Topic:  Outcomes of vocal rest post phonosurgery

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The effect of voice rest on the outcome of phonosurgery for benign laryngeal

lesions: preliminary results of a prospective randomized study.

Conference Paper · October 2014

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Article

The recommendation for a period of voice rest following phonosurgery is common practice, as it is believed to favor postoperative healing by preventing vocal fold scarring. However, there has been no agreement among phonosur- geons, regarding either the type of voice rest (absolute or relative) or the optimal duration. The duration of voice rest most often recommended is between 3 and 7 days,1,2 which is in agreement with experimental histological data from animal models, showing the healing process (re- epithelialization) takes an average of 7 days. Nevertheless, there are as yet no published data on the optimum duration of postoperative voice rest, and the literature lacks prospec- tive, randomized studies comparing periods of short and long duration voice rest.

At present therefore, there is no consensus regarding the optimal period of voice rest following phonosurgery.3,4 With a high variability among phonosurgeons, based on published case reports, absolute voice rest is often preferred over relative, with a mean duration of 3 to 7 days. However,

there are no data available to support either the benefit of the one over the other, or the advantage of a short-term voice rest over a longer one and vice versa.

In favor of vocal rest are studies that provide data from animal model experiments. In 2004, Titze described the influence of phonation-induced stress in the persistence of the inflammatory response postoperatively.5 Cho et al showed in a canine model, that voice rest precipitates the re-epithelialization process, offering protection from per- manent changes at this level as well as in the lamina pro- pria.6 Later, Rousseau et al demonstrated a phonation-induced

560583 AORXXX10.1177/0003489414560583Annals of Otology, Rhinology & LaryngologyKiagiadaki et al research-article2014

1Department of Otolaryngology–Head and Neck Surgery, Louvain University Hospital of Mont Godinne, Yvoir, Belgium

Corresponding Author: Devora Kiagiadaki, MD, PhD, Department of Otolaryngology–Head and Neck Surgery, Louvain University Hospital of Mont Godinne, Yvoir, Belgium, Knossou 96A, 71306, Heraklion, Crete, Greece. Email: [email protected]

The Effect of Voice Rest on the Outcome of Phonosurgery for Benign Laryngeal Lesions: Preliminary Results of a Prospective Randomized Study

Devora Kiagiadaki, MD, PhD1, Marc Remacle, MD, PhD1, George Lawson, MD1, Vincent Bachy, MD1, and Sebastien Van der Vorst, MD, PhD1

Abstract Objectives: According to the literature, voice rest following phonosurgery, as recommended in clinical practice, varies between 3 and 7 days. However, up until now, no randomized trials have been published comparing voice rest of short versus long duration. Methods: This is an ongoing prospective randomized study, comparing strict voice rest of 5 versus 10 days on the voice following phonosurgery. Thirty-one elective patients operated on for benign laryngeal lesions were randomized. They completed pre- and postoperative assessments, including perceptual voice quality (Grade, Roughness, Breathiness, Asthenia, Strain, Instability scale), Voice Handicap Index total score, and voice analysis with both acoustic and aerodynamic measurements. Additional factors such as smoking, vocal abuse, reflux, and preoperative speech therapy were also taken into account. Results: Sixteen patients were randomized to follow 5 days’ voice rest and 15 patients were randomized to 10 days’ voice rest. Statistical analysis showed no significant differences in pre- or postoperative measurements between the 2 groups. However, multilinear regression analysis for the effect of voice rest duration on postoperative values showed a significant improvement in maximum phonation time (MPT) with 10 days’ voice rest. Conclusions: Preliminary results show a benefit of prolonged voice rest (10 days’ duration) on MPT.

Keywords voice rest, phonosurgery, benign laryngeal lesions

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2 Annals of Otology, Rhinology & Laryngology

dynamic tissue remodeling process, during which, up-regu- lation of gene expression and tissue protein levels, includ- ing matrix metalloproteinase-1 (MMP-1), of vocal cover in normal vocal folds takes place.7 These results could indi- cate that the mechanical stress involved in speaking, espe- cially following surgery, could alter, and negatively influence, normal wound healing. On the other hand, vocal loading, decreased inflammation markers found in laryn- geal secretions, and vocal fold fibroblasts, as shown by Branski et al,8 raise the question of whether active phona- tion could have an anti-inflammatory effect in the postop- erative period.

Observational studies have suggested that vocal abuse can predispose to a prolonged dysphonia, postoperatively. According to Koufman and Blalock,9 absolute voice rest seemed to protect from persisting impaired voice quality after surgery for benign and precancerous laryngeal lesions, in comparison with relative voice rest. However, it was dif- ficult to assess the efficacy of voice rest, due to a lack of standardization of assessment tools and the variability in the type of voice rest recommended. Moreover, the 2 most important factors influencing voice outcome were patients’ compliance with voice rest as recommended as well as with preoperative speech therapy.9

According to a review of the literature, voice rest is gen- erally accepted in the initial stages of postoperative healing to avoid the undesirable effects of uncontrolled vocal use.10

In the present randomized prospective study, our aim was to compare the effect of voice rest duration of either 5 or 10 days’ on voice outcome post phonosurgery.

Materials and Methods

This was a prospective randomized, single-blinded, con- trolled study, conducted between January 2013 and March 2014. The participants were elective patients operated on for benign laryngeal lesions. Patients’ characteristics, as well as the laryngeal pathologies included, are listed in Tables 1 and 2, respectively. Vocal cord nodules, polyps, and Reinke’s edema are included in the group of exudative lesions of Reinke’s space (according to Hantzakos et al).11 In all cases, phonosurgery took place in the ambulatory day care center of Louvain University Hospital of Mont– Godinne (Yvoir, Belgium). It was performed under general anesthesia (without curarization) and high frequency jet ventilation, via suspension laryngoscopy. Laser CO2 tech- nology was used (Acublade-Compact Laser 1040C© and Laser Encor©, Lumenis, Santa Clara, CA), with either the super-pulse or ultra-pulse mode. The surgical technique included excision for nodules, polyps, sulcus, and cysts, performed with single shots, of 0.1 s, at a depth of incision of 100 to 200 µ and a power of 10 watts. For Reinke’s edema, the procedure was performed according to Hirano12 and included incision of the epithelium along the length of

Table 1. Patients’ Characteristics.

GRP A (n = 16) GRP B (n = 15) P Total (N = 31)

Age, mean (SD) 47 (8.7) 42.4 (11.3) .08a 46.9 (9) Sex M 5 5 .9b 10 F 11 (68.7) 10 (66.7) 21 (67.7) Vocal professionals 9 (56.3) 9 (60) .8b 18 (58.1) Smoking 4 (25) 5 (33) .9b 9 (29) Vocal abuse 10 (62.5) 6 (40) .37b 16 (51.6) Reflux 5 (31) 3 (20) .76b 8 (25.8) Preoperative speech therapy 4 (25) 5 (33.3) .9b 9 (29)

Values are n and percentage, unless otherwise noted. GRP A, 5 days’ voice rest; GRP B, 10 days’ voice rest; SD, standard deviation. aP < .05, Mann–Whitney test. bP < .05, chi-square test.

Table 2. Distribution of Laryngeal Pathologies.

Excudative Lesions of Reinke’s Space Keratosis Epidermoid Cyst Sulcus Combined Lesion

Group 1 10 (62.5) 1 (6.3) 2 (12.5) 3 (18.8) 0 Group 2 9 (60) 0 2 (13.3) 3 (20) 1 (6.7) Total 19 (61.3) 1 (3.2) 4 (12.9) 6 (19.4) 1 (3.2)

Values are n and percentage.

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Kiagiadaki et al 3

the superior surface of the vocal fold, aspiration of the glue accumulated on Reinke’s space and approximation of the incision edges.13 Patients were discharged home 3 hours later. Oral antibiotic therapy was prescribed prophylacti- cally for 3 days following surgery as well as inhaled ste- roids for 1 week and a proton-pump inhibitor (Pantoprazole, 40 mg, twice a day), until the healing process was completed.

Preoperative voice assessment included aerodynamic measurements (intensity [Int, dB], maximum phonation time [MPT, sec], subglottic pressure [SP, mmH

2 O], and

phonation quotient [PQ], equal to vital capacity/MPT ratio), acoustic analysis of the voice signal (fundamental fre- quency range [F0 range, Hz], jitter % [J], shimmer % [Sh], and dysphonia severity index [DSI]), perceptual grading with the GRBASI (Grade, Roughness, Breathiness, Asthenia, Strain, Instability) scale,14 and self-evaluation with the French version of the VHI.15 DSI is an index com- bining acoustic and aerodynamic measurements16 (DSI = 0.13 × MPT + 0.0053 × F

0 -High – 0.26 × I-Low – 1.18 ×

Jitter (%) + 12.4), and indicates normal voice when scores are toward to positive values (maximum value +5).17 Voice samples were recorded and aerodynamic measurements were made under the same conditions and based on the same protocol, and by the same speech pathologists in our department, by means of the MDVP (Multi Dimensional Voice Program) system (Kay Pentax CSL, 4150, Kay Elemetrics Corporation, Lincoln Park, NJ) in a quiet room. Acoustic measurements (J, Sh) were calculated from the voice sample of a sustained, comfortable, “a,” over 3-5 sec- onds. A Neutrik microphone was used, at a distance of 30 cm from the mouth. Int and F0 range were taken from the voice range profile, where the patient was asked to phonate in the highest and lowest possible intensity and “as high” and “as low” as possible. For the aerodynamic measure- ments, the KAY Pentax Phonatory Aerodynamic System (PAS), Model 6600 was used, including a face mask and a straw-sized mouth catheter. Vital capacity was calculated after a forced expiration, following a deep inspiration, and the best measurement after 2 attempts was taken into account. For SP, the patient was asked to pronounce 3 times “a pa pa” with the mask in place and the catheter over their tongue. Finally, for the calculation of MPT, patients were asked to sustain an “a” for as long as possible after a deep inspiration, and the best measurement after 2 attempts was taken into account.

The same evaluations were repeated postoperatively. Moreover, a brief history including smoking, voice abuse, reflux and preoperative speech therapy was taken at the time of the first evaluation. The delay for the postoperative control was set at 15 days. At the time of first postoperative control, patients’ compliance to voice rest was confirmed and recorded.

The duration of the postoperative period of voice rest was set following the randomization process preoperatively

by the means of Research Randomizer Program.18 Randomization was always performed by the same person. The surgeons were blinded to the voice rest period to which patients had been randomized throughout the study. Postoperative instructions were given either by the assistant or the resident responsible for the patient and patients were recommended to have comply with strict voice rest of either 5 days’ (group A, GRP A) or 10 days’ (group B, GRP B) duration. During the voice-rest period, patients were coun- seled to avoid sports and intense physical activity, coughing or throat-clearing. The gradual reintroduction of habitual voice use was performed under speech-therapy supervision, until the 15th postoperative day.

Statistical Analysis

Summary descriptive statistics are presented as mean (stan- dard deviation) or median (min, max) for continuous vari- ables and as frequencies (%) for categorical ones. The values for the voice assessment parameters were calculated pre– and post–surgical intervention. Their changes postop- eratively, were assessed using the Wilcoxon signed rank test, for the entire study cohort as well as for each group of differing voice rest duration separately. Moreover, pre- and postoperative values, as well as their changes, were com- pared between the 2 groups, by means of nonparametric Mann–Whitney test.

The chi-square test was used to detect any differences in the frequency of possible confounding factors (lesion type, sex, voice profession, smoking, reflux, voice abuse, or pre- operative speech therapy), between GRP A and GRP B.

To explore the influence of voice rest on postoperative measurements, we performed a multiple linear regression analysis for every parameter of the voice assessment mea- surements, taking into account the preoperative values. All statistical tests were carried out at the 2-sided 5% level of significance. Statistical analyses were performed using SPSS 20.0 (SPSS, Chicago, IL).

Results

Differences Between Groups in Terms of Initial Voice Assessment Measurements and Characteristics

No statistically significant differences between the 2 groups were demonstrated, apart from the DSI value preoperatively (median value –1.6 in GRP A and –4.3 in GRP B, P = 0.05) (Tables 1 and 2).

Changes Postoperatively

When the entire cohort of patients was examined, an overall improvement was noted in most of the voice assessment parameters postoperatively, apart from lower intensity

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(which remained stable) and J and Sh which were more per- turbed, although not statistically significantly (P > .05). The parameters of G, R, S, VHI, MPT, VC, and SP showed a statistically significant improvement (P < .05).

Differences Between the Groups in Terms of Measurement Changes Postoperatively

When examining each group separately, we observed parameters that improved significantly (R, S) in both groups; G, MPT, and PQ improved in GRP B, whereas VC and VHI improved in GRP A. DSI showed a slight change toward more positive values, however this change remained non significant within both groups. Jitter stayed within the pathological range in both groups, although less of a decrease was noted in GRP B). Finally, PQ and shimmer increased postoperatively in GRP A (Table 3).

Possible Impact of Confounding Factors

The chi-square test did not reveal any differences between the frequency of sex, type of lesion, voice profession, reflux, vocal abuse, or preoperative speech therapy between the 2 groups, indicating the equality of the groups and the elimination of possible bias between them (Table 1).

Regression Analysis

Multilinear regression analysis for all voice assessment parameters showed a strong impact of voice rest on postop- erative value of MPT (P = .42 for MPT preoperatively and

for voice rest P = .02). Moreover, the R2 value for voice rest indicated that voice rest could predict 44.7% of the postop- erative MPT value, when the preoperative value was omitted.

Discussion

This prospective randomized (single-blinded) trial aimed to explore the possible impact of the duration of voice rest on phonosurgical outcome for benign laryngeal lesions, and whether, therefore, there is any indication in favor of a voice rest of short (5 days) or longer duration (10 days). Having in mind the complexity of vocal cord pathology and function, we attempted to eliminate the possible confound- ing factors, by creating equal groups of patients, operated on and assessed under stable standardized conditions.

The current published body of literature is lacking in prospective randomized studies comparing voice rest of a specific type (relative or absolute) or duration. In the pres- ent study, we gathered controlled data within our patient cohort, in terms of the pathologies included, time of follow- up control, surgical technique and voice evaluation. The time of the first postoperative control was set at 15 days. This time point was selected as it covered the healing period for the pathologies treated (although sulcus and epidermoid cysts need a longer rehabilitation period) and provided a mean between the 2 most commonly recommended periods of voice rest: 5 and 10 days. Voice assessment was always performed during the first postoperative control and in cases such as epidermoid cysts and sulcus, as well as in voice professionals, since healing was completed, voice

Table 3. Preoperative Values of Voice Assessment Measurements.

GRP Apre GRP Apost GRP Bpre GRP Bpost

G, median (min-max) 1 (1-3) 1 (0-3) 1.5 (1-3) 1 (0-3)* R, median (min-max) 2 (0-2) 0.5 (0-3)* 2 (1-3) 0.5 (0-2)* B, median (min-max) 0.5 (1-3) 0 (0-2) 1 (0-2) 0 (0-3) A, median (min-max) 0 (0-2) 0 (0-2) 0 (0-2) 0 (0-2) S, median (min-max) 1 (0-3) 0 (0-3)* 1 (0-2) 0 (0-3)* I, median (min-max) 0 (0-2) 0 (0-2) 0 (0-3) 0 (0-0) VHI 50.1 (19) 32.3 (31.9)* 49.9 (24) 40.4 (30.4) F0 range 270 (152.6) 305.2 (176.3) 384,4 (125.8) 357.2 (214.3) Int low 59.1 (5.2) 59.4 (4.4) 64 (9.5) 58.4 (4.9) Int high 93.8 (7.7) 93 (10.4) 98 (7.3) 95.1 (9.5) VC 3857 (1182) 4219 (926)* 4930 (1515) 5216 (1877) PQ 389.5 (142.7) 436 (234) 493.4 (178.4) 420 (243)* SP 11.9 (5.1) 10.5 (6.5) 10 (3.4) 9.3 (3.2) MPT 11.4 (3.6) 11.5(6) 9.6 (2.6) 15.7 (7.9)* Jitter% 2.6 (1.5) 3.6 (3.2) 2.8 (2.2) 3.2 (2.2) Shimmer% 6.6 (3.7) 7.1 (4) 6.2 (3.5) 6.2 (4) DSI, median (min-max) −1.15 (–5.9-4.5) −1 (–2.5-14.5) −2.8 (–8.8-0) −1.5 (–15-4.6)

Data presented as mean (standard deviation) unless otherwise noted. *P < .05, Wilcoxon signed rank test.

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Kiagiadaki et al 5

recuperation was always effectuated under speech therapy guidance. As the majority of patients (67.7%) were females, we did not include F0 in the parameters examined and we chose F0 range instead. However, our groups were matched in terms of gender as well as in the distribution of pathologies.

To minimize the effect of bias, as well as the effect of confounding factors given the small sample size, we con- firmed that there was no statistical difference between the frequency of possible confounding factors (type of lesion, voice profession, smoking, reflux, vocal abuse, and preop- erative speech therapy) between the 2 groups. Unfortunately, the small group size did not permit us to proceed to further analyze the groups according to laryngeal pathology, which would have otherwise been interesting, given that certain pathologies are known to require longer periods of rehabilitation.

The analysis of our results indicates the only parameter to have improved with longer duration voice rest (10 days) was the MPT. In this group, MPT values were noted to be lower preoperatively (although not significantly) when compared to those of the shorter duration voice rest group, which then increased into normal range postoperatively. This is quite important, as MPT is an aerodynamic measure indicative of vocal efficiency and glottic function suffi- ciency. In the 5 days’ group MPT remained essentially unchanged and close to lower normal values (11.5 seconds). This observation could be explained by the fact that after a 10-day voice rest, both speech therapists and patients felt safer in requesting, and practicing a sustained effort respec- tively, required for MPT measurement. Considering the other aerodynamic measures, we noted a trend toward improvement in postoperative PQ in the 10-day voice rest group compared with a slight deterioration in that of the 5-day voice rest group. A significant decrease in SP was noted in the 10-day voice rest group, although measure- ments remained elevated in both groups postoperatively.

Analysis of the perceptive evaluation parameters did not reveal any changes in the postoperative values or indeed between the groups. As far as the VHI scoring is concerned, we can observe some quantitative differences. For example, postoperative VHI score indicated moderate dysphonia for both groups but resulted in a higher value in GRP B (32.3 versus 40.4). Taking into account the preoperative values, a significant change was observed in the 5 days’ group, as according to Jacobson et al15 a change of 18 points in total score is considered statistically significant which was further confirmed by Wilcoxon rank test. This could be considered as an element in favor of 5 days’ voice rest, however, VHI score stayed in the range of moderate dysphonia (31-60) and was not associated with similar differences in other measures.

Another interesting observation is that neither group demonstrated improvement in acoustic measurements (jitter, shimmer) or a significant improvement in DSI following surgery. The multilinear regression analysis disproved any

influence of voice rest on these parameters, however, showed a significant influence of preoperative values (P = .01 for jitter, .04 for shimmer, and a trend .06 for DSI). Acoustic measurements, were included in the voice assessment proto- col, as proposed by the European Laryngological Society (ELS).19 They reflect F0 and amplitude perturbations and provide an indirect evaluation of the voice source, during a sustained vowel phonation. Although they give additional information on the voice quality, in our experience they can- not be used individually and should be incorporated along with the rest of the parameters, as they represent only 1 aspect of voice assessment. Moreover, the clinical applica- tion of this observation cannot be relied on, given that linear regression models are sample size dependant.

As already mentioned, according to Koufman and Blalock,9 the 2 most important factors influencing voice outcome following surgery was patient compliance with voice rest recommendations, as well as with preoperative speech therapy. In our cohort of patients, the influence of preoperative speech therapy was not proven by statistical analysis, as it was equally distributed between the 2 groups. As far as patient compliance is concerned, all our patients reported they had kept to the voice rest recommendations, except for 1 female professional who kept 10 days’ voice rest instead of the recommended 5 days and was thus ana- lyzed within the GRP B.

Conclusions

With this prospective randomized trial, we attempted to examine the effect of absolute voice rest on voice outcome following phonosurgery for benign laryngeal lesions. The observation of MPT improvement with longer voice rest duration was important, but its significance is limited due to the relatively small number of patients studied. Moreover, patients in the 5 days’ voice rest group seemed relatively more satisfied according to VHI score. No other differences were demonstrated between the 2 groups of voice rest. Therefore, although it wasn’t proven that prolonged voice rest inhibits functional recovery, there were no evidence to suggest additional clinical benefits conferred on patients by the prescription of prolonged voice rest (10 days) in com- parison with that of a shorter duration (5 days). This is an ongoing study, and collecting a larger patients’ sample will permit us to draw safer conclusions.

Acknowledgments

We would like to thank Zoë M. J. Astroulakis, MBBS, BSc, PhD (consultant cardiologist, St George’s Hospital London), for her contribution to the revision of the final manuscript.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

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6 Annals of Otology, Rhinology & Laryngology

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

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