In vivo modeling of acute external superior laryngeal nerve denervation using lidocaine block

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Publication Type thesis
School or College College of Health
Department Communication Sciences & Disorders
Author Barton, Michael Eric
Title In vivo modeling of acute external superior laryngeal nerve denervation using lidocaine block
Date 2008-07-10
Description The external branch of the superior laryngeal nerve (ESLN) innervates the cricothyroid (CT) muscle of the larynx, a vocal fold tensor primarily responsible for pitch elevation. For over 100 years, a controversy has existed regarding the laryngeal signs that should be considered pathognomonic of unilateral ESLN paralysis. Regrettably, little progress has been made in resolving this controversy, as the extant clinical literature is characterized by contradiction and inconsistency. Myriad descriptions exist of the laryngeal behaviors ostensibly associated with unilateral ESLN denervation. To address this longstanding controversy and improve diagnostic precision, this preliminary investigation aimed to model "in vivo" acute, unilateral CT dysfunction by temporarily blocking the ESLN using lidocaine hydrochloride (HCL), and verifying selective denervation using laryngeal electromyography (LEMG). The purpose of this investigation was twofold: (1) to identify the salient laryngeal features associated with acute denervation (i.e., the pathognomonic features of unilateral CT dysfunction), and (2) to identify a set of laryngeal tasks that maximally provoke or reveal ESLN dysfunction, thereby contributing to a set of diagnostic tasks/markers that will improve diagnostic accuracy during clinical assessment. Ten vocally normal adult males (mean age = 25 yrs.; range = 19 to 29 years) underwent lidocaine block of the right ESLN, and flexible videolaryngostroboscopic (FVLS) recordings were acquired before and during the block. Eleven blinded, expert judges (6 laryngologists and 5 Ph.D. speech-language pathologists) rated randomized, pre- vs. during-block recordings of 10 vocal tasks using standard FVLS rating protocols. Contrary to clinical reports, no evidence of hypomobility/sluggishness of the ipsilateral vocal fold, or a reliable pattern of axial rotation of the larynx during high pitch voice was observed. Furthermore, no evidence was observed to support reduced vocal fold longitudinal tension, aryepiglottic fold length asymmetry, phase asymmetry, vocal fold plane differences, or glottic insufficiency, as diagnostic features of unilateral CT dysfunction. Instead, the analysis revealed (1) a pattern of deviation of the petiole of the epiglottis to the side of weakness (i.e., the right) in 60% of participants during a glissando up maneuver produced at normal volume, and (2) a pattern of axial rotation of the posterior commissure to the left and the anterior commissure to right in 50% of participants during a maneuver which rapidly alternated between a maximum vocal fold abduction task (Sniff) and a high-pitched "ee" production. Both of these findings have not been previously reported elsewhere, and potentially represent new diagnostic markers of unilateral CT paralysis. The results are discussed with respect to their clinical implications, and the necessity to explore both females and clinical populations to better appreciate the clinical utility of these diagnostic signs.
Type Text
Publisher University of Utah
Subject Larynx--Innervation; Cricothyroid muscle
Dissertation Institution University of Utah
Dissertation Name MA
Language eng
Relation is Version of Digital reproduction of "In vivo modeling of acute external superior laryngeal nerve denervation using lidocaine block" Accompanying materials available, J. Willard Marriott Library Special Collections, RF21.5 2008 .B37
Rights Management © Michael Eric Barton
Format Medium application/pdf
Format Extent 53,904 bytes
Identifier us-etd2,126881
Source Original: University of Utah J. Willard Marriott Library Special Collections
Conversion Specifications Original scanned on Epson GT-30000 as 400 dpi to pdf using ABBYY FineReader 9.0 Professional Edition
ARK ark:/87278/s68p6f0j
Setname ir_etd
Date Created 2012-04-23
Date Modified 2021-05-06
ID 192609
Reference URL https://collections.lib.utah.edu/ark:/87278/s68p6f0j
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