Comparison of the phonation-related structures among pig, dog, white-tailed deer, and human larynges

There is an important need for good animal models of the larynx for the study of the physiology of phonation. The dog's larynx has been used as an animal model for more than 2 centuries of phonatory research. However, there is some evidence that the pig larynx has advantages over the dog larynx as a model of phonation. Another larynx that is readily available is the deer larynx. In this comparative study, the laryngeal anatomy and function were examined in 4 species--human, pig, dog, and white-tailed deer. Particular attention was directed to those structures that one would predict could affect phonation, from the anatomic and biomechanical point of view. Although the vocal fold length was similar for all 4 species, the larynges described differed in some phonation-related characteristics. The data suggest that from a structural perspective, the pig larynx is a superior model for phonatory research.

Vocal Fold Impact Stress Analysis

Vocal fold impact stress (force/area) has been implicated as a factor possibly contributing to the formation of nodules and polyps. The force of impact of a moving body is related to its acceleration. Since the mass of the folds is relatively constant, one expects impact force to be directly proportional to acceleration. A measure that reflects the relative displacement of the vocal folds is photoglottography (PGG). The velocity and acceleration of the folds are easily obtained by calculating the first and second derivatives of the PGG displacement waveform. This study, therefore, compared the second derivative of the PGG signal with simultaneously measured impact stress in an excised canine larynx model. Glottal transillumination (PGG) was measured with a subglottic transducer. A miniature force transducer placed in the midline between the vocal folds measured impact stress at the midglottal position. For nine different larynges, there was a positive and linear relationship between the second derivative of PGG and impact stress. The statistically significant results support the hypothesis that the second derivative of PGG m ay provide a use fulnoninvasive way to estimate relative vocal fold impact stress.

Role of esophageal pH recording in management of chronic laryngitis: an overview

Chronic laryngitis typically produces symptoms of frequent throat-clearing, soreness, decreased voice quality with use, nonproductive cough, globus sensation, and odynophagia. The endoscopic laryngeal examination usually demonstrates posterior glottic edema, erythema, and increased vascularity and nodularity. There is increasing support for the hypothesis that reflux of acidic gastric contents is often responsible for the symptoms and findings of chronic laryngitis. Prospective trials of acid suppression therapy demonstrate not only efficacy in symptom reduction, but also objective improvement in measurements of voice quality and mucosal erythema. Although traditionally considered the "gold standard" for diagnosis of reflux causing laryngitis, routine esophageal pH recording may result in false negatives in up to 50% of patients. This may confound the diagnosis of chronic laryngitis and delay treatment. Conversely, a positive study during comprehensive therapy may help identify patients who need additional treatment. A single distal probe is probably insufficient for evaluation of a supraesophageal disorder. Current recommendations for double-probe pH study in the evaluation of chronic laryngitis fall into 2 categories: 1) a double-probe pH study is indicated if there is ongoing moderate-to-severe laryngitis despite antireflux precautions and proton pump inhibitor treatment for at least 6 to 12 weeks; and 2) a double-probe pH study is indicated as a baseline measurement before Nissen or Toupet fundoplication. The pH study would also be indicated in patients who have symptoms after fundoplication. There is clearly much more work to be done on the technical issues of obtaining accurate objective data related to laryngeal acidification. In addition, although acid reflux appears to be causative in many cases of chronic laryngitis, further work is indicated to identify reliable testing methods that will predict treatment success.

Quantitative study of mucosal wave via videokymography in canine larynges

OBJECTIVES

Vocal fold mucosal wave movements are thought to be important in determining voice characteristics and quality. To see these movements, high-speed cinematography and videostroboscopy have been used clinically; however, these techniques have disadvantages that make them impractical for quantitative measurement of mucosal wave movements. This study explored the feasibility of using line-scan cameras for mucosal wave analysis.

METHODS

An excised larynx bench model was used to examine the effects of elongation and changes in subglottal pressure on the amplitude, frequency, and phase difference of vocal fold mucosal movements as calculated from line-scan images.

RESULTS

The data showed a positive and linear relationship between an increase in subglottal pressure and amplitude of the mucosal wave; elongation of the vocal folds appeared to decrease the amplitude of mucosal wave upheaval at each level of subglottal pressure. Similarly, increase in subglottal pressure had a positive and linear relationship with increase in frequency of vibration; elongation of the vocal folds further increased the frequency at any given subglottal pressure. Phase difference between the movements of the upper and lower margins of the mucosal lips was estimated and did not appear to be significantly affected by changes in subglottal pressure and elongation.

CONCLUSION

The data presented in this study are consistent with relationships that we would expect to be true from currently accepted models of vocal fold vibration.

Correlation between glottal area and photoglottographic signal in normal subjects

Photoglottography (PGG) is an established technique for depicting the vibratory patterns of the vocal folds. The present study investigates the correlation between the glottal area and the corresponding PGG signal. Six normal (five male, one female) subjects who did not use their voices professionally were investigated during constantly sustained phonation at spontaneous pitches. Laryngostroboscopy was performed in combination with PGG. The simultaneously recorded laryngostroboscopic images and PGG signals were directly digitized and stored on a computer. The correlation between the glottal area and the corresponding PGG amplitudes across each vibratory cycle of the vocal folds was calculated and they were found to be highly and positively correlated (r = 0.973, p < 0.001). The PGG signal reflects changes in the glottal area during the vibration cycle of the vocal folds. The proposed simultaneous laryngostroboscopic and PGG technique has proved to be useful for facilitating the interpretation of changes in glottal area.

Vocal fold physiology

This article examines the physiologic factors responsible for the production of phonation in humans. The article begins with an explanation of the control mechanisms of phonation and theories of vocal fold vibration. The physiologic concepts are based on the myoelastic-aerodynamic, body-cover, and mucosal wave theories. An evaluation of the cover-body theory is explained in terms of pitch control. The factors that regulate the vocal folds to produce pitch changes, intensity variation, and register effects are outlined. The changes in pitch, intensity, and voice qualities are related to the vocal fold mass, tension, subglottic pressure, and airflow generated by the phonatory systems. A brief summary of abnormal voice production is given in terms of disordered physiology and the emerging theory of chaos.

ENT manifestations of gastroesophageal reflux

Reflux laryngitis is a common disease and is probably only one of several laryngeal manifestations associated with GERD. The hypothesis that GER causes laryngeal symptoms and conditions remains to be definitively proved. In many patients, the cause of laryngeal symptoms may well be multifactorial, and to identify definitively those patients in which GER may be playing a role remains a challenge. Documentation of GER using 24-h pH monitoring may assist in identifying such patients. Pharyngeal pH probe monitoring, although not without limitations, may be the optimal method to evaluate such patients in terms of documenting the presence of EPR. A suggested algorithm based on the available data in evaluating and treating patients with suspected reflux laryngitis is shown in Figure 5. First, rule out other causes of hoarseness and laryngitis. An ENT consultation is appropriate for hoarseness present >4 wk. Second, empirically treat with PPIs b.i.d. for 2-3 months, as esophageal and pharyngeal pH monitoring is costly, not readily available, time consuming, and not sensitive in making the diagnosis of GERD related laryngitis. If the patient improves after 2-3 months, therapy should be stopped and the patient observed. If symptoms recur, reinstitution of the PPI at the lowest possible dose or with use of an H2RA to maintain remission should be initiated. Third, if no improvement is noted, the patient should undergo 24-h pH monitoring with an esophageal and, if possible, a pharyngeal probe if the diagnoses of GERD and EPR are still in question. In patients in whom there is a high suspicion for GERD, pH monitoring should be performed on PPI therapy to determine whether acid suppression is adequate. A pH probe should be placed in the stomach if the question to be answered is whether 1) the PPI regimen is maintaining a pH of >4, or 2) if the addition of a bedtime H2RA maintains nocturnal intragastric pH of >4 (52-56). Patients with a completely normal pH study who are on no medications should be referred back to the ENT physician for further evaluation, as other risk factors for chronic laryngitis such as voice overuse may benefit from concomitant voice therapy. If upright reflux is the predominant reflux pattern, increasing the b.i.d. PPI dose is reasonable; but if nighttime supine reflux is predominant, recent literature suggests that the addition of a bedtime H2RA will suppress nocturnal acid breakthrough. There are, however, no long-term studies with the PPI plus H2RA regimen that document persistent nocturnal acid suppression and that show clinically significant differences in patients with nocturnal acid breakthrough. Surgery should be cautiously considered for patients who are unresponsive to PPI therapy and who have documented or undocumented evidence of GERD or EPR. The body of experience concerning GERD and the extraesophageal manifestations of GERD suggests that patients who do not respond to adequate PPI acid suppression will do poorly after antireflux surgery.

Diagnosis and management of chronic laryngitis associated with reflux

Chronic laryngitis symptoms are commonly seen in otherwise healthy people. This article reviews recent progress in our understanding and effective treatment of chronic laryngitis. Clinical experience and prospective treatment and outcome studies have demonstrated objective evidence of the efficacy of treating patients with chronic laryngitis symptoms with nocturnal antireflux precautions and acid-suppressing medications. The role of pH testing and most common errors in treatment are reviewed.

Effects of head extension and tongue protrusion on voice perturbation measures

Head extension with protruded tongue is the position for videolaryngoscopy and simultaneous glottographic recordings including photoglottographic signals. This study investigated the effect of head extension and tongue protrusion on the measures of fundamental frequency, frequency perturbation (jitter), and amplitude perturbation (shimmer). Acoustic signals recorded during sustained vowels were obtained from 49 women and 66 men with no speech or voice disorders in different head-tongue positions. Head extension was associated with increased fundamental frequency and decreased shimmer. In men, head extension did not appear to affect jitter. When the tongue was protruded, head extension tended to lower jitter. For both genders, tongue protrusion was associated with decreased fundamental frequency with head extension. In the men, tongue protrusion tended to increase shimmer when the head was in the neutral position. In the women, tongue protrusion was associated with increased jitter and increased shimmer and was most evident in the head-neutral position. These findings supported a physical linkage hypothesis of the relationship between vocal tract configuration and vocal fold vibration, suggesting that head-tongue position must be taken into account when comparing voice measures.

Effects of simulated source of tremor on acoustic and airflow voice measures

To test the effects of different sources of tremor on the voice, tremor was simulated by external rhythmic perturbation of structures at the subglottal, glottal, and supraglottal levels in 10 healthy subjects. The acoustic and airflow signals simultaneously recorded during sustained phonation in the normal and the 3 simulated tremor conditions were analyzed and compared. Voice measures included: fundamental frequency, 2 short-term perturbation measures (jitter and shimmer), and 3 long-term tremor measures (prominence ratios of the spectral peaks of the acoustic frequency contour, acoustic amplitude contour, and airflow contour). Measures of fundamental frequency and percent shimmer were not significantly affected by the simulated tremors. Measures of percent jitter and the amplitudes of the long-term frequency and amplitude modulations were most prominently increased when respiratory drive was perturbed by simulated tremor. Spectral analysis of the acoustic amplitude contour was most useful in distinguishing the 3 sites of simulated tremor.

Glottographic phase difference in recurrent nerve paralysis

Phase measures with simultaneously recorded electroglottography (EGG) and photoglottography (PGG) signals have been studied in canine models and found to be sensitive to the effect of recurrent laryngeal nerve (RLN) paralysis on vocal fold vibration. This study examined the usefulness of this type of measure in clinical application. The combined glottographic signals were obtained from 5 men with a diagnosis of unilateral RLN paralysis and 5 age-matched controls. In the patient group, EGG waveforms were found to have a consistent phase delay in relation to PGG. A measure of the overall glottographic phase difference (GPD) was found to significantly distinguish the control group (mean GPD = 0.2371 ms) from the patient group (mean GPD = -0.2765 ms). A validity analysis performed on 19 subjects with or without unilateral RLN paralysis confirmed that the GPD test had a relatively high efficiency (91.7%) in detecting unilateral RLN paralysis in the male population.

Acoustic and airflow spectral analysis of voice tremor

Acoustic spectral analysis has been used to describe voice tremor with some success, but no feature distinguishing pathological from normal tremor has been clearly identified. To assist in monitoring voice tremor associated with neurological diseases, objective and quantifiable measures that can distinguish between normal and pathological tremor are desired. This study explored the plausibility of using airflow and acoustic signals to quantify the frequency and amplitude of voice tremor and potentially to distinguish pathological from normal tremor. Subjects were 10 individuals with pathological tremor, most of them individuals with Parkinson's disease, and 10 gender and age-matched individuals with no voice disorder. Simultaneous acoustic and airflow signals were recorded during sustained vowel phonation. The acoustic intensity contours and the airflow signals were submitted to spectral analysis. A peak prominence ratio, defined as the ratio of the spectral peak energy to the overall signal energy, was calculated for each spectral peak below 30 Hz. For each subject, the 6 spectral peaks with the highest peak prominence ratios were selected. Frequency values of the 6 selected acoustic or airflow spectral peaks failed to distinguish tremor group from control group. Peak prominence ratios of the 6 selected acoustic spectral peaks were significantly higher for tremor group than for control group. Although spectral analysis of airflow signals was not useful in differentiating tremor group from control group, acoustic intensity contours and airflow time waveforms were highly and positively correlated in more tremor subjects (90%) than control subjects (40%). This finding suggests that the relationship between acoustic intensity contours and airflow time waveforms may reflect the presence and the source of voice tremor.

Glottographic measures before and after levodopa treatment in Parkinson's disease

OBJECTIVES

Investigate the usefulness of acoustic and glottographic measures for detecting effects of levodopa (L-dopa) treatment on vocal function of individuals with idiopathic Parkinson's disease.

STUDY DESIGN

Compare recordings of vowels sustained at a target comfortable loudness level obtained before and after L-dopa treatment from 15 individuals with idiopathic Parkinson's disease showing signs of tremor.

METHODS

A simultaneous acoustic, airflow, and electroglottographic recording technique was employed to record vowels phonated by subjects before and after L-dopa treatment. Algorithms were developed to derive from the recorded signal measures of fundamental frequency, SPL airflow rate, speed quotient (ratio of glottal opening to closing time time), and short- and long-term phonatory instability. A series of paired Student t tests or signed rank tests were performed to compare the pretreatment and posttreatment groups on these measures.

RESULTS

Measures of speed quotient, acoustic shimmer (cycle-to-cycle amplitude perturbation), and the extent of tremor derived from acoustic intensity contours were found to significantly decrease after medication. Sound pressure level tended to increase after medication. The acoustic jitter (cycle-to-cycle frequency perturbation) and the extent of tremor derived from airflow signals did not significantly differentiate between premedication and postmedication voices.

CONCLUSIONS

Objective measures of acoustic and electroglottographic signals are useful in monitoring the pharmacologic response of Parkinson's disease, reflecting decrease of laryngeal rigidity and short- and long-term acoustic amplitude fluctuation after L-dopa treatment.

Nitric oxide synthase type 3 is increased in squamous hyperplasia, dysplasia, and squamous cell carcinoma of the head and neck

The implication of nitric oxide (NO*) in the multistep process of carcinogenesis prompted us to examine the expression of endothelial constitutive nitric oxide synthase (NOS3) in head and neck squamous cell carcinoma (HNSCCa). Eleven paraffin-embedded samples of normal oral mucosa, 3 reactive oral lesions, 13 samples of squamous dysplasia, and 120 specimens of HNSCCa were immunostained with an anti-NOS3 monoclonal antibody and graded on a 0 to 4+ scale of intensity. Normal squamous mucosa demonstrated very little NOS3 expression. Areas of normal mucosa, reactive mucosa, and dysplastic lesions associated with inflammation tended to demonstrate regional expression of NOS3. Reactive mucosal lesions, squamous dysplasia, and HNSCCa demonstrated a significant (p<.0001) increase in global expression of NOS3. Therefore, NOS3 is expressed very little in histologically normal squamous mucosa, while squamous hyperplasia, dysplasia, and HNSCCa express significantly more NOS3. Regional variation in NOS3 expression appears to be associated with perilesional inflammation.

Voice target time in Parkinson's disease: A preliminary report

A target-matching paradigm was developed to assess the vocal equivalents of reaction and movement time in Parkinson's disease. Six patients with Parkinson's disease and 6 age- and gender-matched control subjects were asked to enunciate /pa/ to reach a target frequency and intensity level in response to a light stimulus. The stimulus and acoustic responses were simultaneously recorded. Measures included laryngeal reaction time, time between stimulus and phonation onset; frequency voice target time, time from phonation onset to target level of frequency; and amplitude voice target time, time from phonation onset to target level of intensity. The 2 subject groups were significantly differentiated by laryngeal reaction time (t = 299.67, df = 10, P = 0.005) and frequency voice target time (t = 148, df = 10, P = 0.014). These data suggest voice target time is a viable tool for assessing the effects of neurologic disorders on voice execution in Parkinson's disease.

Photoglottographic measures in Parkinson's disease

This study examines the usefulness of photoglottographic measures in reflecting the phonatory effect of Parkinson's disease. In the first experiment, data obtained by photoglottography were compared between 15 male patients with Parkinson's disease and 15 normal male speakers of similar age. Six photoglottographic parameters, mean open quotient (OQ), mean speed quotient (SQ), perturbation of open quotient (POQ), perturbation of speed quotient (PSQ), frequency perturbation ratio (FPR), and amplitude perturbation ratio (APR), in sustained vowel phonation were investigated. Increased SQ (t = -2.731, df = 28, P = 0.011) and POQ (t = -2.584, df = 28, P = 0.015) were significantly associated with data from patients in comparison to normal speakers. The FPR, APR, and OQ were not significantly different between normal subjects and patients. A follow-up experiment, including 12 female and 19 male patients with Parkinson's disease, was designed to evaluate the sensitivity of SQ and POQ in detecting vocal dysfunction. The sensitivity of SQ was found to be relatively high (93.5%), while that of POQ was low (45.2%). Methodological issues regarding the effects of gender, age, stage of the disease, and treatment on photoglottographic measures in Parkinson's disease were discussed.

Effect of tape recording on perturbation measures

Tape recorders have been shown to affect measures of voice perturbation. Few studies, however, have been conducted to quantitatively justify the use or exclusion of certain types of recorders in voice perturbation studies. This study used sinusoidal and triangular waves and synthesized vowels to compare perturbation measures extracted from directly digitized signals with those recorded and played back through various tape recorders, including 3 models of digital audio tape recorders, 2 models of analog audio cassette tape recorders, and 2 models of video tape recorders. Signal contamination for frequency perturbation values was found to be consistently minimal with digital recorders (percent jitter = 0.01%-0.02%), mildly increased with video recorders (0.05%-0.10%), moderately increased with a high-quality analog audio cassette tape recorder (0.15%), and most prominent with a low-quality analog audio cassette tape recorder (0.24%). Recorder effect on amplitude perturbation measures was lowest in digital recorders (percent shimmer = 0.09%-0.20%), mildly to moderately increased in video recorders and a high-quality analog audio cassette tape recorder (0.25%-0.45%), and most prominent in a low-quality analog audio cassette tape recorder (0.98%). The effect of cassette tape material, length of spooled tape, and duration of analysis were also tested and are discussed.

Endothelial constitutive nitric oxide synthase (ecNOS) localization in normal and neoplastic salivary tissue

BACKGROUND

Nitric oxide (NO.) has been implicated in the process of carcinogenesis in various organs. This study was designed to investigate the expression of endothelial constitutive nitric oxide synthase (ecNOS) in normal and neoplastic salivary tissues.

METHODS

Paraffin-embedded tissue from 48 salivary tumors and adjacent non-neoplastic tissue was immunohistochemically evaluated for both frequency (percentage) and intensity (1-4+) of staining using a commercially available anti-ecNOS monoclonal antibody.

RESULTS

Expression of ecNOS was predominantly localized to vascular endothelium, skeletal muscle, and to salivary duct luminal epithelium in normal salivary tissue (n = 37). All salivary tumors demonstrated at least 1 + cytoplasmic staining for ecNOS without apparent correlation to most clinical parameters. A tendency toward increased frequency and intensity of ecNOS expression in oncocytic cells, relative to cells with myoepithelial or acinar differentiation, was noted.

CONCLUSIONS

Expression of ecNOS is localized to the luminal cells of normal salivary ducts. Limited expression of ecNOS was found in all the salivary gland tumors examined. This suggests a common histogenesis for this diverse group of tumors, which may reflect different degrees of differentiation toward luminal duct epithelium. The possible role of ecNOS and NO. in salivary gland carcinogenesis is intriguing and warrants further study.

Finite element modeling of vocal fold vibration in normal phonation and hyperfunctional dysphonia: implications for the pathogenesis of vocal nodules

A computer model of the vocal fold was developed using finite element modeling technology for studying mechanical stress distribution over vibrating vocal fold tissue. In a simulated normal phonation mode, mechanical stress was found to be lowest at the midpoint of the vocal fold and highest at tendon attachments. However, when other modes predominated, high mechanical stress could occur at the midpoint of the vocal folds. When a vocal fold mass was modeled, high shearing stress occurred at the base of the modeled vocal fold mass, suggesting that the presence of a vocal nodule or polyp is associated with high mechanical stress at the margins of the mass. This finding supports a hypothesis that mechanical intraepithelial stress plays an important role in the development of vocal nodules, polyps, and other lesions that are usually ascribed to hyperfunctional dysphonia.

Integrated analyzer and classifier of glottographic signals

Electroglottography (EGG) and photoglottography (PGG) are two plausible methods to study voice production for monitoring the patterns of laryngeal vibrations. It has been suggested that measures such as open quotient and speed quotient calculated from glottographic signals can provide useful information regarding pathological phonation. In this paper, an integrated analyzer and classifier of glottographic signals was implemented. The system makes it possible to calculate the measures from digitized EGG and PGG signals automatically in order to examine vocal fold abnormality. The system developed several techniques to extract features from glottographic signals and proposed a statistical classification method that can possibly aid the diagnosis process. To check the reliability of the system, a training set and a test set of glottographic signals from normal people and patients with recurrent/superior laryngeal paralysis were analyzed and classified by the system. The results showed that the system is a useful tool for quantitative study of phonatory pathophysiology and can be used by the examiner who is interested in the clinical examination of glottographic signals. Moreover, glottographic techniques may have some clinical applications in the quantitative documentation of phonatory function in patients with voice disorders but requires further evaluation before clinical application.

Expression of the adenocarcinoma-related antigen recognized by monoclonal antibody 44-3A6 in salivary gland neoplasias

The monoclonal antibody 44-3A6 detects a cell-surface protein that has been shown to be a useful marker in distinguishing adenocarcinomas from other histologic tumor types in a variety of tissues. The objective of this study was to determine whether 44-3A6 could be used as a tool in the classification of salivary gland neoplasms. These complex tumors share overlapping pathologic features but distinct clinical outcomes. This study used 44-3A6 to immunohistochemically describe the pattern and frequency of this antigen in salivary gland neoplasms. Formalin-fixed, paraffin-embedded tissue sections of 22 benign and 26 malignant salivary tumors were evaluated. The patient population consisted of 25 (52.1%) women and 23 (47.9%) men selected from archival pathology files to reflect a range of salivary gland diseases. Normal surrounding salivary glands were found to have intense focal staining almost exclusively localized to ductal luminal cells. There was little staining of either myoepithelial or acinar cells. A wide spectrum of expression was found between and within tumor types, but a trend toward more expression of this antigen with decreasing differentiation was seen. A significant increase in staining was also seen in those tumors with ductal differentiation (n = 41) as opposed to those with predominantly acinar (i.e., acinic cell carcinoma) or myoepithelial (i.e., myoepithelioma; n = 8) differentiation (2.6 vs. 1.3, p < 0.05). No correlation was found between staining intensity and facial paralysis, pain, skin involvement, TNM stage, residual disease, or disease-free or total survival. Therefore this antigen appears to designate a duct luminal phenotype in normal and neoplastic salivary tissues.

Quantitative color analysis of laryngeal erythema in chronic posterior laryngitis

The purpose of this study was to quantitatively analyze the degree of erythema visible in the larynges of normal subjects and of patients with symptoms of chronic posterior laryngitis. Video-documented examinations of laryngoscopy were digitized and then analyzed using computer image analysis software that allowed quantification of average color values, hue, saturation, and brightness from digitized color images. Documented laryngoscopic images from 7 normal subjects and 64 patients complaining of chronic laryngitis symptoms were examined, and additional patient examinations which were obtained and documented during treatment for reflux laryngitis were analyzed. Analysis was made of five different areas of each laryngeal image: the right and left vocal folds, the right and left vocal processes, and the posterior arytenoid mucosa. Data analysis showed that average color value ratings of redness for the patients with chronic laryngitis were significantly (p <0.0561) greater than the average values for normal subjects for the vocal folds. Color values for redness of the posterior laryngeal structures and vocal folds in the patients who were treated for reflux laryngitis were significantly (p <0.05) reduced over time and correlated with the clinical response to treatment. The data suggest that computer color analysis of documented video-laryngoscopic examinations can provide quantitative data on degree of erythema and may be useful as a quantitative means of diagnosis and documentation of treatment outcome for reflux laryngitis.

Quantitative measurement of mucosal wave by high-speed photography in excised larynges

The movement characteristics of mucosal waves of the vocal fold are important components in normal phonation. Quantitative studies of the mucosal wave have used stroboscopic techniques from a supraglottic view. The current study measured displacement of mucosal epithelium during experimental phonation by using high-speed photography from an infraglottic view. Effects of thyroarytenoid contraction, increased mean airflow rate, and variation of vocal fold length were examined in canine larynges. Top and bottom vocal fold "lip" amplitude, fundamental frequency, and phase difference were the dependent variables examined. Thyroarytenoid contraction increased the amplitude of the top and bottom lips, decreased the fundamental frequency, and increased the phase difference. Increase in airflow through the glottis decreased the top lip amplitude and phase difference and appeared to increase the fundamental frequency and to decrease the bottom lip amplitude. Vocal fold lengthening decreased the bottom lip amplitude and increased the fundamental frequency and appeared to decrease the top lip amplitude and phase difference.

Glottographic signal perturbation in biomechanically different types of dysphonia

Glottographic signals may be superior to acoustic signals for tracking glottal source perturbations, since supraglottal vocal tract effects on glottographic signals are relatively minimal compared with the acoustic signal as measured beyond the lips. This study compared the ability of differing signals to differentiate among normal voices and abnormal voices that were due to two categories of biomechanical disease. Acoustic, electroglottographic, and photoglottographic signals recorded during vowel phonation sustained by 26 normal subjects and 65 patients were measured for perturbations of frequency and amplitude. One-way analysis of variance (ANOVA) revealed that amplitude perturbation measures from photoglottographic signals significantly differentiated neuromuscular from mass lesion sources of dysphonia. Acoustic and electroglottographic signal perturbations differentiated between normal and abnormal voices but did not distinguish between the dysphonic characteristics of neuromuscular disorders and those of mass lesions of the vocal folds.

Acoustic measurement of change in voice quality with treatment for chronic posterior laryngitis

Sixteen patients who had symptoms and signs of chronic posterior laryngitis were evaluated before, during, and after treatment with omeprazole and nocturnal antireflux precautions. Data were analyzed for patients who complained of some hoarseness, who had no smoking history, and who completed all of the voice recording protocol. The patients' voices were recorded before, during, and following treatment with omeprazole and nocturnal antireflux precautions. Voice quality was analyzed by perceptual analysis, and acoustic signal data were measured for jitter, shimmer, and signal-to-noise ratio. Measures of jitter, shimmer, and signal-to-noise ratio changed significantly with treatment of posterior laryngitis (p < .01 for change in each of the measures). Acoustic measures showed some trend of deterioration with cessation of treatment, although the overall improvement in acoustic measures of voice quality was still statistically significant after treatment with omeprazole was discontinued. Although perceived abnormality of voice increased and decreased with the magnitude of measured perturbation of the acoustic signal for some patients, the perceptual assessments were not highly correlated with acoustic measures for individual patients, and the perceptual analysis group data did not show a significant change with time during treatment, in contrast to the significance of change in acoustic measures. The data demonstrate that acoustic measures of jitter, shimmer, and signal-to-noise ratio improve significantly with antisecretory and antireflux treatment of chronic posterior laryngitis, and that for individual patients, these are changes that are detected by trained listeners, but not at statistically high levels of confidence.

Cytoplasmic localization of endothelial constitutive nitric oxide synthase in endometrial carcinomas

BACKGROUND

Production of nitric oxide by nitric oxide synthase (NOS) has been implicated in numerous physiologic and pathophysiologic processes including mutagenesis. This study was designed to examine the expression of the endothelial constitutive isoform of NOS (ecNOS) in endometrial carcinomas.

METHODS

Fifty endometrial carcinomas (42 endometrioid, 4 serous papillary, 2 clear cell, and 2 adenosquamous carcinomas) and 21 normal endometrial gland tissue specimens (5 cases of proliferative, 5 early secretory, 5 mid-secretory, and 5 late secretory and 1 menstrual phase endometrium), previously formalin fixed and paraffin embedded, were immunostained using a commercially available anti-ecNOS monoclonal antibody. Localization of ecNOS staining to the plasma membrane, cytoplasm and nuclei was graded with respect to overall staining intensity (0-3+ scale) and frequency (percentage of immunoreactive cells).

RESULTS

Relatively little staining for ecNOS was localized to the plasma membrane in either normal or neoplastic tissues. Normal and hyperplastic endometrial glands demonstrated moderate cytoplasmic and weak nuclear staining in a small percentage of cells. While ecNOS expression was most prominent in epithelial cells, weak expression was also rarely noted in endometrial stroma, blood vessel walls, and endothelium. We found a broad range of ecNOS expression in endometrial carcinomas, predominantly localized to the cytoplasm and nuclei. No statistically significant difference in ecNOS staining frequency or intensity was found between different histologic subtypes of endometrial carcinomas. No apparent correlation was found between ecNOS expression and tumor stage, grade, extension to the lower uterine segment or cervix, nodal or distant metastases, recurrence, or final patient status among patients with endometrioid adenocarcinomas. Endometrioid tumors invading more than 1/2 of myometrial thickness (n = 18) had significantly higher cytoplasmic staining intensity than those tumors limited to the inner 1/2 of myometrium (n = 27; 2.0 vs. 1.3, p < 0.04). Furthermore, a trend toward shorter disease-free survival was noted with increased staining intensity and decreased staining frequency.

CONCLUSIONS

Cytoplasmic and nuclear expression of ecNOS, which is primarily limited to the glandular elements of normal endometrium, is also found to be expressed in endometrial carcinoma. Increased ecNOS staining intensity and decreased frequency tends to correlate with decreased disease-free survival. Lastly, increased cytoplasmic ecNOS staining intensity correlates with increased myometrial invasion.

Videolaryngoscopic evaluation of laryngeal intubation injury: incidence and predictive factors

Bedside videolaryngoscopy of 73 cardiovascular surgical patients was performed before and after intubation to identify risk factors, incidence, and site of injury to the larynx. Nineteen of 44 patients with abnormal preintubation examination findings had granulation tissue present on a vocal process, compared With 3 of 20 patients who had normal findings on preintubation examination (p < 0.05). Recent smoking history was elicited from 2 of 20 patients who had normal findings on preintubation examination and from 20 of the 44 patients who had abnormal findings on preintubation examination (p < 0.01). Laryngeal nerve paresis was identified in 21 of 64 patients after extubation and was present in 7 patients before intubation. Videolaryngoscopy provides a high-quality permanent record of the laryngeal examination and is easily obtained in the critical care setting. Preintubation videolaryngeal evaluation may identify those at risk for more significant intubation injury.

Effects of two breath-holding maneuvers on oropharyngeal swallow

This study quantified the effects of the supraglottic maneuver (SGM) and super supraglottic maneuver (SSGM) on laryngeal and pharyngeal movements before and during swallow. Simultaneous videofluoroscopic and videoendoscopic examinations of oropharyngeal swallowing were performed in eight healthy volunteers with and without maneuvers. Data analysis compared 1) temporal relationships of oropharyngeal events, 2) airway conditions at the time of selected oropharyngeal events, and 3) biomechanical computer analysis of swallowing events. Using these maneuvers, normal subjects produced earlier cricopharyngeal opening, prolonged pharyngeal swallow, some degree of laryngeal valving before swallow, and change in extent of vertical laryngeal position before swallow. These changes are more successful and maintained longer with the SSGM than the SGM. We concluded that breath-holding maneuvers alter not only airway conditions before swallow but also both the temporal relationships and biomechanical events during oropharyngeal swallow.

Timing of glottic closure during normal swallow

BACKGROUND

The purpose of this study was to determine the temporal characteristics and patterns of glottic closure during normal swallow using concurrent videofluoroscopy and videoendoscopy.

METHODS

Three swallows each of four bolus types were examined in eight healthy volunteers with the endoscope in two positions: at the level of the uvula and at the laryngeal vestibule. Data analysis compared: (1) temporal relationships between laryngeal behaviors and oropharyngeal swallow events and (2) airway conditions at the time of key oropharyngeal events.

RESULTS

Although arytenoid adduction and subsequent arytenoid contact occurred as one of the initial events during swallow, the timing of these events was highly variable. On the other hand, true vocal cord (TVC) closure occurred mainly after the onset of laryngeal elevation, and it was affected by bolus volume.

CONCLUSIONS

In normal swallow, arytenoid closure did not always mean complete TVC closure, and complete TVC closure might be accomplished during the process of laryngeal elevation and arytenoid tilting.

Patients with Meniére's disease possess IgE reacting with herpes family viruses

OBJECTIVE

To determine if patients with Meniere's disease possess serum IgE specific for herpes simplex virus (HSV) type 1, HSV type 2, Epstein-Barr virus, and/or cytomegalovirus.

DESIGN

A modified radioallergosorbent test method was employed wherein each serum sample was processed with recombinant protein A to remove competing non-IgE antibodies, and HSV-1, HSV-2, cytomegalovirus, and Epstein-Barr viral proteins were used as potential antigens.

PATIENTS

Ten patients with long-standing active Meniere's disease were tested. Ten age- and gender-matched patients with allergic rhinitis but without Meniere's disease served as control subjects.

RESULTS

IgE specific for HSV-1, HSV-2, Epstein-Barr virus, and/or cytomegalovirus was found in the serum sample of nine of 10 patients with Meniere's disease but only in four of 10 control serum samples. Of the positive subjects tested, seven patients with Meniere's disease were positive for IgE for at least three viruses compared with only two control subjects.

CONCLUSIONS

(1) Most patients with Meniere's disease possess virus-specific IgE in their serum samples; (2) four viruses of the herpes family are capable of inducing such IgE-mediated sensitization; and (3) latent virus-specific, IgE-mediated inflammation may be an important factor in the initiation and/or sustenance of Meniere's disease.

Outcomes of antireflux therapy for the treatment of chronic laryngitis

This study examined outcomes of antireflux and antacid treatment for the signs and symptoms of chronic laryngitis. Patients from a referral institutional practice with chronic laryngitis symptoms, without other apparent causes of laryngeal inflammation, were followed up and examined at progressive stages of antireflux treatment as a case series outcome study. The cases included unselected individuals with a diagnosis of chronic (> 3 months' duration) laryngitis. Patients with chronic throat complaints were treated with nocturnal antireflux precautions, with addition of famotidine 20 mg or omeprazole 20 mg at bedtime for patients who did not respond to antireflux precautions alone. The outcome measures were resolution of symptoms, and change in findings on telescopic laryngoscopy. Chronic throat symptoms of 93 of 182 patients (51%) responded to nocturnal antireflux precautions alone. The complaints of an additional 48 patients resolved with the addition of famotidine 20mg at bedtime to antireflux precautions (77% response). The symptoms of 34 of the remaining 41 patients responded to treatment with omeprazole 20 mg at bedtime. Therefore, symptoms of 96% of patients responded to treatment aimed at preventing reflux of gastric acid. The remaining patients with refractory symptoms had a partial response or no response or chose fundoplication. Erythema and granular mucositis were the most common laryngoscopic findings. Ulceration and granuloma formation were less common, but also responded to antireflux treatment. Some (7) patients required high doses of omeprazole or fundoplication to achieve symptomatic relief and healing of chronic inflammatory changes of the posterior larynx. Relapse of symptoms was common when treatment was stopped.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical measurement of mucosal wave velocity using simultaneous photoglottography and laryngostroboscopy

Simultaneous glottal transillumination or photoglottography (PGG), electroglottography (EGG), and video laryngostroboscopy were used to measure the traveling wave velocity of the vibrating vocal folds during phonation in human subjects. The duration of travel was calibrated from the PGG signal, while the displacement of the upper and lower lips of the vibrating vocal folds was calibrated from parallel laser beams projected onto the vocal folds. The mucosal wave velocity varied with the portion of the glottal cycle. The amplitude of displacement correlated positively with the intensity of phonation and negatively with the fundamental frequency and was decreased for breathy and pressed phonation modes. The velocity of the opening phase segment of the PGG signal directly correlated with the top lip displacement of the vibrating vocal fold, and bottom lip displacement correlated with the closing phase of the PGG signal. Therefore, with suitable calibration, the effects of mucosal lateral displacement may be measured from a PGG signal. Simultaneous measures of PGG, EGG, and stroboscopy provide a three-dimensional representation of glottal vibration that can be numerically analyzed.

Serum immunoglobulins specific for intracellular proteins of squamous cell carcinoma

OBJECTIVE

To determine an autologous humoral immune response to squamous cell carcinoma (SCC) intracellular proteins in patients with SCC.

DESIGN

Intracellular proteins were isolated from 25 different cultured SCC lines. The proteins were used as a source of antigens to measure IgA, IgE, and IgG responses in the serum samples of patients and controls. Antibody response was assessed in both unfractionated and fractionated intracellular proteins.

PATIENTS

The serum samples of 65 patients with SCC and of 65 age- and gender-matched controls were tested.

RESULTS

Antibodies to SCC intracellular proteins were detected in the serum samples of 40 (62%) of the 65 patients with SCC and in the serum samples of 46 (71%) of 65 controls. Thirty (46%) of the patients with SCC and 40 (62%) of the controls had IgE responses, 18 (28%) of the patients and one (2%) of the controls had IgA responses, and 17 (26%) of the patients and 14 (22%) of the controls had IgG responses. An inverse relation was noted between detectable IgE responses and IgA or IgG responses in the patients and the controls. The analysis of antibody response indicated that 28 molecules were recognized predominantly by the serum samples of patients with SCC, but not by the serum samples of controls.

CONCLUSIONS

A substantial proportion of patients with SCC and of controls exhibited an autologous humoral immune response to SCC intracellular proteins. The IgE responses to SCC intracellular proteins were inversely related to IgA or to IgG responses. Different antibody isotypes normally cause markedly different immune functions, and may suggest different roles for the existent immune responses to SCC antigens. We identified many tumor-associated antigens that were selectively recognized by the serum samples of patients with SCC. These antigens could be used to define molecular studies of immune surveillance and selection, and may represent appropriate targets for immunotherapy.

Evaluation and treatment of the unilateral paralyzed vocal fold

The evaluation and treatment of patients with unilateral vocal fold paralysis have evolved as improvements in objective measurements of phonatory function and new modalities for treatment have developed. A thorough history, physical examination, subjective voice evaluation, objective voice analysis, and electromyography are used to make a diagnosis, determine the cause, and plan treatment. The goal of treatment of the patient with a unilateral vocal fold paralysis is to restore normal phonatory function without aspiration. Multiple modalities have developed to allow for restoration of nearly normal phonatory function, and these include voice therapy alone or in combination with injection medialization, laryngoplastic phonosurgery, or laryngeal reinnervation. Otolaryngologists should be familiar with the incidence, cause, evaluation, and state-of-the-art treatment of unilateral vocal fold paralysis of optimize patient care and avoid suboptimal results often seen with antiquated or inappropriate treatment.

Phase I/II vaccination study of recombinant peptide F46 corresponding to the HIV-1 transmembrane protein coupled with 2.4 dinitrophenyl (DNP) Ficoll

In order to evaluate tolerance, toxicity, and in vivo antigenicity, 29 HIV-1-infected patients (eight with ARC and 21 with AIDS) were vaccinated with a synthetic peptide derived from the gp41 transmembrane protein of the HIV-1. This peptide had been coupled with 2.4 dinitrophenyl-Ficoll (F46), a T-cell independent adjuvant. The patients received a single intradeltoid injection of either 0.1 or 0.3 mg of F46. Five of the individuals with AIDS were boostered, four of them twice. Anti-F46 antibody titers were measured before vaccination, and on days 7, 14, 21, 28, 90, 180 and 270 after vaccination. Anti-F46 titers rose at least twofold over prestudy values in 10/21 individuals with AIDS and in 1/8 individuals with ARC at least once during the observation period. The overall response, however, consisted of only weak antibody production that was independent of the dose or patient characteristics. No signs of toxicity or of clinical progression related to the vaccination were observed in this phase I/II trial of a T-cell independent therapeutic vaccine.

Bacterial allergy in nasal polyposis. A new method for quantifying specific IgE

OBJECTIVES

To determine (1) if bacteria-specific serum IgE levels can be more effectively measured by first absorbing competing IgG antibodies from serum and (2) if patients with chronic paranasal sinus disease exhibit a high positive prevalence of bacteria-specific serum IgE.

DESIGN

A modified radioallergosorbent test method was employed wherein each serum sample was absorbed with recProtein A to remove competing non-IgE antibodies, and purified proteins extracted from 16 individual bacteria were used as potential allergens.

PARTICIPANTS

Twenty-four patients with nasal polyposis and 14 with chronic sinusitis, all refractory to conventional medical therapy and requiring endoscopic sinusotomies, were tested. Tested as controls were 10 subjects with chronic allergic rhinitis, without a history of chronic sinus disease, and possessing total serum IgE and inhalant-specific IgE levels equal to or higher than the patient group.

RESULTS

(1) Pretreatment of serum samples with recProtein A resulted in an increase of bacteria-specific radioallergosorbent test sensitivity. (2) Seventeen of 24 patients with polyps, eight of 14 with chronic sinusitis, and one of 10 with chronic allergic rhinitis were determined to be IgE positive when tested with this assay.

CONCLUSIONS

(1) Bacteria-specific serum IgE can be quantified; (2) most patients with nasal polyposis and/or chronic sinusitis possess bacteria-specific IgE in their serum, while subjects with only allergic rhinitis do not; and (3) multiple bacterial species isolated from chronically infected sinuses are capable of inducing IgE-mediated sensitization.

Endopeptidase inhibition and intestinal antigen processing in mice

The role of gastrointestinal digestive processes in the systemic availability of ingested protein antigens was examined by feeding the trypsin inhibitor aprotinin intragastrically to mice and measuring uptake of ovalbumin and 14C-polyethylene glycol (MW 4000) from the gastrointestinal tract. Trypsin and chymotrypsin activities in the intestinal lumen were significantly reduced by aprotinin feeding. Aprotinin slowed stomach emptying, but radioimmunoassays for immunoreactive ovalbumin in the serum of mice prefed aprotinin showed 12-fold elevations within 1 hr after ovalbumin feeding. Uptake of a nonmetabolized macromolecular probe, 14C-polyethylene glycol-4000, increased less than two-fold when fed with aprotinin under the same conditions, indicating that the increased uptake of immunoreactive ovalbumin was not due to changes in intestinal permeability. The results show that inhibition of luminal proteolysis caused significant increases in the serum concentration of immunoreactive ovalbumin, indicating that acute inhibition of luminal proteases permits larger quantities of relatively intact protein to interact with mucosal absorptive surfaces. These results support the hypothesis that pancreatic proteases modulate antigen absorption from the lumen in adult animals.

Inhibition of orally-induced immune tolerance in mice by prefeeding an endopeptidase inhibitor

Intragastric feeding of T-dependent protein antigens to mice induces substantial systemic tolerance in specific antibody and cell-mediated immune responses. To evaluate the role of gastrointestinal digestion in this phenomenon, the trypsin inhibitor aprotinin was fed to adult BDF1 mice prior to tolerogenic feedings of ovalbumin or human gamma globulin. As assessed by measurement of protein-specific antibody responses, aprotinin significantly reduced tolerance induced by feeding carrier protein, but not tolerance induced by parenteral antigen injection. Aprotinin also reduced oral tolerance to ovalbumin as measured by delayed-type hypersensitivity and T cell proliferative responses. However, aprotinin did not alter antibody tolerance to a carrier-associated hapten in the same animals. Feeding of human gamma globulin concomitantly with aprotinin induced specific antibody responses without further immunization, and reduced subsequent tolerance. Aprotinin also increased the level of immunologically detectable ovalbumin found in the serum following antigen feeding. The data support the hypothesis that aprotinin indirectly mediated changes in specific stimuli available to the lymphoid system as a result of alterations in gastrointestinal processing of fed antigens rather than to direct effects of aprotinin upon systemic immune responses.

Effects of denervation on laryngeal muscles: a canine model

The purpose of this study was to chronologically evaluate the changes in functional and histomorphometry of denervated laryngeal muscles. In 14 adult mongrel dogs, a 2.5-cm segment of the right recurrent laryngeal nerve was excised. Videolaryngoscopy and electromyography were performed at 1, 2, 3, 4, 5, 6, and 9 months under intravenous sedation. The animals were then killed, and the laryngeal muscles were processed for histochemical reactions. The mean muscle fiber diameter, standard deviation, and muscle fiber type composition were determined. The findings indicate that, following recurrent laryngeal nerve sectioning, the canine intrinsic laryngeal muscles undergo denervation atrophy for approximately 3 months, after which reinnervation occurs. The source of reinnervation appears to be from regenerated nerve fibers of the sectioned recurrent laryngeal nerve. The nerve fibers nonselectively reinnervated the abductor and adductor muscles of the larynx.

Neuromuscular disorders of the larynx

The voice may be affected adversely by a variety of neuromuscular disorders, including movement disorders, paralysis, and degenerative conditions of the central and peripheral nervous system. The diagnosis of these conditions usually requires high-technology tools, and the results of treatment are variable. Diagnostic considerations, aspects of a complete neurologic examination, an examination of the basic organization of neural control as it relates to the larynx, and treatment options are provided in this article.

Geriatric voice and laryngeal dysfunction

Vocal disorders are a common dysfunction associated with aging that can have a significant effect on the quality of life. An appreciation for the many causes of vocal dysfunction in the elderly is a first step to providing better care for the geriatric patient with complaints about voice dysfunction.

The effect of air flow and medial adductory compression on vocal efficiency and glottal vibration

This study used an in vivo canine model to investigate the effects of varying vocal fold resistance by electrically stimulating the recurrent laryngeal nerve while monitoring medial adductory compression of the vocal folds, glottal airflow, and vocal intensity. The effects of increasing airflow on glottal vibration were also examined stroboscopically and by measurement of open quotient. The results indicated that increasing intensity by medial adductory compression was more efficient than by increasing airflow. Increasing airflow produced a significantly greater open quotient and vocal fold vibratory excursion.

The effect of recurrent laryngeal nerve stimulation on phonation in an in vivo canine model

The present investigation was designed to examine the effect of variation in recurrent laryngeal nerve stimulation (RLNS) on vocal fold vibration. Photoglottography (PGG), electroglottography (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three fundamental frequencies (F0) (100 Hz, 130 Hz, and 160 Hz) for RLNS, using a constant rate of air flow. Increasing RLNS, which caused activation of the intrinsic laryngeal muscles, produced a modest increase in F0, a marked increase in Psub, no change in the open quotient (OQ), and an increase in the closing quotient (CQ). Phase quotient (Qp), which describes the interval between opening of the lower and upper fold margins, decreased with increasing RLNS.

Bedside videolaryngoscopic assessment of intubation trauma

Telescopic laryngoscopic examination was performed at the bedside after extubation in 29 consecutive surgical intensive care unit patients who required endotracheal intubation for more than 16 hours. The examinations were documented with a portable video recording system. The majority of patients exhibited evidence of acute endolaryngeal trauma. Vocal fold ulceration and vocal fold motion abnormalities were the most common lesions. Patients with abnormal larynges were followed up after discharge from the intensive care unit. Most of the identified injuries resolved without intervention. However, silent aspiration was identified frequently in patients with vocal fold paresis and was thought to be a significant factor in postoperative pulmonary complications. Early identification of significant laryngeal trauma and/or vocal fold paresis in critically ill patients is important for both postoperative pulmonary care and voice rehabilitation. This pilot study demonstrated that documentation of the laryngeal examination is feasible in critically ill patients in an intensive care unit setting.

Effect of superior laryngeal nerve stimulation on phonation in an in vivo canine model

We investigated the effect of variation in superior laryngeal nerve stimulation (SLNS) on vocal fold vibration. Photoglottography (PGG), electroglottography (EGG), and subglottic pressure (Psub) were measured in seven mongrel dogs using an in vivo canine model of phonation. The PGG, EGG, and Psub signals were examined at three SLNS frequencies (100 Hz, 130 Hz, and 160 Hz) using a constant rate of air flow. Increasing SLNS, which causes a contraction of the cricothyroid muscle, produced a marked increase in Fo, little change in Psub, an increase in the open quotient, and a decrease in the closed quotient of the glottal cycle.

Effect of vocal fold augmentation on laryngeal vibration in simulated recurrent laryngeal nerve paralysis: a study of Teflon and Phonogel

Flaccid laryngeal nerve paralysis may be treated by vocal fold augmentation with Teflon injection, which is successful to various degrees depending on the subjective interpretation of the patient or clinician. A new material, Phonogel, consisting of cross-linked bovine collagen, is available but not approved for human use in this area. Ten dogs were submitted to videostroboscopy, photoglottography, electroglottography, and acoustic analysis in the normal state, with stimulated recurrent laryngeal nerve paralysis, and with injection of either Teflon or Phonogel. A statistical comparison and the advantages and disadvantages of each material are discussed in relation to this study and its clinical use.

Current and future horizons in laryngeal and voice research

Voice dysfunction is associated with neuromuscular impairment of laryngeal control and is often difficult to diagnose by indirect examination of the larynx. The newer techniques, currently used in the UCLA-Veterans Administration Medical Center Laboratories, provide some methods that aid in the diagnosis of voice impairment by providing documented objective data. Illustrative case reports of disorders of neuromuscular dysfunction of the larynx are presented and future research needs and direction are discussed.