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Biomedical subjects

D G Hanson

Publications and source records attributed to D G Hanson.

At least 19 recordsLinked to original sources

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.

Animals↗

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.

Animals↗

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.

Chronic Disease↗

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, Differential↗

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.

Biomechanical Phenomena↗

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.

Adult↗

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.

Adolescent↗

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.

Adult↗

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.

Adult↗

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.

Animals↗

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.

Adult↗

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.

Acid-Base Equilibrium↗

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.

Adult↗

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.

Adult↗

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.

Aged↗

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.

Antibodies, Monoclonal↗

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.

Adult↗

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.

Chronic Disease↗