Biomedical subjects

James B Kobler

Publications and source records attributed to James B Kobler.

At least 19 recordsLinked to original sources

PubMed2007

Effects of 532 nm pulsed-KTP laser parameters on vessel ablation in the avian chorioallantoic membrane: implications for vocal fold mucosa.

OBJECTIVES: Selective vascular ablation (photoangiolysis) using pulsed lasers that target hemoglobin is an effective treatment strategy for many vocal fold lesions. However, vessel rupture with extravasation of blood reduces selectivity for vessels, which is frequently observed with the 0.45-ms, 585-nm pulsed dye laser. Previous studies have shown that vessel rupture is the result of vaporization of blood, an event that varies with laser pulse width and pulse fluence (energy per unit area). Clinical observations using a 532-nm wavelength pulsed potassium-titanyl-phosphate (KTP) laser revealed less laser-induced hemorrhage than the pulsed dye laser. This study investigated settings for the pulsed KTP laser to achieve selective vessel destruction without rupture using the avian chorioallantoic membrane under conditions similar to flexible laryngoscopic delivery of the laser in clinical practice. STUDY DESIGN: The chick chorioallantoic membrane offers convenient access to many small blood vessels similar in size to those targeted in human vocal fold. Using a 532-nm pulsed KTP laser, pulse width, pulse energy, and working distance from the optical delivery fiber were varied to assess influence on the ability to achieve vessel coagulation without vessel wall rupture. METHODS: Third-order vessels (n = 135) were irradiated: Energy (471-550 mJ), pulse width (10, 15, 30 ms), and fiber-to-tissue distance (1 mm, 3 mm) were varied systematically. RESULTS: Selective vessel destruction without vessel wall rupture was more often achieved by increasing pulse width, increasing the fiber-to-tissue distance, and decreasing energy. Vessel destruction without rupture was consistently achieved using 15- or 30-ms pulses with a fiber-to-tissue distance of 3 mm (pulse fluence of 13-16 J/cm). CONCLUSIONS: This study substantiates our clinical observation that a 532-nm pulsed KTP laser was effective for ablating microcirculation while minimizing vessel wall rupture and hemorrhage.

Animals↗

PubMed2006

The shear modulus of the human vocal fold, preliminary results from 20 larynxes.

Quantification of the elastic properties of the human vocal fold provides invaluable data for researchers deriving mathematical models of phonation, developing tissue engineering therapies, and as normative data for comparison between healthy and scarred tissue. This study measured the shear modulus of excised cadaver vocal folds from 20 subjects. Twenty freshly excised human larynxes were evaluated less than four days post-mortem. They were split along the saggital plane and mounted without tension. Shear modulus was obtained by two different methods. For method 1 cyclical shear stress was applied transversely to the mid-membranous portion of the vocal fold, and shear modulus derived by applying a simple shear model. For method 2 the apparatus was configured as an indentometer, and shear modulus obtained from the stress/strain data by applying an established analytical technique. Method 1 shear model for male larynxes yielded a range from 246 to 3,356 Pa, with a mean value of 1,008 and SD of 380. The range for female larynxes was 286-3,332 Pa, with a mean value of 1,237 and SD of 768. Method 2 indentometer model for male larynxes yielded a range from 552 to 2,741 Pa, with a mean value of 1,000 and SD of 460. The range for female larynxes was 509-1,989 Pa, with a mean value of 1,332 and SD of 428. We have successfully demonstrated two methodologies that are capable of directly measuring the shear modulus of the human vocal fold, without dissecting out the vocal fold cover tissue. The sample size of nine female and 11 male larynxes is too small to validate a general conclusion. The high degree of variability in this small cohort of subjects indicates that factors such as age, health status, and post-mortem delay may be significant; and that there is range of 'normality' for vocal fold tissue.

Biomechanical Phenomena↗

PubMed2006

Hyaluronic acid-based microgels and microgel networks for vocal fold regeneration.

Vocal fold scarring disrupts the viscoelastic properties of the lamina propria that are critical for normal phonation. There is a clinical need for the development of advanced biomaterials that approximate the mechanical properties of the lamina propria for in vivo vocal fold regeneration. We have developed hyaluronic acid (HA)-based microgels and cross-linked microgel networks with tunable degradation and mechanical properties. HA microgels were prepared by cross-linking HA derivatives carrying hydrazide (HAADH) and aldehyde (HAALD) functionalities within the inverse emulsion droplets. Alternatively, poly(ethylene glycol) dialdehyde (PEGDiALD) was employed in place of HAALD. Microgels based on HAADH/HAALD are more resistant to enzymatic degradation than those generated from HAADH/PEGDiALD. In vitro cytotoxicity studies using vocal fold fibroblasts indicate that microgels synthesized from HAADH/HAALD are essentially nontoxic, whereas microgels derived from HAADH/PEGDiALD exhibit certain adverse effects on the cultured cells at high concentration (> or =2 mg/mL). These microgels exhibit residual functional groups that can be used as reactive handles for covalent conjugation of therapeutic molecules. The presence of residual functional groups also allows for subsequent cross-linking of the microgels with other reactive polymers, giving rise to doubly cross-linked networks (DXNs) with tunable viscoelasticity. Mechanical measurements using a torsional wave apparatus indicate that HA-based DXNs exhibit elastic moduli that are similar to those of vocal fold lamina propria at frequencies close to the range of human phonation. These HA-based microgel systems are promising candidates for the treatment of vocal fold scarring, not just as biocompatible filler materials, but as smart entities that can repair focal defects, smooth the vocal fold margin, and potentially soften and dissolve scar tissue.

Aldehydes↗

PubMed2006

Measurements of vocal fold elasticity using the linear skin rheometer.

OBJECTIVE: The linear skin rheometer (LSR), which measures skin visco-elasticity, was adapted for measurements of vocal fold properties. A series of studies was performed on animal and human excised larynges to determine if the LSR technique can be applied to the vocal fold. METHODS: In excised larynges, small patches of mucosa were driven sinusoidally at 0.3 Hz over distances of 1-2 mm using a small probe. Forces in the order of 1 g equivalent gave optimal measurements. Stiffness and viscosity values were derived from stress/strain data. RESULTS: The instrument was able to measure the visco-elasticity of the tissue in a repeatable manner and it could detect areas where the tissue was artificially stiffened. Two-dimensional maps of the mechanical properties of the laryngeal mucosa were obtained showing local variations in elasticity both parallel and perpendicular to the vocal fold edge. Initial studies were undertaken using animal tissue; more recently, the LSR has been successfully used to obtain similar data from human tissue. CONCLUSION: The LSR was been demonstrated to be capable of measuring the elastic properties of the vocal fold in a repeatable and reliable manner. Further studies will now be undertaken to obtain data from a larger sample of human tissue.

Animals↗

PubMed2006

Quantitative and comparative studies of the vocal fold extracellular matrix. I: Elastic fibers and hyaluronic acid.

OBJECTIVES: This study examines the elastic fiber and hyaluronic acid (HA) content of the midmembranous vocal fold laminae propriae (LPs) of humans, dogs, pigs, and ferrets. METHODS: Lamina propria elastin was quantified by measuring the amino acid desmosine, and HA was measured by an enzyme-linked immunosorbent assay-based technique. Quantitative histology was used to evaluate elastin and HA levels in specific LP regions. The distributions of fibrillin-1, a primary microfibrillar component of elastic fibers, and of tropoelastin, an indicator of elastin synthesis, were immunohistochemically analyzed. RESULTS: Elastin and HA constituted 8.5% +/- 2.1% and 0.82% +/- 0.11% of human LP, respectively, relative to tissue total protein. Although the mean LP desmosine levels were similar across species, the mean HA levels in canine (p < 3.1 x 10(-5)), porcine (p < 1.5 x 10(-5)), and ferret (p < 6.6 x 10(-4)) LPs were 3 to 4 times higher than that in humans. Marked interspecies differences in elastin, fibrillin-1, tropoelastin, and HA distributions were observed histologically. CONCLUSIONS: The elastin content of the human LP is roughly twice that of the dermis, whereas the HA content of the human LP is similar to that of the dermis. Although all species had similar levels of desmosine, histologic evaluation indicates that the porcine elastin distribution is most similar to that of the human LP. Fibrillin-1 staining suggests that stress in the human LP may be particularly high in the superior superficial layer, and tropoelastin staining indicates that the rate of LP elastin turnover may vary spatially.

Animals↗

PubMed2006

Quantitative and comparative studies of the vocal fold extracellular matrix II: collagen.

OBJECTIVES: This study examines the collagen content and turnover in the midmembranous vocal fold laminae propriae (LPs) of humans, dogs, pigs, and ferrets. METHODS: The LP collagen levels were assessed by quantifying tissue hydroxyproline. Quantitative histology allowed evaluation of the collagen content in specific LP regions. Several collagen types and two markers of collagen turnover were examined immunohistochemically. RESULTS: Collagen made up 43.4% +/- 2.6% of human LP total protein (TP), with men having approximately 30% higher collagen content than women (p < .024). The collagen levels in pigs (52.6% +/- 1.9% of TP) and ferrets (29.8% +/- 3.7% of TP), but not that in dogs (45.3% +/- 1.2% of TP), varied significantly from that in humans (pigs, p < .016; ferrets, p < .011). Quantitative histology indicated marked interspecies differences in total collagen distribution. Collagen types I, III, and IV were detected in the LP, and spatially complex staining patterns were observed for the two markers of collagen turnover studied. CONCLUSIONS: The collagen content of the human LP is approximately 60% to 70% of that of human dermis. Although canine LP collagen levels are most similar to those of humans, quantitative histology indicates that the collagen distribution of the human LP is best matched by the porcine LP. Collagen types I and III seem to be the dominant LP collagens. Spatial variations in collagen turnover appear to exist that may contribute to normal LP physiology.

Animals↗

PubMed2006

Imaging the human vocal folds in vivo with optical coherence tomography: a preliminary experience.

OBJECTIVES: Optical coherence tomography (OCT) and polarization-sensitive OCT (PS-OCT) are promising noninvasive methods for in vivo, cross-sectional imaging of the microstructure of the vocal folds. Previous studies in other tissues have shown an axial resolution of less than 10 microm and a maximum imaging depth of about 2 mm. The objectives of this pilot study were to obtain images from the vocal folds of subjects who were being evaluated and/or treated for vocal fold disease and to evaluate how well normal and pathologic microstructure could be seen in these images. METHODS: Twenty-six vocal folds in 13 subjects were imaged with a flexible OCT probe. The images were successfully collected from subjects who were either topically anesthetized or under general anesthesia for microlaryngoscopic procedures. RESULTS: The thickness of the epithelium, the relative collagen content of the subepithelial connective tissue, and certain characteristic features of lesions (including cysts, scarring, and papilloma) were seen in the OCT and PS-OCT images. CONCLUSIONS: "Live microscopy" of the human vocal folds is very promising for improved diagnosis, mapping, and treatment planning. To our knowledge, this study is the first application of PS-OCT for in vivo imaging of the human vocal folds.

Humans↗

PubMed2006

Carbon dioxide laser fiber for laryngeal cancer surgery.

OBJECTIVES: The carbon dioxide laser has evolved to be the premier dissecting instrument for hemostatic cutting during endolaryngeal cancer resection. However, dissection is limited to mirror-reflected line-of-sight delivery of the laser. A recently developed flexible, hollow photonic bandgap fiber (PBF) appears to offer advantages in endolaryngeal dissection. METHODS: The suitability of the PBF for human application was evaluated in a canine experiment in which human surgical procedures for microlaryngoscopic en bloc partial laryngectomy were simulated. The specimens that were resected endoscopically and the completion laryngectomy specimen were evaluated histologically. RESULTS: Observations from this experiment revealed that en bloc partial laryngectomy procedures were substantially easier to achieve as compared with prior experience in humans. This improvement resulted from three factors: 1) enhanced tangential dissection due to increased angulation of the laser energy, 2) enhanced procedural orientation due to proprioception of the tissues in contact mode, and 3) improved hemostasis. Histopathologic analysis of the resection margins revealed minimal thermal trauma. CONCLUSIONS: The PBF shows substantial promise for human application in endoscopic partial laryngectomy. It will likely enhance the ability of any surgeon to extend his or her indications for performing endoscopic laryngeal cancer resections regardless of philosophy (en bloc resection or piecemeal).

Animals↗

PubMed2006

Comparison of a flexible laryngoscope with calibrated sizing function to intraoperative measurements.

OBJECTIVES: The objectives were to assess the clinical performance and accuracy of a prototype fiberoptic transnasal laryngeal endoscope with an auxiliary optical system that allows images to be spatially calibrated. METHODS: A novel fiberoptic endoscope was developed that projects green laser beams across the field of view from a separate optical channel. According to the location of the spots in the field of view, the images can be calibrated with a software routine. To assess its performance, we compared measurements of 14 lesions imaged with the calibrated endoscope and during microlaryngoscopy, where a calibration instrument was placed next to the lesions. Four clinicians measured lesion length, width, and area from the collected images. RESULTS: The calibrated endoscope performed as well as current flexible fiberoptic laryngoscopes in terms of image quality and patient comfort. For lesions with well-defined borders, the error ranged from 14% to 23% for length, from 20% to 30% for width, and from 33% to 50% for area across observers. Factors contributing to larger errors in some subjects were identified. CONCLUSIONS: The calibrated endoscope is capable of providing useful sizing information for laryngeal structures, and these measures correspond quite well to more direct measurements in the operating room. Objective sizing of laryngeal lesions is complicated by subjective judgments of lesion boundaries, which can be indistinct in many cases.

Adult↗

PubMed2005

Use of muscle fibrillation for tracking nerve regeneration.

Individual muscle fibers in denervated muscle demonstrate repetitive, spontaneous contraction. Such fibrillation activity disappears in denervated muscle if reinnervation occurs, but this relationship has not been formally studied. To test whether the disappearance of fibrillation can be used to track nerve regeneration, we quantified the presence and subsequent disappearance of electromyographic (EMG) fibrillation potentials and fibrillation-related movement in the rat tongue after unilateral hypoglossal nerve crush at two locations. In mice, fibrillation movement of vibrissae were monitored after unilateral facial nerve crush and compared with the return of symmetrical vibrissae sweeping movements. In both of these rodent cranial motor systems, there was a conspicuous loss of fibrillation at a time when reinnervation is known to take place, suggesting that the visual appearance of fibrillation-related movement can be used as a simple, noninvasive means of tracking nerve regeneration in these popular experimental motor systems.

Animals↗

PubMed2005

Measurement of vocal fold collision forces during phonation: methods and preliminary data.

Forces applied to vocal fold tissue as the vocal folds collide may cause tissue injury that manifests as benign organic lesions. A novel method for measuring this quantity in humans in vivo uses a low-profile force sensor that extends along the length and depth of the glottis. Sensor design facilitates its placement and stabilization so that phonation can be initiated and maintained while it is in place, with minimal interference in vocal fold vibration. In 2 individuals with 1 vibrating vocal fold and 1 nonvibrating vocal fold, peak collision force correlates more strongly with voice intensity than pitch. Vocal fold collision forces in 1 individual with 2 vibrating vocal folds are of the same order of magnitude as in previous studies. Correlations among peak collision force, voice intensity, and pitch were indeterminate in this participant because of the small number of data points. Sensor modifications are proposed so that it can be used to reliably estimate collision force in individuals with 2 vibrating vocal folds and with changing vocal tract conformations.

Biomechanical Phenomena↗

PubMed2005

Endoscopic measurement of vocal fold movement during adduction and abduction.

OBJECTIVES/HYPOTHESIS: Whereas vibration of the vocal folds has been analyzed and modeled in detail, less attention has been paid to quantifying the slower motions of abduction and adduction. Because these gestures reflect neuromuscular function, cartilage geometry, and joint mobility, objective measurement might improve assessment and treatment of patients with neuromuscular or structural disease. STUDY DESIGN: Prospective, observational. METHODS: Twenty-one normal adult volunteers performed a repeated "ee-sniff" task at three rates during flexible endoscopy. Distortion in the images was corrected and frame-by-frame analysis of the angle between the true vocal folds (glottic angle) yielded measures of maximum abduction angle (MAA) and mean angular velocities of abduction (MVAB) and adduction (MVAD). RESULTS: Reliability tests indicated interjudge variability of 3.8 degrees (deg). The mean MAA was 51 deg and ranged from 31 to 77 deg across subjects. The mean MVADs were 229, 309, and 475 deg/s for slow, medium, and fast rates, respectively, and the mean MVABs were 330, 388, and 441 deg/s for slow, medium, and fast rates, respectively. Statistical analysis showed greater influence of gesture rate on adduction than on abduction. CONCLUSIONS: The glottic angle can be reliably measured from flexible endoscopic images and angular velocities of vocal fold abduction and adduction can be determined from analysis of sequential video frames. Accuracy is significantly enhanced by correction of distortion in the images. This approach holds promise for objective characterization of vocal fold function in patients with a variety of disorders.

Adult↗

PubMed2005

A new instrument for intraoperative assessment of individual vocal folds.

OBJECTIVES: Intraoperative assessment of vocal fold vibration during phonomicrosurgery performed under general anesthesia may enhance surgical decision-making. We therefore developed and bench-tested a new device we refer to as the aerodynamic vocal fold driver (AVFD). MATERIALS AND METHODS: The AVFD comprises a hand-held probe that uses airflow to drive individual vocal folds into phonatory-like vibration. This permits stroboscopic visualization of mucosal waves with simultaneous control of subglottal air pressure. In initial experiments to validate the technique, AVFD driven phonation and conventional whole-larynx phonation were compared using excised canine larynges (n = 14). RESULTS: Single vocal fold phonation using the AVFD and whole larynx phonation yielded similar, positive correlations between subglottal pressure and both amplitude and frequency of vibration. Experiments simulating vocal fold scar-related mucosal stiffening by subepithelial injection of fixative showed the expected elevation of phonation threshold pressures as measured with the AVFD. Likewise, unilateral tissue compression injury disrupted vocal fold vibration, and the AVFD was useful for quantifying improvement in the damaged vocal fold after repair with injection of cross-linked hyaluronic acid gel. CONCLUSIONS: These results show that this new instrument has the potential to provide novel and useful information for laryngeal experimentation and to improve phonosurgery.

Air↗

PubMed2005

Measurements of glottal structure dynamics.

Low power, radarlike electromagnetic (EM) wave sensors, operating in a homodyne interferometric mode, are being used to measure tissue motions in the human vocal tract during speech. However, when these and similar sensors are used in front of the laryngeal region during voiced speech, there remains an uncertainty regarding the contributions to the sensor signal from vocal fold movements versus those from pressure induced trachea-wall movements. Several signal-source hypotheses are tested by performing experiments with a subject who had undergone tracheostomy, and who still was able to phonate when her stoma was covered (e.g., with a plastic plate). Laser-doppler motion-measurements of the subject's posterior trachea show small tissue movements, about 15 microns, that do not contribute significantly to signals from presently used EM sensors. However, signals from the anterior wall do contribute. EM sensor and air-pressure measurements, together with 3-D EM wave simulations, show that EM sensors measure movements of the vocal folds very well. The simulations show a surprisingly effective guiding of EM waves across the vocal fold membrane, which, upon glottal opening, are interrupted and reflected. These measurements are important for EM sensor applications to speech signal de-noising, vocoding, speech recognition, and diagnostics.

Biomechanical Phenomena↗

PubMed2005

Midmembranous vocal fold lamina propria proteoglycans across selected species.

OBJECTIVES: We examined the proteoglycan (PG) and associated sulfated glycosaminoglycan (GAG) content of the midmembranous vocal fold lamina propria (LP) of humans, dogs, pigs, and ferrets. METHODS: The LP PG levels were assessed indirectly by quantifying the associated sulfated GAGs, and immunohistochemical analyses of specific PGs and/or GAGs (PGs/GAGs) were conducted. RESULTS: Sulfated GAGs constituted approximately (average +/- SEM) 14.7 +/- 2.1 microg per milligram of tissue total protein in the human LP--similar to levels in canine, porcine, and ferret LPs (p > .05). Immunohistochemical analysis identified versican, chondroitin 4- and 6-sulfate, and heparan sulfate in the LP extracellular matrix--PGs/GAGs previously believed to be localized only intracellularly and in the basement membrane. Observations of PG/GAG staining patterns resulted in identification of microstructurally based subdivisions of canine, porcine, and ferret LPs. CONCLUSIONS: The sulfated GAG concentration in human LP was similar to that of dermis. In contrast to the interspecies similarity in LP sulfated GAG levels, immunohistochemical analysis indicated notable interspecies differences in specific PG/GAG distributions. Moreover, spatial variations in the presence of several PGs/GAGs were observed--variations that may be integral in maintaining normal LP physiology. Finally, the noted canine, porcine, and ferret LP subdivisions may yield insight into the adaptation of LP microstructure to the phonatory needs of each species.

Adult↗

PubMed2005

Imaging the mucosa of the human vocal fold with optical coherence tomography.

OBJECTIVES: Discerning the layered microstructure of the vocal folds is critical for effective phonomicrosurgery. Optical coherence tomography (OCT), a noncontact, noninvasive technology that provides cross-sectional images by means of backscattered light, offers the potential for delineating these layers in vivo. METHODS: The glottal mucosa of 3 human cadaver larynges was imaged with conventional OCT and polarization-sensitive OCT (PS-OCT). Images were obtained through the epithelium and lamina propria. RESULTS: Although the superficial layer of the lamina propria appeared quite homogeneous, the outer surface of the superficial lamina propria was correlated with an increase in backscatter with OCT. The superficial lamina propria and vocal ligament were correlated with a marked increase in tissue birefringence with PS-OCT. CONCLUSIONS: This preliminary study demonstrates the capacity of OCT and PS-OCT for visualizing the layered microstructure of the vocal fold mucosa. We believe that these imaging techniques will have applications in the exploration of solutions to vocal fold scarring and in imaging vocal fold disorders in the clinic and operating room.

Cadaver↗

PubMed2004

Recurrent laryngeal nerve identification and assessment during thyroid surgery: laryngeal palpation.

Electrical identification and monitoring of the recurrent laryngeal nerve (RLN) has been proposed as an adjunct to standard visual identification of the nerve during thyroid and parathyroid surgery. This study was undertaken to assess laryngeal palpation as an intraoperative technique for identifying and assessing the RLN during surgery and to investigate the relation between laryngeal palpation and associated laryngeal electromyographic (EMG) activity. The postcricoid region of the larynx during surgery was palpated through the posterior hypopharyngeal wall to sense posterior cricoarytenoid muscle contraction in response to ipsilateral RLN stimulation (i.e., the "laryngeal twitch response.") Laryngeal palpation was performed in a series of 449 consecutive thyroid and parathyroid surgeries with 586 RLNs at risk. All patients underwent preoperative and postoperative laryngoscopy to assess vocal cord mobility. In a subset of patients, laryngeal palpation and simultaneous laryngeal EMG recordings were compared during intraoperative RLN stimulation. In this series, there was no permanent RLN paralysis. There was one case of temporary RLN paralysis secondary to neural stretch that resolved 6 weeks postoperatively (temporary paralysis rate: 0.2% of patients, 0.2% of nerves at risk). Intraoperative laryngeal palpation of the laryngeal twitch response reliably correlated with normal postoperative vocal cord function. Loss of the laryngeal twitch response occurred in the single case of temporary paralysis in the setting of an anatomically intact nerve. Laryngeal palpation correlated well with simultaneous laryngeal EMG activity. There were no palpation-induced laryngeal injuries or laryngeal edema. There were also no RLN injuries due to repetitive neural stimulation. Intraoperative laryngeal palpation during RLN stimulation is a safe, reliable method for neural monitoring that can assist in RLN identification and assessment during thyroid and parathyroid surgery. Most importantly, it provides important prognostic information regarding ipsilateral vocal cord function at the completion of the initial side of the thyroid or parathyroid surgery. Intraoperative laryngeal palpation allows the surgeon to stage contralateral surgery if RLN damage is diagnosed, thereby avoiding the potential for bilateral vocal cord paralysis. We believe that laryngeal palpation is useful as an adjunct to formal EMG monitoring during thyroid and parathyroid surgery.

Adolescent↗

PubMed2004

A laryngeal dissection station: educational paradigms in phonosurgery.

OBJECTIVES: To introduce a new tool for phonosurgical training and education. A multitude of innovations in complex laryngeal surgery has catalyzed new educational initiatives. Establishing dexterity in phonomicrosurgery is often difficult to achieve while working on patients because of the narrow margin for success. Furthermore, laryngoplastic phonosurgery and open partial laryngectomy require sophisticated knowledge of precise anatomic relationships, which can be difficult to express in images. Finally, many teaching programs do not have a high volume of these procedures, and there is a significant need to transmit this information in continuing education courses. STUDY DESIGN: Prototype design. METHODS: A laryngeal dissection station (LDS) was designed to facilitate the acquisition of high-level procedural skill sets for both transoral and transcervical techniques. RESULTS: This LDS can be used in existing temporal-bone laboratories by using cadaveric larynges. A rectangular frame supports two adjustable holders, one for the larynx and one for the examining speculum of a laryngoscope. Procedures are performed with the larynx fixed in space by a novel fixator. Variation in position and orientation of the components affords simulation of both microlaryngoscopy and open surgery. The dissection station can accommodate virtually any laryngoscope, regardless of size or shape. CONCLUSIONS: This training apparatus should facilitate laryngeal surgical instruction in residency training and continuing medical education. This device and others like it can help establish clinical competency in laryngology, should this become necessary in future educational models of residency training and recertification.

General Surgery↗