Parameters and Scales Used to Assess and Report Findings From Stroboscopy: A Systematic Review

Validity, reliability and reproducibility of the VLS parameters form for the collection of videolaryngostroboscopic basic findings

OBJECTIVE

The videolaryngostroboscopy parameters form (VLSP form) is a diagnostic tool for the collection of videolaryngostroboscopic basic findings through the evaluation of 12 parameters. The aim of the present study is to preliminarily investigate intra- and inter-rater reliability, validity and responsiveness of the VLSP form.

METHODS

A study on a total amount of 160 forms for the evaluation of VLS basic findings was carried out. 80 forms were scored through the VLSP form and 80 with the Voice Vibratory Assessment with Laryngeal Imaging (VALI) form Stroboscopy (S) by four expert phoniatricians, that blindly scored the VLS recordings of 5 subjects without voice disorders and 5 patients with organic voice disorder before and after successful phonosurgery. Intra-rater and inter-rater analysis have been performed for both forms. The scores obtained through VLSP form and VALI form S have been compared to analyse concurrent validity, while VLSP scores before and after phonosurgery have been compared to analyse responsiveness. Finally, each rater annotated the "difficulty" in rating every parameter and its "importance" for the diagnosis.

RESULTS

The VLSP form showed good inter- and intra-rater reliability. It showed a good accuracy for the documentation of changes of laryngeal anatomy and function after phonosurgery, similarly to the VALI form S. The 12 parameters of the VLSP form were judged "Slightly Important" in 28.3% of the samples, "Very Important" in 64.8% of the samples, "Not Difficult" in 73.1% of the samples.

CONCLUSIONS

The results of the present study suggest that the VLSP form is comparable to the VALI form S for the evaluation of videolaryngostroboscopic parameters and is a valid, reliable and reproducible diagnostic tool. It can help voice clinicians in the evaluation of VLS examinations and it allows for a punctual assessment of modifications in laryngeal anatomy and function in pathological conditions and after phonosurgery.

Sensitivity of Videolaryngostroboscopic Rating Tools to Differences in Dysphonia Severity

OBJECTIVES

This study evaluated the validity of two videolaryngostroboscopic (VLS) rating tools to detect differences in VLS ratings between normophonic speakers, mild, and moderate-severely dysphonic speakers.

METHODS

Sixteen rigid VLS exams were obtained from four normophonic controls and 12 speakers with dysphonia (8 =mild, 4 =moderate-severe) secondary to laryngeal pathology. Eight clinicians rated nine vibratory VLS parameters for each exam using both the Voice-vibratory Assessment of Laryngeal Imaging (VALI) tool and a 100 mm visual analog scales (VAS). Ratings obtained for both right and left vocal folds (eg, mucosal wave, amplitude of vibration, nonvibrating portion) were averaged. One rating of overall severity of laryngeal function using a 100 mm VAS also was obtained. ANOVAs were used to evaluate differences in VLS parameters between three speaker groups (normophonic, mildly dysphonic, moderate-severely dysphonic) using these two rating tools.

RESULTS

There were statistically significant differences between controls and moderate-severely dysphonic speakers and for all VLS parameters except phase symmetry (P < 0.05) for both VALI and VAS ratings. Differences between mildly dysphonic and moderate-severely dysphonic and speakers were observed for 4/6 VALI ratings (mucosal wave, nonvibratory portions, phase closure, and regularity) and 5/6 parameters (mucosal wave, amplitude of vibration, nonvibratory portions, phase closure, and regularity) for VAS ratings. Significant differences between controls and mildly dysphonic speakers were not observed for VLS parameter rated using the VALI. There were significant differences between controls and mildly dysphonic speakers for 3/6 parameters (mucosal wave, amplitude of vibration, nonvibratory portion) using a VAS. Ratings of overall severity of laryngeal function differed between all levels of dysphonia severity.

CONCLUSIONS

Significant differences in VLS ratings were observed for comparisons of normophonic and moderate-severely dysphonic speakers and mild to moderately dysphonic speakers using the VALI and the VAS. However, the VAS scale appeared to better differentiate differences in VLS measures between normophonic speakers and those with mild dysphonia. Future studies should consider rating scale sensitivity when VLS rating tools are selected for clinical and research purposes.

The Utility of Stroboscopy in Evaluating Patients with Benign Vocal Fold Lesions

Purpose: The present study aims to provide a comprehensive analysis of the use of stroboscopy as an assessment tool for patients with benign lesions of the vocal folds. Methods: The current study was based on an extensive review of the international bibliography regarding the evaluation of voice in patients with benign lesions of the vocal cords using videostroboscopy. Results: Stroboscopy is a convenient technique used by otolaryngologists that has been established as a valuable diagnostic tool for assessing patients with dysphonia and benign vocal cords lesions. Conclusions: Stroboscopy is recommended in the literature as the preferred method for assessing vocal cord vibratory function. The future poses challenges in standardizing guidelines and quantifying measurements of stroboscopic findings.

The effect of the auditory signal on videolaryngostroboscopy ratings and interpretation

OBJECTIVE

The primary aim of this study was to examine the effect of the videolaryngostroboscopic auditory signal on videolaryngostroboscopy (VLS) ratings and interpretation in normophonic and dysphonic speakers.

STUDY DESIGN

Prospective repeated measures design METHOD: Eight speech-language pathologists evaluated rigid VLS exams obtained from 12 dysphonic speakers with vocal fold pathology and 4 normophonic speakers with normal VLS exams. VLS exams were evaluated with the auditory signal present and absent with a washout period between rating sessions. VLS measures were obtained using the Voice-vibratory Assessment of Laryngeal Imaging (VALI) and a 100mm visual analog scale (VAS). The effects of the auditory signal and its interaction with voice quality severity on 9 VLS ratings, diagnostic billing codes, and treatment recommendations were examined.

RESULTS

There was no effect of auditory information on VLS measures or overall severity of laryngeal function evaluated using the VAS (ps > 0.05). There was a main effect of auditory information and a significant interaction with voice quality severity for only one VLS measure (non-vibrating portion-left) evaluated using the VALI (P = 0.05). Post-hoc analysis for this rating showed significant increases (t-test adjusted P < 0.05) when voice quality severity was moderate-severe (M = 4.8%; SD = 1.65%) and auditory information was present. Agreement in individual clinician's selection of diagnostic codes (73%) and treatment recommendations (65.6%) when auditory cues were present and absent was moderate to high.

CONCLUSION

The presence of the videolaryngostroboscopic auditory signal had a minimal effect on VLS ratings, treatment recommendations, or diagnostic billing codes.

An Exploration of the Risk Factors, Severity, and Sequelae of Vocal Fold Hemorrhage in a Population of Voice Patients Before and After Diagnosis

BACKGROUND

Vocal fold hemorrhage (VFH) is the rupture (usually acute) of a blood vessel within the true vocal fold. The long-term sequelae of VFH on the mucosal wave (MW) and glottic gap on video stroboscopy remain understudied. The primary objective of this study was to investigate the short-term and long-term consequences of VFH through measured and rated analysis of the mucosal wave and glottic gap.

METHODS

The presence of VFH and its extent (limited/moderate vs. extensive VFH) were identified. The primary outcome of this study was mucosal wave, which was assessed on an ordinal scale by three blinded raters pre and posthemorrhage. Only patients who had undergone strobovideolaryngoscopy before sustaining VFH were included. Mucosal wave and glottic gap also were measured using image pixel analysis using the open-access tool, ImageJ (NIH, Bethesda, MD).

RESULTS

Twenty-three subjects were included in this study (mean age 39.78 ± 15.54). Intra-rater reliability for MW ratings was 81.48% ± 6.150% (minimum 77.78%) for all evaluators (κ = 0.519 [0.267-0.772], P < 0.001). Inter-rater reliability analysis revealed 75.56% agreement between evaluators (κ = 0.524 [0.425-0.623], P < 0.001). MWMeasured extrapolated from ImageJ methodology correlated significantly with MWRated (n = 70, r = 0.448, P < 0.001). ΔMWMeasured from baseline to follow-up evaluation were compared for both the initial follow-up visit (FU1) and the second follow-up visit (FU2) [-4.135 ± 31.01 vs. 36.50 ± 39.97, P = 0.025]. Hence, ΔMWMeasured was significantly better by FU2 than FU1, with the larger positive change from baseline representing a greater improvement in the measured mucosal wave. Additionally, there were significant differences in ΔMWRated between those with limited/moderate VFH and those with extensive VFH at FU1. Duration of absolute voice rest correlated significantly with time to VFH resolution. Long-term change in mucosal wave after hemorrhage was assessed using both ΔMWMeasured and MWRated. Based on ΔMWRater, 35.0% of subjects demonstrated ongoing and worse mucosal wave restriction compared to baseline at their most recent follow-up visit. Based on ΔMWMeasured, 50.0% of the subjects showed ongoing and worse mucosal wave restriction compared to baseline at their most recent follow-up visit.

CONCLUSION

Overall long-term restrictions in MW after hemorrhage were present in 35.0% of the subjects based on ratings and 50.0% of the patients based on the measured MW using ImageJ, demonstrating the importance of ongoing study into this pathology and how to prevent it, especially in PVU and professional singers. Patients presenting with extensive hemorrhage were at risk for more prominent, detectable changes in mucosal wave compared to those with limited/moderate hemorrhage in the short-term, defined by a mean FU time of 3 months, but not long-term, characterized by a mean FU time 6 months or greater. Whether the severity of VFH is a true indicator of mucosal wave alterations requires additional study, as does the reliability and validity of ImageJ mucosal wave and glottic gap measurement techniques.

Videostroboscopy Versus High-Speed Videoendoscopy: Factors Influencing Ratings of Laryngeal Oscillation

PURPOSE

The purpose of this study was to determine whether patient voice-related diagnosis, severity of dysphonia, and rater's experience influence the relationship between laryngeal oscillation ratings made from videostroboscopic and high-speed videoendoscopic (HSV) exams.

METHOD

Stroboscopy and HSV exams from 15 patients with adductor spasmodic dysphonia (ADSD) and 15 with benign vocal fold lesions were rated for laryngeal oscillation and closure by 10 licensed speech-language pathologists (SLPs). Raters were divided into low- (< 5 years) and high-experience (> 5 years) groups. Ratings of vocal fold amplitude, mucosal wave, periodicity, phase symmetry, nonvibrating portion of the vocal fold, and glottal closure were examined using an online form adapted from the Voice Vibratory Assessment of Laryngeal Imaging (VALI).

RESULTS

Stroboscopy and HSV ratings were more strongly positively correlated for patients with benign vocal fold lesions (r between .43 and .75) than for those with ADSD (r between .40 and .68). Differences between stroboscopy and HSV exams were significantly greater for ratings of amplitude, mucosal wave, and periodicity in patients with ADSD than for patients with benign vocal fold lesions. Raters with < 5 years of experience showed significantly greater differences between stroboscopy and HSV ratings of amplitude and nonvibrating portion of the vocal fold for patients with ADSD only. Significantly greater differences between ratings of periodicity and phase symmetry were observed in patients with more severe dysphonia.

CONCLUSIONS

Differences in laryngeal ratings made between HSV and stroboscopy exams may be influenced by patient diagnosis, severity of dysphonia, and rater experience. Future study is warranted to determine how the differences observed influence clinical diagnosis and outcomes.

3D VOSNet: Segmentation of endoscopic images of the larynx with subsequent generation of indicators

Video laryngoscope is available for visualizing the motion of vocal cords and aid in the assessment of analyzing the larynx-related lesion preliminarily. Laryngeal Electromyography (EMG) needs to be performed to diagnose the factors of vocal cord paralysis, which may cause patient feeling unwell. Thus, the problem is the lack of credible larynx indicators to evaluate larynx-related diseases in the department of otolaryngology. Therefore, this paper aims to propose a 3D VOSNet model, which has the characteristics of sequence segmentation to extract the time-series features in the video laryngoscope. The 3D VOSNet model can keep the time-series features of three images before and after of the specific image to achieve translation and occlusion invariance, which explicitly signifies that our model can segment and classify each item in the video of laryngoscopy not affected by extrinsic causes such as shaking or occlusion during laryngoscope. Numerical results revealed that the testing accuracy rates of the glottal, right vocal cord, and the left vocal cord are 89.91%, 94.63%, and 93.48%, respectively. Our proposed model can segment glottal and vocal cords from the sequence of laryngoscopy. Finally, using the proposed algorithm computes six larynx indicators, which are the area of the glottal, area of vocal cords, length of vocal cords, deviation of length of vocal cords, and symmetry of the vocal cords. In order to assist otolaryngologists in staying credible and objective when making decisions without any doubt during diagnosis and also explaining the clinical symptoms of the larynx such as vocal cord paralysis to patients after diagnosis, our proposed algorithm provides otolaryngologists with explainable indicators (X-indicators).

Machine Learning in Laryngoscopy Analysis: A Proof of Concept Observational Study for the Identification of Post-Extubation Ulcerations and Granulomas

OBJECTIVE

Computer-aided analysis of laryngoscopy images has potential to add objectivity to subjective evaluations. Automated classification of biomedical images is extremely challenging due to the precision required and the limited amount of annotated data available for training. Convolutional neural networks (CNNs) have the potential to improve image analysis and have demonstrated good performance in many settings. This study applied machine-learning technologies to laryngoscopy to determine the accuracy of computer recognition of known laryngeal lesions found in patients post-extubation.

METHODS

This is a proof of concept study that used a convenience sample of transnasal, flexible, distal-chip laryngoscopy images from patients post-extubation in the intensive care unit. After manually annotating images at the pixel-level, we applied a CNN-based method for analysis of granulomas and ulcerations to test potential machine-learning approaches for laryngoscopy analysis.

RESULTS

A total of 127 images from 25 patients were manually annotated for presence and shape of these lesions-100 for training, 27 for evaluating the system. There were 193 ulcerations (148 in the training set; 45 in the evaluation set) and 272 granulomas (208 in the training set; 64 in the evaluation set) identified. Time to annotate each image was approximately 3 minutes. Machine-based analysis demonstrated per-pixel sensitivity of 82.0% and 62.8% for granulomas and ulcerations respectively; specificity was 99.0% and 99.6%.

CONCLUSION

This work demonstrates the feasibility of machine learning via CNN-based methods to add objectivity to laryngoscopy analysis, suggesting that CNN may aid in laryngoscopy analysis for other conditions in the future.

Intersegmenter Variability in High-Speed Laryngoscopy-Based Glottal Area Waveform Measures

OBJECTIVES/HYPOTHESIS

High-speed videoendoscopy (HSV) has potential to objectively quantify vibratory vocal fold characteristics during phonation. Glottal Analysis Tools (GAT) version 2018, developed in Erlangen, Germany, is software for determining various glottal area waveform (GAW) quantities. Before having GAT analyze HSV videos, segmenters have to define glottis manually across videos in a semiautomatic segmentation protocol. Such interventions are hypothesized to induce variability of subsequent GAW measure computation across segmenters and may attenuate GAT measures' reliability to a certain point. This study explored intersegmenter variability in GAT's GAW measures based on semiautomatic image processing.

STUDY DESIGN

Cohort study of rater reliability.

METHODS

In total, 20 HSV videos from normophonic and dysphonic subjects with various laryngeal disorders were selected for this study and segmented by three trained segmenters. They separately segmented glottis areas in the same frame sets of the videos. Upon analysis of GAW, GAT offers 46 measures related to topologic GAW dynamic characteristics, GAW periodicity and perturbation characteristics, and GAW harmonic components. To address GAT's reliability, intersegmenter-based variability in these measures was examined with intraclass correlation coefficient (ICC).

RESULTS

In general, ICC behavior of the 46 GAW measures across three raters was highly acceptable. ICC of one parameter was moderate (0.5 < ICC < 0.75), good for seven parameters (0.75 < ICC < 0.9), and excellent for 38 parameters (0.9 < ICC).

CONCLUSIONS

Overall, high ICC values confirm clinical applicability of GAT for objective and quantitative assessment of HSV. Small intersegmenter differences with actual small parameter differences suggest that manual or semiautomatic segmentation in GAT does not noticeably influence clinical assessment outcome. To guarantee the software's performance, we suggest segmentation training before clinical application.

LEVEL OF EVIDENCE

2b Laryngoscope, 130:E654-E661, 2020.

Value of pre- and intraoperative diagnostic methods in suspected glottic neoplasia

PURPOSE

To evaluate the individual and combined ability of videostroboscopy (VS), high-speed digital imaging (HSDI), enhanced endoscopy (EE) and saline infusion (SI) to predict neoplasia, defined as glottic precursor lesion (GPL) or T1a glottic cancer, in patients suspected for glottic neoplasia.

METHODS

A nationwide prospective cohort study of patients treated by cordectomy for suspected GPL or T1a glottic cancer from August 1st 2016 to October 31st 2018 was conducted in the five Danish University Departments of Head and Neck surgery. Sensitivity, specificity, negative and positive predictive values, and area under Receiver Operating Curves (AUC-ROC) were calculated with 95% confidence intervals with respect to the histological diagnosis. Logistic regression with an imputation model for missing data was applied.

RESULTS

261 patients aged 34-91 years participated; 79 (30.3%) with non-neoplasia (i.e., inflammation, papilloma, hyperkeratosis) and 182 (69.7%) neoplasia, hereof 95 (36.4%) with GPL and 87 (33.3%) with T1a glottic cancer. Data from 188 VS, 60 HSDI, 100 preoperative EE, 209 intraoperative EE, and 234 SI were analyzed. In the complete case analysis the AUC-ROC of each diagnostic test was low, but increased when the tests were combined and especially if the combination included EE. However, multinomial logistic regression with imputation showed significant association (p < 0.05) only between age, male gender, and perpendicular vasculature in intraoperative EE, and the endpoint neoplasia.

CONCLUSIONS

Intraoperative EE was the most accurate diagnostic method in detecting neoplasia. The prediction ability of methods applied preoperatively was more limited, but improved when test modalities were combined.

Stroboscopic assessment of unilateral vocal fold paralysis: a systematic review

PURPOSE

To review the relevant basic stroboscopic evaluations in unilateral vocal fold paralysis (UVFP). Our aim was twofold: (1) to determine the frequency of use of stroboscopic parameters in outcome evaluation after surgical treatment of UVFP using a Pareto diagram; and (2) to select the most relevant parameters in terms of a significant difference between pre- and post-surgical intervention for UVFP.

METHODS

A systematic review in PUBMED includes studies on stroboscopic evaluation in combination with UVFP and surgical treatment. The review was limited to English studies published between 1990 and March 2018. The most frequently used stroboscopic parameters were identified using a Pareto diagram. Then, 'the percentage of significance' for the most frequently stroboscopic parameters was identified by comparing the number of studies that showed a statistically significant change in pre- and post-treatment results with the total number of studies using the same parameters.

RESULTS

Seven stroboscopic parameters were nominated using the Pareto diagram. In decreasing order of citation frequency, periodicity, edge bowing, mucosal wave, glottic gap, position of vocal fold, amplitude, and symmetry have respective percentages of significance of 87.5%, 83.3%, 77.7%, 64.5%, 60%, 57.1%, and 50%. Five pertinent scales were selected for the most frequent and significant stroboscopic parameters.

CONCLUSIONS

The results indicate that periodicity, edge bowing, mucosal wave, glottic gap, and position of vocal fold represent the five most frequently used and relevant stroboscopic parameters in UVFP evaluation. The current review outlines a proposal scale of these stroboscopic parameters.

PROSPERO REGISTRATION NUMBER

CRD42019126786.

Does the accuracy of case history affect interpretation of videolaryngostroboscopic exams?

OBJECTIVE

To determine the effect of initial diagnostic hypotheses on clinicians' 1) detection and perceived severity of abnormalities, and 2) clinical impressions and treatment recommendations for individuals with and without voice disorders following interpretation of videolaryngostroboscopy (VLS).

METHODS

Thirty-two experienced speech-language pathologists and otolaryngologists specializing in voice disorders read case histories prior to interpreting exams. Case histories suggested specific accurate or inaccurate laryngeal diagnoses, or a control scenario that suggested a normal larynx. The effects of the accuracy of case histories on perceived severity of associated visual-perceptual parameters, clinical impressions, and treatment recommendations were examined.

RESULTS

Significant increases in perceived severity of posterior laryngeal appearance (P < 0.05) and mucosal wave (P < 0.02) were observed when these abnormalities were suggested by case histories. Overall agreement with clinical impressions improved from 49% to 72% when the case history was consistent with the examination. Case histories (accurate and inaccurate) indicating voice symptoms predicted recommendations for treatment above and beyond that of VLS presentation alone, P < 0.001.

CONCLUSION

Case histories suggesting specific abnormalities significantly affected severity ratings for two of three associated visual-perceptual parameters selected as primary outcome measures. Accurate case histories suggesting specific abnormalities increased the probability of detection and perceived severity. Inaccurate case histories led to false-positive findings and failures to detect abnormalities or to interpret them as less severe. Case histories affected visual-perceptual judgments and contributed to decisions about clinical impressions and treatment.

LEVEL OF EVIDENCE

2b Laryngoscope, 130:718-725, 2020.

Resident Education in Laryngeal Stroboscopy and Perceptual Voice Evaluation: An Assessment

OBJECTIVES

To evaluate otolaryngology residents' level of confidence and understanding in interpreting laryngeal stroboscopy.

METHODS

Otolaryngology residents from three residency programs with fellowship-trained laryngologists on faculty were invited to participate. An assessment consisting of a survey and five stroboscopic exams was administered. Each exam consisted of questions on perceptual voice evaluation, laryngoscopic findings, and stroboscopic findings. Scores were compared to answers provided by three fellowship-trained laryngologists.

RESULTS

Thirty-eight of 47 invited residents (80.8%) enrolled in the study. On a five-point likert scale, residents reported low confidence (median = 2, range = 1-4) in interpreting stroboscopy, regardless of training program (P = 0.81). Mean assessment scores were 56.5% ± 11.9, with scores in perceptual voice evaluation = 68.5% ± 10.6; laryngoscopy = 70.2% ± 12.8; and stroboscopy = 45.3% ± 17.8. Residents performed worse on stroboscopy questions compared to laryngoscopy questions (P < 0.0001). There was a significant difference in scores by postgraduate year (P = 0.03), but not by institution (P = 0.34). A moderately positive correlation between reported level of confidence and overall scores (ρ = .47, P = 0.003) was demonstrated.

CONCLUSIONS

Despite didactic and clinical exposure, residents report low confidence in interpreting stroboscopy and scored lower on stroboscopy-specific questions compared to other assessment items. Additional resources and learning opportunities are needed to improve resident confidence and comprehension of stroboscopy.