Objectives Evaluate the effects of asymmetric superior laryngeal nerve stimulation on the vibratory phase, laryngeal posture, and acoustics. Study Design Basic science study using an in vivo canine model. Methods The superior laryngeal nerves were symmetrically and asymmetrically stimulated over eight activation levels to mimic laryngeal asymmetries representing various levels of superior laryngeal nerve paresis and paralysis conditions. Glottal posture change, vocal fold speed, and vibration of these 64 distinct laryngeal activation conditions were evaluated by high speed video and concurrent acoustic and aerodynamic recordings. Assessments were made at phonation onset. Results Vibratory phase was symmetric in all symmetric activation conditions but consistent phase asymmetry towards the vocal fold with higher superior laryngeal nerve activation was observed. Superior laryngeal nerve paresis and paralysis conditions had reduced vocal fold strain and fundamental frequency. Superior laryngeal nerve activation increased vocal fold closure speed, but this effect was more pronounced for the ipsilateral vocal fold. Increasing asymmetry led to aperiodic and chaotic vibration. Conclusions This study directly links vocal fold tension asymmetry with vibratory phase asymmetry; in particular the side with greater tension leads in the opening phase. The clinical observations of vocal fold lag, reduced vocal range, and aperiodic voice in superior laryngeal paresis and paralysis is also supported.

Level of Evidence NA Laryngoscope, 124:742–745, 2014

Objectives The objective is to present clinical outcomes of subglottic and tracheal stenosis treated by flexible bronchoscopic delivery of carbon dioxide (CO2) laser via laryngeal mask airway (LMA). Methods All consecutive, nontracheotomy dependent cases of subglottic and tracheal stenosis treated endoscopically over a 4-year period were retrospectively reviewed. The surgical approach consisted of radial incisions using a flexible fiber-based CO2 laser, balloon dilation, and topical application of mitomycin C. Ventilation during the procedure occurred through the LMA, and the CO2 laser fiber was delivered through the working channel of a flexible bronchoscope passed through the LMA. Number of dilations, period between dilations, and operative times were reviewed. Results Eleven patients who underwent airway intervention during the study period were identified. Average follow-up was 28 months. Etiologies of airway stenosis included intubation injury (6), idiopathic (4), or autoimmune disease (1), requiring an average of 1.3, 1.5, and 3 dilations, respectively. Average operative time was 67 minutes. Autoimmune etiology correlated with more frequent dilations. Conclusion LMA is an effective way to manage ventilation while simultaneously allowing unencumbered flexible bronchoscopic access for laser surgery, balloon dilation, and mitomycin C application for airway stenosis. Long-term success in treating stenosis is achievable using this technique.

Purpose To review our clinical experience with percutaneous injection laryngoplasty at a single institution over a three-year period, and to specifically assess the rate of unintentional injection into the superficial lamina propria (SLP) and compare with results found in the literature. Materials and Methods Medical records were retrospectively reviewed to identify patients who underwent office-based injection laryngoplasty (OBIL) over a three-year period. Video documentation and the written notes of the procedures were reviewed to determine the rate of inadvertent placement of injectate into the SLP. A literature review was performed to identify other reports of this complication and contributing factors. Results 113 consecutive patients were identified who underwent OBIL in the study period. Of these, 100 patients had adequate records and follow-up available for this review. All patients underwent injection augmentation with bovine collagen using a percutaneous trans-membrane or trans-cartilaginous technique. 96 had improvement in their vocal quality and/or effort. Four patients, who were all women, had unintentional injection into the SLP with resultant no change in voice or worsened voice. All superficially placed injectates were managed conservatively. Conclusions Injection into the SLP is a well-recognized possible complication of OBIL. Our results suggest that this complication occurs more often in women than in men, perhaps due to differing laryngeal anatomy and size.

No abstract