and pedagogic strategies contained within were identified. Finally, the cumulative intensity of the treatments was determined. Cumulative intervention intensity was calculated as the product of dose (number of client attempts at target behaviour per session) multiplied by dose frequency (number of times a dose is given per week) and total intervention duration (total period of intervention time) (Baker, 2012; Warren, Fey, & Yoder, 2007). Session duration and home practice were also identified, but not included as part of the calculation for cumulative intervention intensity.

3 2 Muscle tension dysphonia Functional ventricular fold phonation 19–55 (30.3) 26

1 Muscle tension dysphonia 17–77 (NR)

1 Non-organic dysphonia 16–75 (NR)

Non-organic dysphonia 18–71 (43)

Muscle tension dysphonia 17–87 (44)

Case series SCED (7/10) IV II Mathieson et al. (2009) Watson et al. (1993)

Case series IV Demmink-Geertman (2008)

NRCT (4/10) III-1 Demmink-Geertman (2010)

NRCT (4/10) III-1 Carding, Horsley, & Docherty (1999)

RCT (6/10) II Rattenbury et al. (2004)

ote: Level of evidence for group studies rated using the NHMRC level of evidence hierarchy (Coleman et al., 2009); level of evidence for the SCED study rated using that described in Logan et al. (2008); N quality of design ratings based on the PEDro-P scale (Murray et al., 2013); SCED quality rating based on the SCED scale (Tate et al., 2008); classification of MTVD type I and type II based on that described by Baker et al. (2007); confidence in diagnosis rating (0  no confidence; 1  very low confidence; 2  low confidence; 3  moderate confidence; 4  high confidence). RCT, randomized controlled trial; G, group; NRCT, non-randomized control trial; NR, not reported; SCED, single-case experimental design.

3 2 Muscle tension dysphonia 22–54 (42.5)

G1: 22; female; mild-to-moderate G2: 18; female; mild-to-moderate G1: 26; male:female ratio of 1:6; at least moderate G2: 24; male:female ratio of 1:5; at least moderate G1: 11 females; 4 males; NR G2: 13 females; 2 males; NR G3: 12 females; 3 males; NR Ge1: 34; female; NR G2: 34; females; NR G1: 76 females; 25 males; NR G2: 92 females; 34 males; NR G1:8 females; 2 males; mild-to-moderate 1(M) Single subject: male; severe RCT (7/10) II

Design (quality rating)

Pedagogic strategies directly reported in studies. Two studies used biofeedback as a method of client teaching (Rattenbury, Carding, & Finn, 2004; Watson, Allen, & Allen, 1993), trans-nasal flexible laryngoscopy (Rattenbury et al., 2004) and electromyography (Watson et al., 1993). Imagery instruction was also used in Watson et al. (1993) and relaxation instructions were provided in Mathieson, Hirani, Epstein, Baken, Wood, and Rubin (2009). Two studies used generalization of the target behaviour into other contexts by providing home practice (Duong & Kenny, 2009; Watson et al., 1993).

Level of evidence

Intervention

Study

Subject characteristics

The characteristics of each study’s participants (number of participants and severity of disorder) as well as the classification and confidence in voice disorder diagnosis are displayed in Table I. The evaluations according to the level of evidence and the quality rating scales are also shown in Table I. Studies that could be rated using either the PEDro-P or SCED scales (i.e. not Case Series), including fidelity ratings, are shown in Table II.

Number; gender; severity

Age range (mean)

Study characteristics

Duong and Kenny (2009)

Figure 1 shows a flow chart adapted from PRISMA (Moher et al., 2009), indicating the number of publications originally found, excluded and included in the review. Seven studies met the review criteria and were assessed. Excluded papers were not analysed further in this review.

Table I. Study description: Subjects, design and methodological quality.


Search results

Therapy categories, types and approaches. The categories, types and approaches to therapy for each study are shown in Table III. The category, type and approach for some treatment methods could not be determined based on the published material. For a list of specific therapy programs and techniques used in each study, see Appendix C to be found online at http://informahealthcare.com/doi/abs/10.3109/1754 9507.2015.1024169.

Mixed (I and II) Diagnosis/description of VD

Result

Type II

The first author re-extracted all data obtained from included studies for calculation of intra-rater reliability. In order to determine inter-rater reliability, an independent SLP extracted data from two (29%) randomly selected studies. The intra-rater reliability of the data extraction was 99% and the inter rater reliability was 100%.

Type I

Confidence in diagnosis rating

Reliability of data extraction

2


No

Intensity of therapy. The cumulative intervention intensity (product of dose  dose frequency  total intervention duration) could only be calculated for two studies. For the remaining studies, cumulative intervention intensity could not be calculated due to limited reporting of the intensity parameters: dose (number of client acts per session); dose frequency (number of times a dose is given per week); and total intervention time (total period of intervention time) (Baker, 2012; Warren et al., 2007). Only two out of the five studies reported home practice. See Table IV for a description of the parameters of intensity in each study.

No Yes

No

No

Fidelity measurementa Replication Independence of assessors

Pedagogic strategies reported within the cited documents. The pedagogic strategies contained within the referenced documents for a number of direct therapy methods were not considered suitable for analysis because they were used within an individualized approach. There were two remaining studies that examined controlled intervention methods and provided citations: Demmink-Geertman (2010) used a program called Co-ordination Therapy to treat one of their groups and Duong and Kenny (2009) used Vocal Function Exercises (VFE) to treat one group and a partial version to treat another. The citation provided by Demmink-Geertman (2010) was not English and, therefore, any teaching strategies in this document were not analysed. Duong and Kenny (2009) reported a citation which did not use the name “vocal function exercises”; however, there was a set of exercises in the cited document which matched the description of the exercises described in the article. Therefore, the pedagogic strategies used in this document were identified and included explanation of the tasks (Stemple, 1984, pp. 131–132).

a Fidelity

Yes Watson et al. (1993)

of treatment criteria not part of the PEDro-P scale or SCED scale.

Sufficient Raw data Inter-rater treatment recorded reliability sampling Yes Yes Yes Target Control in Sufficient behaviour design baseline defined sampling Yes Yes Yes Clinical History

SCED scale item and fidelity scores

Statistical analysis

Generalization

No No Yes Yes No No

No Yes No No Yes No

Yes No No No No No

Yes Yes

No No

Yes Yes

No Yes Yes

No Yes No

Duong & Kenny (2009) Rattenbury et al. (2004) Carding et al. (1999) Demmink-Geertman (2010)

No

Yes Yes Yes

Yes No No

Yes

No

Yes

No Yes Yes Yes Yes Yes No No

Retention of Intention to Between group more than 85% treat analysis comparisons Blinding of assessors Blinding of Blinding of subjects therapists Concealed allocation Random allocation Eligibility specified Study

Table II. Quality ratings and fidelity measurement.

Baseline comparability

PEDro-P scale item and fidelity scores


Post estimates and variability

aFidelity measurement


Effectiveness of therapy. Outcome measures and significant therapeutic results are shown in Table III. Only the outcomes that were repeatedly measured across phases in the SCED study by Watson et al. (1993) are shown. The acoustic measures jitter and shimmer were used across multiple studies (Carding et al., 1999; Duong & Kenny, 2009; Mathieson et al., 2009); however, these were calculated using different computer programs. The literature recommends against comparison of perturbation scores between different systems (Amir, Wolf, & Amir, 2009; Elisei, 2012), so no comparisons were undertaken on this measure. Effect sizes of significant results are also shown in Table III. The methods for calculating effect sizes that were used by the first author (CE) are outlined in the footnotes below the table. The effect sizes derived from Duong and Kenny (2009) represent maximum values. In that study, data were collected from teachers across 14 different schools. Pre–post within, as well as between, group data were analysed using multiple t-tests. In order to minimize the probability of type 1 error and account for the variance

G1: Direct and Indirect G2: Direct and Indirect

G1: Direct and Indirect G2: Direct and Indirect (plus biofeedback)

G1: No treatment G2: Indirect G3: Indirect and Direct

Rattenbury et al. (2004)

Carding et al. (1999)

Category

Duong and Kenny (2009)

Study

G1: Mix of techniques G2: Mix of techniques

G1: Mix of techniques and programs G2: Mix of techniques and programs (plus therapy trial and biofeedback)

G1: Mix of techniques and a program G2: Mix of techniques and part of program

Type

Treatment Approach

G1: Individual G2: Individual

G1: Individual G2: Individual

G1: Controlled G2: Controlled

Table III. Treatment classifications, outcome measures and results.

Questionnaire: self-assessment of vocal performance and severity Auditory perceptual: overall severity scale (W  0.89) Indirect/fibre-optic laryngoscopy EGG: qualitative scale ratings (W  0.83) MSF0 Acoustic: SNR, jitter and shimmer Telephone review: 24 patients contacted to ascertain further episodes of dysphonia. Timing of Ax: All pre–post therapy except telephone review which occurred 6 months post-treatment.

(Continued)

Acoustic: significant improvement in G1 from pre–post treatment: jitter: p  0.001, d  1.05a; shimmer: p  0.001, d  1.00a; HNR: p  0.001, d  -1.55a. Tonal acoustic: significant improvement in G1 from pre–post treatment: F0 of T3: p  0.016, d  -0.64; F0 of T5: p  0.017, d  -0.35; target F0: p  0.004, d  -0.66; rise size: p  0.017, d  -0.62; rise speed: p  0.002, d  -1.09. Significant difference between G1 and G2: rise speed: higher in G1: p  0.009, d  1.40b. Auditory perceptual: significant improvement in G1: severity rating: p  0.001, d  0.55a. Questionnaire: significant difference between G1 and G2: voice quality: G1 improved rating of loudness: p  0.05, d  0.80b; G1 improved rating of “out of breath in talking”: p  0.05, d  0.77b; voice knowledge: G1 had greater vocal behaviour score: p  0.05, d  0.86b. Auditory perceptual: significant improvement in both groups; G: G1; p  0.01, G2; p  0.01, B: G1; p  0.01, G2; p  0.01, A: G1; p  0.01, G2; p  0.01, S: G1; p  0.01, G2; p  0.01. Questionnaire: significant improvement in VPQ for both groups; G1; p  0.01, d  1.63c, G2; p  0.01, d  1.59c. EGG: significant improvements in both groups; jitter (V): G1; p  0.01, G2; p  0.01; jitter (CS): G1; p  0.01, G2; p  0.01; shimmer (V): G1; p  0.01, G2; p  0.01; shimmer (CS): G2; p  0.01. Efficiency: Significant difference in the efficiency of therapy between G1 and G2: p  0.01 with G2 the most efficient. Questionnaire: Significant difference between the scores of all three groups: G1 vs G2; p  0.05, r  -0.32d, G2 vs G3; p  0.05, r  -0.42d, G1 vs G3; p  0.05, r  -0.59d. Auditory perceptual: Significant difference between the scores of all three groups: G1 vs G2; p  0.05, r  -0.27d, G2 vs G3; p  0.05, r  -0.43d, G1 vs G3; p  0.05, r  -0.62d. EGG: Significant difference between the scores of all three groups; Lx trace scale: G1 vs G2; p  0.05, r  -0.32e, G2 vs G3; p  0.05, r  -0.37e, G1 vs G3; p  0.05, r  -0.66d Acoustic: Significant difference between shimmer values of G1 and G3: p  0.05, r  -0.42d with G1showing greatest improvement

Acoustic: Jitter, shimmer, HNR Tonal acoustic: F0 of broken tone, F0 of rising tone, parameters of pitch movement (target F0, rise time, rise size, rise speed) Auditory perceptual: severity ratings (a  0.951, ICC single ratings  0.795, ICC average ratings  0.951) Questionnaire: voice quality, overall severity, voice knowledge Timing of Ax: pre–post therapy

Auditory perceptual: GRBAS Questionnaire: VPQ EGG: jitter and shimmer on both vowel (V) and connected speech (CS) samples Efficiency: amount of contact time with subjects. Timing of Ax: pre–post therapy

Significant outcomes and effect sizes

Outcome measures



G1: Direct and Indirect G2: Direct (only examples were reported)

G1: NR G2: (normal controls did not receive therapy)

G1: Direct

DemminkGeertman (2008)

Mathieson et al. (2009)

Category

DemminkGeertman (2010)

Study

Table III. (Continued)

Single program

NR

G1: Single program G2: Mix of techniques (possibly inclusive of programs)

Type

Treatment

G1 Controlled

NR

G1: Controlled G2: Individual

Approach

Acoustic: F0, Jitter, Shimmer, NHR, VTI, SPI on V samples. F0, RAP, APQ, NHR, VTI, SPI, PI, DFx1&2, DQx1&2 on CS samples. Formant frequency: F1 and F2 VTD: symptom frequency and symptom severity: Burning, tight, dry, aching, tickling, sore, irritable, lump in throat (a  0.890 at baseline, a  0.893 at 1 week follow-up) Palpatory evaluation: left SCM right SCM, supralaryngeal area, laryngeal resistance, laryngeal position (a  0.886 at pre, a  0.929 at post, a  0.935 at 1 week follow-up) Timing of Ax: pre–post-1 week post: formant frequency, acoustic, symptom severity; pre–post: palpatory evaluation; pre-1 week: symptom frequency

Questionnaire: voice symptoms/complaints (neurovegetative-related, voice-related and non-relevant) (k  0.72) Timing of Ax: pre–post therapy

Questionnaire: voice symptoms/complaints (neurovegetative-related, voice-related and non-relevant) (k  0.58) Timing of Ax: pre–post therapy

Outcome measures


(Continued)

Questionnaire: significant pre–post improvement of complaints in both groups; neurovegetative-related: G1; p  0.001, G2; p  0.05; voice-related: G1; p  0.001, G2; p  0.01. The neurovegetative- and voice-related complaints were considered together in calculation of effect size: G1; d  1.46, G2; d  0.98. Significant group differences post-therapy: voice-related: greater improvement in G1: p  0.015, d  0.43. Questionnaire: significant pre–post improvement in G1: neurovegetative-related: p  0.000 001, d  0.93c; voice-related: p  0.000 000 1, d  1.00c. Significant group difference remains between G1 and G2 post-therapy: voice-related: p  0.000 007, d  0.62b Acoustic: Significant improvement from pre–1 week post: p  0.02, hp2  0.45. VTD: Significant improvement: symptom frequency: pre–1 week post: dry: p  0.016, hp2  0.54; tickling: p  0.003, hp2  0.69; sore: p  0.001, hp2  0.75; irritable: p  0.013, hp2  0.56: symptom severity: pre–post: tight: p  0.003, hp2  0.55; dry: p  0.023, hp2  0.46; aching: p  0.026, hp2  0.42; sore: p  0.001, hp2  0.68: all significant differences in severity maintained at 1 week post, except for the tight variable. Palpatory evaluation: Significant improvement from pre–post: left SCM: p  0.001, hp2  0.93; right SCM: p  0.001, hp2  0.93; supralaryngeal area: p  0.001, hp2  0.89; laryngeal resistance: p  0.001, hp2  0.99.



Direct (plus biofeedback)

Category

One technique reported as an example (possibility that others were used)

Type

Treatment

N/A

Approach EMG: microvolts (non-vocalizing, counting, conversation) Auditory perceptual: Revised Buffalo II Voice Profile Aerodynamic: estimate of subglottal air pressure Fibre-optic endoscopy Timing of Ax: pre–post therapy. However, repeated observations only took place throughout the baseline and treatment phases for EMG

Outcome measures

EMG: Improved levels of microvolts following treatment phase compared to baseline phase across all three behaviours: nonvocalizing: IRD  1.00f; counting: IRD  1.00f; conversation: IRD  1.00f.


ategory, direct vs indirect vs combined; type, single vs mixed use of techniques and/or programs; approach, individual vs controlled; G, group; HNR, harmonics-to-noise ratio; F0, fundamental frequency; C a, cronbach alpha; ICC, intra-class correlation coefficient; d, Cohen’s d; GRBAS, grade roughness breathiness aesthenia strain; VPQ, vocal performance questionnaire; EGG, electroglottography W, Kendall coefficient of concordance; MSF0, mean speaking fundamental frequency; SNR, signal-to-noise ratio; r, Pearson’s correlation; k, cohen’s kappa; NHR, noise-to-harmonic ratio; VTI, voice turbulence index; SPI, soft phonation index; RAP, relative average perturbation; APQ, amplitude perturbation quotient; PI, perturbation irregularity; VTD, Vocal tract discomfort scale; SCM, sternocleidomastoid muscles; hp2, partial eta squared; EMG, electromyography. a Cohen’s d was calculated for dependent samples using reported means and original standard deviations (see Dunlap, Cortina, Vaslow, & Burke, 1996). Standard deviations were calculated using the descriptive statistics function of SPSS (Version 20.0, SPSS Inc., Chicago, IL) with data obtained from the authors of the study. b Cohen’s d was calculated for independent samples using reported means and pooled standard deviations. Pooled standard deviations were calculated by using reported means, group numbers and standard deviations (see Thalheimer & Cook, 2002). c Cohen’s d was calculated for dependent samples using reported means and original standard deviations (see Dunlap et al., 1996). d Pearson’s correlation r was calculated by dividing the z-score by the square root of the reported sample size. Z-scores were calculated using reported U-values and group numbers (see Gravetter & Wallnau, 2009). e Pearson’s correlation r was calculated by dividing the z-score by the square root of the reported sample size. U- and Z-scores were obtained by using reported subject difference scores to conduct a MannWhitney U-test using SPSS (Version 20.0, SPSS Inc.). f Improvement Rate Difference (IRD) was calculated as the difference between two improvement rates (see Parker, Vannest, & Brown, 2009).

Watson et al. (1993)

Study

Table III. (Continued)



due to school, a more appropriate option for statistical analysis in the study conducted by Duong and Kenny (2009) might have been to conduct a Nested ANOVA. Effect sizes could not be calculated for three out of the four outcomes in the study by Rattenbury et al. (2004), as requests to obtain data were not fulfilled.

Not reported

5–10

25–30

Demmink-Geertman (2008)

Mathieson et al. (2009)

Watson et al. (1993)

Note: Cumulative Intervention Intensity  product of dose  dose frequency  total intervention duration; —, unable to calculate; N/A, not applicable.

3840 productions 2/day, 15 minutes/practice

Not reported Demmink-Geertman (2010)

2/week

8 months, i.e. ∼ 32 weeks

— Not reported 1 day

N/A (clinician delivered rotational massage, kneading and stretching of perilaryngeal muscles) 20 attempts for each of the three responses

—

Not reported Not reported Rattenbury et al. (2004) Carding et al. (1999)

Not reported Not reported Not reported

— Not reported Not reported

10 Duong and Kenny (2009)

Not reported

Not reported Not reported

Not reported 8 weeks (including pre and post assessment) G1: 6.1 months (16.8) G2: 5.8 months (15.6) Average of 6.1 months (average of 18.7) 1 day (1) Not reported 1/week

G1: 320 productions G2: 80 productions — — 2/day/weekend 4 weeks 2/day for 5 days/week

G1: 2  of 4 exercises/practice G2: 2  of 1 exercise Not reported Not reported

Session length (minutes) Study

Table IV. Intensity of treatment and home practice.

Dosage (client acts)

Dose frequency

Total intervention duration (sessions)


Home practice

Cumulative intervention intensity (client acts)


Long-term effectiveness of therapy. No study analysed long-term effectiveness of therapy using probability values or, in the case of SCEDs, conducted repeated observations throughout retention phases. Based on patient reports, Carding et al. (1999), however, reported that 21 of the participants denied experiencing voice problems 6 months after treatment. Also, therapeutic gains were retained at two single 3- and 6-month follow-up points in the SCED study conducted by Watson et al. (1993). Reliability of outcome measures. Seven of 22 outcome measures were assessed for reliability. Based on the reported reliability values, outcomes were moderately-to-strongly reliable. The specific reliability values are shown in Table III. It is noted that Carding (1999) examined reliability (using Kendall coefficient of concordance  W) of the acoustic analyses for both within and between operators. While the authors reported p  0.05, the value of W was not reported.

Discussion The purpose of this review was to evaluate the available evidence for behavioural treatment of MTVD from the years 1990 to present. The study aimed to answer three questions relating to the scientific support of treatment: (1) Is behavioural voice therapy effective for treating MTVD? (2) Is one or more methods of therapy more effective than another for the management of MTVD? and (3) If positive effects are shown, what are the active ingredients of voice therapy? Effectiveness of behavioural voice therapy Behavioural voice therapy is complex and various factors are likely to influence client outcomes (Colton, Casper, & Leonard, 2011). Based on the results of this systematic review, behavioural voice therapy is associated with positive treatment effects as supported by the result of 10/11 treatment groups showing significant improvement (with small-tolarge effects), on at least one outcome measure from pre-therapy to immediately post-therapy. That said, based on the limitations in the literature, the authors were unable to confidently answer the first and second research questions. This finding is consistent with previous systematic reviews on voice therapy in general that have shown positive trends associated



with voice therapy but have also identified a number of gaps in the literature including in appropriate reporting standards and the general quality of research (e.g. Speyer, 2008; Ziegler et al., 2010).

participants reported in voice treatment studies. Inclusion of such items into the rating scale is, therefore, unlikely to have increased the confidence ratings found in the present review.

Scope of the literature. Despite the large number of papers identified through the literature search, only seven studies were eligible for analysis in the present review. This was largely related to the exclusion of papers that did not meet the study’s 2b criterion, “Description of voice disorder”. This specific criterion was considered integral due to the many terms used to describe MTVD in the literature. Although used interchangeably, these terms are not always synonymous (Altman, Atkinson, & Lazarus, 2005; Baker, 2008; Voerman, Langeveld, & Van Rossum, 2009). It is acknowledged that a number of participants in papers described as having, for example, Muscle Tension Dysphonia, FVD or non-organic voice disorder (e.g. Liang et al., 2014; Van Lierde, Claeys, De Bodt, & van Cauwenberge, 2007) or vocal nodules (e.g. Menezes, Ubrig-Zancanella, Cunha, Cordeiro, Nemr, & Tsuji, 2011) might have had MTVD but, without explicit statements of an absence of psychogenic and organic aetiology, these studies were not considered appropriate for inclusion. It is possible that a number of non-English language papers, identified through the database searches and initial screening (e.g. Canal, 2013; Guzmán, Callejas, Castro, García-Campo, Lavanderos, Valladares, et al., 2012), might have met the present review’s criteria. However, these papers were not analysed due to the restriction to English as the authors’ only language. Future systematic reviews and meta-analyses should consider translation, if funding permits, in order to increase the number of analysable studies and minimize language bias (Moher, Fortin, Jadad, Jüni, Klassen, Le Lorier, et al., 1996).

Methodology. Although only a small number of studies were analysed in this review, the level of evidence was relatively high compared to the general voice literature (Benninger, 2011). Methodological quality of the group studies evaluated by the PEDro-P included two studies implemented as “gold standard” RCTs that met over half of the quality criteria. The SCED paper (Watson et al., 1993) also met over half the SCED scale quality criteria (Tate et al., 2008). The two NRCTs, however, complied with less than half the quality criteria set by the PEDro-P (Murray et al., 2013). Blinding of participants and therapists were criteria that all studies failed. That said, blinding of participants and therapists is difficult, if not impossible, to achieve in behavioural treatment studies (Togher et al., 2009). Possibly, they should not be considered indicators of research quality in such research (Cherney, Simmons-Mackie, Raymer, Armstrong, & Holland, 2013). The measurement of treatment fidelity was another criterion that was poorly rated across all studies. Although treatment fidelity is not part of the PEDro-P scale or SCED scale, it was assessed in the present study because it is important to the accuracy of intervention delivery (especially considering the complexity of behavioural voice treatment). As none of the studies measured treatment fidelity, the extent to which the results reported by the individual studies reflect accurate interpretation is unknown (O’Donnell, 2008). This made judgement of behavioural therapy effectiveness for the treatment of MTVD difficult. Five of the seven studies reported a wide range of outcome measures, including patient reports and subjective and objective measurements, which is consistent with recommendations that voice evaluation be comprehensive (Roy et al., 2013). However, only one outcome measure was used across more than one study; a questionnaire used in the studies by Demmink-Geertman (2008, 2010). This made it difficult to compare the impact of therapies across studies more broadly. The reliability agreement was moderate-to-strong for those outcome measures with reported reliability values. Values of reliability were only available for seven of the 22 outcome measures, raising the possibility that the results for the remaining 14 outcome measures were unreliable.

Confidence in diagnosis. The confidence in the accuracy of diagnosis was, on average, low. Therefore, the extent to which the results of studies included within this review truly reflect the effects of voice therapy on MTVD alone are questionable. The low confidence ratings are perhaps related to the lack of standard methods of voice evaluation (Roy et al., 2013). It is also important to note that the rating scale items used to assess confidence in diagnosis were considered by the authors to be minimum confidence requirements. Other diagnostic tools have been found useful in differentiating voice disorders, including, for example, laryngeal EMG methods (García-López, Santiago-Pérez, Peñarrocha-Teres, del Palacio, & Gavilan, 2012; Heman-Ackah & Barr, 2006) and spectral analysis (Houtz, Roy, Merrill, & Smith, 2010; Rees, Blalock, Kemp, Halum, & Koufman, 2007). However, based on a search of the literature prior to developing the rating scale, these methods are used infrequently to diagnose

Parameters of intensity. The cumulative intensity of treatment (Baker, 2012; Warren et al., 2007) could be calculated for two of the seven studies. It is likely that, in voice therapy, the intensity of treatment provided interacts with the therapeutic techniques and/ or pedagogic strategies, producing effects that might

300 C. Eastwood et al. range from maximal benefit, to no observable change, to an adverse or undesirable effect (Roy, 2012). Efforts to report all parameters of intervention intensity in future studies are critical to not only establishing the most effective treatment, but also to avoid potential harm.


Individualized therapy. Individualized therapy was an approach used in over half the treatment groups. The definition of individualized therapy was alluded to in only one study (Rattenbury et al., 2004). Here, individualized (or “traditional” therapy as named in the study) was suggested to refer to basing the selection, duration and order of voice therapy techniques on a number of factors including the severity of the voice problem, the personality of the patient, the patient’s understanding of the problem, response to therapy strategies, therapy “trial and error” outcome, and the preferences of the treating voice therapist (Rattenbury et al., 2004, p. 524).

The studies that utilized individualized therapy (Carding et al., 1999; Demmink-Geertman, 2010; Rattenbury et al., 2004) supported the notion that voice therapy might be an effective method of treatment for MTVD. Demmink-Geertman (2010), however, found that the controlled treatment protocol “co-ordination therapy” was more effective than the traditional approach. Furthermore, in this review, studies utilizing an individualized approach added little to the understanding of what specific therapy methods are most effective. Factors responsible for change in behavioural voice therapy Techniques and active ingredients identified in the present study. A large variety of techniques, some pedagogic strategies and different parameters of treatment intensity were identified in this review. However, precisely what was responsible for the positive therapy effects observed in the individual studies was difficult to determine. The third research question, therefore, remained unanswered. Identifying individual factors responsible for therapeutic change was made difficult because six out of the seven studies did not investigate voice techniques or pedagogic strategies in isolation whilst controlling for other potential active ingredients that might have affected the independent variable, including, for example, modelling, explanations and clinician-delivered feedback. The only study that investigated a single therapy in isolation (Mathieson et al., 2009) showed preliminary evidence that reduced resistance of the sternocleidomastoids, as well as muscles in the supralaryngeal and laryngeal areas, might be responsible for improvement in voice-related measurements as a result of Laryngeal Manual Therapy; however, studies

with experimental control are required to determine the factors responsible for therapeutic change. Active ingredients in other areas of voice literature. When viewing voice therapy in the general literature, similarities to the present review are observed. Some of the most well known treatments in the literature in English (e.g. VFE, LMRVT) have reported significant improvement in a number of outcome measures following a period of therapy (Bassiouny, 1998; Nanjundeswaran, Li, Chan, Wong, Yiu, & VerdoliniAbbott, 2012; Sauder, Roy, Tanner, Houtz, & Smith, 2010); however, there have been few studies to determine precisely what is responsible for the treatment effects observed (Roy, 2012). Importance of determining active ingredients. A concern regarding the limited understanding of how and why voice therapy works is that a clinician’s ability to deliver the active ingredients is essential to the provision of effective therapy (Baker, 2012). Without an understanding of (a) what the specific active ingredients are; (b) their desirable and undesirable responses; and (c) the relationship of their responses to different dosages and combinations with other techniques and/or pedagogic strategies, there is a potential for clinicians to administer therapy that is sub-optimal or detrimental. This might include prolonged therapy duration, damage to laryngeal tissue and lowered quality-of-life (Roy, 2012). Recommendations for future research and clinical practice Development of an internationally accepted protocol for assessment and classification of voice disorders. We recommend continued efforts to reach an agreed upon framework for voice diagnosis and classification. This should enhance the ability of researchers to develop effective treatments tailored to specific voice disorders of different aetiologies, including MTVD. With the current absence of internationally accepted voice diagnostic and classification systems (Roy et al., 2013), we suggest that future treatment studies clearly document specific assessment procedures used and explicitly report aetiological origins of participants’ voice disorders. Increasing the scientific rigour of research and reporting. In order to allow for more accurate interpretation of results and study replication, we recommend that future investigations (a) provide access to detailed treatment manuals which document all aspects of treatment, including the techniques, pedagogic strategies and all parameters of intensity and (b) document treatment fidelity such as recording clinician and patient compliance with documented procedures and practice, respectively, using scripts in treatment research and publishing treatment



protocols prior to commencement of research (e.g. Murray, McCabe, & Ballard, 2012). We suggest that investigations examining both the therapeutic and physiological effect of single voice techniques and/or pedagogic strategies in isolation are also conducted. Studies of this type will assist in the identification of the active ingredients responsible for therapeutic change. Once these data have been obtained, interactions between different voice techniques or pedagogic strategies when used in combination, as well as manipulation of treatment intensity should be examined. Testing such treatment protocols through logically ordered sequences of research activities, such as the five-phase model for clinical outcome research outlined by Robey (2004) would provide a clearer evidence-base for the behavioural treatment of MTVD. Practice-based evidence. As is the case in many areas of SLP practice, the current lack of research evidence supporting differential application of behavioural methods for treating MTVD requires clinicians to benchmark their therapeutic outcomes (Perry & Shaw, 2000). If published, this may add to the evidence-base, stimulate change and improve quality of intervention (John, Enderby, & Hughes, 2005). Conclusion Systematic reviews can provide the highest level of evidence upon which to recommend E3BP, which is essential for providing clients with optimal treatment. Overall, the results of this study suggest that voice therapy for treatment of MTVD is associated with positive changes to outcome measures immediately following a period of therapy. However, there is an obvious need for high quality and systematic research in order to expand the evidence-base for the behavioural treatment of MTVD. Acknowledgements The authors acknowledge the following people for their assistance with aspects of the review: Dr Rob Heard, Loren Apokourastos, Katrina Blyth, Danielle Stone, Aimee Clark, Ellie Sugden and Claire Layfield. Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper. References Altman, K. W., Atkinson, C., & Lazarus, C. (2005). Current and emerging concepts in muscle tension dysphonia: A 30-month review. Journal of Voice, 19, 261–267. Andrews, M. (1999). Manual of voice treatment: pediatrics through geriatrics. San Diego and London: Singular Publishing Group.

Amir, O., Wolf, M., & Amir, N. (2009). A clinical comparison between two acoustic analysis softwares: MDVP and Praat. Biomedical Signal Processing and Control, 4, 202–205. Aronson, A. E. (1985). Clinical voice disorders (2nd ed.). New York: Thieme Publications. Baker, E. (2012). Optimal intervention intensity. International Journal of Speech-Language Pathology, 14, 401–409. Baker, J. (2008). The role of psychogenic and psychosocial factors in the development of functional voice disorders. International Journal of Speech-Language Pathology, 10, 210–230. Baker, J., Ben-Tovim, D. I., Butcher, A., Esterman, A., & McLaughlin, K. (2007). Development of a modified diagnostic classification system for voice disorders with inter-rater reliability study. Logopedics Phonatrics Vocology, 32, 99–112. Baker, J., Oates, J. M., Leeson, E., Woodford, H., & Bond, M. J. (2014). Patterns of Emotional Expression and Responses to Health and Illness in Women With Functional Voice Disorders (MTVD) and a Comparison Group. Journal of Voice, 28, 762–769. Bassiouny, S. (1998). Efficacy of the accent method of voice therapy. Folia Phoniatrica et Logopaedica, 50, 146–164. Benninger, M. S. (2011). Levels of evidence in the voice literature. Journal of Voice, 25, 653–656. Boone, D. R., & McFarlane, S. C. (1993). A critical view of the yawn-sigh as a voice therapy technique. Journal of Voice, 7, 75–80. Boone, D, & McFarlane, S. C. (1988). The voice and voice therapy (4th ed.). Englewood Cliffs, NJ: Prentice Hall. Canal, M. B. F. (2013). An aproach to the human voice, its physiology and rehabilitation. Revista de Logopedia, Foniatria y Audiologia, 33, 36–49. Carding, P. (2000). Evaluating voice therapy: Measuring the effectiveness of treatment. London: Whurr Publishers. Carding, P. N., Horsley, I. A., & Docherty, G. J. (1999). A study of the effectiveness of voice therapy in the treatment of 45 patients with nonorganic dysphonia. Journal of Voice, 13, 72–104. Carding, P. N., Horsley, I. A., & Docherty, G. J. (1998). The effectiveness of voice therapy for patients with non-organic dysphonia. Clinical Otolaryngology and Allied Sciences, 23, 310–318. Chan, A. K., McCabe, P., & Madill, C. J. (2013). The implementation of evidence-based practice in the management of adults with functional voice disorders: A national survey of speechlanguage pathologists. International Journal of Speech-Language Pathology, 15, 334–344. Cherney, L. R., Simmons-Mackie, N., Raymer, A., Armstrong, E., & Holland, A. (2013). Systematic review of communication partner training in aphasia: Methodological quality. International Journal of Speech-Language Pathology, 15, 535–545. Coleman, K., Norris, S., Weson, A., Grimmer-Somers, K., Hillier, S., Merlin, T., et al. (2009). NHMRC additional levels of evidence and grades for recommendations for developers and guidelines: Stage 2 consultation, early 2008-end June 2009. Canberra, National Health and Medical Research Council, Australia. Colton, R. H., Casper, J. K., & Leonard, R. (2011). Understanding voice problems: A physiological perspective for diagnosis and treatment. Baltimore, MD: Lippincott Williams and Wilkins. Demmink-Geertman, L. (2008). Neurovegetative symptoms and complaints before and after voice therapy for nonorganic habitual dysphonia. Journal of Voice, 22, 315–325. Demmink-Geertman, L. (2010). Differential effects of voice therapies on neurovegetative symptoms and complaints. Journal of Voice, 24, 585–591. Demmink-Geertman, L, & Duits-Schouten, S. (2006). The Coordination Therapy According to Elfriede Ocker (2nd ed.). Amsterdam: Harcourt Publishers. Dollaghan, C. A. (2007). The handbook for evidence-based practice in communication disorders. Baltimore, MD: Paul H. Brookes Publishing. Dunlap, W. P., Cortina, J. M., Vaslow, J. B., & Burke, M. J. (1996). Meta-analysis of experiments with matched groups or repeated measures designs. Psychological Methods, 1, 170–177.


302 C. Eastwood et al. Duong, D. N., & Kenny, D. T. (2009). Randomized controlled trial of vocal function exercises on muscle tension dysphonia in vietnamese female teachers. Journal of Otolaryngology - Head and Neck Surgery, 38, 261–278. Elisei, N. G. (2012). Acoustic analysis of normal and pathological voices using two different systems: Anagraf and praat. Interdisciplinaria, 29, 339–357. Estill, J. (1997). Compulsory figures of voice: a user’s guide to voice quality. Santa Rosa, CA: Estill Voice Training Systems. Fawcus, M. (1986). Voice disorders and their management. London: Croom Helm. Fischer, M. J., Gutenbrunner, C., & Ptok, M. (2009). Intensified voice therapy: A new model for the rehabilitation of patients suffering from functional dysphonias. International Journal of Rehabilitation Research, 32, 348–355. García-López, I., Santiago-Pérez, S., Peñarrocha-Teres, J., del Palacio, A. J., & Gavilan, J. (2012). Laryngeal electromyography in diagnosis and treatment of voice disorders. Acta Otorrinolaringologica (English Edition), 63, 458–464. Gartner-Schmidt, J. L., Roth, D. F., Zullo, T. G., & Rosen, C. A. (2013). Quantifying component parts of indirect and direct voice therapy related to different voice disorders. Journal of Voice, 27, 210–216. Gravetter, F. J., & Wallnau, L. B. (2009). Statistics for the behavioral sciences (8th ed.). Belmont, CA: Wadsworth Cengage Learning. Guzmán, M., Callejas, C., Castro, C., García-Campo, P., Lavanderos, D., Valladares, M. J., et al. (2012). Therapeutic effect of semi-occluded vocal tract exercises in patients with type i muscle tension dysphonia. Revista de Logopedia, Foniatria y Audiologia, 32, 139–146. Harris, T., & Harris, S. (1998). The voice clinic handbook. London: Whurr Publishers. Heman-Ackah, Y. D., & Barr, A. (2006). The value of laryngeal electromyography in the evaluation of laryngeal motion abnormalities. Journal of Voice, 20, 452–460. Hinckley, J. J., & Douglas, N. F. (2013). Treatment fidelity: Its importance and reported frequency in aphasia treatment studies. American Journal of Speech-Language Pathology, 22, S279. Hocevar-boltezar, I., Radšel, Z., & Zlargi, M. (1997). The role of allergy in the etiopathogenesis of laryngeal mucosal lesions. Acta Oto-Laryngologica, 117, 134–137. Houtz, D. R., Roy, N., Merrill, R. M., & Smith, M. E. (2010). Differential diagnosis of muscle tension dysphonia and adductor spasmodic dysphonia using spectral moments of the long‐ term average spectrum. The Laryngoscope, 120, 749–757. Ishii, K., Yamashita, K., Akita, M., & Hirose, H. (2000). Age-related development of the arrangement of connective tissue fibers in the lamina propria of the human vocal fold. Annals of Otology, Rhinology and Laryngology, 109, 1055–1064. Joffe, V., & Pring, T. (2008). Children with phonological problems: a survey of clinical practice. International Journal of Language & Communication Disorders, 43, 154–164. John, A., Enderby, P., & Hughes, A. (2005). Comparing outcomes of voice therapy: A benchmarking study using the therapy outcome measure. Journal of Voice, 19, 114–123. Johnson, T. S. (1985). VARP–voice abuse reduction program. New York, NY: Taylor & Francis. Kaderavek, J. N., & Justice, L. M. (2010). Fidelity: An essential component of evidence-based practice in speech-language pathology. American Journal of Speech-Language Pathology, 19, 369–379. Krousel-Wood, M. (1999). Practical considerations in the measurement of outcomes in healthcare. The Ochsner Journal, 1, 187–194. Kuhn, J., Toohill, R. J., Ulualp, S. O., Kulpa, J., Hofmann, C., Arndorfer, R., et al. (1998). Pharyngeal acid reflux events in patients with vocal cord nodules. The Laryngoscope, 108, 1146–1149. Li, N., Heris, H., & Mongeau, H. (2013). Current understanding and future directions for vocal fold mechanobiology. Journal of Cytology & Molecular Biology, 1, 1–9.

Liang, F. Y., Yang, J. S., Mei, X. S., Cai, Q., Guan, Z., Zhang, B. R., et al. (2014). The vocal aerodynamic change in female patients with muscular tension dysphonia after voice training. Journal of Voice, Logan, L. R., Hickman, R. R., Harris, S. R., & Heriza, C. B. (2008). Single‐subject research design: Recommendations for levels of evidence and quality rating. Developmental Medicine & Child Neurology, 50, 99–103. Ma, E. P. M., & Yiu, E. M. L. (2001). Voice activity and participation profile: Assessing the impact of voice disorders on daily activities. Journal of Speech, Language, and Hearing Research, 44, 511–524. Martin, S. (1987). Working with dysphonics. Oxon, England: Winslow Press. Martins, R. H. G., Gonçalvez, T. M., Pessin, A. B. B., & Branco, A. (2014). Aging voice: Presbyphonia. Aging Clinical and Experimental Research, 26, 1–5. Maryn, Y., De Bodt, M., & Van Cauwenberge, P. (2006). Effects of biofeedback in phonatory disorders and phonatory performance: A systematic literature review. Applied Psychophysiology and Biofeedback, 31, 65–83. Mathieson, L. (2001). Greene and Mathieson’s the voice and its disorders. London: Whurr Publishers. Mathieson, L., Hirani, S. P., Epstein, R., Baken, R. J., Wood, G., & Rubin, J. S. (2009). Laryngeal manual therapy: A preliminary study to examine its treatment effects in the management of muscle tension dysphonia. Journal of Voice, 23, 353–366. Menezes, M. H. M., Ubrig-Zancanella, M. T., Cunha, M. G. B., Cordeiro, G. F., Nemr, K., & Tsuji, D. H. (2011). The relationship between tongue trill performance duration and vocal changes in dysphonic women. Journal of Voice, 25, e167–e175. Moher, D., Fortin, P., Jadad, A., Jüni, P., Klassen, T., Le Lorier, J., et al. (1996). Completeness of reporting of trials published in languages other than English: Implications for conduct and reporting of systematic reviews. The Lancet, 347, 363–366. Moher, D., Liberati, A., Tetzlaff, J., & Altman, D. G. (2009). Preferred reporting items for systematic reviews and metaanalyses: The PRISMA statement. Annals of Internal Medicine, 151, 264–269. Moncher, F. J., & Prinz, R. J. (1991). Treatment fidelity in outcome studies. Clinical Psychology Review, 11, 247–266. Murray, E., McCabe, P., & Ballard, K. J. (2012). A comparison of two treatments for childhood apraxia of speech: Methods and treatment protocol for a parallel group randomised control trial. BMC Pediatrics, 12, 112. Murray, E., McCabe, P. & Ballard, K. J. (2014). A systematic review of treatment outcomes for children with childhood apraxia of speech. American Journal of Speech Language Pathology, 23, 486–504. Murray, E., Power, E., Togher, L., McCabe, P., Munro, N., & Smith, K. (2013). The reliability of methodological ratings for speechBITE using the PEDro‐P scale. International Journal of Language & Communication Disorders, 48, 297–306. Nanjundeswaran, C., Li, N. Y., Chan, K. M., Wong, R. K., Yiu, E. M.-L., & Verdolini-Abbott, K. (2012). Preliminary data on prevention and treatment of voice problems in student teachers. Journal of Voice, 26, 816.e811–816.e812. O’Donnell, C. L. (2008). Defining, conceptualizing, and measuring fidelity of implementation and its relationship to outcomes in K–12 curriculum intervention research. Review of Educational Research, 78, 33–84. Parker, R. I., Vannest, K. J., & Brown, L. (2009). The improvement rate difference for single-case research. Exceptional Children, 75, 135–150. Perdices, M., Schultz, R., Tate, R., McDonald, S., Togher, L., Savage, S., et al. (2006). The evidence base of neuropsychological rehabilitation in acquired brain impairment (ABI): How good is the research? Brain Impairment, 7, 119–132. Perry, A. R., & Shaw, M. A. (2000). Evaluation of functional outcomes (speech, swallowing and voice) in patients attending speech pathology after head and neck cancer treatment (s):


Development of a multi-centre database. Journal of Laryngology & Otology, 114, 605–615. Prater, R. J., & Swift, R. W. (1984). Manual of voice therapy. Boston Mass: College-Hill Press. Rattenbury, H. J., Carding, P. N., & Finn, P. (2004). Evaluating the effectiveness and efficiency of voice therapy using transnasal flexible laryngoscopy: A randomized controlled trial. Journal of Voice, 18, 522–533. Rees, C. J., Blalock, P. D., Kemp, S. E., Halum, S. L., & Koufman, J. A. (2007). Differentiation of adductor-type spasmodic dysphonia from muscle tension dysphonia by spectral analysis. Otolaryngology--Head and Neck Surgery, 137, 576–581. Robey, R. R. (2004). A five-phase model for clinical-outcome research. Journal of Communication Disorders, 37, 401–411. Roy, N. (2012). Optimal dose-response relationships in voice therapy. International Journal of Speech-Language Pathology, 14, 419–423. Roy, N., Barkmeier-Kraemer, J., Eadie, T., Sivasankar, M. P., Mehta, D., Paul, D., et al. (2013). Evidence-based clinical voice assessment: A systematic review. American Journal of Speech-Language Pathology, 22, 212–226. Roy, N., Merrill, R. M., Gray, S. D., & Smith, E. M. (2005). Voice disorders in the general population: Prevalence, risk factors, and occupational impact. Laryngoscope, 115, 1988–1995. Roy, N., Nissen, S. L., Dromey, C., & Sapir, S. (2009). Articulatory changes in muscle tension dysphonia: Evidence of vowel space expansion following manual circumlaryngeal therapy. Journal of Communication Disorders, 42, 124–135. Ruotsalainen, J. H., Sellman, J., Lehto, L., Jauhiainen, M., & Verbeek, J. H. (2007). Interventions for treating functional dysphonia in adults. Cochrane Database of Systematic Reviews, 3, 1–28. Ruotsalainen, J. H., Sellman, J., Lehto, L., & Verbeek, J. (2008). Systematic review of the treatment of functional dysphonia and prevention of voice disorders. Otolaryngology - Head and Neck Surgery, 138, 557–565. Sataloff, R. T., Hawkshaw, M. J., Divi, V., & Heman-Ackah, Y. D. (2007). Physical examination of voice professionals. Otolaryngologic Clinics of North America, 40, 953–969. Sauder, C., Roy, N., Tanner, K., Houtz, D. R., & Smith, M. E. (2010). Vocal function exercises for presbylaryngis: a multidimensional assessment of treatment outcomes. Annals of Otology Rhinology and Laryngology-Including Supplements, 119, 460–467. Schlosser, R. W., Wendt, O., & Sigafoos, J. (2007). Not all systematic reviews are created equal: Considerations for appraisal. Evidence-Based Communication Assessment and Intervention, 1, 138–150. Schulz, K. F., Chalmers, I., Hayes, R. J., & Altman, D. G. (1995). Empirical evidence of bias. JAMA: the Journal of the American Medical Association, 273, 408–412. Schwartz, S. R., Cohen, S. M., Dailey, S. H., Rosenfeld, R. M., Deutsch, E. S., Gillespie, M. B., et al. (2009). Clinical practice guideline: hoarseness (dysphonia). Otolaryngology-Head and Neck Surgery, 141, S1–S31.

Supplementary material available online Supplementary Appendix A, B and C to be found online at http://informahealthcare.com/doi/abs/ 10.3109/17549507.2015.1024169.

Systematic review of voice treatment 303 Smith, E., Verdolini, K., Gray, S., Nichols, S., Lemke, J., Barkmeier, J., et al. (1996). Effect of voice disorders on quality of life. Journal of Medical Speech-Language Pathology, 4, 223–244. Speyer, R. (2008). Effects of voice therapy: A systematic review. Journal of Voice, 22, 565–580. Stemple, J. C. (1984). Clinical voice pathology: Theory and management. Columbus, OH: Charles E. Merrill. Tate, R. L., Mcdonald, S., Perdices, M., Togher, L., Schultz, R., & Savage, S. (2008). Rating the methodological quality of single-subject designs and n-of-1 trials: Introducing the Single-Case Experimental Design (SCED) Scale. Neuropsychological Rehabilitation, 18, 385–401. Tate, R. L., Perdices, M., Rosenkoetter, U., Wakim, D., Godbee, K., Togher, L., et al. (2013). Revision of a method quality rating scale for single-case experimental designs and n-of-1 trials: The 15-item Risk of Bias in N-of-1 Trials (RoBiNT) Scale. Neuropsychological Rehabilitation, 23, 619–638. Thalheimer, W., & Cook, S. (2002). How to calculate effect sizes from published research: A simplified methodology. Work-Learning Research. www.work-learning.com/effect_ sizes.htm. pp. 1–9. Thyme, K., & Frøkjær-Jensen, B. (2001). The accent method: A rational voice therapy in theory & practice. Speechmark Publishing Limited, UK. Togher, L., Schultz, R., Tate, R., McDonald, S., Perdices, M., Smith, K., et al. (2009). The methodological quality of aphasia therapy research: An investigation of group studies using the PsycBITETM evidence‐based practice database. Aphasiology, 23, 694–706. Van Lierde, K. M., Claeys, S., De Bodt, M., & van Cauwenberge, P. (2007). Long-Term Outcome of Hyperfunctional Voice Disorders Based on a Multiparameter Approach. Journal of Voice, 21, 179–188. Verdolini, A. K. (2008). Lessac-Madsen Resonant Voice Therapy: Clinician manual. San Diego, CA: Plural Publishing Inc. Voerman, M. S., Langeveld, A. P. M., & Van Rossum, M. A. (2009). Retrospective study of 116 patients with non-organic voice disorders: Efficacy of mental imagery and laryngeal shaking. Journal of Laryngology and Otology, 123, 528–534. Warren, S. F., Fey, M. E., & Yoder, P. J. (2007). Differential treatment intensity research: A missing link to creating optimally effective communication interventions. Mental Retardation and Developmental Disabilities Research Reviews, 13, 70–77. Watson, T. S., Allen, S. J., & Allen, K. D. (1993). Ventricular fold dysphonia - Application of biofeedback technology to a rare voice disorder. Behavior Therapy, 24, 439–446. Wilson, S. (1987). Voice problems in children (3rd ed.). Baltimore: Williams & Wilkins. Ziegler, A., Gillespie, A. I., & Verdolini Abbott, K. (2010). Behavioral treatment of voice disorders in teachers. Folia Phoniatrica et Logopaedica, 62, 9–23. Zvoch, K. (2012). How does fidelity of implementation matter? Using multilevel models to detect relationships between participant outcomes and the delivery and receipt of treatment. American Journal of Evaluation, 33, 547–565.

Parenteral treatment of episodic tension-type headache: a systematic review.

Prevalence of voice disorders in the elderly: a systematic review of population-based studies.

Voice disorders in teachers. A review.

The pharmacological treatment of voice disorders.

Treatment of Female Sexual Pain Disorders: A Systematic Review.

Nonpharmacologic treatment of functional abdominal pain disorders: a systematic review.

The Effectiveness of Physiotherapy and Complementary Therapies on Voice Disorders: A Systematic Review of Randomized Controlled Trials.

Improving access to psychological therapies in voice disorders: a cognitive behavioural therapy model.

Clinical Presentation of Patients With Tension Pneumothorax: A Systematic Review.

Environmental and Behavioural Determinants of Leptospirosis Transmission: A Systematic Review.

HIV behavioural interventions targeted towards older adults: a systematic review.

The Effects of Expiratory Muscle Strength Training on Voice and Associated Factors in Medical Professionals With Voice Disorders.

Cognitive Behavioural Therapy for anorexia nervosa: a systematic review.

Efficacy of turmeric in the treatment of digestive disorders: a systematic review and meta-analysis protocol.

E-therapy in the treatment and prevention of eating disorders: A systematic review and meta-analysis.

Health literacy and the pharmacological treatment of anxiety disorders: a systematic review.

mHealth based interventions for the assessment and treatment of psychotic disorders: a systematic review.

Aripiprazole for the treatment of tic disorders in children: a systematic review and meta-analysis.

N-acetyl cysteine in the treatment of obsessive compulsive and related disorders: a systematic review.

The assessment and treatment of postural disorders in cerebellar ataxia: a systematic review.

The association between interpersonal problems and treatment outcome in the eating disorders: A systematic review.

Biofeedback for psychiatric disorders: a systematic review.

The Association of Cardiovascular Disorders and Falls: A Systematic Review.

Efficacy of manual therapy in the treatment of tension-type headache. A systematic review from 2000-2013.