Pattern of Gross Displacement of the Vocal Fold in Adduction and Abduction Movements

The pattern of gross displacement of the vocal fold during adduction and abduction was studied in 4 adult fresh human larynges (2 males and 2 females). Markers were placed on specific sites along the edge of the vocal fold. Preliminary observations showed upward and lateral movement of the free edge during abduction. The vocal fold as a whole glides into and fills the cavity of the laryngeal ventricle. To quantify this observation 14 larynges (8 males and 6 females) were studied, using a technique designed to measure vertical and horizontal displacement of the vocal fold. An average of a 1.34 mm elevation and 4.43 mm lateral excursion were observed at mid-vocal fold level. A model for studying the pattern of vocal fold abduction is suggested and discussed.     

Comparative Histology and Vibration of the Vocal Folds: Implications for Experimental Studies in Microlaryngeal Surgery

Objectives/Hypothesis To determine the most suitable animal model for experimental studies on vocal fold surgery and function by a histological comparison of the microflap surgical plane and laryngeal videostroboscopy (LVS) in different species of animals. A second goal was to determine how the layered vocal fold structure in humans and three different animal species affects surgical dissection within the lamina propria. Study Design Prospective laboratory. Methods Three larynges each from dogs, monkeys, and pigs were compared with three ex vivo human larynges. Microflap surgery was performed on one vocal fold from each larynx. Both the operated and nonoperated vocal folds were examined histologically using stains specific for elastin, mature collagen, and ground substance. Based on the histological results, LVS was performed on two dogs and two pigs after first performing a tracheotomy for ventilation and airflow through the glottis. Arytenoid adduction sutures were placed to facilitate vocal fold adduction. Results The distributions of the collagen and elastin fibers were found to differ among the species with concentrations varying within species. Unlike the human vocal fold, which has a higher elastin concentration in the deeper layers of the lamina propria, both the pig and the dog had a thin band of elastin concentrated just deep to the basement membrane zone in the superficial layer. Just deep to this thin band, the collagen and the elastin were less concentrated. The monkey vocal fold had a very thin mucosal layer with less elastin throughout the mucosa. The microflap dissections in each of the dog, pig, and human vocal folds were similar, being located within that portion of the superficial lamina propria where the elastin and mature collagen are less concentrated. The microflap plane in the monkey vocal fold was more deeply located near the vocalis fibers. Despite the differences in elastin concentration, the microflap plane in both the dog and the pig was found to be similar to that in humans. The dog anatomy was much more suitable for microsuspension laryngoscopy and stroboscopic examination. The dog vocal folds vibrated in a similar fashion to human vocal folds with mucosal waves and vertical phase differences, features not seen in the pig vocal folds. Conclusions Based on both the histological and stroboscopic results, the dog was believed to be a more suitable animal model for studies on vocal fold surgery, acknowledging that no animal's laryngeal anatomy is identical to that of the human. The dog LVS model presented allows for longitudinal laryngeal studies requiring repeated examinations at multiple time periods with histological correlation applied at sacrifice.     

Vocal fold injection: review of indications, techniques, and materials for augmentation

Vocal fold injection is a procedure that has over a 100 year history but was rarely done as short as 20 years ago. A renaissance has occurred with respect to vocal fold injection due to new technologies (visualization and materials) and new injection approaches. Awake, un-sedated vocal fold injection offers many distinct advantages for the treatment of glottal insufficiency (vocal fold paralysis, vocal fold paresis, vocal fold atrophy and vocal fold scar). A review of materials available and different vocal fold injection approaches is performed. A comparison of vocal fold injection to laryngeal framework surgery is also undertaken. With proper patient and material selection, vocal fold injection now plays a major role in the treatment of many patients with dysphonia.     

Anatomy of the chinchilla bulla and eustachian tube: I. Gross and microscopic study

The middle ear mucosa and eustachian tube of the normal chinchilla were studied quantitatively and under light microscopy to determine the distribution of each cell type of the lining epithelium and subepithelial gland. The middle ear mucosa consisted of columnar epithelium, cuboidal epithelium, and squamous epithelium. The lining epithelium of the eustachian tube was ciliated pseudostratified columnar epithelium. These epithelia were composed of ciliated, secretory, nonciliated (nonsecretory), and basal cells. The density of the ciliated cells was highest in the columnar epithelium area of the transitional zone of the middle ear mucosa. However, the density of the secretory cells was highest in the pharyngeal orifice of the eustachian tube. The nonciliated cell density was highest in the squamous epithelium area of the middle ear mucosa and decreased progressively toward the tympanic orifice of the eustachian tube. In the eustachian tube, the nonciliated cell density was highest in the pharyngeal portion of the eustachian tube, especially in the upper portion of the lateral wall. The subepithelial glands were tubuloacinar mixed glands composed of serous demilunes and mucous acini. The glands were localized primarily in the pharyngeal orifice and pharyngeal portion of the eustachian tube, and their ductal openings were present primarily in the inferior portion of the eustachian tube.     

Research opportunities at the Institute of Laryngology and Otology, London.

Emphasis is placed on the need to encourage original research in our training programs. This implies an obligation to help trainees inexperienced in research to bridge the gap between theory and practice. Four examples of patterns of research at a postgraduate institute are presented. All are in areas in some way relevant to carcinoma of the larynx: a) the effect of experimental hypothermia on transplanted tumors in rats; b) isotope detection of deep vein thrombosis following head and neck surgery; c) stomal calibre after laryngectomy related to airflow, esophageal voice and cineradiographic appearances; d) a case-controlled study of the etiologic role of asbestos in laryngeal cancer. These studies are still in progress but some preliminary observations can be reported.