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Commun Sci Disord > Volume 29(4); 2024 > Article
갑상선 술 후 증후군을 위한 음성치료법의 효과

초록

배경 및 목적

갑상선 절제술 후 증후군(Post-Thyroidectomy Syndrome, PTS)은 갑상선 절제술 후 신경학적 손상 없이 나타나는 음성 문제를 지칭한다. 본 연구는 PTS의 음성문제를 개선하기 위해 고안된 Voice therapy method of PTS (VT-PTS)의 효과를 확인하는 것을 목적으로 한다. VT-PTS는 PTS의 음도문제가 후두-기관 고착이라는 주요한 원인을 전제로 고안된 치료법이다.

방법

연구의 대상자는 남성 2명, 여성 10명 총 12명이다. 대상자 선정은 이비인후과 두경부 전문의로부터 PTS로 진단받고, 언어재활사에 의해 음성치료가 권고되며 주관적인 음도문제를 호소하는 대상자 중 무작위로 선정되었다. VT-PTS는 언어재활사에 의한 직접 음성 치료(VT-1)와 가정 내 자가 훈련(VT-2)으로 구성되었다. 음성 평가는 음향 분석(F0, jitter, shimmer, NHR, 최대 음역, 최소 음역, 음역 범위)과 주관적 음성 평가(K-VHI-10, K-VFI, TVQ)를 실시하였다. 음성측정은 갑상선 절제술 후 약 2주 후인 VT-1수행 전과 수행 직후, VT-2 수행 후 실시하였다.

결과

VT-PTS 수행에 따른 대상자의 음성을 음향학적으로 분석한 결과, F0 (p=.014), 최대 음역(p<.001), 음역 범위(p<.001)가 유의미하게 증가하였다. 본페로니 보정(α=.0167)에 의해 jitter (p=.046), shimmer (p=.017)는 감소하였으나 유의하지 않았다. KVHI-10 (p=.003), K-VFI (p=.014), TVQ (p=.002) 점수는 VT-2 이후 유의미하게 감소하였다.

논의 및 결론

VT-PTS는 객관적 및 주관적 음성평가 모두에서 개선을 나타내며 PTS의 음성개선에 효과적인 방법으로 나타났다. 특히, PTS의 주요한 음성문제인 음도문제 개선에 효과적이었다. 본 연구는 임상현장에서 PTS를 치료하는 언어 재활사가 참고할 수 있는 근거기반 자료를 제공한다는 점에 의의를 갖는다. 향후 연구에서는 비대면 음성 치료와 수술 후 자가 연습을 위한 앱 개발이 필요하겠다.

Abstract

Objectives

This study aimed to demonstrate the effectiveness of Voice Therapy for Post- Thyroidectomy Syndrome (VT-PTS). The primary cause of PTS is the impairment of vertical movement in the larynx due to adhesion of the infrahyoid muscles or laryngeal-tracheal structures.

Methods

The study included 12 participants (2 males and 10 females) diagnosed with PTS by a laryngologist. All participants reported subjective voice problems and were recommended for voice therapy by a speech-language pathologist. Participants were randomly assigned to the study. The VT-PTS program consisted of VT-1 (direct voice therapy conducted by a speech-language pathologist) and VT-2 (self-practice at home). Voice assessments included acoustic analyses (F0, jitter, shimmer, NHR, maximum pitch, minimum pitch, and pitch range) and subjective voice evaluations (K-VHI-10, K-VFI, and TVQ).

Results

Acoustic analyses indicated significant increases in F0 (p=.014), maximum pitch (p<.001), and pitch range (p<.001) following VT-1 and VT-2. According to the Bonferroni correction, jitter (p=.046) and shimmer (p=.017) were not statistically significantly reduced. The K-VHI-10 (p=.003), K-VFI (p=.014), and TVQ (p=.002) also demonstrated significant decreases after VT-2.

Conclusion

VT-PTS showed significant improvements in both objective and subjective voice evaluations, demonstrating its effectiveness in addressing voice problems in PTS. Notably, it was highly effective in addressing pitch-related problems, which are the primary voice problems in PTS. This study is valuable as it provides evidence- based support for speech-language pathologists in treating PTS in clinical fields. Future research should try non-face-to-face voice therapy and the development of applications to support post-surgical self-practice.

According to 2020 statistics from the Korean National Cancer Information Center, thyroid cancer is the most common cancer, accounting for 11.8% of all cancers. It also ranks first in prevalence, comprising 21.5% of all cancers. Interestingly, the 5-year relative survival rate for thyroid cancer is reported to be 100% (National Cancer Information Center, 2023). These positive treatment outcomes have shifted focus toward daily recovery and enhancing post-operative quality of life. Consequently, there has been growing interest in addressing voice problems resulting from thyroidectomy. Approximately 30-80% of patients undergoing thyroidectomy experience voice problems such as vocal paralysis or postthyroidectomy syndrome (PTS). These problems often result in communication challenges that significantly impact quality of life (de Pedro Netto et al., 2006; Ryu et al., 2013). Voice problems associated with thyroidectomy can be categorized into neurological voice disorders caused by damage to the superior laryngeal nerve (SLN) or recurrent laryngeal nerve (RLN), and non-neurological voice problems that occur without nerve injury. For neurological voice disorders such as vocal fold paralysis, primary treatment methods involve surgical approaches, including vocal fold injection, thyroplasty, and laryngeal reinnervation. When combined with voice therapy, these methods can significantly enhance therapeutic outcomes (Han, Han, & Namm, 2009). Voice therapy serves as a primary treatment for unilateral vocal fold paralysis and can be initiated independently of surgical interventions for voice improvement. It involves multiple therapy sessions conducted by speech-language pathologists (Kumrow & Dahlen, 2002; Yoon & Hong, 2020). Recently, instead of waiting for natural recovery or performing thyroplasty, proactive treatment through early vocal fold injections has been implemented to support the restoration of vocal function (Rosen, 2000). Conversely, voice problems that occur after thyroidectomy without laryngeal nerve injury are referred to as PTS (Hong, 2014). Symptoms of PTS can arise even after a simple thyroidectomy that preserves laryngeal nerves. Most patients report experiencing easy voice fatigue, difficulty with high-pitched voices and singing (Park, Mok, Chung, & Lee, 2015), sensory changes around the surgical site (paresthesia), vague voice changes, a feeling of choking, sudden sharp pain, and neck discomfort (Stojadinovic et al., 2008). These symptoms typically begin to improve approximately one month after surgery; however, problems such as difficulty with high-pitch and singing often require 1-2 years to show noticeable improvement (Kim et al., 2016; Lee, 2016). PTS is explained as resulting from factors such as intubation-related trauma, impaired blood circulation to the larynx, adhesions of the strap muscles, or vertical movement disorders caused by adhesions between the larynx and trachea. Additional contributing factors include fibrosis during the healing process following damage to the cricothyroid or cervical muscles. Among these, vertical movement disorders due to adhesions of the strap muscles or laryngeal-tracheal structures are considered the primary causes of PTS, as they are associated with dysfunction in the extralaryngeal mechanism (Myers, Hong & Kim, 1997).
The American Thyroidectomy Guidelines recommend that all patients undergoing thyroid surgery undergo a comprehensive voice evaluation. Preoperative voice evaluation provides critical insights into potential post-operative voice changes and expected recovery progressions. They also support the early diagnosis of vocal fold paralysis, reduce delays in treatment caused by missed diagnoses, and help preempt potential legal complications (Yoon & Hong, 2020). Postoperative voice evaluations are equally essential, playing a pivotal role in identifying voice disorders that may occur without nerve injury, diagnosing vocal fold paralysis, and monitoring long-term outcomes (Chandrasekhar et al., 2013). Furthermore, the Korean Clinical Practice Guidelines for Managing Voice Changes after Thyroid Surgery (Care and Management of Voice Change in Thyroid Surgery: Korean Society of Laryngology, Phoniatrics and Logopedics Clinical Practice Guideline) emphasize the necessity of voice therapy to optimize vocal function and improve voice-related quality of life following thyroidectomy. According to the guidelines, 86.1% of study participants agreed on the importance of voice therapy, highlighting its effectiveness in addressing various voice disorders not only in cases involving nerve damage but also in those without neurological injury (Ryu et al., 2022).
Various interventions have been implemented to facilitate early social reintegration and improve the quality of life for patients undergoing thyroidectomy. Takamura et al. (2005) reported that performing head and neck stretching exercises starting from the second-week post-thyroidectomy can help prevent adhesions, which are a key cause of PTS; as well as reduce subjective neck discomfort, and ultimately enhance the quality of life. Similarly, Jang, Chang, Kim, Moon, and Son (2014) found that initiating neck exercises the day after surgery led to significantly greater improvements in neck discomfort, surgical site adhesions, and neck range of motion compared to starting the exercises two weeks post-surgery. Their findings suggest that early neck exercises within two weeks after thyroidectomy can promote an active return to society. However, both studies lacked interventions conducted by speech-language pathologists and did not include voice-related measurements. Conversely, Lee, An, Chang, Jeong, and Son (2015) conducted interventions facilitated by speech-language pathologists to examine neck mobility, discomfort, and voice changes. They reported that neck exercises and diaphragmatic breathing practices were performed for two weeks after surgery. These practices were effective in improving subjective voice quality and respiratory function for phonation by the third week. However, no significant differences were found in acoustic variables, including the voice range profile (VRP).
Therefore, this study developed a voice therapy method to address the vertical movement disorder of the larynx caused by adhesions in the strap muscles or between the larynx and trachea, identified as the primary cause of PTS symptoms such as difficulties with singing and high-frequency pitches. The study aims to demonstrate the effectiveness of voice therapy in PTS by utilizing both objective and subjective voice evaluations and to highlight the necessity of voice therapy. The Voice Therapy Method for Post-Thyroidectomy Syndrome (VT-PTS) consists of two parts: VT-1, a direct voice therapy part conducted by a speech-language pathologist, and VT-2, a patient’s self-practice. The VT-2 part was designed to accommodate the circumstances and emotional needs of patients and caregivers, who undergo prolonged treatment schedules, including low-iodine diets and radiation therapy after thyroidectomy. This study aims to compare voice measurement outcomes before and after VT-1 and following VT-2. The goal is to determine the effectiveness of direct voice therapy as part of the VT-PTS, and to confirm that voice problems caused by PTS can be improved and maintained through patient self-practice. Additionally, the study seeks to provide evidence-based intervention strategies to advance the field.

METHODS

Participants

The participants in this study were patients who underwent thyroidectomy at Chungbuk National University Hospital. They were selected based on the following criteria: (1) a diagnosis of PTS by a laryngologist, (2) confirmation by the surgeon that no nerve injury occurred during surgery, (3) subjective complaints of pitch-related voice problems, and (4) identification by a speech-language pathologist (SLP) through voice evaluations as having pitch problems requiring intervention. Participants meeting these criteria were randomly assigned to the study. The participants included 12 individuals (2 males and 10 females). Their mean age was 49.60 years (±10.34). Exclusion criteria included respiratory diseases, reflux disorders, neurological disorders, sensory impairments, a history of head and neck surgeries, or any cosmetic treatments that could potentially affect voice quality. All participants underwent surgery performed by a single experienced surgeon. The types of thyroidectomy among the participants included 8 who underwent total thyroidectomy and 4 who underwent lobectomy.

Procedure

VT-PTS

VT-PTS was established based on the premise that PTS results from dysfunction in the extra laryngeal mechanism. This dysfunction is caused by adhesions in the strap muscles or between the larynx and trachea. Its primary goal is to improve pitch-related problems, particularly difficulties with singing and high-frequency ranges, through voice therapy. This approach seeks to prevent these pitch problems from persisting for 1-2 years. This method consists of two stages. VT-1 involves direct voice therapy conducted by an SLP two weeks after thyroidectomy. VT-2 consists of self-practice performed by the patient at home for two weeks.
This therapy method was conducted by a SLP (grade 1) with seven years of clinical experience in voice disorders at a university hospital’s otolaryngology department. VT-1 included neck exercises to address neck discomfort and normalize the vertical movement of the larynx, as well as semi-occluded vocal tract exercises (SOVTE). The application of SOVTE aims to prevent unstable vocal fold vibrations caused by abnormal external laryngeal muscle activity and to avoid compensatory phonation. It also strengthens the vocal production mechanism. In this study, water resistance straw phonation and humming were selected from among various SOVTE techniques. SOVTE is a method that facilitates easy resonance perception. Its low phonation threshold pressure (PTP) reduces the risk of phonotrauma during high-pitch phonation practice. Water resistance straw phonation is easier to perform than other SOVTE methods due to the use of a tool. Similarly, humming was included in this study because it is a simple method and is perceived as a familiar and approachable form of phonation. VT-2 was composed based on VT-1, focusing on elements designed to facilitate vertical laryngeal movement, enabling patients to perform the exercises independently at home. Each VT-1 session ran for 40 minutes. VT-2 was recommended to be performed six times per day for two weeks, with each session taking approximately five minutes.
The authors provided feedback and education during VT-1 sessions to ensure patients could perform VT-2 without difficulty. VT-1 included a process where the SLP modeled the exercises, the patient imitated them, and the SLP provided feedback. If the patient performed the exercises incorrectly, the SLP facilitated selfcorrection. Emphasis was placed on the importance of practicing independently at home without an SLP. Although the authors did not require patients to keep detailed records of their VT-2 practice, all participants reported following the SLP’s recommendation to perform six sessions daily. The program’s procedures and details are presented in Table 1.

Measurement

To compare voice outcomes following VT-PTS, measurements were conducted before and after VT-1, and after completing VT-2 for two weeks (Figure 1). The study initially planned to begin the experiment at two weeks post-thyroidectomy. However, due to changes in the physician’s schedule, VT-1 was conducted at an average of 16.56 days post-thyroidectomy. The duration of each program was calculated using the participants’ visit dates. Voice measurements included objective evaluations using acoustic analysis and subjective evaluations based on patient-centered voice-related questionnaires. Objective acoustic analyses were conducted three times: before and after VT-1, and after completing VT-2. Subjective voice evaluations, using voice-related questionnaires, were conducted twice: before VT-1 and after completing VT-2. For acoustic analysis, participants were asked to sustain the vowel /a/ at a comfortable pitch and intensity in a noise-controlled environment with a microphone placed approximately 10 cm from the mouth. The analysis was performed using the multi-dimensional voice program (MDVP) of the computerized speech lab (CSL, Model 4500B) by PENTAX medical. From the sustained phonation samples, the authors selected a stable 1.5-second segment and analyzed fundamental frequency (F0), jitter percent, shimmer percent, and noise-to-harmony ratio (NHR). Sustained phonation was performed twice, and the more stable sample was selected for analysis. In addition, the VRP was used to measure maximum pitch, minimum pitch, and pitch range. Participants performed three pitch gliding tasks using the vowel /a/. During acoustic analysis, environmental noise was maintained below 50 dB, following the guidelines of Lee and Kim (2020).
Subjective voice evaluations were conducted using the Korean voice handicap index-10 (K-VHI-10), the Korean version of the vocal fatigue index (K-VFI), and the thyroidectomy-related voice questionnaires (TVQ). The K-VHI-10 consists of 10 items, with scoring on a 0-4 scale and a total possible score ranging from 0 to 40. Higher scores indicate a negative impact of voice disorders on daily life (Yun, Kim, Son, & Choi, 2008). The K-VFI evaluates perceived vocal fatigue and consists of 19 items, scored on a 0-4 scale, with total scores ranging from 0 to 76. Three items are positively worded and are reverse-scored (Nanjundeswaran, Jacobson, Gartner-Schmidt, & Abbott, 2015). The TVQ is designed to evaluate voice-related issues in patients immediately after thyroid surgery and consists of 20 items. It includes symptoms associated with laryngopharyngeal reflux, swallowing difficulties, and general voice-related problems. The questionnaire is scored on a 0-4 scale, with total scores ranging from 0 to 80. Higher scores indicate dis-comfort or difficulties associated with voice changes after thyroidectomy (Chun et al., 2012).

Statistical Analysis

Subjective voice evaluation results (before VT-1 and after VT-2) were analyzed using Wilcoxon’s signed-ranks test. Additionally, a Friedman test, a nonparametric statistical method for repeated measures, was conducted to compare acoustic analysis results at three time points: before VT-1, immediately after VT-1, and after VT-2. Both analyses were conducted with significance determined at a 95% confidence level (α=.05).
Pairwise comparisons (before and immediately after VT-1, before VT-1 and after VT-2, and immediately after VT-1 and after VT-2) were also performed using Wilcoxon’s signed-ranks test. To control Type I errors, Bonferroni correction was applied to the pairwise comparisons. Consequently, individual tests were performed at a corrected significance level (α=.0167), corresponding to a 98.33% confidence level.
Statistical analyses were performed using SPSS (Statistics Package for the Social Sciences, version 21.0; IBM Corp., Armonk, NY, USA).

RESULTS

Comparison of Objective Voice Evaluation Results Following VT-PTS

Table 2 compares the acoustic analysis results before and after VT-1 and after VT-2. Based on the Bonferroni correction, a p-value of ≤.0167 was required for statistical significance. Jitter did not show statistically significant differences, changing from .82% before VT-1 to .44% immediately after VT-1 and increasing to .65% after VT-2 (p=.046). Similarly, Shimmer did not indicate statistically significant changes, reducing from 5.17% before VT-1 to 3.42% immediately after VT-1 and further to 1.32% after VT-2 (p=.017). NHR decreased from .154 before VT-1 to .133 immediately after VT-1 and .017 after VT-2, but the changes were not statistically significant (p=.059).
F0, Max pitch, Min pitch, and Pitch range were analyzed separately by gender. Statistical tests were conducted only for female participants. F0 increased significantly from 170.51 Hz before VT-1 to 179.56 Hz immediately after VT-1 and 186.24 Hz after VT-2 (p=.014). Pairwise comparisons indicated significant differences between before and immediately after VT-1 (p=.028) and between before VT-1 and after VT-2 (p=.009), but not between immediately after VT-1 and after VT-2 (p=.203). Max pitch, Min pitch, and Pitch range also showed significant changes. Max pitch increased from 394.12 Hz before VT-1 to 389.46 Hz immediately after VT-1 and 407.65 Hz after VT-2 (p<.001). Min pitch decreased from 139.34 Hz before VT-1 to 132.82 Hz immediately after VT-1 and further to 123.49 Hz after VT-2 (p=.007). Pitch range expanded from 209.34 Hz before VT-1 to 256.65 Hz immediately after VT-1 and 284.16 Hz after VT-2 (p<.001). Pairwise comparisons for Max pitch showed significant differences between before and immediately after VT-1 (p=.005) and between immediately after VT-1 and after VT-2 (p=.005). No significant difference was indicated between before VT-1 and after VT-2 (p=.059). For Min pitch, no significant differences were shown between before and immediately after VT-1 (p=.098) or between immediately after VT-1 and after VT-2 (p=.028). However, a significant difference was indicated between before VT-1 and after VT-2 (p=.013). For Pitch range, significant differences were shown across all comparisons: before and immediately after VT-1 (p=.005), before VT-1 and after VT-2 (p=.005), and immediately after VT-1 and after VT-2 (p=.007) (Table 2), (Figures 2, 3).
For the two male participants, individual results were presented. F0 increased after VT-1 compared to before VT-1 but decreased after VT-2. Specifically, F0 for Participant 1 (P1) was 110.68 Hz before VT-1, 125.19 Hz immediately after VT-1, and 111.70 Hz after VT-2. For Participant 2 (P2), F0 was 92.14 Hz before VT-1, 103.41 Hz immediately after VT-1, and 101.24 Hz after VT-2. Max pitch for P1 and P2 increased after VT-1 and further increased after VT-2. P1’s Max pitch was 205.57 Hz before VT-1, 303.36 Hz immediately after VT-1, and 346.37 Hz after VT-2. For P2, Max pitch was 222.87 Hz before VT-1, 240.73 Hz immediately after VT-1, and 290.54 Hz after VT-2. Min pitch showed varying patterns. For P1, Min pitch increased from 82.83 Hz before VT-1 to 85.16 Hz immediately after VT-1 and remained at 85.16 Hz after VT-2. For P2, Min pitch decreased from 88.37 Hz before VT-1 to 83.34 Hz immediately after VT-1 but increased to 89.47 Hz after VT-2. The pitch range for both participants expanded after VT-1 and continued to increase after VT-2. P1’s Pitch range increased from 122.74 Hz before VT-1 to 218.20 Hz immediately after VT-1 and 261.21 Hz after VT-2. P2’s Pitch range increased from 134.50 Hz before VT-1 to 157.39 Hz immediately after VT-1 and 201.07 Hz after VT-2 (Table 3).

Comparison of Subjective Voice Evaluation Results Before and After VT-PTS

Table 4 compares the subjective voice evaluation results before VT-1 and after VT-2. The K-VHI-10 also showed a significant decrease, with an average score of 9.42 before VT-1 and .75 after VT-2 (p=.003). Similarly, the K-VFI showed a statistically significant re-duction, with an average score of 13.25 before VT-1 and 3.83 after VT-2 (p=.014). The TVQ showed a statistically significant reduction, with an average score of 13.92 before VT-1 and 6.92 after VT-2 (p=.002) (Figure 4).

DISCUSSION & CONCLUSION

Pitch modulation during phonation depends on both the cricothyroid muscle in the vocal folds and the vertical movement of the larynx. Vertical laryngeal movement plays a crucial role in both the pharyngeal phase of swallowing and pitch control during phonation. Laryngeal elevation tightens the vocal folds to increase pitch for high-pitched phonation, whereas laryngeal lowering relaxes them, lowering the pitch. These movements are driven by external laryngeal muscles. Among them, the suprahyoid muscles elevate the larynx, while the infrahyoid muscles pull it downward. Especially, the thyrohyoid muscle, distinct from other infrahyoid muscles, contributes to laryngeal elevation and actively enhances pitch during high-pitched phonation (Hong, 2014). In PTS, pitch problems—such as decreased fundamental frequency and difficulty controlling phonation during singing or high-pitched sounds—are primarily attributed to vertical movement disorders of the larynx. These disorders are caused by adhesions in the strap muscles (a subset of the infrahyoid muscles) or between the larynx and trachea. Scar tissue formed in the thyroidectomy area leads to adhesions between the larynx and surrounding tissues or between the strap muscles and subcutaneous layers, restricting vertical laryngeal movement (Hong & Kim, 1997). The VT-PTS in this study was custom-designed to address the characteristics of PTS. It aims to improve vertical laryngeal movement and strengthen the voice production mechanism, thereby encouraging stable vocal fold vibration. Furthermore, it is a method designed to prevent secondary voice problems such as compensatory phonation.
To summarize the results of this study, jitter, and shimmer, which represent the stability of pitch and intensity based on the periodicity of vocal fold vibrations, were not statistically significant according to the Bonferroni correction. However, they showed a decrease following the VT-PTS. Jitter decreased immediately after VT-1 but slightly increased after VT-2, though it remained lower than before VT-1. Shimmer consistently decreased, reaching its lowest value after VT-2. In female participants, F0, maximum pitch, and pitch range increased after VT-1 and continued to increase after VT-2. Minimum pitch decreased after VT-1 and decreased further after VT-2. These results indicate that VT-PTS not only increases the fundamental frequency and improves vocal fold vibration but also expands the range of minimum and maximum pitch, thereby increasing the overall pitch range. A post-hoc analysis was conducted to examine whether the effects of direct therapy were maintained and whether self-practice effectively improved voice outcomes. Especially notable findings from the post-hoc analysis include changes in F0. While F0 did not decrease after VT-1, it showed a decline after VT-2. Additionally, pitch range increased not only between pre- and post-VT-1 and between post-VT-1 and post-VT-2 but also between pre-VT-1 and post-VT-2. This increase in pitch range implies an expansion of both maximum and minimum pitch. Subjective voice evaluations showed a reduction in K-VHI-10, K-VFI, and TVQ scores after VT-PTS compared to pre-VT-PTS scores.
In conclusion, the findings of this study suggest that VT-PTS, consisting of one session of direct therapy and six daily sessions of self-practice over two weeks, is an effective intervention for addressing pitch-related problems, the primary vocal concern in PTS. Additionally, VT-PTS improves voice-related quality of life and reduces vocal fatigue. VT-1 of VT-PTS included general neck exercises aimed at alleviating neck discomfort, as described by Takamura et al. (2005) and Jang et al. (2014). It also featured exercises directly facilitating vertical laryngeal movement, such as lifting the head while swallowing water and pulling the chin back after raising the head with an open mouth. These exercises are de-signed to stimulate the movement of the strap muscles and skin tissue, helping to prevent and minimize the progression of adhesions. The SOVTE component of VT-1 employed humming and water resistance straw phonation, which are easy to imitate and perform. These tasks, which include pitch gliding, extended phonation at varying pitches, and singing, allow participants to experience smooth and efficient vocal fold vibrations, thereby preventing compensatory phonation. By creating unique aerodynamic conditions, SOVTE makes high-pitched phonation easier while minimizing phonotrauma. This makes it particularly suitable for practicing high-pitch production involving laryngeal elevation (Kim et al., 2021). VT-2 was composed of selected elements from VT-1. Participants had already experienced these exercises during VT-1 sessions and received feedback from SLPs on proper performance, reporting that they performed the exercises with sincerity and minimal difficulty. VT-2 consisted of three exercises aimed at improving vertical laryngeal movement to address adhesions in the strap muscles and between the larynx and trachea, as well as water resistance straw phonation. VT-PTS is a tailored therapeutic approach for PTS that not only provides a practical reference for clinical application but also demonstrates the effectiveness of SLPled interventions for addressing post-thyroidectomy voice problems.
This study’s findings align with those of earlier research, such as Lee et al. (2015), which utilized neck exercises and diaphragmatic breathing; Lee, Kim, Ryu, and Woo (2018), which included postsurgical site massage; and Nam et al. (2013), which implemented voice hygiene and vocal function exercises (VFE). However, this study differs from Lee et al. (2015) in that it verified voice improvement through both objective and subjective voice evaluations. Additionally, unlike Lee et al. (2018), which provided interventions four weeks post-surgery, this study implemented early intervention at 16 days post-surgery. Nam et al. (2013) reported that voice recovery required six weeks post-treatment. In contrast, this study estimated the direct causes of pitch problems and performed treatments, achieving recovery within four weeks. Thyroid cancer treatment may include both surgery and radiation therapy. VT-PTS is tailored to this treatment process, offering one session of direct therapy followed by self-practice. This makes VT-PTS an efficient and advanced voice therapy method. Lee and Park (2021) reported improvements in voice outcomes by providing both face-to-face treatment and non-face-to-face treatment to patients with vocal fold paralysis after thyroidectomy.
This study has several limitations. While participants were randomly assigned, the study did not classify them by surgery type or account for gender differences. The small sample size and the absence of a comparison group were additional limitations. Participants verbally confirmed performing VT-2 sincerely, although their performance was not objectively measured. Future studies should include comparisons with a control group, consider the age of participants, and conduct longitudinal studies to examine the long-term maintenance of therapeutic effects. Lastly, the authors observed that patients undergoing voice therapy after thyroidectomy or following functional voice disorders or laryngeal microsurgery showed a particularly serious and committed attitude toward treatment. Patients appeared to make substantial efforts to perform VT-PTS correctly. SLPs should understand these characteristics and approach voice evaluation and therapy for thyroidectomy patients with a professional and empathetic attitude.

Figure 1.
Research process.
csd-29-4-938f1.jpg
Figure 2.
Comparison results of acoustic analysis (female).
csd-29-4-938f2.jpg
Figure 3.
Comparison results of max and min pitch, pitch range and F0 (female).
csd-29-4-938f3.jpg
Figure 4.
Comparison results of subjective voice evaluation.
csd-29-4-938f4.jpg
Table 1.
Voice therapy method for post-thyroidectomy syndrome
Stage Content
VT-1: Direct voice therapy (40 minute) Neck exercise
1. Stretch the shoulders and arms.
2. Bend the head downwards, Lift the head upwards.
4. Turn the head to the right/left.
5. Lifting upward after turning head to the right/left.
6. Swallow water after lifting the head upwards.
7. Open the mouth, lift the head, and pull the chin.
SOVTE
1. Humming phonation
 -Pitch gliding, pitch sustained (low, middle, high)
2. Water resistance straw phonation (Straw 4 mm×18 cm, depth 7 cm)
 -Pitch gliding, pitch sustained (low, middle, high)
 -Singing (happy birthday to you)
VT-2: Patient self-practice (5 minute) 1. Water resistance straw phonation (Straw 4 mm×18 cm, depth 7 cm)
 -Pitch gliding, pitch sustained (low, middle, high)
 -Singing (happy birthday to you)
2. Lifting upward after turning head to the right/left.
3. Swallow water after lifting the head upwards.
4. Open the mouth, lift the head, and pull the chin.
※ Recommended six times a day
Table 2.
Comparison results of acoustic analysis
Before VT-1
Immediately after VT-1
After VT-2
χ2 p Post-hoc
Mean (± SD) Median Mean (± SD) Median Mean (± SD) Median
jitter .82 (± .70) .76 .44 (± .19) .44 .65 (± .53) .39 6.167 .046 -
shimmer 5.17 (± 2.76) 4.46 3.42 (± 1.22) 3.58 3.22 (± 1.32) 2.83 8.167 .017 -
NHR .154 (± .029) .146 .133 (± .018) .139 .133 (± .017) .133 5.660 .059 -
F0 (female) 170.51 (± 17.46) 173.46 179.56 (± 14.89) 180.13 186.24 (± 14.32) 189.70 8.600 .014 a < c**
Max pitch (female) 349.14 (± 98.02) 351.62 389.46 (± 88.49) 375.99 407.65 (± 78.86) 384.61 16.800 < .001 a < b**
a < c**
Min pitch (female) 139.79 (± 15.74) 137.61 132.82 (± 15.87) 137.56 123.49 (± 15.01) 126.52 9.800 .007 a < c*
Pitch range (female) 209.34 (± 98.20) 189.46 256.65(± 81.94) 232.20 284.16 (± 74.93) 257.53 18.200 < .001 a < b**
b < c**
a < c**

Max pitch=maximum pitch in Hz; Min pitch=minimum pitch in Hz; Pitch range=Pitch range in Hz; a=before VT-1; b=after VT-1; c=after VT-2.

* p < .05,

** p < .01,

*** p < .001.

Table 3.
Comparison results of acoustic analysis in male
Before VT-1
Immediately after VT-1
After VT-2
P1 P2 P1 P2 P1 P2
F0 110.68 92.14 125.19 103.41 111.70 101.24
Max pitch 205.57 222.87 303.36 240.73 346.37 290.54
Min pitch 82.83 88.37 85.16 83.34 85.16 89.47
Pitch range 122.74 134.50 218.20 157.39 261.21 201.07

Max pitch= maximum pitch in Hz; Min pitch= minimum pitch in Hz; Pitch range= Pitch range in Hz; P1= male participant 1; P2= male participant 2.

Table 4.
Comparison results of subjective voice evaluation
Before VT-1
After VT-2
z p-value
Mean SD Median Mean SD Median
K-VHI-10 9.42 3.55 10.00 0.75 1.06 0.00 -2.934 .003
K-VFI 13.25 13.13 11.00 3.83 7.32 1.50 -2.447 .014
TVQ 13.92 12.03 11.00 6.92 8.27 2.00 -3.063 .002

SD= standard deviation; K-VHI-10= Korean version of voice handicap index-10; KVFI= Korean version of vocal fatigue index; TVQ= thyroidectomy related voice questionnaires.

REFERENCES

Chandrasekhar, S. S., Randolph, G. W., Seidman, M. D., Rosenfeld, R. M., Angelos, P., Barkmeier-Kraemer, J., ..., & Robertson, P. J. (2013). Clinical practice guideline: improving voice outcomes after thyroid surgery. Otolaryngology— Head & Neck Surgery, 148(6), S1–S37.
crossref pmid
Chun, B. J., Bae, J. S., Chae, B. J., Hwang, Y. S., Shim, M. R., & Sun, D. I. (2012). Early postoperative vocal function evaluation after thyroidectomy using thyroidectomy related voice questionnaire. World Journal of Surgery, 36(10), 2503–2508.
crossref pmid
de Pedro Netto, I., Fae, A., Vartanian, J. G., Barros, A. P. B., Correia, L. M., Toledo, R. N., ..., & Angelis, E. C. D. (2006). Voice and vocal self‐assessment after thyroidectomy. Head & Neck, 28(12), 1106–1114.
crossref pmid
Han, J. H., Han, M. W., & Nam, S. Y. (2009). Management principle of unilateral vocal fold paralysis. Journal of The Korean Society of Laryngology, Phoniatrics & Logopedics, 28(12), 1106–1114.

Hong, K. H. (2014). Post-thyroidectomy syndrome. Korean Journal of Otorhinolaryngology-Head & Neck Surgery, 57(5), 297–303.
crossref
Hong, K. H., & Kim, Y. K. (1997). Phonatory characteristics of patients undergoing thyroidectomy without laryngeal nerve injury. Otolaryngology Head & Neck Surgery, 117(4), 399–404.
crossref pmid
Kim, H., Keum, B. R., Kim, G. H., Jeon, S. S., Kim, H., Kim, S. K., ..., & Park, I. S. (2016). Analysis of voice and swallowing symptoms after thyroidectomy in patients without recurrent laryngeal nerve injury in early postoperative period. Journal of The Korean Society of Laryngology, Phoniatrics & Logopedics, 27(2), 108–113.
crossref
Kim, J. S., Choi, S. H., Lee, K., Choi, C. H., Wang, S. G., & Lee, D. W. (2021). Vocal fold vibration characteristics during SOVTE using a vibration simulator and digital kymography. Communication Sciences & Disorders, 26(4), 921–932.
crossref
Kumrow, D., & Dahlen, R. (2002). Thyroidectomy: understanding the potential for complications. Medsurg Nursing, 11(5), 228–235.
pmid
Lee, C. Y., An, S. Y., Chang, H., Jeong, H. S., & Son, H. Y. (2015). Aerodynamic features and voice therapy interventions of functional voice disorder after thyroidectomy. Journal of The Korean Society of Laryngology, Phoniatrics & Logopedics, 26(1), 25–33.
crossref
Lee, G., & Park, S. N. (2021). A case of voice therapy for patient who voice changed after total thyroidectomy using contactless voice and speech therapy service platform. Journal of The Korean Society of Laryngology, Phoniatrics & Logopedics, 32(1), 43–47.
crossref
Lee, J. S., Kim, J. P., Ryu, J. S., & Woo, S. H. (2018). Effect of wound massage on neck discomfort and voice changes after thyroidectomy. Surgery, 164(5), 965–971.
crossref pmid
Lee, S. W. (2016). Management of post-throidectomy voice problems: surgeon’s perspectives. Korean Journal of Otorhinolaryngology-Head & Neck Surgery, 59(1), 1–8.
crossref
Jang, J. Y., Chang, Y. S., Kim, E. H., Moon, J. H., & Son, Y. I. (2014). Early neck exercises to reduce post-thyroidectomy syndrome after uncomplicated thyroid surgery: a prospective randomized study. Journal of Korean Thyroid Association, 7(1), 70–76.
crossref
Lee, S. J., & Kim, J. (2020). Clinical usefulness of estimated speaking fundamental frequency using the voice and speech range profiles in voice disorders. Communication Sciences & Disorders, 25(2), 480–488.
crossref
Myers, E. N., Hong, K. H., & Kim, Y. K. (1997). Phonatory characteristics of patients undergoing thyroidectomy without laryngeal nerve injury. Otolaryngology-Head & Neck Surgery, 117(4), 399–404.
crossref pmid
Nam, I. C., Bae, J. S., Chae, B. J., Shim, M. R., Hwang, Y. S., & Sun, D. I. (2013). Therapeutic approach to patients with a lower‐pitched voice after thyroidectomy. World Journal of Durgery, 37(8), 1940–1950.
crossref pmid
Nanjundeswaran, C., Jacobson, B. H., Gartner-Schmidt, J., & Abbott, K. V. (2015). Vocal fatigue index (VFI): development and validation. Journal of Voice, 29(4), 433–440.
crossref pmid
National Cancer Information Center. (2023). Cancer as a statistic. Retrieved from https://www.cancer.go.kr/lay1/S1T639C640/contents.do.

Park, K. N., Mok, J. O., Chung, C. H., & Lee, S. W. (2015). Does postthyroidectomy syndrome really exist following thyroidectomy? Prospective comparative analysis of open vs. endoscopic thyroidectomy. Clinical & Experimental Otorhinolaryngology, 8(1), 76–80.
crossref pmid pmc
Rosen, C. A. (2000). Phonosurgical vocal fold injection: procedures and materials. Otolaryngologic Clinics of North America, 33(5), 1087–1096.
crossref pmid
Ryu, C. H., Lee, S. J., Cho, J. G., Choi, I. J., Choi, Y. S., Hong, Y. T., ..., & Lim, J. Y. (2022). Care and management of voice change in thyroid surgery: Korean society of laryngology, phoniatrics and logopedics clinical practice guideline. Clinical & Experimental Otorhinolaryngology, 15(1), 24–48.
crossref pmid pmc
Ryu, J., Ryu, Y. M., Jung, Y. S., Kim, S. J., Lee, Y. J., Lee, E. K., ..., & Chung, K. W. (2013). Extent of thyroidectomy affects vocal and throat functions: a prospective observational study of lobectomy versus total thyroidectomy. Surgery, 154(3), 611–620.
crossref pmid
Stojadinovic, A., Henry, L. R., Howard, R. S., Gurevich-Uvena, J., Makashay, M. J., Coppit, G. L., ..., & Solomon, N. P. (2008). Prospective trial of voice outcomes after thyroidectomy: evaluation of patient-reported and clinician-determined voice assessments in identifying postthyroidectomy dysphonia. Surgery, 143(6), 732–742.
crossref pmid
Takamura, Y., Miyauchi, A., Tomoda, C., Uruno, T., Ito, Y., Miya, A., ..., & Kuma, K. (2005). Stretching exercises to reduce symptoms of postoperative neck discomfort after thyroid surgery: prospective randomized study. World Journal of Surgery, 29, 775–779.
crossref pmid
Yoon, S. Y., & Hong, H. J. (2020). Perioperative management of the voice in thyroid cancer. Journal of The Korean Society of Laryngology, Phoniatrics & Logopedics, 31(2), 49–55.
crossref
Yun, Y. S., Kim, H., Son, Y. I., & Choi, H. S. (2008). Validation of the Korean voice handicap index (K-VHI) and the clinical usefulness of Korean VHI-10. Korean Journal of Communication & Disorders, 13(2), 216–241.

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