Real-time, high-resolution ultrasonography of the vocal folds--a prospective pilot study in patients before and after thyroidectomy

Techniques of detecting recurrent laryngeal nerve palsy in patients undergoing thyroid surgery: Pearls and pitfalls

Though permanent vocal cord palsy consequent to recurrent laryngeal nerve (RLN) injury is rare following thyroidectomies, its consequences are grave enough for it to be the most feared complication postoperatively. Anesthesiologists and surgeons take various precautions to prevent its occurrence and employ various methods for its early detection. They include direct visualization of the nerve intraoperatively, use of intraoperative nerve monitoring, and post-extubation visualization of vocal cord mobility by use of direct or indirect methods. In the present narrative review, we aim to discuss the clinical evidence pertaining to the various methods adopted for the prevention and early detection of RLN palsy during thyroidectomy.

A Prospective Study Evaluating the Feasibility and Accuracy of Post-operative Laryngeal Ultrasonography (LUSG) in Assessment of Vocal Cord Function After Esophagectomy

BACKGROUND

Vocal cord paresis (VCP) is a serious complication after esophagectomy. Conventional diagnosis of VCP relies on flexible laryngoscopy (FL), which is invasive. Laryngeal ultrasonography (LUSG) is non-invasive and convenient. It has provided accurate VC evaluation after thyroidectomy but it is unclear if it is just as accurate following esophagectomy. This prospective study evaluated the feasibility and accuracy of LUSG in VC assessment on day-1 after esophagectomy.

METHODS

Consecutive patients from a tertiary teaching hospital who underwent elective esophagectomy were prospectively recruited. All received pre-operative FL, and post-operative LUSG and FL on Day-1, each performed by a blinded, independent assessor. The primary outcomes were feasibility and accuracy of LUSG in the diagnosis of VCP on Day-1 post-esophagectomy. The accuracy of voice assessment (VA) was analyzed.

RESULTS

Twenty-six patients were eligible for analysis. The median age was 70 years (66-73). Majority were male (84.6%). Twenty-five (96.2%) received three-phase esophagectomy. Twenty-four (96%) had same-stage anastomosis at the neck. Three (11.5%) developed temporary and one (3.8%) developed permanent unilateral VCP. Overall VC visualization rate by LUSG was 100%; sensitivity, specificity, positive predictive value, negative predictive value (NPV) and accuracy of LUSG were 75.0%, 100%, 100%, 98.0%, 98.1% respectively, and superior to VA. Combining LUSG with VA findings could pick up all VCPs i.e. improved sensitivity and NPV to 100%.

CONCLUSION

LUSG is a highly feasible, accurate and non-invasive method to evaluate VC function early after esophagectomy. Post-operative FL may be avoided in patients with both normal LUSG and voice.

Can Transcutaneous Laryngeal Ultrasonography Systematically Quantify Vocal Fold Movement?-A Feasibility Study

OBJECTIVES

Several studies have assessed adult vocal fold movement using transcutaneous laryngeal ultrasonography (TLUSG) during the perioperative period of thyroidectomy. However, the movement was not objectively quantified. This study aimed to provide a feasible and objective method for assessing vocal fold movement using TLUSG.

STUDY DESIGN

Feasibility study.

METHODS

TLUSG was performed during calm breathing and breath-holding in healthy adult volunteers. The morphology and anatomy of the larynx were observed and measured using an ultrasonic self-contained measurement function. At the end of the calm inspiratory and breath-holding phases, vocal fold angle, vocal fold length, distance from vocal process to the midline, distance from anterior vocal commissure to arytenoid cartilage, distance from false vocal fold to the midline, and distance from the anterior horn of thyroid cartilage to false vocal fold were measured. Data were analyzed using a t test (significance <0.05).

RESULTS

The ultrasonic images were satisfactory in all 40 healthy adult volunteers (age 19-35 years; body mass index 18.55-23.93 kg/m2; 20 men and 20 women). There were no significant differences in all laryngeal parameters between the left and right sides in both phases (P > 0.05). Moreover, all differences in laryngeal parameters between the end of the calm inspiratory phase and the breath-holding phase were statistically significant (P < 0.05), regardless of sex.

CONCLUSION

The relevant positional parameters of the vocal fold, arytenoid cartilage, and false vocal fold and their differences before and after vocal fold movement in healthy adult volunteers can be obtained objectively using TLUSG.

Normative data for certain vocal fold biomarkers among young normophonic adults using ultrasonography

PURPOSE

The current study aimed to profile vocal fold morphology, vocal fold symmetry, gender and task-specific data for vocal fold length (VFL) and vocal fold displacement velocity (VFDV) in young normophonic adults in the age range of 18-30 years using ultrasonography (USG).

METHODS

Participants underwent USG across quiet breathing, /a/ phonation and /i/ phonation tasks, and acoustic analysis was conducted to explore the relationship between USG and acoustic measures.

RESULTS

The study found that males have longer vocal folds than females, and overall greater velocities were observed in /a/ phonation, followed by /i/ phonation, with the lowest velocity observed in the quiet breathing task.

CONCLUSIONS

The obtained norms can be used as a quantitative benchmark for analyzing the vocal fold behavior in young adults.

Factors Associated With Injury to Recurrent Laryngeal Nerve in Patients Undergoing Surgery for Thyroid Cancer: A Single-centre Study Using Translaryngeal Ultrasound

AIMS

Intraoperative injury to the recurrent laryngeal nerve (RLN) is a serious complication occurring more frequently in patients with thyroid cancer than in those with benign thyroid diseases. However, data on the risk factors for RLN injury among patients with thyroid cancer are scarce. Currently, RLN injury is diagnosed by laryngoscopy, but translaryngealultrasonography (TLUS), which is less invasive, appears to have a similar accuracy. Herein, we analysed risk factors ofintraoperative RLN injury in patients with thyroid cancer and assessed the diagnostic performance of TLUS.

PATIENTS AND METHODS

In this prospective study, we enrolled patients undergoing surgery for thyroid cancer from October 2020 to October 2021. Medical and surgical variables were analysed as risk factors of RLN injury. TLUS was compared with laryngoscopy in diagnosing RLN injury.

RESULTS

There were 185 patients who underwent 196 surgeries. Of all surgeries, 23 (11.7%) caused RLN injury ascertained on laryngoscopy. Compared with laryngoscopy, TLUS displayed high sensitivity (97.7%; 95%CI: 94.3%-99.4%) and specificity (100%; 95% CI: 82.4%-100%). Before surgery, medical and surgical characteristics did not differ significantly between patients with or without RLN injury, but RLN entrapment by tumour was more frequent in those with the injury (P < 0.001). The risk of RLN injury was increased in patients undergoing thyroidectomy with lateral neck dissection (OR = 4.53; 95% CI: 1.29-14.32) and in those with lymph node metastases (OR = 2.76; 95% CI: 1.03-7.01).

CONCLUSION

Intraoperative RLN injury in patients with thyroid cancer is more common after operations requiringgreater resections and with lymph node involvement. TLUS could be used to diagnose RLN injury.

Clinical usefulness of transcutaneous laryngeal ultrasonography in otolaryngology practice during COVID-19 pandemic: a literature review

As a consequence of the outbreak of SARS-CoV-2, the clinical practice of otolaryngologists underwent profound transformations. Non-aerosol-generating procedures have been researched and implemented. Transcutaneous laryngeal ultrasonography (TLUSG) provides a rapid and noninvasive method to assess laryngeal function and can support the management of laryngeal disorders. With the aim of investigating the clinical usefulness of TLUSG in otolaryngology practice, a review of the literature published on PubMed, Cochrane Library and Ovid/ Medline databases was performed up to March 2022. 38 studies were eligible to be included in the review. The selected papers were divided into six topics of interest: evaluation of vocal cords function, diagnosis of laryngeal disorders in infants and children, evaluation of swallowing disorders, assessment of laryngeal cancer and other laryngeal lesions, ultrasound-guided cricothyroidotomy, ultrasound-guided laryngeal electromyography. The results of this review demonstrated that TLUSG, applied to ENT practice, can be a valid method for dynamic laryngeal assessment and airway management, since it is time-efficient, non invasive, well tolerated and easily performed.

Application of Translaryngeal Ultrasound (TLUS) in Patients with Neck Surgery-A Single-Centre, Prospective Cohort Study on Technique Evaluation

PURPOSE

The primary objective of this study was to assess the value of translaryngeal ultrasound (TLUS) in assessing vocal fold (VF) function in patients after thyroid, parathyroid and neck lymph node surgery.

METHODS

A total of 219 patients that underwent 230 surgical procedures were enrolled in this prospective study. The study was conducted from October 2020 to October 2021. Patients' VFs were analysed independently with TLUS and laryngoscopy before and after the surgery. Various TLUS variables, such as vocal folds displacement velocity (VFDV), arytenoids symmetry and angle between VFs, were measured. The questionnaire evaluating discomfort caused to patients by both methods was conducted.

RESULTS

Of the 230 surgeries in this study, 85% were from oncological indications. The incidence of RLN injury was 10.4%. The accuracy of TLUS compared to laryngoscopy was 98.3%, with sensitivity 98.1%, specificity 100%, PPV 100% and NPV 83.3%. Laryngoscopy was found to cause significantly more discomfort than TLUS. VF visibility was lower in men; smokers; and patients with higher BMI (32 vs. 28 kg/m2), multifocal cancer, higher left lobe volume and higher fT3 levels. Arytenoid symmetry VFDV was lower for "e" and "i" right side and "i" left side in injured/disabled VFs/RLN.

CONCLUSIONS

TLUS can be an excellent and non-invasive method of VF evaluation in most patients. There are some technical aspects that can improve its accuracy. Sometimes, RLN injury after the surgery, especially among oncological patients, is unavoidable. Therefore, it is vital to diagnose dysphonia early with convenient methods, such as TLUS.

Use of POCUS in the Diagnosis of Paradoxical Vocal Cord Movement

ABSTRACT

Point-of-care ultrasound has been instrumental in allowing providers to make prompt diagnoses at the bedside but has been historically underutilized for the diagnosis of upper airway processes, including paradoxical vocal fold motion (PVFM), also known as vocal cord dysfunction. PVFM is characterized by adduction of the vocal cords during inspiration, resulting in stridor and shortness of breath. This case report describes a teenage girl who presented to the pediatric emergency department (ED) with difficulty breathing. Point-of-care ultrasound diagnosed PVFM, which was confirmed with bedside flexible laryngoscopy by otorhinolaryngology (ENT) in the ED.

Transcutaneous Laryngeal Ultrasonography for Assessing Vocal Cord Twitch Response in Thyroid Operation during Predissection Vagus Nerve Stimulation

BACKGROUND

In this study, we aimed to report our experience with the use of intraoperative transcutaneous laryngeal ultrasonography (TLUSG) to evaluate the vocal cord twitch response during predissection vagus nerve stimulation in thyroid surgeries and examine the reliability of this technique when compared with that of laryngeal twitch palpation (LTP).

STUDY DESIGN

The prospective data collection of consecutive patients who underwent open thyroidectomy with intraoperative neuromonitoring (IONM) was reviewed retrospectively. We recorded the electromyographic activity and assessed the vocal cord twitch response on LTP, TLUSG. We compared the accessibility, sensitivity, and specificity of the techniques.

RESULTS

A total of 110 patients (38 men and 72 women) with 134 nerves at risk were enrolled. The vocal cord was assessable by TLUSG in 103 (93.6%) patients and by LTP in 64 (59.1%) patients. Two patients showed negative predissection IONM signal but positive on TLUSG and the presence of laryngeal twitch response confirmed by laryngoscopy. Fourteen patients showed positive IONM signals and presence of the vocal cord twitch response on TLUSG but not on LTP. The sensitivity and specificity were 70.21% and 100%, respectively, for LTP, and those both were 100% for TLUSG. For patients who could be assessed using both techniques, TLUSG had better accuracy than LTP (100% vs 80.33%, p = 0.0005).

CONCLUSIONS

The innovative intraoperative application of TLUSG is better for evaluating the laryngeal twitch response than LTP. This technique provides practical troubleshooting guidance for patients with no IONM signals during predissection vagus nerve stimulation.

Translaryngeal ultrasound in thyroid surgery: state of the art review

BACKGROUND

Clinical voice assessment prior to thyroid and parathyroid surgery is essential, but the paradigm of indirect laryngoscopy (IDL), when indicated, has been challenged by the risk of aerosolised SARS-Cov-2 during endoscopy of the aerodigestive tract. Translaryngeal ultrasound (TLUS) to assess the vocal cords has been proposed as a safe, non-invasive and sensitive alternative. The aim of this review was to verify TLUS as a viable tool for perioperative laryngeal assessment.

METHOD

A literature review was performed using Medline, Embase, Cochrane Database of Systematic Reviews, Cochrane Database of Abstracts of Reviews of Effects, Cochrane Central Register of Controlled Trials and Scopus with the following search strategy: (vocal cord OR vocal fold OR glottic OR glottis OR vocal ligaments OR rima glottidis) AND (ultras* OR sonograph* OR echography OR echotomography).

RESULTS

Fifteen studies were included in this review. All studies compared TLUS to IDL in visualizing the vocal cords in adults. Ten studies compared pre-operative TLUS to IDL where 50.6-100% of vocal cords were successfully visualized. Nine studies compared post-operative TLUS to IDL and reported visualization between 39.6% and 100%. Pre- and post-operative negative predictive values ranged from 60% to 100%.

CONCLUSION

Whilst promising, successful visualization of the cords is limited by inter-user variability, older age and male gender. Thus, we see the role of TLUS as an alternative to IDL in the post-operative setting in the young patient following uncomplicated surgery with a normal voice on clinical examination, to confirm recurrent laryngeal nerve integrity while minimizing the risk of aerosolization.

Transcutaneous Laryngeal Ultrasound for Vocal Cord Paralysis Assessment in Patients Undergoing Thyroid and Parathyroid Surgery-A Systematic Review and Meta-Analysis

Recurrent laryngeal nerve injury is an important complication following thyroid and parathyroid surgery. Recently, Transcutaneous laryngeal ultrasound (TLUSG) has emerged as a non-invasive alternative to laryngoscopic examination for vocal cord (VC) assessment. The aim of the systematic review and meta-analysis was to determine its diagnostic accuracy in reference to laryngoscopy. It was conducted in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. MEDLINE, Scopus, Cochrane library and Web of Science databases were searched to identify relevant articles. Sixteen studies were included in the review. Pooled diagnostic accuracy was calculated based on weighted arithmetic mean and plotting forest plot. The pooled visualization rate was 86.28% and 94.13% preoperatively and postoperatively, respectively. The respective pooled sensitivity and specificity was 78.48% and 98.28%, and 83.96% (CI 95%: 77.24-88.50%) and 96.15% (CI 95%: 95.24-96.88%). The diagnostic accuracy improved if transverse and lateral approaches, and valsalva maneuver were utilized. Male gender and older age were the most crucial risk factors for VC non-visualization. TLUSG is an efficacious screening tool for vocal cord palsy due to its high sensitivity. It is likely to prevent unnecessary laryngoscopic examination in around 80% of patients, with the potential for becoming a gold standard for specific (female/young) patient cohort through assimilative modifications use, increasing expertise and development of objective measurements in the future.

Perioperative transcutaneous laryngeal ultrasonography to assess vocal cord function in thyroid surgery

BACKGROUND

Early diagnosis of vocal cord iatrogenic injury is crucial, as is perioperative vocal cord evaluation.

METHODS

Vocal cord mobility detected via transcutaneous laryngeal ultrasonography was compared with that detected via laryngoscopy (the reference). The vocal cord visualization rate of ultrasonography for evaluation of mobility was explored.

RESULTS

The diagnostic odds ratio of transcutaneous laryngeal ultrasonography was 303.2212 (95% CI, [86.7944; 1059.3198]). The area under the summary receiver operating characteristic curve was 0.944. The sensitivity, specificity, and negative predictive value were 0.9154 [0.8471; 0.9548], 0.9771 [0.9541; 0.9887], and 0.9915 [0.9868; 0.9946], respectively. The vocal cord visualization of ultrasonography used to evaluate vocal cord mobility was high (0.9572 [0.9091; 0.9804]).

CONCLUSIONS

Since transcutaneous laryngeal ultrasonography has the advantage in vocal cord visualization, it can be considered when laryngoscopy is unavailable or patients refuse laryngoscopy. Also, it is diagnostically accurate regardless of the used landmarks, VCP definition, and timing for application.

Surface kinematic and depth-resolved analysis of human vocal folds in vivo during phonation using optical coherence tomography

SIGNIFICANCE

The human vocal fold (VF) oscillates in multiple vectors and consists of distinct layers with varying viscoelastic properties that contribute to the mucosal wave. Office-based and operative laryngeal endoscopy are limited to diagnostic evaluation of the VF epithelial surface only and are restricted to axial-plane characterization of the horizontal mucosal wave. As such, understanding of the biomechanics of human VF motion remains limited.

AIM

Optical coherence tomography (OCT) is a micrometer-resolution, high-speed endoscopic imaging modality which acquires cross-sectional images of tissue. Our study aimed to leverage OCT technology and develop quantitative methods for analyzing the anatomy and kinematics of in vivo VF motion in the coronal plane.

APPROACH

A custom handheld laryngeal stage was used to capture OCT images with 800 A-lines at 250 Hz. Automated image postprocessing and analytical methods were developed.

RESULTS

Novel kinematic analysis of in vivo, long-range OCT imaging of the vibrating VF in awake human subjects is reported. Cross-sectional, coronal-plane panoramic videos of the larynx during phonation are presented with three-dimensional videokymographic and space-time velocity analysis of VF motion.

CONCLUSIONS

Long-range OCT with automated computational methods allows for cross-sectional dynamic laryngeal imaging and has the potential to broaden our understanding of human VF biomechanics and sound production.

2021 Update on airway management from the Anaesthesia Continuing Education Airway Management Special Interest Group

Airway Management is the key for anaesthetists dealing with patients undergoing diagnostic procedures and surgical interventions. The present coronavirus pandemic underpins even more how important safe airway management is. It also highlights the need to apply stringent precautions to avoid infection and ongoing transmission to patients, anaesthetists and other healthcare workers (HCWs). In light of this extraordinary global situation the aim of this article is to update the reader on the varied aspects of the ever-changing tasks anaesthetists are involved in and highlight the equipment, devices and techniques that have evolved in response to changing technology and unique patient and surgical requirements.

Ultrasonography diagnostic validity in structural and functional laryngeal disorders

Background

The diagnostic approach for patients with laryngeal lesions differs among otolaryngologists. Indirect laryngoscopy, flexible fibrooptic laryngoscopy, CT, and MRI are all modalities used for diagnosis. Ultrasonography is noninvasive, non-irradiating, and safe. The availability, affordability, and usability of portable ultrasound units have undergone dramatic improvements. It is well tolerated by patients, dynamic technique that can be performed easily in phonation, quickly performed, and allows for photo-documentation. Our objective is to evaluate the laryngeal ultrasound as a diagnostic tool to evaluate different laryngeal structure as regard laryngeal dynamics (range and abnormality), and anatomic structures. This prospective study was carried out on individuals in “blinded for peer review” hospitals. They were divided into group I (healthy volunteers), group II (unilateral vocal fold paralysis), and group III (patients underwent vertical hemilaryngectomies). All patients were subjected to full history taking, detailed head and neck examination, and fibrooptic nasopharyngolaryngoscopy then all patients underwent laryngeal sonographic examination. The photos were analyzed to identify various laryngeal structures and to measure glottic areas and inter-arytenoid distances.

Results

After recognition of laryngeal anatomic details and different measurements, we found that the percent of change in length and area were much less in group III than group I or II. Another important finding is that glottic area during respiration is related significantly to interarytenoid length during respiration with a statistically significant regression coefficient.

Conclusion

Laryngeal ultrasound is a valid diagnostic tool for imaging laryngeal structures and measuring various distances and areas inside the larynx. It is recommended to consider ultrasonography as a reliable imaging modality, and at least a useful adjunct to endoscopy when identification of airway patency, vocal fold mobility, or structural alterations is suspected. To our best knowledge, this study may contain a hitherto undescribed correlation between inter-arytenoid length and glottic area.

A prospective study evaluating the feasibility and accuracy of very early postoperative translaryngeal ultrasonography in the assessment of vocal cord function after neck surgery

BACKGROUND

Early recognition of postoperative vocal cord palsy enhances postoperative care. Translaryngeal ultrasonography can assess vocal cord function accurately and noninvasively, but it is unclear whether it is feasible or accurate when done immediately after extubation in the recovery room owing to possible interference from laryngeal swelling. This study assessed the feasibility and accuracy of translaryngeal ultrasonography in this setting.

METHODS

Consecutive patients undergoing neck operations were subjected to translaryngeal ultrasonography and flexible direct laryngoscopy 1 day before and day 7 after thyroidectomy and parathyroidectomy. Translaryngeal ultrasonography was performed early in the recovery room immediately after extubation in the operating room. A standardized assessment protocol was used. Patient parameters were compared between those with assessable and unassessable vocal cords.

RESULTS

Sixty-five patients (91 recurrent laryngeal nerves-at-risk) were analyzed after excluding 2 male patients who failed preoperative translaryngeal ultrasonography. Fifty-six patients underwent thyroidectomy and 9 parathyroidectomy. The median age (range) was 57 (46-69); 44 (68%) were women. Sixty-one patients (94%) had assessable bilateral vocal cords on translaryngeal ultrasonography in the recovery room. Translaryngeal ultrasonography in the recovery room findings corresponded completely with day-7 findings on direct laryngoscopy. Long operative time was associated with nonassessable vocal cords on translaryngeal ultrasonography in the recovery room (P = .026).

CONCLUSION

Very early postoperative translaryngeal ultrasonography in the recovery room after neck surgery is highly feasible and accurate. Long operative time may hinder the use of translaryngeal ultrasonography in the recovery room.

[Evaluation the velocity of vocal fold movements in adults by duplex Doppler scanning]

AIM

To evaluate the velocity of vocal fold movements by duplex Doppler scanning in adults during breathing, talking and phonation.

METHODS

Twenty healthy volunteers (18 women and 2 men) without of voice problems were investigated with scanners Logic-7 or Aloka 1100 by the linear transducer 7-10 MHz. The thyroid cartilage was used as an acoustic window. The dependence between the vocal fold velocity and volume and pitch of the voice were estimated using Spearman correlation.

RESULTS

The velocity of movements of the vocal folds during breathing was from 5 to 16 cm/s, during talking and phonation - from 9 to 110 cm/s. Coefficient of Spearman correlation between the voice pitch and the vocal fold velocity was +0.9±0.1 an average, between volume of the voice and the vocal fold velocity was - 0.7±0.1.

CONCLUSION

Duplex Doppler ultrasound scanning of the larynx allows measuring the velocity of vocal fold's movements during breathing, conversation and phonation. The fold's velocity increases with increasing of the voice volume and decreases with increasing the voice pitch. Duplex Doppler ultrasound scanning may be useful for early detection of disorders of mobility of the vocal folds.

Transcutaneous Laryngeal Ultrasonography for the Assessment of Laryngeal Function After Thyroidectomy: A Review

OBJECTIVE

This review set out to examine the applicability of transcutaneous laryngeal ultrasonography (TLUSG) for the assessment of laryngeal function after thyroidectomy.

METHODS

An integrative review of the literature was performed using Medline/PubMed, LILACS, and SciELO databases. The methodological quality of the studies was analyzed using the appraisal tool for cross-sectional studies.

RESULTS

All 8 included articles investigated laryngeal function with regard to the risk of vocal fold immobility after thyroidectomy. The results regarding the diagnostic power of TLUSG for this assessment are controversial, and there is a tendency to use this examination as a screening procedure for subsequent confirmation by flexible laryngoscopy.

CONCLUSIONS

Transcutaneous laryngeal ultrasonography is a viable, noninvasive, and useful tool to assess laryngeal function after thyroidectomy, but current available evidence suggests that it does not replace flexible laryngoscopy for the diagnosis of vocal fold immobility.

Functional analysis of vocal folds by transcutaneous laryngeal ultrasonography in patients undergoing thyroidectomy

BACKGROUND

Transcutaneous laryngeal ultrasound (TCLUS) can assess Vocal folds (VF) by subjectively identifying mobility or objectively by calculating vocal fold displacement velocity (VFDV). Optimal diagnostic approach (subjective assessment, VFDV estimation or a combination of both) is unresolved; hence, we conducted this prospective study in patients undergoing thyroidectomy.

METHOD

Two anaesthetists performed TCLUS pre- and post-operatively for functional assessment of 200 VFs on 100 patients. Their findings were compared with pre-operative flexible laryngoscope (FL) performed by surgeons and with post-operative C-Mac video laryngoscope (C-Mac VL) by another independent anaesthetist. Correlation between FL and TCLUS findings and inter-rater agreement between TCLUS findings of both anaesthetists was analysed. Decision curve analysis (DCA) was performed to compare clinical benefit of hoarseness, subjective VF movement, VFDV, and combined assessment for detecting disabled VFs.

RESULTS

We found good correlation between VF mobility on TCLUS and FL (Spearman's r = 0.93, P < 0.0001) as well as C-Mac VL (Spearman's r = 0.83, P < 0.0001) with excellent inter-rater agreement between both anaesthetists. DCA showed combined assessment to have marginally higher clinical benefit than other diagnostic approaches at intermediate threshold probabilities while its benefit was similar to subjective evaluation at higher threshold probabilities.

CONCLUSION

Provided achievement of optimal acoustic window, TCLUS can reliably assess disabled VFs with FL reserved for their confirmation or doubtful cases. Subjective assessment of VF mobility should suffice in most cases with additional VFDV estimation reserved pre-operatively for situations with higher risk of VFs disability, and post-operatively when subjective VF assessment findings are discordant from pre-operative status.

Shear Wave Elastography to Assess False Vocal Folds in Healthy Adults: A Feasibility Study

OBJECTIVES

The aim of the study was to investigate the feasibility of using ultrasound shear wave elastography to quantify mechanical properties and movement symmetry of false vocal folds positioned in adduction and abduction.

METHODS

We prospectively measured the shear wave velocity (SWV) within the bilateral false vocal folds in 10 healthy adults using acoustic radiation force impulse imaging. From a transcutaneous approach at the level of thyroid cartilage, 5 SWV measurements were obtained within each side of the false vocal folds twice in adduction and again in abduction for each participant. Configuration-related differences in the SWV within false vocal folds were compared between adduction and abduction, in addition to differences between the right and left false vocal folds and between men and women, by a paired t test. We developed an SWV index [(SWV_greater - SWV_lesser )/SWV_greater ] to assess movement symmetry between the right and left false vocal folds. Intraobserver agreement on repeated measures was examined by the intraclass correlation coefficient.

RESULTS

The 10 participants included 5 men and 5 women. We observed that the SWV within false vocal folds was significantly higher in adduction than in abduction (P < .001). The SWV within false vocal folds in adduction was also significantly higher in women compared to men (P < .001). There was no significant difference in the SWV between the right and left false vocal folds in adduction or in abduction or between men and women in abduction (P > .05). The mean SWV index was 0.05 (range, 0.03-0.07). The intraclass correlation coefficient for intraobserver agreement was 0.89 (P < .001).

CONCLUSIONS

Shear wave elastography seems to be feasible to quantify mechanical properties and evaluate the symmetry of false vocal folds in healthy adults.

Ultrasound strain imaging in assessment of false vocal folds in adults: A feasibility study

PURPOSE

The aim of the study is to investigate the feasibility of ultrasound strain imaging (USI) in assessing magnitude and symmetry of false vocal folds (FVF) deformation as a quantitative marker for estimating FVF movement.

METHODS

From October 2016 to July 2017, we performed USI of FVF in 44 adults [33 healthy controls and 11 subjects with unilateral vocal fold motion impairment (VFMI), 17 men and 27 women, mean age 43 years]. Real time ultrasound data of FVF in different configuration (abduction and adduction) was acquired through transcutaneous anterior-mid neck. Peak to valley strain (strain magnitude of maximum to minimum) representing the largest FVF deformation was estimated using 2-D speckle tracking. We developed peak to valley strain index [(Peak to valley strain _right - Peak to valley strain _left)/Peak to valley strain _maximum] to assess the symmetry of FVF deformation.

RESULTS

The difference in peak to valley strain between left and right FVF was significant in subjects with VFMI, whereas it was not in healthy controls. The peak to valley strain index was small (≤0.25) in symmetric FVF deformation in healthy controls whereas it was large (≥0.53) in asymmetric FVF deformation in subjects with VFMI. The area under receiver operating characteristics for peak to valley strain index in the determining asymmetric FVF deformation was 1.

CONCLUSION

Our results suggest that USI seems feasible to quantify both magnitude and symmetry of FVF deformation in adults. Further validation of USI in assessing VFMI is warranted.

Assessment of functionality of vocal cords using ultrasound before and after thyroid surgery: An observational study

Background and Aims:

The preservation of recurrent laryngeal nerve (RLN) is an essential part of thyroid surgery. The various methods to test the normal functionality of vocal cords (VCs) include direct visualisation under the fiber bronchoscope, indirect laryngoscopy, laryngeal muscles electromyography, computed tomography (CT), and magnetic resonance imaging (MRI). We aimed to assess the usefulness of ultrasound (USG) in the examination of VC morphology and movement.

Methods:

After Institutional Ethical Committee (IEC) clearance, 65 American Society of Anesthesiologists physical status I/II patients between the age group 18 and 60 years scheduled for thyroid surgery were enrolled in this observational study. All patients underwent USG examination before, immediately after and 2 days after thyroidectomy. The vocal fold (VF) displacement velocity (VFDV) was recorded and analysed. If any VF disorder was detected, the patients underwent two additional examinations: 2 and 3 months after thyroidectomy. All the findings were correlated with those of video rhinolaryngoscope (VRL).

Results:

The visualisation rate of the VCs with USG was 96.9% whereas with VRL was 100%. Two patients had preoperative VC palsy that was picked up by USG and confirmed by VRL. The sensitivity and specificity of USG as a tool to detect paralysis were 100% CI = (0.34, 1.00) and 93.44% CI = (0.84, 0.97), respectively.

Conclusion:

USG examination can prove to be a good, noninvasive, cheap alternative to VRL in examination for functionality of VCs perioperatively.

[The laryngeal condition in the patients presenting with euthyroid multinodular goiter as evaluated by direct laryngoscopy]

The objective of the present study was to improve diagnostics of disturbances in the laryngeal condition of the patients presenting with euthyroid multinodular goiter with special reference to the condition of the upper respiratory passages. The preoperative characteristic of 398 patients included the description of the predominant clinical syndrome (the neoplastic and compressive variants) and specification of the morphological type of the disease to promote the decrease of operative activity with respect to colloidal proliferative goiter. Direct laryngoscopy was employed in addition to the traditional diagnostic techniques during both the surgical operation and the follow-up observation. Hoarseness developed in the postoperative period in 13.4% to 16.9% of the patients. Postoperative transient and persistent laryngeal paresis was documented in 1.5% and from 1.5% to 4.2% of the cases respectively. Direct laryngoscopy revealed the symptoms of laryngitis and laryngotracheitis as well as foci of leukoplakia, laryngeal cysts and nodules, besides disturbances in the mobility of the vocal chordae. It is concluded that the above pathological changes in the laryngeal structures should be identified during the preoperative examination of the patients presenting with euthyroid multinodular goiter while direct laryngoscopy must be included in the program of postoperative supervision.

Sonographic Dynamic Description of the Laryngeal Tract: Definition of Quantitative Measures to Characterize Vocal Fold Motion and Estimation of Their Normal Values

Vocal fold motion was analyzed during free breathing using two-dimensional dynamic ultrasound imaging. Two cadavers were first analyzed to define easily identifiable landmarks. Motion of the laryngeal tract was then analyzed in an axial plane. Left and right arytenoids and thyroid cartilage were defined on images corresponding to abduction and adduction of the laryngeal tract. Associated area measurements were established for 50 healthy subjects. All area indices were significantly larger during abduction than adduction. Symmetry of motion was established by comparing each hemi-larynx, and mobility fractions were defined. Normal values of laryngeal motion during free breathing were thus established.

Point-of-Care Sonographic Findings in Acute Upper Airway Edema

We describe a case where a patient presented with acute angiotensin-converting enzyme inhibitor (ACE-I) induced angioedema without signs or symptoms of upper airway edema beyond lip swelling. Point-of-care ultrasound (POCUS) was used as an initial diagnostic test and identified left-sided subglottic upper airway edema that was immediately confirmed with indirect fiberoptic laryngoscopy. ACE-I induced angioedema and the historical use of ultrasound in evaluation of the upper airway is briefly discussed. To our knowledge, POCUS has not been used to identify acute upper airway edema in the emergency setting. Further investigation is needed to determine if POCUS is a sensitive and specific-enough tool for the identification and evaluation of acute upper airway edema.

In vivo cross-sectional imaging of the phonating larynx using long-range Doppler optical coherence tomography

Diagnosis and treatment of vocal fold lesions has been a long-evolving science for the otolaryngologist. Contemporary practice requires biopsy of a glottal lesion in the operating room under general anesthesia for diagnosis. Current in-office technology is limited to visualizing the surface of the vocal folds with fiber-optic or rigid endoscopy and using stroboscopic or high-speed video to infer information about submucosal processes. Previous efforts using optical coherence tomography (OCT) have been limited by small working distances and imaging ranges. Here we report the first full field, high-speed, and long-range OCT images of awake patients’ vocal folds as well as cross-sectional video and Doppler analysis of their vocal fold motions during phonation. These vertical-cavity surface-emitting laser source (VCSEL) OCT images offer depth resolved, high-resolution, high-speed, and panoramic images of both the true and false vocal folds. This technology has the potential to revolutionize in-office imaging of the larynx.

Synchronous video laryngoscopy and sonography of the larynx in children

Unlike laryngoscopy, laryngeal sonography is easily applicable, well tolerated by young children and less exhausting for the examiner. The aim of this study was to determine if sonography can adequately visualize the laryngeal structures and vocal fold movements of children. Synchronic video laryngoscopy and sonography of the larynx were performed in 35 children (aged 2-8 years) without a laryngeal disease. 10 investigators at differing stages of otolaryngological training were tasked with identifying vocal fold movement and specific anatomical structures after seeing (1) the sonography-only video and (2) the sonography video with a laryngoscopy video overlay. The percentage of correct identification of the structures and the vocal cord movement with and without additional video-overlay was compared. A sonographical view of the larynx could be found and the following anatomical structures were identified: subcutaneous fat tissue, left and right sternohyoid and thyrohyoid muscles, thyroid cartilage, left and right vocal folds, left and right paraglottic spaces, left and right side arytenoid cartilages, and rima glottides. Concerning the evaluation of the videos amongst the investigators: they identified >80 % of vocal fold movement and the targeted anatomical structures except the arytenoid cartilages (only up to 63 %), having the sonography only. In combination with the laryngoscopy video-overlay, investigator detection rates significantly improved (>90 % of vocal fold movement, p < 0.001; >90 % in most anatomical structures, (p < 0,001). Laryngeal sonography is a helpful diagnostic tool to identify laryngeal structures and the movement of the vocal folds in children.

Multiplanar 3D ultrasound imaging to assess the anatomy of the upper airway and measure the subglottic and tracheal diameters in adults

OBJECTIVE

To evaluate the feasibility of using three-dimensional (3D) ultrasound to assess the anatomy of the airway.

METHODS

11 young volunteers were recruited for 3D ultrasound and MRI of the airway. 3D ultrasound data were obtained from the level of the true vocal cords, cricoid cartilage and upper trachea. Multiplanar 3D ultrasound images were rendered and compared visually with corresponding MRI and cadaver anatomical sections. The anteroposterior (AP) and transverse diameter of the subglottic space and transverse diameter of the upper trachea were also measured in the 3D ultrasound and MR images and compared.

RESULTS

The airway anatomy was clearly delineated in the multiplanar 3D ultrasound images. It was also possible to identify the cricothyroid junction, and a simple method to measure the AP diameter of the subglottic space using this landmark is described. We were also able to accurately measure the transverse diameter of the upper trachea, but the transverse diameter of the subglottic space was overestimated using ultrasound. There was a strong correlation for the AP diameter measurement (r=0.94, p<0.05) and moderate correlation for the transverse diameter measurement (r=0.82, p=0.002) of the subglottic space, and a strong correlation for the transverse diameter measurement (r=0.91, p<0.05) of the upper trachea, in the ultrasound and MR images.

CONCLUSION

The anatomy of the adult airway can be assessed using 3D ultrasound. It can also be used to accurately measure the AP diameter of the subglottic space and the transverse diameter of the upper trachea.

ADVANCES IN KNOWLEDGE

This is the first report to describe the use of 3D ultrasound to evaluate the anatomy of the upper airway and accurately measure the AP diameter of the subglottic space and the transverse diameter of the upper trachea.

Ultrasound imaging of the larynx and vocal folds: recent applications and developments

PURPOSE OF REVIEW

This article reviews recent clinical applications of ultrasound imaging in laryngeal examinations and new developments in imaging techniques for laryngeal tissue characterization.

RECENT FINDINGS

The B-mode image has become a popular tool for identifying masses, lesions, and nodules at the vocal folds, and combining the B-scan with Doppler imaging makes it possible to also evaluate their functionality. The B-mode image has been used to diagnose lesions and paralysis in vocal folds in children, and to evaluate nerve function by visualizing the structure of the larynx and the movement of the bilateral vocal folds. Ultrasound Nakagami imaging based on the statistics of backscattered signals is a new parametric imaging method that complements the conventional B-scan for tissue characterization. Nakagami imaging is a functional ultrasound imaging tool for visualizing the relative concentrations of collagen and elastic fibers, which are key factors influencing the biomechanical properties of the vocal folds.

SUMMARY

Future clinical applications could combine conventional B-mode and Nakagami images to allow physicians to simultaneously evaluate the morphology and scatterer properties of laryngeal tissues.

Imaging vibrating vocal folds with a high speed 1050 nm swept source OCT and ODT

Vocal fold vibration is vital in voice production and the correct pitch of speech. We have developed a high speed functional optical coherence tomography (OCT) system with a center wavelength of 1050 nm and an imaging speed of 100,000 A-lines per second. We imaged the vibration of an ex-vivo swine vocal fold. At an imaging speed of 100 frames per second, we demonstrated high quality vocal fold images during vibration. Functional information, such as vibration frequency and vibration amplitude, was obtained by analyzing the tissue surface during vibration. The axial direction velocity distribution in the cross-sectional images of the vibrating vocal folds was obtained with the Doppler OCT. The quantitative transverse direction velocity distribution in the cross-sectional images was obtained with the Doppler variance images.