Ultrasound-guided injection into the lateral crico-arytenoid muscle: a pilot study.

OBJECTIVES: The anterior, percutaneous Botulinum neurotoxin (BoNT) injection in the lateral cricoarytenoid muscle (LCA) guided by laryngeal electromyography (LEMG) is considered the golden standard treatment for several neurolaryngological disorders. The study presented in this article aims to assess the effectiveness of an alternative approach by which the injection is performed laterally under ultrasound monitoring. STUDY DESIGN: Anatomical dissection study in human cadavers. SETTINGS: Academic health care center. METHODS: Ultrasound-guided bilateral dye (0.1 mL of dye solution containing cold-curing polymers, latex, acrylates, acrylic esters, alcohol, and green color) injection in the LCA was performed by means of 24G needles and 1 mL syringes using the lateral approach. The dye location and distribution were assessed by anatomic dissection, performed immediately after the injection. RESULTS: In 9/10 specimens, the dye was exclusively detectable in the LCA. In 1/10 case (left side), the dye could not be delivered in the LCA because of unintended penetration of the thyroid cartilage by the needle during injection. Anatomic dissection confirmed that the dye spread neither into the thyroarytenoid (TA) nor the cricothyroid muscle (CT). CONCLUSIONS: The anatomic dissection following lateral dye injection in the LCA under ultrasound guide confirmed the precision of this approach in delivery a substance exclusively in a pre-determined target. This feature makes this method an interesting addition or alternative to the standard LEMG-guided BoNT injection at least when the LCA is its target. LEVEL OF EVIDENCE: III.

Differences in Glottal Closure and Visibility of the Anterior Commissure during Rigid-90°, Rigid-70°, and Flexible Laryngostroboscopy.

INTRODUCTION: The conventional rigid-90° and rigid-70° laryngostroboscopy has been so far considered the gold standard in assessing the vibratory behavior of the vocal folds and the glottal closure configuration during phonation. Meanwhile, this rigid laryngostroboscopy is more and more replaced by flexible chip-on-tip systems. The aim of this study was to evaluate the influence of these different endoscopic techniques on glottal closure configuration and on visibility of the complete focal fold length including anterior commissure during phonation. METHODS: Twenty-one euphonic subjects were enrolled (mean age 34.6 ± 9.5; m = 10, f = 11). They were examined with the three laryngoscopic techniques (conventional rigid-90°, rigid-70°, and flexible chip-on-tip laryngoscopy during low and high voice pitch with soft and loud voice intensity). For evaluating the degree of glottal closure, a modified classification of Södersten et al. was applied and the visibility of the anterior commissure was evaluated. The correlation of the three endoscopic techniques was assessed with Cohen and Fleiss' kappa. RESULTS: In even low loud phonation, the rigid-90° and rigid-70° endoscopies revealed a complete closure of the glottis in only 47.6% of subjects but with flexible endoscopy in 81%. The complete vocal fold length with anterior commissure was best visible with flexible endoscopy in 90.5% in low-soft and high-soft phonation. The rigid-90° endoscopy showed a slight agreement in comparison with the flexible endoscopy in regard to the types of vocal fold closure with a Cohen's kappa coefficient k = 0.199. The rigid-90° endoscopy showed an almost perfect agreement with k = 0.84 when compared to the rigid-70° endoscopy. The flexible endoscopy compared to the rigid-70° endoscopy showed a fair agreement with k = 0.346. CONCLUSION: We found mainly corresponding results in both rigid-90° and rigid-70° endoscopic techniques which can be explained by the same transoral approach with the tongue pulled out, whereas the flexible transnasal endoscopy mainly gives a better view on the anterior commissure. The influence of transorally or transnasally guided endoscopic techniques needs to be considered in interpretation of laryngostroboscopic parameters like vocal fold closure and supraglottal hyperactivity.

Effect of FFP2/3 Masks on Voice Range Profile Measurement and Voice Acoustics in Routine Voice Diagnostics.

INTRODUCTION: Voice diagnostics including voice range profile (VRP) measurement and acoustic voice analysis is essential in laryngology and phoniatrics. Due to COVID-19 pandemic, wearing of 2 or 3 filtering face piece (FFP2/3) masks is recommended when high-risk aerosol-generating procedures like singing and speaking are being performed. Goal of this study was to compare VRP parameters when performed without and with FFP2/3 masks. Further, formant analysis for sustained vowels, singer's formant, and analysis of reading standard text samples were performed without/with FFP2/3 masks. METHODS: Twenty subjects (6 males and 14 females) were enrolled in this study with an average age of 36 ± 16 years (mean ± SD). Fourteen patients were rated as euphonic/not hoarse and 6 patients as mildly hoarse. All subjects underwent the VRP measurements, vowel, and text recordings without/with FFP2/3 mask using the software DiVAS by XION medical (Berlin, Germany). Voice range of singing voice, equivalent of voice extension measure (eVEM), fundamental frequency (F0), sound pressure level (SPL) of soft speaking and shouting were calculated and analyzed. Maximum phonation time (MPT) and jitter-% were included for Dysphonia Severity Index (DSI) measurement. Analyses of singer's formant were performed. Spectral analyses of sustained vowels /a:/, /i:/, and /u:/ (first = F1 and second = F2 formants), intensity of long-term average spectrum, and alpha-ratio were calculated using the freeware praat. RESULTS: For all subjects, the mean values of routine voice parameters without/with mask were analyzed: no significant differences were found in results of singing voice range, eVEM, SPL, and frequency of soft speaking/shouting, except significantly lower mean SPL of shouting with FFP2/3 mask, in particular that of the female subjects (p = 0.002). Results of MPT, jitter, and DSI without/with FFP2/3 mask showed no significant differences. Further mean values analyzed without/with mask were ratio singer's formant/loud singing, with lower ratio with FFP2/3 mask (p = 0.001), and F1 and F2 of /a:/, /i:/, /u:/, with no significant differences of the results, with the exception of F2 of /i:/ with lower value with FFP2/3 mask (p = 0.005). With the exceptions mentioned, the t test revealed no significant differences for each of the routine parameters tested in the recordings without and with wearing a FFP2/3 mask. CONCLUSION: It can be concluded that VRP measurements including DSI performed with FFP2/3 masks provide reliable data in clinical routine with respect to voice condition/constitution. Spectral analyses of sustained vowel, text, and singer's formant will be affected by wearing FFP2/3 masks.

Pre- and intraoperative acoustic and functional assessment of the novel APrevent® VOIS implant during routine medialization thyroplasty.

PURPOSE: Persistent unilateral vocal fold paralysis (UFVP) with glottal insufficiency often requires type I medialization thyroplasty (MT). Previous implants cannot be adjusted postoperatively if necessary. The newly developed APrevent® VOIS implant (VOIS) can provide postoperative re-adjustment to avoid revision MT. The objective of this pilot study is to evaluate the VOIS intraoperatively concerning voice improvement, surgical feasibility and device handling. METHODS: During routine MT, VOIS was applied short time in eight patients before the regular implantation of the Titanium Vocal Fold Medialization Implant (TVFMI™). In all patients, perceptual voice sound analysis using R(oughness)-B(reathiness)-H(oarseness)-scale, measurement of M(aximum)-P(honation)-T(ime) and glottal closure in videolaryngoscopy were performed before and after implanting VOIS/TVFMI™. Acoustic analyses of voice recordings were performed using freeware praat. Surgical feasibility, operative handling and device fitting of VOIS and TVFMI™ were assessed by the surgeon using V(isual)-A(nalog)-S(cale). Data were statistically analyzed with paired t test. RESULT: All patients showed significant improvement of voice sound parameters after VOIS/TVFMI™ implantation. The mean RBH-scale improved from preoperative R = 2.1, B = 2.3, H = 2.5 to R = 0.6, B = 0.3, H = 0.8 after VOIS and R = 0.5, B = 0.3, H = 0.8 after TVFMI™ implantation. The mean MPT increased from preoperative 7.9 to 14.6 s after VOIS and 13.8 s after TVFMI™ implantation. VOIS/TVFMI™ achieved complete glottal closure in 7/8 patients. The satisfaction with intraoperative device fitting and device handling of VOIS was as good as that of TVFMI™. CONCLUSION: The novel APrevent® VOIS implant showed similar intraoperative voice improvement compared to routinely used TVFMI™ without adverse device events and with safe device fitting.

Inter-rater reliability of seven neurolaryngologists in laryngeal EMG signal interpretation.

PURPOSE: Laryngeal electromyography (LEMG) has been considered as gold standard in diagnostics of vocal fold movement impairment, but is still not commonly implemented in clinical routine. Since the signal interpretation of LEMG signals (LEMGs) is often a subjective and semi-quantitative matter, the goal of this study was to evaluate the inter-rater reliability of neurolaryngologists on LEMGs of volitional muscle activity. METHODS: For this study, 52 representative LEMGs of 371 LEMG datasets were selected from a multicenter registry for a blinded evaluation by 7 experienced members of the neurolaryngology working group of the European Laryngological Society (ELS). For the measurement of the observer agreement between two raters, Cohen's Kappa statistic was calculated. For the interpretation of agreements of diagnoses among the seven examiners, we used the Fleiss' Kappa statistic. RESULT: When focusing on the categories "no activity", "single fiber pattern", and "strongly decreased recruitment pattern", the inter-rater agreement varied from Cohen's Kappa values between 0.48 and 0.84, indicating moderate to near-perfect agreement between the rater pairs. Calculating with Fleiss' Kappa, a value of 0.61 showed good agreement among the seven raters. For the rating categories, the Fleiss' Kappa value ranged from 0.52 to 0.74, which also showed a good agreement. CONCLUSION: A good inter-rater agreement between the participating neurolaryngologists was achieved in the interpretation of LEMGs. More instructional courses should be offered to broadly implement LEMG as a reliable diagnostic tool in evaluating vocal fold movement disorders in clinical routine and to develop future algorithms for therapy and computer-assisted examination.

Applicability of Selective Electrical Surface Stimulation in Unilateral Vocal Fold Paralysis.

OBJECTIVE: Selective electrical surface stimulation (SES) of the larynx is not yet routinely considered therapy option in treatment of unilateral vocal fold paralysis (UVFP). Goal of this monocentric feasibility study was to provide systematic data on applicability of SES of intrinsic laryngeal muscles in UVFP under consideration of sensitivity and discomfort thresholds and nonselective side effects. METHODS: Thirty-two UVFP patients were included in the study. Symmetric triangular-shape, charge-balanced pulse widths (PWs) of 1, 10, 25, 50, 100, 250, and 500 milliseconds (ms) were tested with increasing amplitudes (AMPs). The stimulation was delivered as a train of five pulses using square surface electrodes. Selective laryngeal responses were examined by flexible laryngoscopy. Nonselective side effects (swallowing reflex, coughing, different severity degrees of unspecific strap muscle/platysma response) were judged by observation. RESULTS: Selective laryngeal response could be triggered in 28/32 (87.5%) patients during respiration/rest and in 26/32 (81.3%) patients during phonation. The most effective PWs for the selective eliciting of selective bilateral vocal fold adduction are comprised between 50 and 100 ms in combination with an average AMP comprised between 7.1 and 7.2 mA. CONCLUSION: Our results indicate that, in UVFP patients, PWs comprised between 50 and 100 ms in combination with a median AMP between 7.1 and 7.2 mA are expected to deliver in >75% of the cases a specific, effective, and safe bilateral adduction of the VF. LEVEL OF EVIDENCE: 3 Laryngoscope, 131:E2566-E2572, 2021.