ORIGINAL RESEARCH |
https://doi.org/10.5005/jp-journals-10023-1254 |
Mind the Vocal Process Level Gap! A Telltale Sign for Arytenoid Adduction
1,3Department of Laryngology, Dr Jayakumars Institute of Laryngology, Thiruvananthapuram, Kerala, India
2Department of ENT, Sree Mookambika, Institute of Medical Science and Research, Kulashekharam, Kanykumari, Tamil Nadu, India
Corresponding Author: Vivek Soman, Department of Laryngology, Dr Jayakumars Institute of Laryngology, Thiruvananthapuram, Kerala, India, Phone: +91 9447776906, e-mail: viveksoman3@gmail.com
Received: 27 February 2024; Accepted: 22 April 2024; Published on: 17 July 2024
ABSTRACT
Background: Unilateral vocal fold paralysis (UVFP) often results from neoplastic or iatrogenic damage to the recurrent laryngeal nerve or vagus nerve. It can have harmful effects on the patient’s quality of life owing to dysphonia and aspiration. The configuration of glottic closure in patients with UVFP is variable and unique in each case depending on the position of the immobile vocal fold, which is determined by factors such as intact nerve supply to the muscles, the extent of reinnervation, synkinesis, and compensatory laryngeal postures. Medialization thyroplasty and arytenoid adduction (AA) are effective treatments for medializing the paralyzed vocal cord; nevertheless, the indications and benefits of each procedure remain controversial. Historically, AA has been indicated for patients with vertical height mismatch and those with a maximum phonatory duration of <6 seconds. The success of laryngeal framework surgery largely depends on achieving an excellent phonatory closure. Pathophysiologically, AA stimulates the action of lateral cricoarytenoid muscle (LCA).
Objectives: (1) To study the prevalence of different types of phonatory gaps in patients presenting with unilateral vocal fold palsy; (2) to identify whether a gap at the vocal process level is the most predictive factor preoperatively regarding whether AA is required or not.
Materials and methods: The retrospective cohort study was done from the digital data archives of the senior author containing the laryngoscopic findings of unilateral vocal fold palsy patients in whom type I thyroplasty with or without arytenoid rotation was done during a period of 2021–2022. The laryngoscopic findings of these patients were compared both pre- and postoperatively to assess for the closure of phonatory gap at different levels.
Results: Of the 30 study subjects, males were 40% and females were 60%. In most cases, 73.3% had a phonatory gap at the thyroarytenoid (TA) and vocal process level, followed by 16.7% having a gap at the TA level, and 6.7% gap at the vocal process level only and 3.3% gap at the body of arytenoid level only. Around 66.7% of the subjects underwent arytenoid rotation and medialization thyroplasty, whereas 33.3% underwent type I thyroplasty alone. Out of the 19 patients who underwent AA, the gap at the vocal process level was closed in 17 patients with a p-value of 0.006, which is statistically significant (Fischer’s exact test).
Conclusion: The gap at the level of the vocal process of arytenoid may predict the patients who require AA and help in the preoperative planning of patients regarding the type of laryngeal framework surgery to be selected.
Keywords: Phonatory gap, Unilateral vocal fold palsy, Vocal process
How to cite this article: Soman V, Hareendranath Saralakumari S, Menon JR. Mind the Vocal Process Level Gap! A Telltale Sign for Arytenoid Adduction. Int J Phonosurg Laryngol 2024;14(1):1–4.
Source of support: Nil
Conflict of interest: None
INTRODUCTION
Unilateral vocal fold palsy (UVFP) results from dysfunction of recurrent laryngeal nerve or vagus nerve innervating the larynx. It is a more common condition than bilateral vocal cord palsy and typically presents with a breathy voice. It is a common otolaryngological condition, with the most common cause being iatrogenic from surgical injury to the recurrent laryngeal nerve.1 UVFP can have a significant impact on the quality of life of the sufferer, medialization laryngoplasty (ML), and arytenoid adduction (AA) and reinnervation procedures are being proposed for the long-term management of unilateral vocal cord palsy. These procedures are intended to improve glottic competence with associated improvement of voice and swallowing outcomes.2 Medialization laryngoplasty was first described by Isshiki et al., where a window is cut in the thyroid cartilage and a material (often Silastic or Gore-Tex) is inserted to medialize the true vocal fold.3 Arytenoid adduction was also originally described by Isshiki et al. as a method of correction in case of wide phonatory gap accomplished by rotating arytenoid cartilage of paralyzed vocal fold which is often done in conjunction with ML.4
Arytenoid adduction which theoretically simulates the action of lateral cricoarytenoid muscle (LCA) is usually accompanied by medialization thyroplasty to improve the postoperative vocal outcome. Arytenoid adduction is rarely done in isolation and a difference of opinion exists as to whether the addition of AA is needed along with ML. There are no clear-cut selection criteria in the existing literature that can predict whether AA is needed in unilateral vocal palsy preoperatively. Doing AA in addition to ML demands extra surgical time and an increased risk of complications.5,6 So it is vital in preoperatively determining the cases that require AA also with ML for the proper planning and counseling for the surgical procedure. A review of the literature found little information pertaining to the gap at the level of vocal process that was ascertained preoperatively as an indication for AA.
The objectives of the present study are:
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To study the prevalence of different types of phonatory gaps in patients presenting with unilateral vocal fold palsy.
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To identify whether a gap at the vocal process level is the most predictive factor preoperatively regarding whether AA is required or not.
MATERIALS AND METHODS
A retrospective cohort study was undertaken by reviewing videolaryngoscopic findings of 30 cases of UVFP from the digital archives of the senior author in whom type 1 thyroplasty along with or without arytenoid rotation was done during the study period of 2021–2022. The Institutional Review Board approved the study. The cases of laryngeal trauma, history of previous irradiation to the neck, history of injection laryngoplasty or prior laryngeal framework surgery, cases of cricoarytenoid joint pathology, and cases with a history of bilateral vocal fold palsy were excluded from the study. All patients underwent a comprehensive assessment and management process in accordance with the standard protocol of the department. This involved recording their medical history, conducting a thorough clinical evaluation, and confirming the diagnosis. This was followed by a flexible endoscopic examination of the larynx using a Storz Chip on tip CMOS Video-Rhino-Laryngoscope (Tuttlingen, Germany) with a diameter of 3.7 mm. This examination was conducted while the patient was comfortably seated and phonating a sustained vowel at their habitual pitch and intensity.
Following appropriate counseling, patients who provided their informed consent were assigned to undergo type 1 thyroplasty, either with or without AA. These procedures were performed under monitored anesthesia care, allowing for real-time auditory and visual feedback to fine-tune the voice and make informed decisions regarding the need for AA during the operation. The decision to perform AA was based on failure to achieve satisfactory voice improvement intraoperatively with ML alone. Two laryngologists reviewed the preoperative and postoperative video recordings for confirmation of findings and diagnosis to make the assessment. Gaps at the different levels, namely thyroarytenoid (TA), at the vocal process level, and body of arytenoid level were determined by still image captured at the point of maximum adduction during phonation. Prior to the surgery, all patients participated in voice therapy sessions aimed at the correction of compensatory supraglottic hyperfunction.
Statistical Analysis
The data was collected, coded, and entered into Microsoft Excel. Descriptive statistics were described in terms of frequencies and percentages. The comparisons of qualitative variables were done using the Chi-squared/Fischer’s exact test. Statistical analysis was carried out in Statistical Package for the Social Sciences (SPSS) software 26.0 (SPSS Inc. Released 2021; SPSS for Windows, Trial version 26.0, Chicago, SPSS Inc.) The level of significance was set at p-value < 0.05.
RESULTS
Of the 30 cases of UVFP studied 12 (40%) were males and 18 (60%) were females (Fig. 1). A total of 25 (83.3%) cases had left-sided vocal fold palsy, whereas 5 (16.7%) had right sided vocal fold palsy (Table 1). The gap was analyzed at three levels, mainly—the TA level, at the vocal process level, and at the body of the arytenoid level. Around 73.7% of patients demonstrated gaps at both TA and vocal process levels, with TA alone in 16.7%, vocal process alone in 6.7% and the body of arytenoid level in 3.3% (Fig. 2). TA and vocal process level gap remained the predominant gap pattern in both males and females when the gender-wise analysis was done (Fig. 3). Only one patient in our study had a posteriormost phonatory gap at the level of the body of arytenoid process. Around 66.7% of patients underwent both AA and ML whereas 33.3% of patients underwent ML alone (Fig. 4). No patient in our study group was subjected to only AA. There is a statistically significant association found between the cases that undergone AA and closure achieved at the vocal process level after surgery among the patients with a gap noted at the vocal process level with a p-value = 0.006 (Table 2). On the other hand, no statistically significant association (p = 1) was noted in the gap at the TA level in the same patients who underwent AA (Table 3).
Fig. 1: Gender distribution of the study sample
| Side | Frequency | Percentage |
|---|---|---|
| Left | 25 | 83.3% |
| Right | 5 | 16.7% |
| Total | 30 |
Fig. 2: Analysis of the different levels of phonatory gap
Fig. 3: Distribution of type of gap among males and females
Fig. 4: Type of laryngeal framework surgery done
| AA | V closure | p-value# | |
|---|---|---|---|
| Achieved | Not achieved | ||
| AA done | 17 (89.5%) | 2 (10.5%) | 0.006** |
| AA not done | 1 (20%) | 4 (80%) | |
#, Fischer’s exact test; **, statistically significant
| AA | T closure | p-value# | |
|---|---|---|---|
| Achieved | Not achieved | ||
| AA done | 16 (84.2%) | 3 (15.8%) | 1.0** |
| AA not done | 5 (100%) | 0 | |
#, Fischer’s exact test; **, statistically not significant
DISCUSSION
Females (60%) were the predominant group in our study with a male:female ratio of 1:1.5. The study by Nourmahnad et al. in 2023 regarding sociodemographic factors in vocal fold palsy also showed females predominance with 62% females and 38% males.7 The study by Menon et al. in cases of UVFP had a male: female ratio of 1.2:1.8 In the analysis of laterality in our study, 25 patients (83.3%) had left-sided palsy and five patients (16.7%) had right-sided palsy. In the study by Spataro et al. in relation to the etiology and presentation of unilateral vocal fold paralysis (UVFP), 621 (66.2%) patients had left-sided UVFP, while 317 (33.8%) patients had right-sided UVFP.9 Single institutional analysis of trends in vocal fold palsies spanning over 45 years by Takano et al., revealed 510 cases (64.0%) of left vocal fold paralysis, 209 (26.2%) cases of right vocal fold paralysis, and 78 (9.8%) cases were bilateral.10 We believe that since most of the cases in our study are postsurgical cases, there is a predominance on the left side as the longer course of nerve on the left side makes it more susceptible. Li et al. assessed the glottic closure patterns in type I thyroplasty with or without AA by determining the closure at the midmembranous vocal fold, closure just anterior to the vocal processes, and closure in the respiratory (cartilaginous) glottis.11 Vertical height difference between the vocal folds was also assessed. A visual analog scale (VAS) was used to assess the closure at the respective levels. The raters were independently asked to predict whether AA is needed or not in a VAS where the low likelihood is 0 and the high likelihood is 100. They found significant improvement in postoperative scores over preoperative scores for all groups for almost all rated parameters (closure at the midmembranous vocal fold, closure just anterior to the respiratory glottis, closure in the respiratory glottis, and vertical height difference). No significant improvement was demonstrated in pre- and postoperative closure scores of the respiratory glottis or vertical height in the thyroplasty group with silastic implants. However, the correlation was found for all areas of closure, with worse closure scores correlating with higher likelihood scores of predicting needing an AA.10
Our study specifically assessed closure in three areas—(1) anterior two-thirds (region of TA muscle); (2) at the vocal process level (where the two vocal cords normally meet on adduction); and (3) closure at respiratory glottis level (body of arytenoid level). Obtaining a good phonatory and closure is regarded success in laryngeal framework surgery in UVFP as inadequate glottic closure can lead to increased phonatory effort and a breathy quality of voice.
In our study, 67% of cases required both ML and AA, whereas 33% of cases required ML only. Around 53% of cases required combined medialization with AA, whereas 47% required AA alone in the study by Menon et al.8 This is a higher percentage than what is seen in the literature, which is 30% of thyroplasties, because most of our cases present late and patients present with varied compensatory patterns that necessitate a combined procedure in a greater proportion of the cases.12,13
Physiologically glottis is primarily closed by three intrinsic muscles. Thyroarytenoid is responsible for closure at the anterior two-thirds level, lateral cricoarytenoid is responsible for closure at the vocal process level and interarytenoid closes the glottis at the body of arytenoid level. Thyroplasty alone fails in repositioning the arytenoid into its normal physiological position. This explains the reason for yielding an unsatisfactory result in many cases of unilateral vocal fold palsy when ML is done alone.14 AA is accomplished by passing a suture between the muscular process of the arytenoid cartilage and the thyroid cartilage which rotates and adducts the arytenoid cartilage on the paralyzed side to the midline. So performing AA in addition to ML completely closes the glottic gap in patients with gaps at both the TA level and vocal process level.
Debates exist in selecting the appropriate indication for these two commonly performed laryngeal framework surgeries in the current literature. Some surgeons rarely perform an AA, whereas others perform AA (with or without a ML) in all or most of the cases. Some surgeons prefer an arytenoidopexy to an AA15,16
Some surgeons use AA only if adequate voice is not obtained with ML alone. However, the intraoperative assessment of phonation is limited by the fact that it may be affected by the level of sedation, the position of the patient, and the resultant postoperative edema if the surgery takes a long time. Improved posterior glottic closure and vertical height discrepancies are two of the most common explanations offered as to why AA may be beneficial.17 But these two parameters are difficult to determine objectively in the preoperative period. So our study aims at identifying a simple, reliable indicator of AA preoperatively on videolaryngoscopy, which can predict the necessity while contemplating the surgery
In our study, we found out that in a patient who underwent AA, the closure achieved at the vocal process level is statistically significant with a p-value = 0.006. On the other hand, in such patients, no statistically significant association was noted for the gap at the TA level (p = 1). Arytenoid adduction pulls the paralyzed vocal process of the arytenoid medially and inferiorly so that vocal processes meet in the midline. So close scrutiny of the gap at the vocal process level as observed on videolaryngoscopy preoperatively predicts the need for AA.
In our study, the gap noted in the body of the arytenoid region was noted in only one case (3%). This is the least common type of gap pattern noted. The vocal process level gap was closed completely in 17 out of 19 in whom AA was done. The two patients whose vocal process level gap couldn’t be closed completely also showed a significant reduction in the gap on postoperative videolaryngoscopy and had a good voice outcome after surgery.
CONCLUSION
Unilateral vocal fold paralysis can have a significant impact on the person’s quality of life, affecting their voice and swallowing. Surgical procedures like ML and AA aim to improve voice and swallowing outcomes. The need for AA alongside ML and preoperative laryngoscopic findings that can predict the need for AA is not clearly defined in the existing literature. The present study reveals that TA level and vocal process level gap are the commonest patterns of gap in UVFP and the gap at the vocal process level can predict the need for AA during the surgical planning of the patient in the preoperative period.
Understanding the factors that influence the decision to perform AA allows laryngologists to confidently incorporate this procedure into their surgical approach.
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