David H. Slavit

Quantitative Videostroboscopic Measurement of Glottal Gap and Vocal Function: An Analysis of Thyroplasty Type I:

The goal of surgical medialization of the vocal fold is to attain complete glottic closure. The purpose of this study is to quantify the glottal gap and to examine the relationship between glottal gap and vocal function perioperatively in thyroplasty type I. Glottal gap area was measured in 20 patients at the point of maximum closure of vocal fold vibration in digitized laryngeal stroboscopic images and was normalized by the square of vocal fold length. Glottal gap area thus measured was correlated with results obtained from well-accepted acoustic, aerodynamic, and perceptual measures of vocal function. The glottal gap was significantly reduced after thyroplasty type I. In patients with small preoperative glottal gaps, the amplitude of vocal fold vibration was significantly improved. This study verifies that quantitative videostroboscopic measurement of the glottal gap is a useful means of objective evaluation of glottic incompetence and of the results of thyroplasty type I.

Physiologic Assessment of Arytenoid Adduction

Arytenoid adduction as described by Isshiki is a surgical technique used to improve vocal quality by adducting the arytenoid cartilage of a paralyzed vocal fold, medializing the fold, and closing the posterior glottic aperture. Surgical results of this operation were evaluated by preoperative and postoperative voice recordings, laryngoscopy, and stroboscopy. Objective measurements of vocal jitter, shimmer, and signal to noise ratio were done to assess changes in the vibratory patterns, and analysis of data from 12 patients revealed improved glottic function postoperatively. Often an anterior medialization procedure, primarily a type I thyroplasty, was used to supplement the posterior medialization achieved by adduction of the arytenoid. Arytenoid adduction is recommended as an effective and reliable treatment for posterior glottic insufficiency.

Teflon Granulomas and Overinjection of Teflon: A Therapeutic Challenge for the Otorhinolaryngologist:

We have found that Teflon granulomas and the overinjection of Teflon with the resulting laryngeal dysfunction, although uncommon, present a challenge to the otorhinolaryngologist, due in large part to the inflammatory reaction to the injected Teflon. This report addresses the management of 16 patients (12 women and 4 men) treated surgically for symptoms secondary to Teflon granulomas or vocal folds that had been overinjected with Teflon. The presenting symptoms varied and included airway obstruction, cough, choking, swallowing difficulties, and dysphonia. In each case the granuloma and Teflon were removed endoscopically via a lateral cordotomy. A second procedure to address dysphonia due to vocal cord lateralization was frequently required and presents the challenge for the surgeon to select the appropriate procedure and time of intervention. The results of this retrospective review suggest that resolution of inflammatory changes and fibrosis subsequent to Teflon removal requires significant lengths of time and that thyroplasty techniques provide a means for medialization without reintroduction of the original inflammatory material.

Vocal Fold Atrophy: Quantitative Glottic Measurement and Vocal Function

Videostroboscopic glottic measurements and vocal function were evaluated in 41 vocal fold atrophy patients with bowed vocal folds. The amount of bowing in the resting position and the glottal gap area and vibratory amplitude during phonation were measured from digitized videostroboscopic images. Vibratory amplitude was not decreased on atrophic vocal folds. With the same amount of total bowing, the glottal gap area for bilateral atrophy was smaller than for unilateral atrophy. These results suggest that vocal fold atrophy is not disadvantageous to thyroplasty type I, and that bilateral procedures may produce a better outcome than a unilateral procedure in the treatment of bilateral atrophy. Acoustic, aerodynamic, and perceptual parameters of vocal function were measured. The acoustic high-frequency power ratio and the H-index correlated with the glottal gap area. The mean flow rate correlated with the amount of bowing. The degree of dysphonia was related to the size of the glottal gap and bowing.

Noninvasive Technique for Estimating Subglottic Pressure and Laryngeal Efficiency

The clinical assessment of aerodynamic parameters is important in the physiology and pathophysiology of laryngeal function. Vocal efficiency is among these objective measurements and can be calculated from simultaneous recordings of subglottic pressure, airflow, and sound intensity. Modern techniques allow us to accurately determine sound intensity and airflow. However, methods to determine subglottic pressure are either invasive or laborious. We have evaluated a noninvasive, indirect method to determine subglottic pressure by using a technique based on the interruption of transglottic airflow during phonation. The correlation between the indirectly acquired subglottic pressure measured in the oral cavity by using this technique and the subglottic pressure obtained directly by translaryngeal puncture in human volunteers was highly significant in 35 trials (r = .92, p < .01). This study describes a reliable technique for the noninvasive measurement of subglottic pressure, sound intensity, and airflow.

Arytenoid adduction and type I thyroplasty in the treatment of aphonia.

Arytenoid adduction is a procedure used to medialize the paralyzed vocal fold, closing the posterior glottis. Isshiki type I thyroplasty allows medialization of the anterior membranous vocal fold. Using the arytenoid adduction, in combination with Isshiki type I thyroplasty as needed, five patients were treated for aphonia. Surgical results were evaluated with voice recordings, electroglottography, and photoglottography. Jitter ratio, shimmer ratio, and signal-to-noise ratio were measured. Laryngeal stroboscopy and glottography were used to assess the mucosal wave and vibratory nature of the vocal folds. After operation, vocal function was restored. Analysis of data from these five aphonia patients revealed improved glottic phonatory function. The arytenoid adduction in combination with the Isshiki type I thyroplasty is an effective technique for aphonia caused by a significant posterior glottic gap with unilateral vocal-cord paralysis.

Glottographic analysis of phonation in the excised canine larynx.

An excised canine larynx model of phonation was developed to assess the effect of vocal fold length and tension on glottographic waveforms. The canine larynx in an experimentally produced phonatory model vibrated in a two-mass system comparable to human voice production. The recorded glottographic waveforms for the excised canine larynx were similar to signals recorded in humans in the chest register. Vocal fold length, longitudinal vocal fold tension, glottic width, and airflow rate were varied while simultaneous measurements were made of the subglottic pressure, electroglottographic signal, photoglottographic signal, and acoustic signal. The model used is illustrated and discussed, with emphasis on the method of simulating the actions of all of the intrinsic laryngeal muscles, including the thyroarytenoid muscles. The open quotient and speed quotient, calculated from the glottographic signals, were dependent on vocal fold length and tension and glottic width. These results suggest that glottographic analysis, particularly speed quotient and open quotient, provide valuable information on vocal fold vibration during phonation, and may be important in assessing laryngoplasty procedures.

Study of phonation in the excised canine larynx.

Previous studies have demonstrated that the laryngeal muscles responsible for pitch variation and vocal efficiency are the cricothyroid muscles, affecting longitudinal tension of the vocal folds, and the thyroarytenoid muscles, controlling the lateral stiffness of the vocal folds. Longitudinal tension in the vocal fold is easily simulated in the excised canine larynx. The effect of the thyroarytenoid muscle, however, has not been adequately analyzed. To simulate the effect of the thyroarytenoid muscle, small balloons were placed in the paraglottic space at the level of the vocal folds in 10 excised canine laryngés. These balloons (Fogarty catheters) could be inflated in increments to simulate the effect of the thyroarytenoid muscle contraction in altering the lateral stiffness of the vocal fold. During phonation subglottic pressure, vocal fold longitudinal tension and balloon size were systematically varied. The photoglottographic and electroglottographic signals, sound intensity, and airflow rate were measured. Multiple regression analysis showed that sound intensity was directly related to subglottic pressure (p < 0.001) and inversely related to balloon size (p < 0.001). Vocal efficiency was directly related to subglottic pressure (p < 0.001). Frequency of vibration was directly related to balloon size (p < 0.05), vocal fold tension (p < 0.001), and subglottic pressure (p < 0.001). Open quotient was directly related to vocal fold tension (p < 0.01) and inversely related to balloon size (p < 0.001). Clinical implications of these results will be discussed.

Phonatory Vocal Fold Function in the Excised Canine Larynx

The development of valid objective measurements of vocal cord vibration during phonation is a goal of current research in laryngeal physiology. An excised canine larynx was used to study the effects of vocal cord tension, air flow rate, and glottic width on glottographic parameters. The electroglottographic and photoglottographic waveforms were simultaneously recorded as the vocal cord tension, glottic width, and air flow rate were systematically varied. These glottographic waveforms were analyzed to determine the open quotient and speed quotient. Multiple regression analysis of the data obtained from 10 larynges showed the open quotient to be directly related to vocal fold tension (p< 0.001), glottic width (p < 0.01), and fundamental frequency (p < 0.001). Speed quotient was inversely related to glottic width and subglottic pressure (p < 0.05). Regression analysis also showed frequency of vibration to be directly related to tension (p < 0.001) and inversely related to glottic width (p < 0.001), with different combinations of glottic tension and width capable of producing the same frequency. The open and speed quotients thus reflect the changes in the vibratory patterns of the vocal folds produced by alterations in tension and width. The clinical implications of these results will be discussed, with emphasis on glottography as an objective assessment of the various laryngeal framework procedures being performed.

Rhinolift Operation in the Treatment of the Aging Nose

Disturbance of the normal relationship between the caudal border of the upper lateral cartilage and the cephalic margin of the lobular cartilage—the so-called “cul-de-sac” area—can result in alar collapse and nasal airway obstruction. This may be caused by either the aging process or trauma, both surgical and nonsurgical. Rhinolift is a surgical procedure that was developed for the treatment of the aging ptotic nasal tip. We have applied this technique to patients with nasal airway obstruction resulting from alar collapse. Elevation of the cephalic margin of the lobular cartilage to a position superficial to the upper lateral cartilage restores the normal relationship between these two structures. The upper lateral cartilage then assists in stenting the vestibule open, and thereby improves nasal breathing. Over the past 10 years, 20 patients have had rhinolifts at our institution for the relief of nasal airway obstruction. Concomitant surgery included nasal septal reconstruction in 12 patients, polypectomy in one patient, and placement of a silicone rubber septal prosthesis for closure of a large septal perforation in three patients. Rhinolift was the sole procedure used for the correction of valvular pathology in 10 patients. The other 10 patients had modifications made in their upper lateral cartilage along with the rhinolift. Five patients described restoration of normal nasal breathing, while 14 patients showed partial symptomatic improvement. One patient reported no improvement in nasal breathing. Rhinolift is a safe effective surgical technique for functional improvement of nasal breathing in patients with alar collapse resulting from inadequate cartilaginous support.