Journal of Laryngology and Voice

: 2020  |  Volume : 10  |  Issue : 1  |  Page : 1--6

Voice outcome after coblation-assisted microlaryngeal surgery -Our experiences at a tertiary care teaching hospital

Santosh Kumar Swain, Loknath Sahoo, Swaha Panda 
 Department of Otorhinolaryngology, IMS and SUM Hospital, Siksha “O” Anusandhan University, Bhubaneswar, Odisha, India

Correspondence Address:
Santosh Kumar Swain
Department of Otorhinolaryngology, IMS and SUM Hospital, Siksha “O” Anusandhan University, Kalinga Nagar, Bhubaneswar - 751 003, Odisha


Background: Benign vocal fold lesions are a common laryngeal pathology found in routine clinical practice. Microlaryngeal surgery is useful for excision of the pathology. Coblation-assisted microlaryngeal surgery for benign lesions of the vocal folds is a new technique for the treatment of vocal fold lesions. The objective of this study was to assess the voice outcome following coblation-assisted microlaryngeal surgery for benign vocal fold lesions. It also assessed the vocal fold function after coblation excision of the benign fold lesions by using video stroboscopic analysis. Materials and Methods: This was an analytical retrospective study where 54 patients of benign vocal fold lesions participated. All the 54 patients were selected for coblation-assisted microlaryngeal surgery. Perceptual analysis of voice was done by using GRBAS scoring. The voice analysis was done with the help of PRAAT software (Version 5.3.51) and fundamental frequency, jitter, shimmer, and harmonics to the noise ratio were analyzed. Stroboscopy was done in all cases for evaluating the vocal fold function by using glottic closure and pattern of mucosal wave. All the parameters were analyzed preoperatively and at 3 weeks, 6 weeks, and 3 months postoperatively. Results: The perceptual analysis of voice showed a significant improvement of the GRBAS score after coblation-assisted microlaryngeal surgery (P < 0.001). The acoustic analysis revealed that all parameters improved after surgery (P < 0.001). Stroboscopy findings also SHOWED improved vocal fold functions. Conclusion: Coblation-assisted microlaryngeal surgery is a safe and effective treatment modality for benign vocal fold lesion with excellent voice outcome.

How to cite this article:
Swain SK, Sahoo L, Panda S. Voice outcome after coblation-assisted microlaryngeal surgery -Our experiences at a tertiary care teaching hospital.J Laryngol Voice 2020;10:1-6

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Swain SK, Sahoo L, Panda S. Voice outcome after coblation-assisted microlaryngeal surgery -Our experiences at a tertiary care teaching hospital. J Laryngol Voice [serial online] 2020 [cited 2020 Nov 26 ];10:1-6
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Benign lesions of the vocal folds are common findings of the larynx in clinical practice, which require microlaryngeal surgery.[1] Vocal fold polyps are often solitary originating from the edge of the vocal folds.[2] Phonotrauma is an important cause for the origin of vocal fold pathology. Phonotrauma may be due to the overuse of voice among voice demanding occupations. Voice abuse is forced voice production by strain in the neck, head and shoulder area, which leads to hoarse quality of voice.[3] In addition to the voice abuse, smoking, laryngopharyngeal reflux and anticoagulant treatment may predispose to vocal fold pathology among patients those are having abuse or misuse of voice. Coblation technology can be utilized for surgical excision or debulking of the pathology of the larynx and trachea, such as sessile polyps or tumors. Coblation technique is based on bipolar plasma devices which act at a relatively lower temperature and gently dissolve or excise or shrink the target lesion with minimal thermal injury to the surrounding healthy tissue.[4] Coblation techniques help to provide ablation, resection, coagulation, and hemostasis of the blood vessels.[4] The PROcise™ LW plasma wands (Smith and Nephew Surgical Minuteman Rd, Andover, MA, USA) are helpful for excision of the bulky and sessile lesions of the larynx. It is designed for precise, controlled removal of the laryngeal lesions. It also has an ultra-slim wand shaft, which is useful for accessing the vocal folds, trachea, and suitable for surgery in narrow laryngeal anatomy.

Coblation technology is not only useful for ablation, coagulation, irrigation and but also useful for doing suction in a single-use device.[5] Coblation-assisted microlaryngeal surgery has the advantages of short duration of the procedure, less bleeding, short hospital stay, and minimal complications. Other than these advantages, coblation technology also reduces the risk of airway fire in comparison to the laser or electrosurgical devices.[4] This study assessed the voice outcome after coblation-assisted microlaryngeal surgery for benign vocal fold lesions where video-endoscopic, acoustic, and perceptual analysis of the voice were done in all patients before and after surgery.

 Materials and Methods

This study was conducted between March 2015 and April 2020. This study was approved by the institute's ethical committee. The participants of this study were selected from adult patients who attended the outpatient department of otorhinolaryngology in the age group between 18 years and 65 years. All the participants were diagnosed with benign lesions of the vocal fold, such as vocal fold polyp, vocal nodules, papilloma, cysts, and vocal fold keratosis. The diagnosis was made with the help of indirect laryngoscopy and videolaryngoscopy by using 70° rigid endoscope (Karl Storz 8700 CP). Patients that were diagnosed with benign vocal fold lesion along with malignant lesions of the vocal folds, co-morbidities such as uncontrolled diabetes mellitus or hypertension were excluded from this study. All the participating patients were explained about the study, and informed consents were obtained. A detail clinical history, such as voice abuse and smoking habit, were taken followed by clinical examinations of the patients. Laryngeal endoscopy with the help of 70° endoscope, video stroboscopy, acoustic and perceptual analysis of voice were done for all patients before surgery and after surgery in scheduled follow-ups. Postoperatively voice outcome was assessed by perceptual and acoustic voice analysis, and vocal fold function was examined by stroboscopic analysis in each follow-up visit. GRBAS score (Grade, Roughness, Breathiness, Asthenia, and Strain score) was used for perceptual voice assessment by a speech pathologist. The GRBAS is rated on a four-point scale such as 0-No perceived abnormality; 1 - Mild abnormality; 2 - Moderate abnormality; 3 - Severe abnormality. PRAAT (Version 5.3.51) software Paul Boersma and David Weenink (software developer), University of Amsterdam, Amsterdam, Netherlands was used for acoustic analysis such as fundamental frequency (F0), Jitter, shimmer, and harmonics to noise ratio (HNR). All patients were asked to sustain the vowel at a comfortable pitch. All the measurements were made with the help of a microphone kept at 15 cm from the lips. The patient's voice samples such as sustained vowels, narrative speech, and reading sentences were recorded and played on headphones of two experienced speech therapists who were blinded about the study, and they received the voice samples and scores to each component of the GRBAS. A comparison was then done between the scores of the two speech therapists. Videolaryngoscopy was done by an otolaryngologist, whereas acoustic and perceptual analysis of voice was done by the speech therapist. In this study, all patients underwent microlaryngeal surgery with the help of coblation under general anesthesia. Laryngeal wand was used in microlaryngeal surgery. All patients were advised voice rest for 72 h, and anti-reflux medication was given to each patient for 2 weeks. Postoperative follow-up was done at 3rd week, 6th week and 3rd months after surgery. Repeated assessment of analysis of variance (ANOVA) was used to analyze the data of this study. For comparing different clinical variables among different subgroups, independent Student's t- test was utilized. Mann–Whitney U-test was used to compare non-Gaussian variables between the sub-groups. The P value < 0.005 was considered statistically significant.


This study included 54 patients who underwent coblation-assisted excision of the different lesions of the vocal folds. The mean age of the participants was 45 years, with a standard deviation of 8.569. The youngest patient in this study was 18 years and eldest was 65 years. There were 30 males and 24 females with male-to-female ratio 1.8:1. The maximum numbers of patients were seen in the age group of 34–42 years. The most common lesion found in this study was vocal fold polyp (42.59%) [Table 1]. Vocal cysts were seen equally in number among males and females. In female patients, vocal nodules were more common, whereas vocal polyps were more common in males. The rarest lesion in this study was laryngeal keratosis, which was mostly found in males. The most common clinical presentation in this study was hoarseness of voice. Other clinical presentations found in the study patients were vocal fatigue (48.14%), voice abuse (42.59%), and strain during speaking (40.74%) [Table 2]. Only two patients presented a history of previous surgery of the larynx, where both of them were diagnosed with recurrent laryngeal papillomatosis. Out of 54 patients, 13 were smokers and quit smoking after the diagnosis of the disease.{Table 1}{Table 2}

The perceptual analysis of the voice was analyzed by a speech pathologist with the help of the GRBAS score. The preoperative GRBAS score was 8, with a range of 5–13 [Table 3]. The median GRBAS score improved to 5 at the first postoperative (at 2nd week) follow up visit. There were consistent improvements of the GRBAS score in all stages of postoperative follow-up. At the last follow up visit i.e., in 3rd month, the median GRBAS score was 2. Repeated assessment of ANOVA was used to analyze the data of this study. There was improvement of the mean GRBAS score after laryngeal surgery and at every postoperative follow up was found to be significant (P < 0.001). The data analysis showed a significant difference between mean scores at each visit (P < 0.001).{Table 3}

The acoustic analysis of the voice was analyzed before and after surgery with the help of electro-acoustic voice recording and spectrographic analysis of the fundamental frequency (F0), jitter, shimmer, and HNR by using PRAAT software (Version 5.3.51). Different acoustic parameters were assessed separately for males and females with measures ANOVA. The mean fundamental frequency (F0) before surgery in females was 192.05 Hz, which increased to 225.04 Hz in the 3rd month [Table 4]. In males, the fundamental frequency changed from 143.4 Hz during preoperative time to 127.55 Hz at the 3rd month after surgery during follow-up [Table 4]. The analysis of F0 was done by repeated measures ANOVA, which revealed a significant difference during the preoperative period and each follow up after surgery with F0 value (P < 0.0001). There were no significant differences among the F0 values at each follow-up visit (P > 0.05). The mean shimmer before surgery was 10.6% in males and 10.9 in females. The mean shimmer was reduced to 4.8% in males and 5.2% in females at third (third month) follow up visit [Table 5]. There was a significant improvement of shimmer values after surgery in comparison to preoperative measurements (P < 0.001). Between each follow-up visit, there was a significant difference of the mean shimmer values (P < 0.001). Before surgery, the mean jitter among males was 3.28% and 3.5% among females [Table 5]. There was a significant difference of preoperative mean jitter and postoperative follow-up visits (P < 0.0001). However, there was a statistically significant difference between jitter values at each postoperative follow-up visit (P > 0.05). In males, the mean HNR was 3.4 before surgery, which improved to 19.4 at the 3rd month visit. In females, the HNR before surgery was 3.8, which increased to 19.5 by 3rd month follow-up. In overall, HNR showed a significant difference (P < 0.0001) between preoperative and postoperative follow up visits and also among all the follow-up visits [Table 5]. Stroboscopic assessment was made in pre- and post-operative period for studying the morphology of the vocal folds in all patients. Two patients presented with recurrent lesion after third follow-up in case of recurrent papillomatosis. Glottic mucosal wave patterns were studied in all cases. Mucosal wave pattern of the vocal fold was studied to assess amplitude, symmetry, and periodicity. Postoperative stroboscopy picture showed symmetric, regular normal waves for all patients except two (3.70%), which had recurrent lesions.{Table 4}{Table 5}


Benign lesions of the vocal folds are commonly seen in routine clinical practice. These lesions of the vocal folds are caused by excessive and incorrect vocalization or bad habits.[6] The most important etiological factors associated with benign vocal fold pathologies are voice abuse or overuse, leading to hoarseness of voice.[6] In this study, the most common clinical presentation among participants was hoarseness of voice. These lesions are seen in the most active age group of life and more commonly in males.[7] In this study, the most common age group was in 34 years to 42 years with preponderance among males. This observation is supported by another study by Stewart.[8] The most common benign lesion of the vocal fold was vocal polyp in this study (42.59%), as observed in other studies.[9],[10] There are different surgical techniques used for the treatment of benign lesions of the vocal folds, but the voice outcome following microlaryngeal surgery is often challenging for the surgeons as well as patients. Refinements of the micro-surgical techniques for laryngeal pathology by Strong, Bochayer, Hirano, etc., have helped to enhance the quality of the voice.[11],[12] Carbon dioxide laser is being increasingly used for benign lesions of the vocal folds. Although several studies show good voice outcomes with carbon dioxide laser, many centres are avoiding it due to concerns regarding lateral thermal injury. In our study, we used low-frequency coblation for evaluating voice outcome and vocal fold function following the excision of the benign lesions of the vocal fold.

Coblation technology is a minimally invasive technique which provides less invasive treatment with quicker recovery and short hospitalization.[13] In coblation-assisted microlaryngeal surgery, the larynx is exposed by a laryngoscope and uses a low-temperature plasma technology for resection of the laryngeal lesions. Coblation technology is an excellent tool which provides ablation, resection, coagulation of the soft tissue, and hemostasis of the vessels in one surgical device. It helps to reduce postoperative laryngeal edema and decrease intra-operative metastasis in the case of malignant lesions.[14] Coblation-assisted microlaryngeal surgery is better than conventional microlaryngeal surgery, whereas the lasers need a large number of personnel for ensuring safety and effective result. Laser is more costly, and heat produced by it increases the chance of scarring and tissue damage. There are some other limitations of the laser such as potential for airway fires and so special endotracheal tubes are required for anesthesia, vocal fold web, mucosal burns, stenosis, and glottic incompetence.[15],[16] Use of coblation in microlaryngeal surgery in place of traditional electrocautery or laser can reduce the chance of airway fires.[17] One study comparing laser with coblation for laryngeal papillomatosis showed that coblation is associated with a good surgical outcome without damaging the underlying architecture of the vocal folds, lowering the chance of recurrence and results in good postoperative voice quality, which favors our study.[18] Coblation is an unique tool useful for suction, ablation as well as coagulation without causing injury to the architecture of the vocal folds and resulting good voice quality.

PROcise™ LW plasma wand is usually used in coblation technique, this has excellent features. These features include: (a) Long and low profile malleable wand which allows increased surgical field visualization, adjustable to specific anatomy and accessible to anterior commissure of the glottis; (b) enhance flat active electrode of the wand which enables efficient bipolar ablation and coagulation during microlaryngeal surgery; (c) it has unique integrated saline irrigation and suction facilities so that maximum saline delivery can be made to the active electrode, and this is possible regardless of the orientation of the wand.[5] Coblation-assisted microlaryngeal surgery helps to complete excision of the lesions in very short duration along with precision which would be difficult with other techniques for vocal fold lesions such as papillomatosis extending to the undersurface of the vocal fold and involving anterior commissure of the glottis, which is not easily assessed without causing injury to the adjacent tissues.[19],[20] Microscopic surgery with coblation has advantages of less bleeding, short duration procedure, increased completion rate, and better voice quality in comparison to other techniques.[21]

This study was done to assess the voice outcome and vocal fold function in coblation-assisted microlaryngeal surgery for benign vocal fold lesions. There were several scoring systems available for perceptual analysis of the voice. GRBAS provides a simple scoring system for assessing the degree of voice changes. In this study, all the parameters associated with GRBAS were improved. The median GRBAS score was 9 before surgery, which improved to 2 at the third follow up after surgery, which was statistically significant [Table 3]. In our study, there was improvement of the mean GRBAS score after laryngeal surgery and at every postoperative follow up and was found to be significant (P < 0.001). This is supported by another study where the majority of the patients showed improvement of the voice and no evidence of the recurrence of the benign laryngeal lesions.[22]

The voice outcome was also objectively assessed by acoustic analysis. The parameters of acoustic analysis, such as fundamental frequency, shimmer (%), jitter (%), and HNR were analyzed in this study. In this study, there was a significant improvement of shimmer values after surgery in comparison to preoperative measurements (P < 0.001) and also between each follow-up visit, there was a significant difference of the mean shimmer values (P < 0.001). In this study, there was a significant difference of preoperative mean jitter, and postoperative follow-up visits (P < 0.0001), whereas there was a statistically significant difference between jitter values at each postoperative follow-up visit (P > 0.05). The two important parameters of the voice are pitch and intensity, which were measured by jitter and shimmer. The measurements of these parameters were done to compare pre- and post-operative values. Two of these considered important indicators for vocal fold functions.[23] Both parameters revealed significant improvement postoperatively [Table 4] and [Table 5]. One study which favored to this result showed a significant improvement noted in measures of perturbation, i.e., jitter and shimmer. Improvement in jitter was more as comparison to shimmer i.e., perturbation in pitch improved more than perturbation in intensity after surgery.[18]

There are several studies which show the F0 range that measures the efficacy of the treatment. The normal value for F0 in males is 107–146 Hz and in females is 197–227 Hz. This study showed that F0 changed to more physiological in both males and females after surgery. HNR is an index (quantitative) for the degree of hoarseness of voice. In this study, HNR compared pre- and post-operatively, showed statistically significant improvement. The acoustic characteristic of the voice is based on the mass and tension of the vocal folds. The better outcomes of the acoustic parameters can be explained on the basis of betterment in vibratory characteristics of the vocal folds. There were several studies that showed coblation to be an effective tool for laryngeal lesions, but none had analyzed the voice quality.[24],[25] In this study, we analyzed the voice quality pre and postoperatively and found significant improvement.[18] Stroboscopy was used to provide excellent picture of the vocal folds along with patterns of mucosal fold vibration. The two important parameters, such as glottic closure pattern and mucosal wave, are responsible for voice quality.[26] In this study, glottic closure and normal mucosal waves were seen in 97% cases. Complete closure is determined by improved contact between the vocal folds after coblation microlaryngeal surgery. Mucosal wave tends to become normal and regular after coblation assisted microlaryngeal surgery, which causes better generation of pressure development in the subglottis, so better amplitude of the vocal fold vibration.[27] One study documented that the voice recovery is faster with coblation assisted microlaryngeal surgery than laser.[28] This study supported our outcome after coblation assisted microlaryngeal surgery for benign vocal fold lesions. One author documented normal vocal fold, and normal voice after coblation-assisted microlaryngeal; surgery for benign vocal fold lesion, which favors this study and proved the advantages of minimal damage of the underlying tissues of the larynx and bloodless field.[29]

There is still debate about the duration of the voice rest needed after surgery. We suggested 48–72 h of absolute voice rest after surgery. Speech therapist helped the patients to slowly rehabilitate full speech after 2 weeks. Longer duration of absolute voice rest is avoided as patient compliance reduces with longer voice rest.


Benign lesions of the vocal folds are a common cause of hoarseness of voice. Treatment of these lesions not only aims for excision of the lesions but also for getting acceptable voice and prevent the recurrence of the lesions. This study demonstrated that the use of coblation in microlaryngeal surgery significantly improved the outcome of the success rate of surgery and voice outcome of the patient. It is helpful for a bloodless field, avoiding surrounding tissue damage and also reduces operation time. Thus, coblation assisted microlaryngeal surgery is worthy of clinical application for benign vocal fold lesions. Coblation-based bipolar plasma devices help to do surgery at a relatively low temperature, which cause dissolving of the vocal fold lesions with minimal thermal injury to adjacent healthy tissue. It has excellent role in the treatment of laryngeal or vocal cord benign pathology, which provides less invasive treatment with quicker recover and shorter hospital stay.

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Conflicts of interest

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