Video Laryngeal Endoscopy: A Voice Therapy Tool

Helen Rattenbury*; Dr. Paul Cardingb; Paul Finn#

*University of Newcastle and North Tyneside General Hospital

bUniversity of Newcastle and Freeman Hospital, Newcastle

#University of Teesside

Introduction

Voice therapists have been using Video Laryngeal Endoscopy (VLE) in clinical practice for over 20 years (Karnell 1994). The purposes of these VLE examinations include the confirmation of the medical diagnosis; the formation of a voice therapy diagnosis and planning voice therapy. VLE has also been reported to be useful as a voice therapy tool (Karnell 1994) however, there has been little scientific evidence to date to support this role.

Therapeutic Applications of VLE

The reported possible therapeutic applications of VLE are outlined below.

VLE can be used as a prognostic indicator. VLE is used to identify the most successful voice therapy technique for each voice patient during a pre therapy probing session. The patient is instructed by the voice therapist to attempt various voice therapy techniques with the scope in situ. The technique that produces the most successful change in the disordered phonatory physiology can then chosen for a full course of voice therapy.
VLE can be used as a patient information tool. The importance of shared knowledge base between the patient and the therapist has been recognised when treating voice (Mathieson 2001). The use of recorded, or real time VLE examinations provides the patient with a tangible focus for therapy. Increased patient understanding of the problems with their phonatory physiology can improve motivation in therapy.
VLE can also be used as a visual laryngeal biofeedback tool. The patient is able to view the television monitor during their own VLE examination. Therapy techniques can be modified by the patient in real time, in order to match an improved voice quality with an improved visual image.

These therapeutic applications of VLE have been reported in an anecdotal manner in the literature. There is no scientific evidence to prove that VLE-assisted voice therapy is effective, or may provide any benefit to current practice.

The Aim

The aim of this study was to measure the effectiveness of VLE-assisted voice therapy. The null hypothesis was that VLE-assisted voice therapy would be ineffective in terms of improvements in voice quality and voice related quality of life measures. This aim was addressed as part of a wider study of the effectiveness and efficiency of VLE-assisted voice therapy and the wider role of VLE in voice therapy practice (not reported here).

Study Design

24 subjects recruited from the regular caseload of a busy voice therapy department and treated using VLE-assisted voice therapy. All subjects were ‘perceptually dysphonic’ (an overall ‘Grade’ of at least ‘2’ using the GRBAS scale (Hirano 1981), dysphonic for no more than 12 months, motivated to change, have no history of significant psychiatric illness and be over 16 years of age. All subjects were treated by the same voice therapist with 15 years voice therapy experience. All subjects were diagnosed following a voice therapy VLE examination prior to commencement of the study. VLE as a prognostic indicator and a patient information tool was used with all subjects. The use of VLE as a visual laryngeal biofeedback tool depended upon the tolerance of each patient to repeated VLE examinations.

Outcome Measures

Pre and post VLE-assisted voice therapy measures were taken in a standard manner from each subject. Due to the multidimensional nature of voice a package of voice-related outcome measures was required to measure the effectiveness of voice therapy. The outcome measures used in this study are outlined below.

Perceptual Auditory Rating of Voice Quality. The voice therapist makes a judgement regarding the auditory characteristics of the voice. In order to quantify this judgement, a rating scale is used. The rating scale chosen for this study was the GRBAS (Hirano 1981) scale. This has been found to be reliable, internationally acceptable and has been recommended as the minimum standard perceptual measure in the UK (Carding, Carlson et al. 2000c).
Patient Questionnaire Measurement. The impact the voice problem has upon the patient’s voice-related quality of life can be ascertained via a questionnaire. The Patient Questionnaire of Vocal Performance (PQVP) (Carding and Horsley 1992) was chosen for this study due to its reliability, its standardisation on a UK population and its small burden to complete.
Intsrumental Acoustic Measurement (EGG). To support the above outcome measures, a measure of percentage jitter and percentage shimmer was also calculated. These parameters have been found to provide a valid measure of the stability of the voice signal and have been recommended for use as part of a voice-related outcome measures package (Dejonckere, Bradley et al. 2001). The Laryngograph® electroglottography package was used to calculate these parameters due to its ability to analyse connected speech (also analysed in the perceptual auditory rating of voice quality).

In order to prevent bias in the judgement of the perceptual quality, a voice therapist experienced in using the GRBAS scale, but blind to the identity and treatment stage of the subjects, rated each voice sample. The overall ‘Grade’ was used as the outcome measure. The total score of the PQVP was used as the overall outcome measure for the patient questionnaire measurement. Instrumental acoustic measurement was reported for the percentage jitter and shimmer for both sustained vowel samples and connected speech samples.

Statistical Analysis Methods

In order to prove that VLE-assisted voice therapy was effective a difference in the voice-related outcome measures had to be statistically significant. This was defined as a p-value of W 0.05. The results for the perceptual rating of voice quality were analysed using a Wilcoxon’ Signed Ranks Test as the data was categorical and paired. The results for the patient questionnaire measurement were analysed using a Paired Samples T-Test as the data was continuous and paired. The results for the instrumental acoustic measurement were analysed using a Wilcoxon Signed Ranks Test as, although the data was continuous it was censored due to some measurement problems. This made the data non-parametric and paired.

Results

The 24 subjects had a mean age of 45.4 years (age range 17-87). The male:female ratio was 1:5.

Perceptual Auditory Rating of Voice Quality

Parameter	Pre- median (n=23)	Post- median (n=24)	Pre- range (n=23)	Post- range (n=24)	p-value
Grade	3.0	1.0	0-3	0-3	<0.01	*

* result significant at 5% level. P-values from Wilcoxon Signed Ranks test.

The overall rating of ‘Grade’ of voice quality was found to have improved significantly post VLE-assisted voice therapy.

Patient Questionnaire Measurement (min score 12 – maximum score 60)

Pre- mean	Pre- SD	Post- mean	Post- SD	p-value
33.8	(8.6)	20.1	(6.5)	<0.01	*

* result significant at 5% level. P-values from Paired Samples T-Test.

The total score of the PQVP improved significantly following VLE-assisted voice therapy. VLE-assisted voice therapy was found to be effective regarding the patient reported voice-related quality of life.

Instrumental Acoustic Measurement (Laryngograph®)

Parameter	Pre- median (n=24)	Post- median (n=24)	Pre- range (n=24)	Post- range (n=24)	p-value
Jitter vowel (%)	84.1	31.2	0.2-100.0	0.0-100.0	<0.01	*
Jitter conn. speech (%)	67.6ª	19.9	9.7-100.0ª	5.8-78.6	<0.01	*
Shimmer vowel (%)	45.8	2.7	0.1-100.0	0.0-100.0	<0.01	*
Shimmer conn. speech (%)	47.4ª	15.0	8.8-100.0ª	4.1-56.3	<0.01	*

* result significant at 5% level. P-values from Wilcoxon Signed Ranks test

ª n=23

VLE-assisted voice therapy produced a statistically significant improvement in percentage jitter and shimmer for samples of both sustained vowels and connected speech.

Discussion

This study represents the first VLE-assisted voice therapy effectiveness study. The results indicate that VLE-assisted voice therapy is an effective treatment option for voice patients. More research is needed into the impact of each of the three therapeutic applications on the effectiveness of voice therapy. The possible benefits of VLE-assisted voice therapy over traditional voice therapy practice should also be investigated. VLE is still a relatively new addition to voice therapy and every effort should be made to scientifically examine the effectiveness of novel treatment approaches in order to be clinically accountable.

References

Carding, P., E. Carlson, et al. (2000c). "Formal perceptual evaluation of voice quality in the United Kingdom." for the British Voice Association.

Carding, P. N. and I. A. Horsley (1992). "An evaluation study of voice therapy in non-organic dysphonia." European Journal of Disorders of Communication 27: 137 - 158.

Dejonckere, P., P. Bradley, et al. (2001). "A basic protocol for functional assessment of voice pathology, especially for investigating the efficacy of (phonosurgical) treatments and evaluating new assessment techniques." European Archives of Otorhinolaryngology 258: 77 - 82.

Hirano, M. (1981). Clinical examination of voice, Springer.

Karnell, M. (1994). Videoendoscopy: From velopharynx to larynx. San Diego, California, Singular Publishing Group, Inc.

Mathieson, L. (2001). Greene and Mathieson's The voice and Its disorders. London and Philadelphia, Whurr Publishers.

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