Seth Dailey

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The Shear Modulus of the Human Vocal Fold in a Transverse Direction

by Eric Goodyer, Seth Dailey, and Eric Goodyer

The aim of this study was to measure the shear modulus of the vocal fold in a human hemilarynx, s... more The aim of this study was to measure the shear modulus of the vocal fold in a human hemilarynx, such that the data can be related to direction of applied stress and anatomical context. Dynamic spring rate data were collected using a modified linear skin rheometer using human hemilarynges, and converted to estimated shear modulus via application of a simple shear model. The measurement probe was attached to the epithelial layer of the vocal fold cover using suction. A sinusoidal force of 3 g was applied to the epithelium, and the resultant displacement logged at a rate of 1 kHz. Force measurement accuracy was 20 mg and position measurement accuracy was 4 mm. The force was applied in a transverse direction at the midmembranous point between the vocal process and the anterior commissure. The shear modulus of the three female vocal folds ranged from 814 to 1232 Pa. The shear modulus of the three male vocal folds ranged from 1021 to 1796 Pa. These data demonstrate that it is possible to obtain estimates for the shear modulus of the vocal fold while preserving anatomical context. The modulus values reported here are higher than those reported using parallel plate rheometry. This is to be expected as the tissue is attached to surrounding structures, and is under natural tension.

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Stretch calculated from grip distance accurately approximates mid-specimen stretch in large elastic arteries in uniaxial tensile tests

Journal of the Mechanical Behavior of Biomedical Materials, 2015

The mechanical properties of vascular tissues affect hemodynamics and can alter disease progressi... more The mechanical properties of vascular tissues affect hemodynamics and can alter disease progression. The uniaxial tensile test is a simple and effective method for determining the stress-strain relationship in arterial tissue ex vivo. To enable calculation of strain, stretch can be measured directly with image tracking of markers on the tissue or indirectly from the distance between the grips used to hold the specimen. While the imaging technique is generally considered more accurate, it also requires more analysis, and the grip distance method is more widely used. The purpose of this study is to compare the stretch of the testing specimen calculated from the grip distance method to that obtained from the imaging method for canine descending aortas and large proximal pulmonary arteries. Our results showed a significant difference in stretch between the two methods; however, this difference was consistently less than 2%. Therefore, the grip distance method is an accurate approximation of the stretch in large elastic arteries in the uniaxial tensile test.

Pulmonary artery relative area change is inversely related to ex vivo measured arterial elastic modulus in the canine model of acute pulmonary embolization

Journal of Biomechanics, 2014

A low relative area change (RAC) of the proximal pulmonary artery (PA) over the cardiac cycle is ... more A low relative area change (RAC) of the proximal pulmonary artery (PA) over the cardiac cycle is a good predictor of mortality from right ventricular failure in patients with pulmonary hypertension (PH). The relationship between RAC and local mechanical properties of arteries, which are known to stiffen in acute and chronic PH, is not clear, however. In this study, we estimated elastic moduli of three PAs (MPA, LPA and RPA: main, left and right PAs) at the physiological state using mechanical testing data and correlated these estimated elastic moduli to RAC measured in vivo with both phase-contrast magnetic resonance imaging (PC-MRI) and M-mode echocardiography (on RPA only). We did so using data from a canine model of acute PH due to embolization to assess the sensitivity of RAC to changes in elastic modulus in the absence of chronic PH-induced arterial remodeling. We found that elastic modulus increased with embolization-induced PH, presumably a consequence of increased collagen engagement, which corresponds well to decreased RAC. Furthermore, RAC was inversely related to elastic modulus. Finally, we found MRI and echocardiography yielded comparable estimates of RAC. We conclude that RAC of proximal PAs can be obtained from either MRI or echocardiography and a change in RAC indicates a change in elastic modulus of proximal PAs detectable even in the absence of chronic PH-induced arterial remodeling. The correlation between RAC and elastic modulus of proximal PAs may be useful for prognoses and to monitor the effects of therapeutic interventions in patients with PH.

A study of phonomicrosurgical arm support postures using a magnetic motion tracking system

The Laryngoscope, Jan 25, 2015

To study the different arm support postures used in phonomicrosurgery by using a magnetic-based p... more To study the different arm support postures used in phonomicrosurgery by using a magnetic-based phonomicrosurgery instrument tracking system (MPTS). Through quantitative motion parameter data collected from four arm support postures (elbow support [ES], forearm support [FS], forearm and hand support, and no support), phonomicrosurgical operation postures were analyzed and compared. Prospective cohort study. Seven subjects operated on phonomicrosurgical simulation cutting tasks with four arm support postures while being monitored by MPTS. The motion parameters, including operation time, path length, depth perception, and motion smoothness were analyzed. The subjects' cutting quality was also calculated. With the FS, the nondominant hand showed improved S, better D, and shorter P (P < 0.05). Better motion control in the dominant hand resulted from ES posture (P < 0.05). Better operation quality was associated with increased motion control in the nondominant hand. Forearm sup...

The Collaborative Medical and Behavioral Management of Chronic Cough

Perspectives on Voice and Voice Disorders, 2009

P6C-13 High Frequency Ultrasonic Characterization of Human Vocal Fold Tissue

Proceedings of the IEEE Ultrasonics Symposium

ABSTRACT

Transillumination for needle localization in the larynx

The Laryngoscope, 2015

Transillumination through laryngeal soft tissue may be used to direct percutaneous transcricothyr... more Transillumination through laryngeal soft tissue may be used to direct percutaneous transcricothyroid membrane subepithelial needle placement in the larynx. Cadaver simulation (canine and human). Lighted devices, including sialendoscopes and fiberoptic cables, were tested as transilluminating obturators in trocars and needles through multiple studies to identify appropriate illumination, monitoring, and equipment for successful localization of needle/trocar tips placed within laryngeal tissue. Lighted 250-micron fiberoptic cables within 23-gauge needles were successfully placed percutaneously through the cricothyroid membrane and maneuvered submucosally into Reinke&amp;amp;amp;amp;amp;amp;amp;amp;#39;s space, the midlateral vocal fold, and through the thyroarytenoid gap with monitoring via flexible transnasal laryngoscopy. Technical adaptations in the course of study permitted successful simulation of clinical use in full cadaver study for accurate injection laryngoplasty, confirmed by laryngeal dissection following collagen injection. Small caliber fiberoptic cables are useful as transilluminating obturators to accurately direct needle position within laryngeal tissue. Clinical application of this new technique is anticipated to improve the accuracy of percutaneous needle localization in the larynx, as well as to assist in directed instrumentation of the larynx from an external approach. N/A. Laryngoscope, 2015.

Is mitomycin C useful as an adjuvant therapy in endoscopic treatment of laryngotracheal stenosis?

The Laryngoscope, 2015

The effect of upper airway surgery on voice

Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery, 2002

Our goal was to assess patient perception and acoustic characteristics of voice before and after ... more Our goal was to assess patient perception and acoustic characteristics of voice before and after upper airway surgery. We conducted a prospective assessment of 44 surgical patients preoperatively and postoperatively at a tertiary care, academic hospital. Operations included septoplasty and turbinectomy (n = 28) and septoplasty, turbinectomy, uvulopalatopharyngoplasty, and tonsillectomy (n = 16). Patient opinion measures included Voice Handicap Index score, perception of vocal resonance, and change in voice. Acoustic measures included assessment of the relative amplitude of selected formants (resonances) of the vocal tract. Mean Voice Handicap Index scores were unchanged after surgery. Nine patients (20%) perceived their voice to be improved after surgery. None perceived the voice to be worse. Postoperative changes in relative formant amplitudes were statistically significant. These changes caused the acoustic features to become more representative of normative data than the preopera...

A Laryngeal Dissection Station: Educational Paradigms in Phonosurgery

by James Kobler and Seth Dailey

The Laryngoscope, 2004

Objectives: To introduce a new tool for phonosurgical training and education. A multitude of inno... more 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 mod-els of residency training and recertification.

Office-Based Pulsed Dye Laser Treatment for Hemorrhagic Telangiectasias and Epistaxis

The Laryngoscope, 2003

ABSTRACT

Pharmacotherapy of UES Spastic Disorder

Principles of Deglutition, 2012

Aerodynamic, Acoustic, and Vibratory Comparison of Arytenoid Adduction and Adduction Arytenopexy

The Laryngoscope, 2008

Adduction arytenopexy (AP) with thyroplasty provides improved physiologic placement of the vocal ... more Adduction arytenopexy (AP) with thyroplasty provides improved physiologic placement of the vocal fold and therefore provides improved acoustic, aerodynamic, and vibratory function as compared with arytenoid adduction (AA) with thyroplasty. Five cadaveric human larynges were prepared by removing supraglottic tissues and fixing the nontest vocal fold medially on the cricoid facet with a needle in a physiologic phonating position. Each test vocal fold was then sequentially tested using an excised larynx phonation system, first with AA with silastic medialization and then converted to AP without changing the contralateral fold position or silastic wedge. The excised larynx setup allowed for simultaneous collection of data, specifically subglottic pressure (including measurement of phonation threshold pressure [PTP]), mean airflow, acoustic output, and full-frame high-speed digital video. Aerodynamic evaluation was similar for each group with similar subglottic pressure versus output curves. Conditions involving AP typically had PTP values that were 80% of that for comparable AA conditions. Acoustic evaluation revealed differences between the two groups. Each AA was found to be vibrating with two dominant frequencies with their associated harmonics. Each AP vibrated at a single dominant frequency with its harmonics. AP provides improved vocal outcomes by decreasing system noise and decreasing PTP, which may lead to a stronger glottal signal with decreased vocal effort.

Technique of En Block Laser Endoscopic Frontolateral Laryngectomy for Glottic Cancer

The Laryngoscope, 2004

During the last 30 years, there has been expansion of the role of endoscopic partial laryngectomy... more During the last 30 years, there has been expansion of the role of endoscopic partial laryngectomy procedures since Jako, Strong, and Vaughan explored the possibilities of CO2 laser microlaryngeal procedures. Despite the fact that a number of investigators have verified the validity of endolaryngeal laser resection of mid-sized glottic cancer, there are many who are unfamiliar with the technique and others who are uncomfortable with sectioning the tumor to facilitate its resection. In the past 3 years, 15 patients underwent successful en block resection of mid-sized glottic cancer (T1b 2, T2b 11, T3 2). Because en block resection is more consistent with open oncologic approaches, this method should widen the acceptance of this approach in selected lesions. The nuances of en block endoscopic frontolateral laryngectomy are presented with the hope that more surgeons will adopt this philosophy as an aspect of their armamentarium.

Vocal fold reconstruction: A novel flap

The Laryngoscope, 2013

Assessment of fine needle aspiration feasibility and specimen adequacy for molecular diagnostics of benign vocal fold lesions

The Laryngoscope, 2013

The use of molecular testing is becoming more significant for the diagnosis and classification of... more The use of molecular testing is becoming more significant for the diagnosis and classification of disease. The application of fine-needle aspiration (FNA) biopsy as the means of sampling lesions in union with molecular testing could be a powerful combination in laryngology. The objectives of this study were to investigate 1) if FNA was feasible to sample benign vocal fold lesions; 2) if FNA samples provided sufficient RNA quality for molecular analysis; and 3) if gene expression of FNA samples matched paired surgical excised specimens. Prospective cross-sectional. Fifteen vocal fold specimens were obtained from adult patients undergoing routine surgical removal for benign vocal fold lesions using FNA and surgical excision. Comparisons were made between FNA and excision biopsies for RNA quality. Correlative analysis was completed for RNA expression of nine genes, including decorin (DCN), connective tissue growth factor (CTGF), vascular endothelial growth factor (VEGF), collagen type VI alpha 3 (COL6A3), superoxide dismutase 1 (SOD1), glutathione S-transferase (GST2), collagen type I alpha 2 (COL1A2), ATP binding cassette (ABC), and procollagen I alpha 1 (COL1A1). FNA and excision samples demonstrated similar RNA quality (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 0.05). Per gene expression, four out of nine genes were moderately correlated between the paired samples (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.05). FNA of the vocal fold lamina propria is technically feasible to perform. Further improvement in the FNA technology is desirable to optimize RNA quality for reliable gene expression analysis.

Evidence-based management of hoarseness (dysphonia)

Otolaryngology - Head and Neck Surgery, 2009

... Evidence-based management of hoarseness (dysphonia) Seth Schwartz, MD, MPH (moderator); Richa... more

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Recommendations of the Neurolaryngology Study Group on laryngeal electromyography

by Seth Dailey, Clark Rosen, Henri Ford, and Andrew Blitzer

Otolaryngology - Head and Neck Surgery, 2009

The Neurolaryngology Study Group convened a multidisciplinary panel of experts in neuromuscular p... more The Neurolaryngology Study Group convened a multidisciplinary panel of experts in neuromuscular physiology, electromyography, physical medicine and rehabilitation, neurology, and laryngology to meet with interested members from the American Academy of Otolaryngology Head and Neck Surgery, the Neurolaryngology Subcommittee and the Neurolaryngology Study Group to address the use of laryngeal electromyography (LEMG) for electrodiagnosis of laryngeal disorders. The panel addressed the use of LEMG for: 1) diagnosis of vocal fold paresis, 2) best practice application of equipment and techniques for LEMG, 3) estimation of time of injury and prediction of recovery of neural injuries, 4) diagnosis of neuromuscular diseases of the laryngeal muscles, and, 5) differentiation between central nervous system and behaviorally based laryngeal disorders. The panel also addressed establishing standardized techniques and methods for future assessment of LEMG sensitivity, specificity and reliability for identification, assessment and prognosis of neurolaryngeal disorders. Previously an evidence-based review of the clinical utility of LEMG published in 2004 only found evidence supported that LEMG was possibly useful for guiding injections of botulinum toxin into the laryngeal muscles. An updated traditional/narrative literature review and expert opinions were used to direct discussion and format conclusions. In current clinical practice, LEMG is a qualitative and not a quantitative examination. Specific recommendations were made to standardize electrode types, muscles to be sampled, sampling techniques, and reporting requirements. Prospective studies are needed to determine the clinical utility of LEMG. Use of the standardized methods and reporting will support future studies correlating electro-diagnostic findings with voice and upper airway function.

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Clinical practice guideline: Hoarseness (Dysphonia)

Otolaryngology - Head and Neck Surgery, 2009

This guideline provides evidence-based recommendations on managing hoarseness (dysphonia), define... more This guideline provides evidence-based recommendations on managing hoarseness (dysphonia), defined as a disorder characterized by altered vocal quality, pitch, loudness, or vocal effort that impairs communication or reduces voice-related quality of life (QOL). Hoarseness affects nearly one-third of the population at some point in their lives. This guideline applies to all age groups evaluated in a setting where hoarseness would be identified or managed. It is intended for all clinicians who are likely to diagnose and manage patients with hoarseness. PURPOSE: The primary purpose of this guideline is to improve diagnostic accuracy for hoarseness (dysphonia), reduce inappropriate antibiotic use, reduce inappropriate steroid use, reduce inappropriate use of anti-reflux medications, reduce inappropriate use of radiographic imaging, and promote appropriate use of laryngoscopy, voice therapy, and surgery. In creating this guideline the American Academy of Otolaryngology-Head and Neck Surgery Foundation selected a panel representing the fields of neurology, speech-language pathology, professional voice teaching, family medicine, pulmonology, geriatric medicine, nursing, internal medicine, otolaryngologyhead and neck surgery, pediatrics, and consumers. RESULTS: The panel made strong recommendations that 1) the clinician should not routinely prescribe antibiotics to treat hoarseness and 2) the clinician should advocate voice therapy for patients diagnosed with hoarseness that reduces voice-related QOL. The

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Diagnostic and Therapeutic Pitfalls in Phonosurgery

Otolaryngologic Clinics of North America, 2006

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