Biomedical subjects
D G Hanson
Publications and source records attributed to D G Hanson.
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.
Frequency, intensity, and target matching effects on photoglottographic measures of open quotient and speed quotient.
Measurements of Open Quotient (OQ) and Speed Quotient (SQ) were made from photoglottographic signals of normal male subjects during phonation. Samples were obtained at spontaneous levels of fundamental frequency and intensity, and at nine specified frequency/intensity combinations. OQ increased with fundamental frequency. OQ change was not significant for change in intensity and there was no significant interaction between frequency and intensity. Changes in SQ with variations of frequency and intensity were not significant. However, SQ did increase significantly when spontaneous phonation was compared to target matching phonation at similar frequency/intensity. Changes in both OQ and SQ across comfortable frequency and intensity ranges were relatively small in comparison to changes in OQ and SQ reported for pathological phonation.
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.
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.
Office-based system for voice analysis.
There has been recent growing interest in the analysis of various electronically recorded signals as potential tools for objective assessment of vocal dysfunction. In the past, analysis of such signals required an expensive multitrack FM recorder, mainframe computer system, customized software, and significant time commitment. This report describes an adaptation of commercially available components that allow digital recording of multiple electronic signals, storage of data, and subsequent signal analysis using an inexpensive personal microcomputer system. Commercially available software for manipulation and examination signals is discussed as adapted for examination of glottographic and acoustic signals. The relatively inexpensive availability of similar computer systems will, hopefully, encourage assessment of the clinical applications of objective techniques of voice quality.
Responses of antigen-specific long-term murine T cell lines to wheat gliadin fractions.
Recent evidence suggests that the four electrophoretically defined gliadin subfractions (alpha, beta, gamma and omega) of wheat can induce the typical pathological finding of coeliac disease. We have prepared long-term murine T cell lines to gliadin and its four major subfractions. The cell lines were tested in proliferative assays with each homologous gliadin subfraction, and to the other gliadin subfractions. There was some cross-reactivity, with unfractionated gliadin and its alpha-subfraction being the most antigenic, while omega-gliadin was the least. These data demonstrate that gliadin components are effective stimuli for specific T cell responses, and further suggest that the alpha-gliadin subfraction generates the highest specific responses. This accords with observations in man that all four gliadin subfractions exacerbate coeliac mucosa, but that the alpha-subfraction is the most active.
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.
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.
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.
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.
An accurate method of Teflon injection using functional phonosurgery.
A technique for Teflon injection is described that allows the laryngologist to assess vocal fold vibration during general anesthesia. A tracheostomy tube fitted with a rostral air line allows translaryngeal airflow. During endoscopy with a bivalved laryngoscope, the cords are approximated manually. Vocal fold vibration is produced with the cords adducted. The precise site of defects in glottic closure is clearly seen and corrected with Teflon injection. In cases where standard Teflon injection has failed, utilization of this method has allowed substantial voice improvement. The ability to assess vibratory function of the vocal folds during direct suspension laryngoscopy enhances the precision of vocal fold augmentation techniques in difficult rehabilitation cases.
Identification of synchronous esophageal tumors in patients with head and neck cancer.
Patients with a primary head and neck neoplasm are at risk for additional malignancies of the upper aerodigestive tract, which may be asymptomatic. This phenomenon may reflect the regional carcinogenic influence of alcohol and tobacco abuse. A review of the recent literature documents the value of performing laryngoscopy, bronchoscopy, and esophagoscopy on all patients being staged for head and neck tumors to identify second synchronous cancers, the presence of which may significantly alter the treatment plan.
Glottographic measures of vocal fold vibration: an examination of laryngeal paralysis.
Photoglottography and electroglottography were applied to groups of patients with recurrent laryngeal nerve paralysis, superior laryngeal nerve paralysis, and combined recurrent and superior laryngeal nerve paralyses of idiopathic causes. Individual patients with resection of the vagal nerve above the origin of the superior laryngeal nerve were also studied. Open Quotient and Speed Quotient were calculated from the photoglottography signals. Speed Quotient values significantly differentiated recurrent laryngeal nerve paralysis from idiopathic paralysis and superior laryngeal nerve paralysis, as well as from normal function. Data from patients with vagal resection clearly differentiated them from patients with recurrent laryngeal nerve paralysis. The measure of Open Quotient distinguished pathological phonation from normal, but was not as useful for separation of differing lesions. Electroglottography appeared to be less useful than photoglottography. The pathophysiology underlying the observed glottographic signals is discussed.
Reflux as an etiological factor of carcinoma of the laryngopharynx.
This study examined charts and 16-mm pictures or videotapes of 138 patients with carcinoma of the larynx treated during the last 10 years. Among these patients, 19 were nonsmokers and nondrinkers or only light social drinkers with moderate to severe gastroesophageal reflux (GER). Serial cinephotographs are presented with follow-up of up to 10 years. The common presence of GER in these nonsmoking, nondrinking patients and the probable role of this chronic irritative disorder as a causative agent in carcinoma of the laryngopharynx are discussed.
Trichloroacetic acid (TCA) precipitability of 125I in the blood of mice fed 125I.
A recent study showed that after feeding 125I-labelled proteins or free 125I to mice, as much as 40% of total radioactivity in the circulation precipitated upon mixing whole blood with 10% trichloroacetic acid. We examined this potential limitation to the use of radiolabelled tracers for studies on intestinal digestion of proteins and protein uptake, and identified its mechanism. BALB/c mice were gavage-fed or injected intravenously (i.v.) with Na125I. Blood obtained at 15 min was added directly to 10% trichloroacetic acid (TCA) or was processed to obtain serum or plasma. On mixing with 10% TCA, 25-33% of the radioactivity in whole blood was precipitated; less than 2% of the radioactivity in plasma or serum was precipitated. In vitro studies identified hemoglobin as the primary carrier protein participating in this reaction. If hemoglobin was replaced by methemoglobin or cyanomethemoglobin, then the reaction with 125I did not occur, suggesting that iron in the heme group may be the site for 125I binding and that iron must be in its reduced or ferrous form (Fe2+). The administration of non-radioactive NaI in vivo or its addition to reaction mixtures in vitro completely inhibited the precipitation of 125I by hemoglobin in the presence of TCA. Thus the addition of non-radioactive iodide to TCA stock solutions may effectively prevent non-specific binding of 125I to free hemoglobin released unintentionally during venipuncture or at other stages of blood processing.
Clearance, localization and catabolism of intravenously administered protein antigens in lactating mice.
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