Extraluminal laryngotracheal fixation with absorbable miniplates

OBJECTIVE

To determine if miniplates made of polydioxanone can be used successfully for extraluminal laryngotracheal fixation.

DESIGN

Twelve rabbits underwent anterior and posterior laryngotracheofissure with extraluminal fixation of the divided segments with polydioxanone miniplates. Three control animals did not undergo plating. Animals were killed after 2, 4, and 12 weeks. Larynges were removed and examined to determine the intraluminal area and histologic status of the repair site.

RESULTS

The intraluminal area of the animals in the experimental group was 1.6 times that of those in the control group. The trachea was relined with respiratory mucosa by 2 weeks. Little inflammatory reaction was evident. Plate resorption was almost complete at 12 weeks.

CONCLUSION

Polydioxanone plating is a feasible and well-tolerated method of extraluminal laryngotracheal fixation. It may be useful in the treatment of grade 2 or 3 subglottic stenosis.

Morphologic study of the laryngeal taste buds in the cat

The distribution of laryngeal taste buds (TBs) and their neutral components in the cat were investigated by immunohistochemistry and electron microscopy. The antisera used in this study were against cytokeratin, protein gene product 9.5 (PGP9.5), neuron-specific enolase (NSE), S-100 protein, calbindin D, calcitonin gene-related peptide (CGRP), and substance P (SP). Taste bud cells were specifically immunoreactive to the antibodies of human cytokeratin subtypes 8 and 18 (CAM5.2). On observation with CAM5.2, TBs were seen distributed on the laryngeal surface of the epiglottis and spread caudally along the aryepiglottic folds, reaching peak density at the laryngeal side of the arytenoid tubercle. The PGP9.5 and NSE immunoreactivities were recognized in TB cells and nerve fibers, both within the TBs and in the subepithelial connective tissue. S-100 protein immunoreactivities were not found in any of the cells in the TBs but were found exclusively in the subepithelial neural elements. The calbindin-D, CGRP, and SP immunoreactivities were confined to a part of the neural elements that was very thin. Taste pores, taste villi, neuronal varicosity, and synapselike structures were observed by scanning and transmission electron microscopic study. From these results it is considered that the TBs act as a chemical receptor.

[Morphology and histochemistry of lymphatic vessels of the upper aerodigestive tract: a clinically oriented study]

BACKGROUND

Exact knowledge of lymphatic morphology and histochemistry is required to understand the clinical importance of the lymphatic system of the upper aerodigestive tract. Publications in this field are rare.

METHODS

Light and electronmicroscopic examinations were carried out on lymphatics of the upper aerodigestive tract. Enzyme, immune and histochemical investigations were also performed on 764 tissue specimens from this region.

RESULTS

The discontinuous basement membrane surrounding the initial lymphatic contains laminin, type IV collagen, and fibronectin and is usually continued by a fibrillar elastic apparatus that is less developed than dermal lymphatics. 5'-nucleotidase, adenylatcyclase, and guanylatcyclase activity in lymphatics is not as high as it is in blood capillaries. The endothelium of collecting lymphatics contains high concentrations of factor VIII associated antigen, while it is found in the endothelium of initial lymphatics only in small amounts or not at all. Histochemical studies of the endothelium of lymphatics show a positive lectine binding reaction for UEA I, PNA, DBA, GS I, MPA, and RCA I.

CONCLUSIONS

The histochemical results obtained allow easy differentiation of lymphatics and blood capillaries. The vessel type differentiation is relevant for the examination of organ-related lymphatic systems, to determine whether tumor cell nests are located in lymphatics, blood capillaries, or artificial tissue gaps.

Dynamic magnetic resonance imaging of vocal cord closure during deglutition

BACKGROUND & AIMS

Vocal cord closure is instrumental in airway protection during deglutition. Conventional imaging of vocal cord closure and reopening during deglutition requires invasive and nonphysiological methods. The aim of this study was to characterize the biomechanical properties of normal vocal cord adduction/abduction during deglutition using echoplanar magnetic resonance imaging, a technique that has the capability of imaging soft-tissue motion with real-time temporal resolution.

METHODS

The movements of laryngeal and vocal cord structures during swallowing were determined in 11 normal volunteers by single slice and axially reformatted multislice coronal echoplanar images.

RESULTS

During swallowing, the larynx ascended to peak elevation, maintained peak elevation for a discrete interval, and descended to its resting position. Vocal cord adduction occurred with a symmetric tent-like configuration at the midpoint of maximal laryngeal elevation, whereas vocal cord abduction occurred at the midpoint of laryngeal descent. Spatial analysis of vocal cord configuration during adduction determined that the vocal cords attained an initial parallel configuration during ascent, followed by closure at peak laryngeal elevation.

CONCLUSIONS

These results show that the vocal cords adduct and abduct synchronously with laryngeal ascent and descent, respectively, during deglutition. Echoplanar magnetic resonance imaging constitutes a novel tool used to assess clinical abnormalities of deglutitive laryngeal function.

G. Paul Moore Lecture. Rational thought: the impact of voice science upon voice care

Recent evolution in scientific knowledge and technology has led to monumental improvement in the standard of care for patients with voice disorders. New concepts in anatomy, physiology, measurement, and analysis have provided voice care professionals with not merely better understanding, but moreover an extensive vocabulary with which to think about voice function and dysfunction. Previously, we had to depend too much upon anecdote and "the art of medicine." Thanks to scientific advances, we now have the tools we need for rational thought about the human voice. This is the fundamental change responsible for recent great advances in voice care.

Histological structure of the vocal fold in the human larynx

Histological analysis of the human vocal folds, focused particularly on the lamina propria of the vocal muscle of fetuses, infants, and adults in horizontal laryngeal sections, allowed us to show the differences in morphology and composition according to the laryngeal development. Our results indicate that the origin of the vocal fold is independent of the origin of the other portions of the larynx, and the influence of the zone known as macula flava in the maturation of the vocal fold is an age-related process.

Anatomy of the larynx, trachea, and bronchi

This article reviews the anatomy of the larynx, trachea, and bronchi. It emphasizes the structure of the laryngeal framework, the innervation and blood supply of the larynx and trachea, the anatomic differences between the pediatric and adult larynx and trachea, and the relational anatomy of structures surrounding the trachea and bronchi.

A study of radiologic imaging techniques and airway grading to predict a difficult endotracheal intubation

STUDY OBJECTIVES

To study whether a detailed radiographic examination of neck and upper airway can help identify normal looking patients in whom endotracheal intubation may be difficult; determine whether such parameters as identified by magnetic resonance imaging (MRI) can also be identified in a soft tissue radiograph; and to study the correlation between oropharyngeal appearance, based on Mallampati's classification, and laryngoscopic findings in a large number of patients requiring endotracheal intubation.

DESIGN

Prospective.

SETTING

University medical center.

PATIENTS

20 adult patients in whom an unanticipated difficult endotracheal intubation was encountered, and a control group of 20 patients in whom endotracheal intubation was easily accomplished.

INTERVENTIONS

Difficult-to-intubate patients were identified according to prospectively established criteria. Control subjects, in whom the trachea was easily intubated, were matched for age, gender, height, weight, and oropharyngeal appearance.

MEASUREMENTS AND MAIN RESULTS

In all 40 study patients, a soft tissue radiograph and an MRI scan of the neck were obtained. We measured 21 parameters from both radiographic studies. There were no significant differences between the two groups in 20 of 21 measured parameters on MRI scans and soft tissue radiographs. Only one measurement--the distance between the uppermost visible part of the airway and the posterior pharyngeal wall (measured from MRI scans only)--between the two groups achieved statistical significance. The values recorded from MRI and soft tissue radiographs were not significantly different. Airway grading system first suggested by Mallampati had a fair correlation with laryngoscopy findings associated with a difficult endotracheal intubation.

CONCLUSIONS

No significant difference between the two groups could be identified on soft tissue radiography or MRI scans.

[Function and morphology of the larynx of the domestic guinea pig. An animal model for laryngologic and phoniatric research?]

The present study was undertaken to collect data on fundamental functional and morphological features of the guinea pig larynx using frequency analysis of animal vocalizations and light and scanning electron microscopy. Vocalizations of healthy animals were recorded in an anechoic chamber and were analyzed with short-time fourier transformation (color spectrograms). From the multitude of vocalization patterns produced by the guinea pig, distress squeals were selected as a typical, reproducible, voiced sound. These were stereotyped, upward-frequency modulated, multiharmonic signals with a formant-like structure. The fundamental frequency of this sound rose by about 1.5 octaves and reached up to 6 kHz near the end of the call. The different regions of the endolaryngeal epithelia showed morphological properties that corresponded to proposed functional significance. Keratinized squamous epithelium covered the supraglottic region. The marginal rim of the vocal cord was covered by a very thin epithelium with very flat cells covered with short microvilli. The subepithelial space was filled with loose connective tissue. The subglottic region was covered by respiratory epithelia. Based on these findings, we propose that the larynx of the guinea pig can be used as a model in phoniatric and laryngological research.

The laryngeal mask airway for awake diagnostic bronchoscopy. A retrospective study of 200 consecutive patients

The laryngeal mask airway (LMA) provides a view of the larynx and moving vocal cords without loss of airway control and can be used in flexible fibreoptic bronchoscopy for both anaesthetized and awake patients. In this retrospective review of 200 consecutive patients over a 30 month period, bronchoscopy was successful via the LMA in all but one patient using a technique of topical anaesthesia and sedation. The LMA directs the fibrescope to the glottis, allows respiratory function to be monitored and oxygen to be given. Complication rates were similar to those reported for transnasal awake bronchoscopy. Insertion of the LMA in the awake fasted patient is safe and easily achieved.

Normal topography of the conus elasticus. Anatomical bases for the spread of laryngeal cancer

The topographic relations of the conus elasticus were studied with special regard to the local spread of laryngeal cancer. Sections of twelve plastinated adult human larynges were investigated. Lateral from the median cricothyroid ligament, the conus elasticus reveals two broad gaps containing adipose tissue and blood vessels. Along these routes, tumors of the larynx may easily extend into the ventral extralaryngeal tissues by continuous growth. Fibres of the conus elasticus cover the entire cranial surface of the vocalis muscle near the muscle's insertion at the thyroid cartilage. This part of the conus elasticus has been termed "thyroglottic ligament" in the fetus [22]. In the adult, this ligament prevents early cancer of the anterior vocal cords from invading adjacent structures. Other collagenous fibres continuous with the conus elasticus provide only an incomplete layer separating the lateral cricoarytenoid and the thyroarytenoid muscle. These fibres do not constitute an effective barrier against cancer growth.

Relationship of peak flow rate and peak velocity time during voluntary coughing

The differences in phonation between men and women are thought to occur from anatomical differences in the larynx. However, it is not known if there are any differences in cough dynamics between the sexes. We investigated this by asking 100 healthy, non-smoking adults (50 male) to perform a voluntary cough into a tussometer. Each volunteer coughed at four different lung volumes, ranging from total lung capacity to functional residual capacity. There was a positive correlation between peak velocity time and cough peak flow rate in both males (r = 0.73, P < 0.001) and females (r = 0.78, P < 0.001). Multiple regression analysis showed that height (P < 0.05) and sex (P < 0.001) were significant determinants of the relationship between peak flow rate and peak velocity time. In a height-matched subgroup, sex differences remained significant (P < 0.05). This may be related to anatomical differences in laryngeal structure and may have implications when using tussometry to assess laryngeal function.

Absorbable gelatin powder injection for transient vocal cord paralysis

In the early 1900s, glottic insufficiency in patients with vocal cord paralysis was corrected by injecting paraffin intralaryngeally. Since then, injecting absorbable gelatin powder into the vocal cord has become an acceptable short-term solution for transient paralysis of a single vocal cord. Although relatively uncommon, this procedure has few complications and is an option for patients when vocal cord function is expected to return within one year.

Cervical spine movement during laryngoscopy with the Bullard, Macintosh, and Miller laryngoscopes

BACKGROUND

Direct laryngoscopy requires movement of the head, neck, and cervical spine. Spine movement may be limited for anatomic reasons or because of cervical spine injury. The Bullard laryngoscope, a rigid fiberoptic laryngoscope, may cause less neck flexion and head extension than conventional laryngoscopes. The purpose of this study was to compare head extension (measured externally), cervical spine extension (measured radiographically), and laryngeal view obtained with the Bullard, Macintosh, and Miller laryngoscopes.

METHODS

Anesthesia was induced in 35 ASA 1-3 elective surgery patients. Patients lay on a rigid board with head in neutral position. Laryngoscopy was performed three times, changing between the Bullard, Macintosh, and Miller laryngoscopes. Head extension was measured with an angle finder attached to goggles worn by the patient. The best laryngeal view with each laryngoscope was assessed by the laryngoscopist. In eight patients, lateral cervical spine radiographs were taken before and during laryngoscopy with the Bullard and Macintosh blades.

RESULTS

Median values for external head extension were 11 degrees, 10 degrees, and 2 degrees with the Macintosh, Miller, and Bullard laryngoscopy (P < 0.01), respectively. Significant reductions in radiographic cervical spine extension were found for the Bullard compared to the Macintosh blade at the atlantooccipital joint, atlantoaxial joint, and C3-C4. Median atlantooccipital extension angles were 6 degrees and 12 degrees for the Bullard and Macintosh laryngoscopes, respectively. The larynx could be exposed in all patients with the Bullard but only in 90% with conventional laryngoscope (P < 0.01).

CONCLUSIONS

The Bullard laryngoscope caused less head extension and cervical spine extension than conventional laryngoscopes and resulted in a better view. It may be useful in care of patients in whom cervical spine movement is limited or undesirable.

Radiolabeled antibody combined with external radiotherapy for the treatment of head and neck cancer: reconstruction of a theoretical phantom of the larynx for radiation dose calculation to local tissues

We propose to use radiolabeled antibodies in combination with external beam radiotherapy to improve locoregional control of head and neck cancer. In this case radiation toxicity to mucosa may become a dose-limiting factor and a calculation of the possible compensatory decrease to the external beam radiotherapy would be needed. For this purpose, the following theoretical phantom of a representative organ of this anatomic region, the larynx, was reconstructed and local dosimetric data were derived for a selection of beta-emitting isotopes. The phantom was reconstructed as cylindrical concentric tubes using the established values of an outer diameter of 38 mm and a height of 44 mm. Published mean adult larynx weight (28 g) and cartilage weight (14.7 g) were used. Mean mucosa weight from 5 mucosa samples of our patients was calculated to be 2.0 +/- 0.4 (SD) g. The remaining weight was apportioned to a fat/muscle compartment (11.3 g). The specific gravity of cartilage (1.10 g/cm3), mucosa (1.04 g/cm3), and fat/muscle (1.04 g/cm3) were used to cross-check the volume/mass disparity of the theoretical tubular tissue shells. The established maximum glottic diameter of 24 mm was used to calculate the central air column volume. Mean laryngeal tumor volume from 8 representative laryngeal tumors was 4.4 +/- 3.1 cm3. Tissue compartment thickness was 660 microns for mucosa, 3100 microns for muscle/fat, and 3320 microns for cartilage. These values allowed the calculation of dose absorbed fractions for a number of theoretical radioimmunoconjugates by extending the established calculation of absorbed fractions for spheres of known diameter to absorbed fractions of tissue planes (annuli) of known thickness. We calculated a Deq for the respective tissues in the larynx for 131I-, 186Re-, 188Re-, 67Cu-, 90Y-, and 153Sm-labeled HMFG1. Compensatory decrease to the external radiotherapy dose is 1.1 Gy for each injection of the radioimmunoconjugate we propose to use (131I-HMFG1). This would be best implemented through the modification of the external radiotherapy fractions falling within 2 effective half-lives of this radioconjugate in the mucosa.

Biophysics of underwater hearing in the clawed frog, Xenopus laevis

Anesthetized clawed frogs (Xenopus laevis) were stimulated with underwater sound and the tympanic disk vibrations were studied using laser vibrometry. The tympanic disk velocities ranged from 0.01 to 0.5 mm/s (at a sound pressure of 2 Pa) in the frequency range of 0.4-4 kHz and were 20-40 dB higher than those of the surrounding tissue. The frequency response of the disk had two peaks, in the range of 0.6-1.1 kHz and 1.6-2.2 kHz, respectively. The first peak corresponded to the peak vibrations of the body wall overlying the lung. The second peak matched model predictions of the pulsations of the air bubble in the middle ear cavity. Filling the middle ear cavity with water lowered the disk vibrations by 10-30 dB in the frequency range of 0.5-3 kHz. Inflating the lungs shifted the low-frequency peak downwards, but did not change the high-frequency peak. Thus, the disk vibrations in the frequency range of the mating call (main energy at 1.7-1.9 kHz) were mainly caused by pulsations of the air in the middle ear cavity; sound transmission via the lungs was more important at low frequencies (below 1 kHz). Furthermore, the low-frequency peak could be reversibly reduced in amplitude by loading the larynx with metal or tissue glue. This shows that the sound-induced vibrations of the lungs are probably coupled to the middle ear cavities via the larynx. Also, anatomical observations show that the two middle ear cavities and the larynx are connected in an air-filled recess in submerged animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Intrinsic fibre architecture and attachments of the human epiglottis and their contributions to the mechanism of deglutition

Two mechanisms have been proposed which address the downfolding of the epiglottis during swallowing. The passive mechanism (Fink et al. 1979) focuses on passive mechanical forces transmitted through the median hyoepiglottic ligament and pre-epiglottic adipose tissue to the epiglottis. The active mechanism (Ekberg & Sigurjonsson, 1982) expands the passive mechanism to include active contributions from the aryepiglotticus and thyroepiglotticus muscles. By means of laryngeal microdissection and whole mount orcein staining, distinct bands of fascial condensations were identified running from the lateral edge of the epiglottis just superior to the attachment of the median hyoepiglottic ligament to the hyoid bone near the ends of the greater horns. Neither the proposed active nor the passive mechanisms address the possible contribution of these paired lateral hyoepiglottic ligaments to epiglottic downfolding. Computer image analysis of videofluoroscopic examinations of swallowing was then used to assess the dynamic movements of the larynx during swallowing. It was observed that the downfolding of the epiglottis occurred in the same video frame as initiation of anterior displacement of the hyoid bone and thyrohyoid approximation. Based on the anatomical and dynamic relationship of the epiglottis to other laryngeal structures, we propose that as the larynx elevates and the hyoid bone moves anteriorly, these lateral ligaments exert traction preferentially on the upper third of the epiglottis to bring it to a position below the horizontal.

Thyroid cartilage movements during breathing

We measured lateral (outward) thyroid cartilage displacement (TCD) of the larynx in six supine anesthetized (intravenous chloralose) dogs. Combined left and right TCDs were measured with linear transducers attached by a thread to the thyroid alae. During tidal breathing via a tracheostomy, phasic inspiratory TCD occurred in all dogs [0.66 +/- 0.2 mm (mean +/- SE)] together with phasic inspiratory electromyographic activity in the cricothyroid (CT) and posterior cricoarytenoid (PCA) muscles. During brief tracheal occlusions, TCD increased significantly to 1.27 +/- 0.2 mm (P = 0.001), accompanied by an increase of 95-115% in the peak CT and PCA electromyograms. Bilateral supramaximal electrical stimulation of the external branches of the superior laryngeal nerve (ExSLN) produced a TCD of 9.9 +/- 0.8 mm; however, similar stimulation of the recurrent laryngeal nerve (RLN) produced a TCD of only 1.33 +/- 0.1 mm (P = 0.0001). Furthermore, bilateral section of the ExSLN in five dogs significantly reduced tidal TCD by 48.7 +/- 24.4% (P < 0.05), and bilateral section of both the ExSLN and RLN resulted in slight phasic inward TCD (-0.06 +/- 0.05 mm). Thus, it appears that the activities of both the CT and RLN-innervated muscles (probably the PCA muscle) contribute to tidal breathing TCD. These findings suggest that inspiratory dilation of the hypopharynx is mediated by contractions of CT and PCA muscles.

Assessment of patient position for fiberoptic intubation using videolaryngoscopy

STUDY OBJECTIVE

To compare laryngoscopic appearance obtained during flexible fiberoptic laryngoscopy with the patient's atlanto-occipital joint in the neutral and extended positions.

DESIGN

Controlled clinical trial with each patient (in the neutral position) acting as his or her own control.

SETTING

University teaching hospital.

PATIENTS

20 adult ASA physical status I and II patients, without anatomical airway abnormalities, undergoing elective surgical procedures.

INTERVENTIONS

Fiberoptic laryngoscopy was performed on each patient with his or her atlanto-occipital joint in the neutral and extended positions.

MEASUREMENTS AND MAIN RESULTS

Photographs of the laryngoscopic appearances were graded on a scale of 1 to 4 by a blinded observer according to the proportion of the laryngeal inlet visible. Atlanto-occipital extension improved laryngoscopic appearance in 14 cases and produced no change in the remaining 6.

CONCLUSION

Atlanto-occipital extension is a useful maneuver during attempted fiberoptic intubation.

[Functionally determined area changes in the oro-pharyngo-laryngeal vocal tract of singers as shown by magnetic resonance tomography]

The oro-pharyngeal-laryngeal resonating spaces were studied in 12 singers at varying stages of their training by means of medio-sagittal MRI images, and the results were compared. The singers were requested to sing /a/ /u/ and /i/ at various pitches and with increasing loudness. The total oro-pharyngo-laryngeal areas were integrated by means of the MRI sections. The relationship between the oro-pharyngeal and pharyngo-laryngeal areas was determined, as well as their ratio to total area. With increasing volume there was increase in the area of the oro-pharyngeal component with no change in the pharyngo-laryngeal component. The relationship of the partial areas depends on the extent of training of the singer.

The laryngeal mask airway for dental surgery--a review

The ideal airway requirements for oral surgery are the provision of a stable, unobstructed airway, protection of the lungs from aspiration, minimal interference with the surgical field and a low complication rate. Neither the nasal mask nor endotracheal tube meet these requirements. The laryngeal mask airway (LMA), provides a third type of airway for consideration in oral surgery that offers some of the benefits of intubation and avoids many of the associated hazards. It can be inserted without use of a laryngoscope or muscle relaxants, and is designed to produce an airtight seal around the laryngeal inlet. It provides a secure airway suitable for spontaneous or controlled ventilation and acts as an airtight throat pack. Scavenging of waste gases is possible, and it is well tolerated during recovery. A modification, specifically designed for head, neck and dental anaesthesia, has recently become available. The purpose of this article is to provide a brief overview of the LMA with special emphasis on its use in oral surgery.

Laryngotracheal anatomy and physiology

Thorough knowledge of the laryngotracheal anatomy and physiology is a prerequisite for understanding the pathophysiology and for an adequate treatment of patients with anomalies, stenoses and other pathology in this area. The larynx is part of the upper respiratory tract, our voice organ and it prevents the passage of secretion and food to the lower airways. Anatomical differences between adults and children, males and females are important to consider, as the size of the structures underlies the decision for the size of tubes and cannulas to be used. Knowledge of the muscles and mucosa is important in augmentation, e.g. in phono-surgery and for procedures in patients with laryngeal palsy. The trachea with its location causes specific problems in the treatment of stenoses and tumours. The mucociliary system is nowadays being more focused upon.

Morphometry of the larynx in horizontal sections

PURPOSE

Until recently, only few studies on laryngeal morphometry in the horizontal plane, which used unreliable techniques, have been reported. The established methods of whole-organ serial sectioning of the larynx serve the purpose of histological investigation very well. Because they cause major tissue shrinkage, these techniques are not useful for morphometry. Nevertheless, normal data of laryngeal horizontal anatomy are of great surgical and diagnostic interest. Data on endolaryngeal angles, airway lumina, and the thickness of parts of the laryngeal skeleton can be helpful in the planning of endolaryngeal surgical intervention or the transcutaneous placement of electrodes for laryngeal electromyography. The aim of this study was to establish a method for the production of whole-organ serial sections that allows for the collection of exact and reliable morphometrical data.

MATERIALS AND METHODS

A total of 20 fresh human cadaver larynges were investigated in this study. Nineteen measurements on three different planes were obtained in each larynx. The larynges were shock-frosted using liquid propane and nitrogen and then cut with a slicing machine. Measurements were obtained using a computer-aided analyzing system.

RESULTS

The collected data give an exact and extensive description of the morphometrics of laryngeal structures such as thyroid and cricoid cartilage, arytenoid cartilages, vocal cords, and endolaryngeal airways at different section levels.

CONCLUSION

This study is the first to provide detailed anthropometric data on whole-organ sections of the larynx following a new method. This technique of using serial sections of the investigated specimen avoids artifacts caused by tissue fixation. Thus, it may be considered being particularly suited to the conduction of anthropometric studies on human larynges.