High-speed digital imaging of the larynx: recent advances

High speed digital videolaringoscopy: evaluation of vocal nodules and cysts in women

PURPOSE

To evaluate and compare the parameters of Digital kymography obtained through the High-speed Videolaryngoscopy of women without laryngeal disorders, of women with vocal fold nodules and of women with vocal cysts.

METHODS

A cross-sectional observational study in which 60 women aged 18 years and 45 years were selected. Three study groups were formed: 20 women without laryngeal disorder forming the control group (Group 1), 20 women with diagnosis of vocal fold nodules forming Group 2 and 20 women with diagnosis of vocal cysts forming Group 3. Subsequently the participants were evaluated by High-speed Videolaryngoscopy for analysis and comparison of laryngeal images using Digital kymography. The laryngeal parameters processed by the program KIPS® were: minimum, maximum and mean opening; dominant amplitude of the left and right vocal folds; dominant frequency of the right and left vocal folds; and close.

RESULTS

The analysis of Digital kymography suggests that the presence of the vocal fold nodules and the vocal cysts tend to restrict more to the maximum and minimum opening of the vocal fold and the dominant amplitude of the opening variation in the middle region of the glottis.

CONCLUSION

Digital kymography parameters were similar in the presence of vocal fold nodules and vocal cysts lesions.

Laryngeal Image Processing of Vocal Folds Motion

This review provides a comprehensive compilation, from a digital image processing point of view of the most important techniques currently developed to characterize and quantify the vibration behaviour of the vocal folds, along with a detailed description of the laryngeal image modalities currently used in the clinic. The review presents an overview of the most significant glottal-gap segmentation and facilitative playbacks techniques used in the literature for the mentioned purpose, and shows the drawbacks and challenges that still remain unsolved to develop robust vocal folds vibration function analysis tools based on digital image processing.

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.

Synchronized, concurrent optical coherence tomography and videostroboscopy for monitoring vocal fold morphology and kinematics

Voice disorders affect a large number of adults in the United States, and their clinical evaluation heavily relies on laryngeal videostroboscopy, which captures the medial-lateral and anterior-posterior motion of the vocal folds using stroboscopic sampling. However, videostroboscopy does not provide direct visualization of the superior-inferior movement of the vocal folds, which yields important clinical insight. In this paper, we present a novel technology that complements videostroboscopic findings by adding the ability to image the coronal plane and visualize the superior-inferior movement of the vocal folds. The technology is based on optical coherence tomography, which is combined with videostroboscopy within the same endoscopic probe to provide spatially and temporally co-registered images of the mucosal wave motion, as well as vocal folds subsurface morphology. We demonstrate the capability of the rigid endoscopic probe, in a benchtop setting, to characterize the complex movement and subsurface structure of the aerodynamically driven excised larynx models within the 50 to 200 Hz phonation range. Our preliminary results encourage future development of this technology with the goal of its use for in vivo laryngeal imaging.

Fundamental Frequency in Excised Human Larynges after Anterior Glottic Web Formation of Various Extents

Objective

To determine the effect of vocal fold anterior web formation on fundamental frequency with a cadaveric excised larynx model.

Study Design

Experimental study with excised human larynges.

Setting

Academic tertiary care hospital.

Subjects and Methods

Sixteen freshly excised human larynges were evaluated with high-speed videoendoscopy and digital kymography during artificially produced vibration. Each larynx was assessed in 4 conditions: preoperative controls and after 25%, 33%, and 50% decreases in the vibratory portion of the vocal folds. The following parameters were evaluated: fundamental frequency, periodicity, vocal fold vibration amplitude, phase symmetry, and glottic closure.

Results

The mean fundamental frequencies were 208.87, 250.20, 292.37, and 342.67 Hz for preoperative controls and 25%, 33%, and 50% reductions in vibratory length of the vocal folds, respectively. Fundamental frequency increased with each increase in anterior glottic web extent, and the difference among the groups was statistically significant in absolute values in hertz and in semitone elevation. The mathematical models for estimating postoperative fundamental frequency had a statistically significant coefficient. The vibration of the vocal folds remained periodic in all larynges before and after the procedures.

Conclusion

There was a significant and progressive increase in the fundamental frequency with each enlargement of anterior glottic web. Based on the control frequency, mathematical models could estimate the value of the fundamental frequency after the procedure.

Influence of glottal closure on the phonatory process in ex vivo porcine larynges

Many cases of disturbed voice signals can be attributed to incomplete glottal closure, vocal fold oscillation asymmetries, and aperiodicity. Often these phenomena occur simultaneously and interact with each other, making a systematic, isolated investigation challenging. Therefore, ex vivo porcine experiments were performed which enable direct control of glottal configurations. Different pre-phonatory glottal gap sizes, adduction levels, and flow rates were adjusted. The resulting glottal closure types were identified in a post-processing step. Finally, the acoustic quality, aerodynamic parameters, and the characteristics of vocal fold oscillation were analyzed in reference to the glottal closure types. Results show that complete glottal closure stabilizes the phonation process indicated through a reduced left-right phase asymmetry, increased amplitude and time periodicity, and an increase in the acoustic quality. Although asymmetry and periodicity parameter variation covers only a small range of absolute values, these small variations have a remarkable influence on the acoustic quality. Due to the fact that these parameters cannot be influenced directly, the authors suggest that the (surgical) reduction of the glottal gap seems to be a promising method to stabilize the phonatory process, which has to be confirmed in future studies.

The Pharyngoesophageal Segment After Total Laryngectomy

Objective:

The aim of the present study was to characterize the pharyngoesophageal segment in laryngectomees who rated themselves as functional tracheoesophageal speakers.

Methods:

Voice perceptual assessment, high-resolution videomanometry of swallowing and phonation, and high-speed camera recording during phonation provided information about the anatomy and function of the pharyngoesophageal segment.

Results:

Fourteen patients were included in the study. The voice assessments presented high intra/inter-listener reliability. We found a significant correlation between roughness and poor voice quality, hyperfunction and poor intelligibility, and poor voice quality, long time since the operation, and old age. High-resolution videomanometry during phonation revealed decreasing mean pressures from the distal esophagus to the pharynx and confirmed low resting pressures at the pharyngoesophageal segment and low esophageal peristaltic contraction pressures after laryngectomy in comparison to normal subjects. The neoglottis shape was mainly circular and presented a strong mucosal wave in most of the patients on the high-speed camera recording.

Conclusions:

Perceptual voice assessment and high-speed camera recordings provided baseline information about voice characteristics and vibration regularity of the neoglottis. Additionally, the quantitative measures obtained with high-resolution videomanometry may have clinical applicability as reference data in voice rehabilitation after total laryngectomy.

Impact of Cricothyroid Muscle Contraction on Vocal Fold Vibration: Experimental Study with High-Speed Videoendoscopy

OBJECTIVES

The aim of this study was to evaluate the effects of cricothyroid muscle contraction on vocal fold vibration, as evaluated with high-speed videoendoscopy, and to identify one or more aspects of vocal fold vibration that could be used as an irrefutable indicator of unilateral cricothyroid muscle paralysis.

STUDY DESIGN

This was an experimental study employing excised human larynges.

METHODS

Twenty freshly excised human larynges were evaluated during artificially produced vibration. Each larynx was assessed in three situations: bilateral cricothyroid muscle contraction, unilateral cricothyroid muscle contraction, and no contraction of either cricothyroid muscle. The following parameters were evaluated by high-speed videoendoscopy: fundamental frequency, periodicity, amplitude of vocal fold vibration, and phase symmetry between the vocal folds.

RESULTS

Although neither unilateral nor bilateral cricothyroid muscle contraction altered the periodicity of vibration or the occurrence of phase asymmetry, there was a significant decrease in fundamental frequency in parallel with decreasing longitudinal tension. We also found an increase in vibration amplitude of right and left vocal folds, which were similar in terms of their behavior for this parameter in the various situations studied.

CONCLUSION

Our results suggest that differences in vibration amplitude and phase symmetry between vocal folds are not reliable indicators of unilateral cricothyroid muscle paralysis.

Laryngeal examination in thyroid and parathyroid surgery: An American Head and Neck Society consensus statement: AHNS Consensus Statement

This American Head and Neck Society (AHNS) consensus statement discusses the techniques of laryngeal examination for patients undergoing thyroidectomy and parathyroidectomy. It is intended to help guide all clinicians who diagnose or manage adult patients with thyroid disease for whom surgery is indicated, contemplated, or has been performed. This consensus statement concludes that flexible transnasal laryngoscopy is the optimal laryngeal examination technique, with other techniques including laryngeal ultrasound and stroboscopy being useful in selected scenarios. © 2016 Wiley Periodicals, Inc. Head Neck 38: 811-819, 2016.

Laryngeal High-Speed Videoendoscopy: Rationale and Recommendation for Accurate and Consistent Terminology

PURPOSE

The authors discuss the rationale behind the term laryngeal high-speed videoendoscopy to describe the application of high-speed endoscopic imaging techniques to the visualization of vocal fold vibration.

METHOD

Commentary on the advantages of using accurate and consistent terminology in the field of voice research is provided. Specific justification is described for each component of the term high-speed videoendoscopy, which is compared and contrasted with alternative terminologies in the literature.

RESULTS

In addition to the ubiquitous high-speed descriptor, the term endoscopy is necessary to specify the appropriate imaging technology and distinguish among modalities such as ultrasound, magnetic resonance imaging, and nonendoscopic optical imaging. Furthermore, the term video critically indicates the electronic recording of a sequence of optical still images representing scenes in motion, in contrast to strobed images using high-speed photography and non-optical high-speed magnetic resonance imaging. High-speed videoendoscopy thus concisely describes the technology and can be appended by the desired anatomical nomenclature such as laryngeal.

CONCLUSIONS

Laryngeal high-speed videoendoscopy strikes a balance between conciseness and specificity when referring to the typical high-speed imaging method performed on human participants. Guidance for the creation of future terminology provides clarity and context for current and future experiments and the dissemination of results among researchers.

High-speed video or video stroboscopy in adolescents: which sheds more light?

OBJECTIVE

The primary objective of this study was to compare the utility of high-speed video (HSV) to videostroboscopy (VS) in the assessment of adolescents with normal and abnormal larynges. A secondary objective was to evaluate the ease of assessment of adolescents with HSV.

STUDY DESIGN

Case series with chart review.

SETTING

Tertiary academic health care center.

SUBJECTS AND METHODS

This study involved a retrospective review of recordings of 7 adolescents assessed with both HSV and VS. The 14 recordings were randomized and presented to 4 groups of blinded evaluators: 2 fellowship-trained laryngologists, 2 speech language pathologists (SLP) with multiyear experience working in a voice clinic, 2 pediatric otolaryngologists, and 2 otolaryngology residents. Raters were asked to evaluate the videos using a standardized scoring tool. Raters also completed a questionnaire assessing their opinion of the HSV and VS recordings.

RESULTS

Evaluators required more time to complete their assessment of VS recordings (2.95 min ± 2.41 min) than HSV recordings (2.31 min ± 1.92 min) (P = .004). There was no difference in ease of evaluation (P = .878) or diagnostic accuracy within evaluator groups by recording modality (P = .5). The overall agreement between VS and HSV was moderate (kappa [SE] = 0.446 [0.029]). The debrief questionnaire revealed that 5 of 8 (62.5%) preferred VS to HSV.

CONCLUSION

This is the first comparative study between HSV and VS in patients under 18 years of age. HSV permitted faster evaluation than VS, but there was no difference in diagnostic accuracy between the 2 modalities. The evaluators preferred VS to HSV.

Improvement of vocal pathologies diagnosis using high-speed videolaryngoscopy

Introduction The study of the dynamic properties of vocal fold vibration is important for understanding the vocal production mechanism and the impact of organic and functional changes. The advent of high-speed videolaryngoscopy (HSV) has provided the possibility of seeing the real cycle of vocal fold vibration in detail through high sampling rate of successive frames and adequate spatial resolution.

Objective To describe the technique, advantages, and limitations of using HSV and digital videokymography in the diagnosis of vocal pathologies.

Methods We used HSV and digital videokymography to evaluate one normophonic individual and four patients with vocal fold pathologies (nodules, unilateral paralysis of the left vocal fold, intracordal cyst, and adductor spasmodic dysphonia). The vocal fold vibration parameters (glottic closure, vibrational symmetry, periodicity, mucosal wave, amplitude, and glottal cycle phases) were assessed.

Results Differences in the vocal vibration parameters were observed and correlated with the pathophysiology.

Conclusion HSV is the latest diagnostic tool in visual examination of vocal behavior and has considerable potential to refine our knowledge regarding the vocal fold vibration and voice production, as well as regarding the impact of pathologic conditions have on the mechanism of phonation.

Recovery of vibratory function after vocal fold microflap in a rabbit model

OBJECTIVES/HYPOTHESIS

The purpose of this study was to evaluate the return of vibratory function and restoration of vibration amplitude and symmetry after vocal fold microflap surgery.

STUDY DESIGN

Prospective in vivo animal model.

METHODS

Microflap surgery was performed on 30 New Zealand white breeder rabbits. The left vocal fold received a 3-mm epithelial incision and mucosal elevation, while the contralateral vocal fold was left intact to serve as an internal control. Quantitative analysis of amplitude ratio and lateral phase difference were measured using high-speed laryngeal imaging at a frame rate of 10,000 frames per second from animals undergoing evoked phonation on postoperative days 0, 1, 3, 5, and 7.

RESULTS

Quantitative measures revealed a significantly reduced amplitude ratio and lateral phase difference on day 0 after microflap. These impairments of vibratory function on day 0 were associated with separation of the vocal fold's body-cover layer. Amplitude ratio increased significantly by day 3 after microflap, with further increases in vibration amplitude on days 5 and 7. While the amplitude ratio improved significantly on day 3, lateral phase difference decreased significantly on day 3, and returned to normal on days 5 and 7.

CONCLUSIONS

High-speed laryngeal imaging was used to investigate the natural time course of postmicroflap recovery of vibratory function. Results revealed the restoration of vibration amplitude and lateral phase difference by days 3 to 7 after microflap. The time period of improved vibratory function observed in this study coincides with the end of the well-documented inflammatory phase of vocal fold wound repair.

LEVEL OF EVIDENCE

N/A.