Effect of BAEP monitoring on hearing preservation during acoustic neuroma resection.

We measured the effect of brainstem auditory evoked potential (BAEP) monitoring on hearing preservation in acoustic neuroma resection in 90 consecutive patients with monitoring compared with 90 historical controls matched for tumor size and preoperative hearing status. In small tumors (less than 2 cm), BAEP monitoring was associated with a higher rate of hearing preservation and a greater chance that the hearing preserved was clinically useful. Changes in the BAEP intraoperatively showed a good correlation with postoperative hearing status.

Physiologic assessment of Isshiki type III thyroplasty.

Isshiki type III thyroplasty is a laryngeal framework surgical procedure that lowers a patient's pitch. To objectively assess the procedure, preoperative and postoperative voice recordings, as well as electroglottography and photoglottography were performed. Jitter, shimmer, and glottographic quotients were measured to assess changes in vibratory pattern. The mean and range of frequencies in contextual speech was also determined. Analysis of the preoperative and postoperative data from two patients with over 1 year follow-up showed a decrease in frequency of vibration. Postoperatively, the vocal folds still vibrated in a regular pattern as described by the myoelastic-aerodynamic theory. There was no increase in jitter or shimmer quotient. The Isshiki type III thyroplasty appears capable of lowering fundamental frequency of speech without adversely affecting the vibratory mode of the vocal folds.

Influence of size and etiology of glottal gap in glottic incompetence dysphonia.

This study investigates the relationship between glottal gap and vocal function in patients with glottic incompetence dysphonia. Twenty patients with vocal fold paralysis (VFP), 17 patients with vocal fold atrophy (VFA), and five patients with sulcus vocalis (SV) were examined. Glottal gap area at the most closed point of vibration was measured using digitized videostroboscopic images. Glottal gap area was correlated with acoustic and aerodynamic measures of vocal function. Patients with VFP had the largest glottal gaps and had significantly worse vocal function than did the patients with VFA or SV. Regardless of groups, however, where glottal gap size was similar, there was no difference in vocal function. Therefore vocal function was mainly influenced by glottal gap size, not by whether glottic incompetence was the result of VFP, VFA, or SV.

Quantitative criteria for predicting thyroplasty type I outcome.

The purpose of this study was to ascertain the relation between preoperative glottal gap and postoperative vocal function in thyroplasty type I. Twenty-two of 64 patients who underwent thyroplasty type I between 1987 and 1994 were studied. In preoperative digitized laryngostroboscopic images, the glottal-gap, width (GGW), shape, and area were examined at the maximum closure of vibration and normalized by membranous vocal-fold length (MVFL). Postoperative vocal function analysis was performed with aerodynamic and acoustic measurements and compared with preoperative videostroboscopic images. In patients with preoperative posterior GGW of less than 10% of MVFL, postoperative vocal function was significantly better than in other patients. Although thyroplasty type I is an excellent medialization technique, it may need to be combined with a posterior closure procedure in patients with large posterior gaps.

Effects of thyroplasty type I on vocal fold vibration.

OBJECTIVE: To ascertain effects of medialization thyroplasty on vocal fold vibration in glottic incompetence dysphonia. STUDY DESIGN: Quantitative videostroboscopic glottic measurements and vocal function study were perioperatively undertaken in 20 patients undergoing Isshiki's thyroplasty type I. METHODS: In digitized images, the glottal area, glottal width, posterior glottal width, and amplitude over an entire glottal cycle were measured and normalized by membranous vocal fold length. The ratio of closed phase to total phase of vibratory cycle was calculated from the data of the glottal area and the glottal width at the middle point of the membranous vocal fold. Well-accepted acoustic, aerodynamic, and perceptual measures analyzed vocal function. RESULTS: Glottal area and glottal width were reduced after surgery. While preoperative closure of glottal area was incomplete in all 20 patients, incomplete closure was obtained in 16 patients after surgery. In these 16 patients, closure of glottal width at the middle point of the membranous vocal fold was complete, whereas a posterior glottal gap remained in 14 patients. Closed phase over one cycle of glottal width waveform and amplitude of vocal fold vibration were increased after surgery. Glottal area, glottal width, posterior glottal width, and closed phase over one cycle of glottal width waveform correlated with vocal function measures. CONCLUSIONS: Thyroplasty type I reduces a glottal gap and increases closed phase over one cycle and amplitude of vocal fold vibration, although a posterior glottal gap remains. With the improved glottic vibration, thyroplasty type I provides more efficient phonation in patients with glottic incompetence dysphonia.

Auditory monitoring during acoustic neuroma removal.

Preservation of hearing has become attainable for patients with small acoustic neuromas. Brain-stem auditory evoked response was monitored intraoperatively in 60 patients undergoing acoustic neuroma surgery via the posterior fossa approach. The overall rate of hearing preservation was 30% in the monitored group and 20% in 60 patients who were matched for tumor size and preoperative hearing level and underwent the same surgical procedure but without intraoperative brain-stem auditory evoked response monitoring. The rate of hearing preservation was correlated with tumor size: with tumors less than or equal to 1 cm, hearing was preserved in 82% of monitored and 36% of unmonitored patients; hearing was not preserved with tumors larger than 3 cm. Intraoperative brain-stem auditory evoked response monitoring appears to have improved the preservation of hearing during removal of small tumors.

Reconstruction of caudal end of septum. A case for transplantation.

OBJECTIVE: To examine the results of complete removal and reconstruction of the caudal end of the septum with emphasis on long term success. DESIGN: A case series reviewing the surgical outcome of 45 consecutive cases of transplantations for severely deformed of absent caudal ends of the septum. After at least 18 months, all 45 patients were given a postoperative evaluation. SETTING: All procedures were performed at Mayo Clinic, Rochester, Minn. PATIENTS: Forty-five patients (36 male and nine females) ranged in age from 7 to 78 years, with a mean age of 38 years. Twenty-seven patients had severe caudal end deformities, and 18 patients had absent or flaccid caudal end. OUTCOME MEASURES: Subjective assessment included the opinion of the patient, rhinologic examination, and photographic analysis. Anterior mask rhinomanometry was performed to measure nasal resistance. Clinically noted complications were documented when present. RESULTS: Subjectively, 36 (80%) of the 45 patients reported "normal" nasal breathing, and seven patients (15.6%) reported improved nasal breathing. Objective preoperative and postoperative rhinomanometry data, available in 28 cases, was related to the subjective findings. The longevity of the caudal end transplant was confirmed by reviewing the data from the 33 patients who were followed up more than 1 year. Ninety percent of the patients were free of complications. CONCLUSION: Objective and subjective results showed excellent long-term results. The caudal end of the nasal septum can be removed safely and reconstructed.

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 larynges. 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 less than 0.001) and inversely related to balloon size (p less than 0.001). Vocal efficiency was directly related to subglottic pressure (p less than 0.001). Frequency of vibration was directly related to balloon size (p less than 0.05), vocal fold tension (p less than 0.001), and subglottic pressure (p less than 0.001). Open quotient was directly related to vocal fold tension (p less than 0.01) and inversely related to balloon size (p less than 0.001). Clinical implications of these results will be discussed.

Effect of superior laryngeal nerve on vocal fold function: an in vivo canine model.

Assessment of laryngeal framework surgery requires an awareness of the effect of vocal fold mass, stiffness, and position on voice production. The vibratory pattern of vocal folds during phonation depends on the subglottic pressure as well as the mass and stiffness of the folds. To assess the effect of variations in vocal fold tension with contraction of the cricothyroid muscle on phonation, eight mongrel dog larynges were studied in vivo. Photoglottography, electroglottography, and subglottic pressure were simultaneously recorded as airflow rate and superior laryngeal nerve (SLN) stimulation were varied. Stimulation of the SLN was modified by varying the frequency and voltage of the stimulating electrical signal. Multiple regression analysis of the data revealed a direct relationship between the voltage of SLN stimulation and frequency of vibration (p less than 0.001) at constant subglottic pressure. Increases in the stimulating voltage to the SLN also led to an increase in open quotient (p less than 0.001), but no statistically significant change in speed quotient, subglottic pressure, or sound intensity. Changing the frequency of SLN stimulation had only a modest effect on the frequency of vibration. These results are consistent with the reported findings of an increase in frequency and open quotient with increased tension in an in vitro canine model. The glottographic measurement open quotient appears to be an estimator of cricothyroid contraction and longitudinal vocal fold tension, and may be clinically applicable to the assessment of superior laryngeal nerve injuries and laryngeal framework procedures.

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 wave-forms 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 less than 0.001), glottic width (p less than 0.01), and fundamental frequency (p less than 0.001). Speed quotient was inversely related to glottic width and and subglottic pressure (p less than 0.05). Regression analysis also showed frequency of vibration to be directly related to tension (p less than 0.001) and inversely related to glottic width (p less than 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.

Regulation of phonatory efficiency by vocal fold tension and glottic width in the excised canine larynx.

An excised canine larynx was used to assess the effects of glottic width and vocal fold tension on acoustic power, aerodynamic power, and vocal efficiency. Multiple regression analysis of the data obtained from 10 larynges revealed that with increased vocal fold tension there is a logarithmic decline in radiated acoustic power, while aerodynamic power remains constant (p less than .05). Vocal efficiency has a similar logarithmic decrease with increased tension (p less than .05). With narrowing of the glottis, the acoustic power increases more than the aerodynamic power delivered to the larynx, and the efficiency increases. The inverse relationships glottic width has with acoustic power and vocal efficiency are best described by a reciprocal model (p less than .01). There is a negative linear relationship between glottic width and aerodynamic power. These results suggest that within the larynx the energy conversion is regulated by glottic aperture and longitudinal vocal fold tension. The optimal width for efficiency appears to be the narrowest width that produces phonation within the modal register, whereas increased tension decreases the efficiency of the glottis.

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.

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.

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.

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 less than .01). This study describes a reliable technique for the noninvasive measurement of subglottic pressure, sound intensity, and airflow.

Turbinoplasty for concha bullosa: a non-synechiae-forming alternative to middle turbinectomy.

A large pneumatized middle turbinate (concha bullosa) may require surgical reduction. Partial middle turbinectomy, especially when done simultaneously with uncinectomy and ethmoidectomy, results in an increased risk for adhesion formation in the middle meatus. Turbinoplasty is a procedure that results in a significant reduction of the width of the middle turbinate without injuring its mucosal surfaces. A 4-year experience with this procedure showed almost complete elimination of the synechiae problem.

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.