David G. Hanson

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 denervation on laryngeal muscles: A canine model

The purpose of this study was to chronologically evaluate the changes in function 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.

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 Parkinsons disease.

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.

Genetic Sensorineural Deafness in Adults

Progressive genetic sensorineural hearing loss is a common problem in adults which is frequently incorrectly diagnosed or escapes diagnosis as to etiology altogether. If the hearing problem becomes manifest in the twilight of the patients life it is often identified with the nondescriptive term “presbycusis.” In all patients with sensorineural hearing loss, extrinsic (environmental) causes should be ruled out after which intrinsic or genetic etiology should strongly be considered, recognizing that extrinsic factors can be superimposed. A group of young adults was studied and diagnosed as having genetic progressive hearing loss. Polytomography ruled out the theoretical possibility of cochlear otosclerosis. The diagnosis of this disorder rests most heavily on the history and audiometric configuration which is characteristically flat or basin shaped with fairly good discrimination. Of further diagnostic significance was the fact that some patients, early in the course of their difficulty, presented with a predominantly low- or high-frequency loss which, over time, assumed a flat audiometric shape. The most important pathological finding from human temporal bone studies was atrophy of the stria vascularis.

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.

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.

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.