Researches

Spasmodic Dysphonia is a type of voice disorder caused by vocal cord spasms resulting into an abnormal voice. According to Ludlow1, Adductor spasmodic dysphonia (ADSD) af-

fects close to 90% of spasmodic dysphonia patients and is characterized by voice breaks during vowels during speech due to intermittent hyperadduction of the vocal folds. Abductor spas-

modic dysphonia (ABSD) is relatively rare and involves intermittent voiceless voice breaks due to prolonged voiceless consonants before initiation of the following vowel. The prevalence

was noted to be higher among women than men with a prevalence rate of 0.98% based on a

retrospective study by Cohen et. al.2

Surgical approaches provide long-term benefits in the control of symptoms of dysphonia. One of the surgical approaches is the Type II Thyroplasty which purpose is to hold the vocal folds further apart, reducing the interference of the spasmodic hyperadductions in the

voice, according to Ludlow. 1

There are several instruments used to assess the quality of life of patients with dysphonia which are The Voice Handicap Index-10 developed by Rosen et al in 2004, Pediatric Voice Handicap Index by Zur et al in 2007, Voice Handicap Index-Partner by Zraick et al in 2007, Vocal Performance Questionnaire by Carding et al in 1999, Voice Symptom Scale by Deary et al in 2003, Voice Activity and Participation Profile by Ma and Yiu in 2001, Voice-Related Quality of Life by Hogikyan and Sethuraman in 1999. Another assessment tool is the Voice Handicap Index developed by Jacobson et al in 1997 which measures the effect of dysphonia on social, emotional, and physical contexts and individual’s daily activities. According to Lemos, et. al3., Voice Handicap Index was found to have a high sensitivity and specificity to measure voice self-perception. A Filipino VHI version was developed by Umali and Hernandez which is composed of 30 statements of experiences and reactions to voice disorders. The Filipino VHI included ten statements which described the impact of a person’s voice disorder on his or her daily activities (Functional subscale); ten statements which described how the patient feels about the voice disorder (Emotional subscale); and ten statements which described self-perceptions of physical manifestations of dysphonia such as laryngeal discomfort and the voice pitch (Physical subscale). (Lim, et al., 2010)4

Spasmodic dysphonia (SD) is a task specific, focal dystonia characterized by

involuntary spasms of the laryngeal muscles. SD is typically an adult-onset disorder that is

more prevalent in women (nearly 80%) than in men. The National Spasmodic Dysphonia

Association estimates that 50,000 people in North America are affected by SD. It can present

in a variety of forms (adductor, abductor, tremor and mixed), each exhibiting distinct vocal

symptoms. Adductor SD (ADSD) has been considered the most common form of SD and is

characterized by irregular tight or strained-strangled voice stoppages that are caused by the

intermittent hyper-adduction of the vocal folds during phonation. (Vanryckeghem M, et al.,

2015)5

According to Isshiki, there have been basically two different techniques to lateralize

the vocal folds either with or without creating a perforation at the anterior commissure. Under

local anesthesia, the thyroid cartilage isincised at the midline, leaving the underlying soft tissue

intact. During phonation, the incised cartilage edges are pulled apart at varying distances,

approximately 4 mm, to see whether any voice change occurs. To ensure sufficient glottal

separation, a perforation is created at the anterior commissure by piercing with an injection

needle, and the resulting perforation is closed with a tiny composite graft harvested from the upper ridge of the thyroid cartilage. Two silicone wedges are used, below and above the

anterior commissure, to maintain the separation. A portion of the strap muscle is switched as a

muscle flap to the space between the incised cartilage to further seal it off from the airway. In

the second method, the only difference from the other is that there is no perforation at the

anterior commissure; only lateralized edges are maintained using wedges. The whole surgical

technique is therefore simpler, taking a much shorter time.

Based on the study done by Isshiki et al6 in 2001, midline lateralization thyroplasty or

thyroplasty type II were performed on six patients with SD, and in five of them the surgery has

been successful in relieving vocal stress–strain. The advantages of the surgery include: 1)

optimal glottal closure for phonation can be adjusted, 2) no recurrence is likely to occur, 3) no

damage is induced on the physiological function of phonation such as paralysis, 4) it is

reversible if it were found ineffective intraoperatively, and 5) readjustment is possible when

needed.

According to a study done by Sanuki7 in 2007, type II thyroplasty with a titanium bridge

was found to be a very effective therapy for Adductor Spasmodic Dysphonia (AdSD). The

voice in AdSD may be classified into three types: strangulated, tremulous, and interrupted.

Postoperatively, perceptual analysis was improved. Approximately 70% of the patients had

excellent self-judged voices, and the rest improved to good or fair. These outcome measures

justify the continued treatment of AdSD with type II thyroplasty.

PRAAT is a computer program for analyzing, synthesizing, and manipulating speech.

It allows the user to record a sound with a microphone or any other audio input device, or to

read a sound from a sound file on disk, which will then allow to be able to have a look `inside'

the sound. It is called ``PRAAT''; the imperative form of to speak in Dutch. (Boersma, P. &

Weenink, D., 2001)9 PRAAT’s voice analysis output consists of a waveform of the analyzed signal, a spectrogram, and a voice report. The Voice Report is useful for the evaluation of a

series of vocal parameters related to: F0 (median pitch, mean pitch, minimum pitch, maximum

pitch); temporary vocal interruption: Voicing (fraction of locally unvoiced frames; number of

voice breaks; degree of voice breaks) micro perturbation of frequency: Jitter which expresses

the regularity of the vibratory cycle, the perturbation of the F0 mean and is related to the degree

of hoarseness (Roughness); microperturbation of amplitude: Shimmer which expresses the

perturbation of the glottic vibration amplitude, which is the amplitude of the sound wave, and

it is related to the degree of voice breathiness and to intensity variations; spectral energy

balance between harmonic and disharmonic components: signal noise (mean autocorrelation,

mean H/N, mean N/H). Mean N/H indicates the amount of noise in relation to the harmonics

of the signal: the higher its value, the more the overall degree of voice quality is lowered.

(Mezzedimi, C., et al, 2016)10

According to Ludlow1, spasmodic dysphonia develops without warning or any clear antecedent events in middle age. ‘Speech interruption,’ a characteristic fluency break commonly associated with stuttering is frequently experienced by individuals with Adductor

Spasmodic Dysphonia due to irregular muscular spasms. In relation, Spasmodic Dysphonia has

been consistently reported to restrict individuals from social and occupational participation

based on a study by Vanryckeghem and Ruddy.5

This study aims to determine the pre-operative and post-operative status and quality of life of patients with spasmodic dysphonia who underwent Isshiki Thyroplasty Type II, at Veterans Memorial Medical Center using the English or Filipino version of the Voice Handicap Index and the Praat voice analysis program.

General Objective

1. To compare the quality of life of patients with spasmodic dysphonia before and after Isshiki Thyroplasty Type II.

Specific Objectives

1. To determine the demographic profile and clinical characteristic of patients with spasmodic dysphonia who underwent Isshiki Thyroplasty Type II.
2. To compare the pre-operative and post-operative quality of life scores of the participants using the English or Filipino Voice Handicap Index.
3. To compare the Praat scores pre operatively, intraoperatively, and post operatively of patients with spasmodic dysphonia who underwent Isshiki Thyroplasty Type II.

This is a tertiary hospital-based, cross sectional analytical research design and ambispective type of study conducted at the Department of Otorhinolaryngology- Head and Neck Surgery of Veterans Memorial Medical Center for 3 years. Patients included in this study are the following: (1) patients diagnosed with Spasmodic Dysphonia, (2) can read, write, understand and converse in Filipino or English, (3) patients who underwent Isshiki Thyroplasty Type II, and (4) adult patients. Excluded in this study are (1) patients who are unable to read, write, and converse in Filipino or English, (2) patients who have other impairments. Purposive sampling was used in the study. Detailed history and complete ENT examination was done. Informed and written consents were obtained from all patients. Demographics such as age, gender, educational status, occupation were also collected. The consultants who underwent fellowship training at Isshiki Memorial Medical Center (Specializing on Phonosurgery) in Japan and the residents of the Department of Otorhinolaryngology - Head and Neck Surgery performed the surgery following a standardized procedure. The Praat program was also used pre-operatively, intraoperatively, and post operatively in analyzing phonetic speech. Post operatively, voice handicap index and PRAAT scores were measured after 24 hours, 1 week, and 1 month. There were no conflict of interest arising from financial, familial, propriety considerations of the principal investigator or study site.

Voice Handicap Index (VHI)

The Voice Handicap Index developed by Jacobson and the validated Filipino Voice

Handicap Index version of Umali and Hernandez was used in this study. It is a thirty item self-

administered questionnaire wherein the functional subscale consisted of statements that describe the impact of voice disorder in daily activities, emotional subscale consisted of statements representing the patient's affective responses to voice disorder, and physical subscale consisted of statements about patient’s self perception of different physical manifestations of dysphonia like voice pitch and laryngeal discomfort.

A five-point Likert scale was used to determine the patient’s agreement to the statements. Responses are 0-never, 1- almost never, 2 - sometimes, 3 - almost always, 4 – always. The severity of handicap was interpreted to be directly proportional to the numeric value assigned by the patient to each statement. The total assessment of handicap was measured by obtaining the mean of the scores on all 30 statements, which is the total VHI score. The VHI overall score was categorized as follows: minimal amount of handicap for scores 0 to 30, moderate amount of handicap for scores between 31 to 60, and serious amount of handicap for scores more than 60.

PRAAT Program

PRAAT is a computer program for analyzing, synthesizing, and manipulating speech

developed by Paul Boersma and David Weenink at the Institute of Phonetic Sciences of the

University of Amsterdam in 1992. PRAAT offers the possibility to record mono and stereo

sounds and to edit and analyse sounds regarding intensity, pitch height, duration, or formants.

Sample Size

The number of participants was computed using a 95% level of confidence and 80% power of the study. With an estimated standard deviation of 0.50 based from a previous study, at least 17 patients are needed to detect a 0.60 difference in the pre-op and post-op scores.

Where:

n = is the number of subjects needed per group/arm

SD = estimated SD based on the variable of main interest = 0.76

Zα = 95% confidence level = 1.96

Zβ= 80% power of the study = 1.28

e = measure of effect (difference in the pre-op and post-op score) = 0.65 – 0.048

=0.6

Currently, there are a total of 14 patients in the study.

Data Processing and Analysis

Data was encoded and tallied in SPSS version 17 for windows. Descriptive statistics

was generated for all variables. For nominal data frequencies and percentages were computed.

For numerical data, mean ± SD were generated. Analysis of the different variables were done

using the following test statistics:

Paired T-test was used to compare pre-operative and post-operative Voice Handicap

Index scores of patients with spasmodic dysphonia.

Repeated Measures ANOVA was used to compare the Praat scores pre-operatively,

intraoperatively and post-operatively of patients with spasmodic dysphonia who underwent

Isshiki Thyroplasty Type II.

This study included 15 patients with Spasmodic Dysphonia who underwent Thryoplasty Type II from 2018 to 2022. The demographic characteristics of the subjects included in this study are shown in Table 1. It was observed that the mean age of the patients who were diagnosed with Adductor Spasmodic Dysphonia is 37 years old. Currently, there are a total of 15 patients, 4 are male which comprises 26.67% and 11 are female which comprises 73.33% of the current study population.

The Voice Handicap Index scores of patients were compared pre-operatively and post-operatively. In Table 2, it shows that the mean scores of the patients preoperatively is 88.33 which corresponds to Severe handicap. This showed a decrease in mean score of 54 at 24-hours post operatively, which corresponds to Moderate handicap. Post operative scores after 1 week showed a decrease in VHI scores with a mean score of 37 which still corresponds to Moderate handicap. At 1 month post-operatively, it showed a mean score of 26 which corresponds to Mild handicap. The p-value is 0.001 which is statistically significant.

Praat voice analysis showed that vocal jitters ranged from 2.275% to 10.125% with mean pre operative score of 5.99% which is considered abnormal. On the other hand, post-operative vocal jitters ranges from 0.517% up to 3.443% with a mean score of 1.12% which is still considered abnormal. 

Vocal shimmers has a mean of 12.86% ranging from 2.613% up to 22.85% pre-operatively which is not considered pathological. At the same time, post-operative results showed a range from 4.105% up to 16.916% with a mean score of 10.04% post-operatively, which is also considered non pathological.

Lastly, Harmonic to Noise Ratio (HNR) show that pre-operative HNR is less than 7 dB

denoting an asthenic or dysphonic voice where a mean score of 4.836dB and a range of 1.823

dB up to 12.841 dB were collected. In contrast, post-operative scores were from 3.678 dB up

to 20.934 dB with a mean score of 12.67 indicating a more sonorant and harmonic voice.

According to literature, Spasmodic Dysphonia is a disease which mainly affects

females. In our study, spasmodic dysphonia was noted to be present in 11 females out of 15

total participants.

The validated Filipino Voice Handicap Index is a self-administered 30-item questionnaire that determines the functional, physical and emotional impact of voice disorders. The total assessment of handicap is measured by obtaining the mean of the scores on all 30 statements, which is the total VHI score. A score of 0-30 is a low score and indicates a minimal amount of handicap associated with the voice disorder. A score of 31-60 indicates a moderate amount of handicap due to dysphonia. A score of 61-120 represents a significant and serious amount of handicap due to dysphonia. 4 In our study, pre-operative Voice Handicap Index Scores were noted to be ranging from 61 up to 125 with a mean score of 88.33 (Table 1). The post-operative scores range from 37 up to 85 after 24 hours, with a mean score of 54.27 or moderate voice handicap. At 1 week post operatively, the scores range from 12 to 64 or moderate handicap. While at 1 month post operatively, the scores range from 4 to 49 or mild handicap. In a study done by Sanuki and Isshiki7 in 2007, they concluded that Type II thyroplasty is a highly effective therapy for patients with Spasmodic Dysphonia. In this study, patients had Severe handicap preoperatively and after undergoing Isshiki Thyroplasty Type II, the VHI scores decreased which correspond to Mild handicap after 1 month. This shows that there is relief of the symptoms of spasmodic dysphonia and Isshiki Thyroplasty Type II improve the quality of life of patients after undergoing the surgery.

The Praat voice analysis software is a computer software developed by Paul Boersma and David Weenink of the Institution of Phonetics Sciences of the University of Amsterdam.9 It evaluates voice acoustic parameters such as jitter, shimmer, and harmonics to noise ratio.9 Measurements of these parameters has been proven to be useful in describing vocal characteristics which are crucial in measuring the severity of a Spasmodic Dysphonia.

Jitter is a parameter defined as frequency of variation from cycle to cycle. It is affected

by lack of control of vibration of the cords hence the voices of the patients with pathologies

often have a higher percentage of jitter.12 Various sources consider 0.5 to 1% jitter for sustained

phonation as normal.In our study, pre-operative Jitters ranged from 2.27% up to 10.125% with

a mean of 5.99%. Post operatively, vocal jitters scores showed a range of 0.52% to 3.443% with a mean of 1.12%. This showed that the scores had a significant decrease post operatively

which is close to the considered normal value.

On the other hand, vocal shimmers relate to amplitude variation of the sound wave. Shimmers which are less than 3% for adults is considered pathological. Results showed pre- operative vocal shimmers had a range of 2.61% up to 22.85% and a mean score of 13.63%. Post operatively, vocal shimmersshowed a range of 4.105% to 16.92% with a mean of 10.05%. Shimmer changes with the reduction of glottal resistance and mass lesions on the vocal cords and correlates to breathiness of voice12 which are not present in patients with spasmodic dysphonia, hence, vocal shimmer scores yielded non-pathological sound waves.

Lastly, Harmonic to Noise Ratio is the assessment ratio between periodic components

and non-periodic components comprising a segment of speech.12 A voice sound with a high HNR is associated with a sonorant and harmonic voice. Therefore, HNR measures the effi-

ciency of speech.12 A low HNR that is less than 7dB denotes an asthenic voice or dysphonia.[8] Our results show that pre-operative HNR ranged from 1.82 up to 12.84 with a mean score of 4.83 and post operative HNR scores ranging from 3.678 dB to 20.9 dB with a mean of 12.67 dB. In our study, scores were noted to increase post-operatively which is associated with a sonorant and harmonic voice. This shows that post-operatively, ADSD patients did not sound dysphonic.

Patients who underwent Isshiki Thyroplasty Type II showed an improvement in the

Voice Handicap Index scores after the surgery, from Severe handicap to Mild handicap. It

significantly provides a long-term definitive therapy for patients suffering with Spasmodic

Dysphonia. The vocal jitters in Praat voice analysis were noted to be abnormal preoperatively

and post operatively, however, it showed a significant decrease post operatively which is close

to the considered normal value. Shimmer changes with the reduction of glottal resistance and

mass lesions on the vocal cords and correlates to breathiness of voice which are not present in

patients with spasmodic dysphonia, hence, vocal shimmer scores yielded non-pathological

sound waves. Harmonics-to-Noise-Ratio reflects the efficiency of speech and scores were

noted to increase post-operatively which is associated with a sonorant and harmonic voice. In

conclusion, there is significant improvement in the quality of life and voice of patients with

spasmodic dysphonia who underwent Isshiki Thyroplasty Type II.

We recommended the continuation of this study to be able to include more subjects and

to perform a prospective study in determining the success rate of Isshiki Thyroplasty Type II

for patients with Spasmodic Dysphonia. Furthermore, this study may determine the efficacy of

the technique in Filipinos diagnosed with Spasmodic Dysphonia.

We would like to acknowledge our department chair, Dr. Gerardo E. Cruz, for the encouragement and guidance throughout this research. To our assistant department chair Dr. Joanne Sebastiana M. De Ramos and our research consultant, Dr. Natividad A. Almazan, we thank you for the time and effort in editing this research.

We would also like to extend our sincerest gratitude to the pioneer of phonosurgery,

Professor Nobuhiko Isshiki who passed away in August 2022, for being an inspiration to pursue

this study, and for all the knowledge imparted together with our other mentors Dr. Masahiro

Tanabe, Dr. Shinya Hiroshiba, and Dr Yutaka Toya.

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