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Annals of Otology, Rhinology & Laryngology

2014, Vol. 123(4) 271–278

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DOI: 10.1177/0003489414525022

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Article

Introduction

Laryngeal electromyography (LEMG) is commonly used

for the assessment of neuromuscular disorders of the lar-

ynx.

Laryngeal electromyography is the only direct mea-

sure of laryngeal muscle activity, and although it provides

general information about the function of the laryngeal

musculature, its in-office clinical utility beyond general

appreciation of gross neuromuscular function is debat-

able.

2,3

Studies regarding clinical usefulness of LEMG have

not addressed the question of LEMG reliability both within

a patient and across clinical testing sessions. Nonclinical

and experimental investigations using LEMG have the

advantage of signal processing software, control of environ-

mental conditions to reduce electromagnetic field noise,

tasks that provide graded control of laryngeal muscle

recruitment, and less constrained time frames under which

to perform LEMG. Because many variables may affect

LEMG reliability, it remains unknown whether clinical

office-based LEMG, often performed qualitatively, without

vocalization control parameters and under less than optimal

recording conditions, can be considered a reliable and clini-

cally meaningful diagnostic tool.

Laryngeal electromyography has been used for research

and assessment of the function of the intrinsic laryngeal

muscles for more than 60 years and has been shown to be

useful in revealing the function of the laryngeal muscula-

ture and demonstrating the dynamic control of this muscu-

lature during voicing.

4-7

Laryngeal electromyography is

frequently used in conjunction with stroboscopic/

525022

AOR

XXX10.1177/0003489414525022Annals ofOtology,Rhinology&Laryngology

Croake et al

research-article

2014

College of Health Sciences, University of Kentucky, Lexington,

Kentucky, USA

College of Medicine, University of Kentucky, Lexington, Kentucky, USA

Corresponding Author:

Daniel J. Croake, MM, MS, Department of Rehabilitation Sciences,

College of Health Sciences, University of Kentucky, Room 120H

Wethington Building, 900 South Limestone Street, Lexington, KY 40536-

0200, USA.

Email:

djcroa2@uky.edu

Reliability of Clinical Office-Based

Laryngeal Electromyography

in Vocally Healthy Adults

Daniel J. Croake, MM, MS

, Joseph C. Stemple, PhD

, Timothy Uhl, PhD

Sanford Archer, MD, FACS, FAAOA

, and Richard D. Andreatta, PhD

Abstract

Objective:

This study aimed to conduct a 3-session reliability assessment of the laryngeal electromyography (LEMG)

signal in healthy participants during intensity controlled vocalization tasks. We hypothesized that vocal intensity level and

testing session would affect LEMG measures.

Methods:

This prospective study used a 2-factor repeated measures design. Seven participants underwent bipolar needle

LEMG of the right thyroarytenoid muscle. Data were collected over 3 testing sessions using vocalization tasks performed

with visually guided intensity feedback targets (65 and 75 dB SPL). Root mean square amplitudes in microvolts were

analyzed for within-session and between-session reliability.

Results:

The main effect for intensity was found to approach significance (

= 5.71,

= .054). However, intraclass

correlation coefficients (ICCs) using a 2-factor mixed random effect model indicated poor to fair signal reliability between

testing sessions (ICC = 0.56 at 65 dB, 0.40 at 70 dB). Intraclass correlation coefficients for within-session data indicated

excellent reliability for all testing conditions (0.84–0.98).

Conclusion:

Using a quantitative analysis protocol to inform an essentially qualitative technique, our results indicated

that there was generally poor to fair reliability in the LEMG signal over testing sessions. Vocal intensity was an important

variable that affected LEMG signal reliability. Standardization of LEMG protocols using vocal control parameters and

quantitative analyses may help improve LEMG reliability in clinical settings.

Keywords

LEMG, motor units, neuromuscular, thyroarytenoid

Reprinted by permission of Ann Otol Rhinol Laryngol. 2014; 123(4):271-278.