COMPARISON OF CONCENTRIC NEEDLE VERSUS HOOKED-WIRE ELECTRODES IN THE CANINE LARYNX

BACKGROUND: The use of a specific electrode type in laryngeal electrom yography has not been standardized. Laryngeal electromyography is usua lly performed with hooked-wire electrodes or concentric needle electro des. Hooked-wire electrodes have the advantage of allowing laryngeal m ovement with ease and comfort, whereas the concentric needle electrode s have benefits from a technical aspect and may be advanced, withdrawn , or redirected during attempts to appropriately place the electrode. OBJECTIVES: This study examines whether hooked-wire electrodes permit more stable recordings than standard concentric needle electrodes at r est and after large-scale movements of the larynx and surrounding stru ctures. A histologic comparison of tissue injury resulting from placem ent and removal of the two electrode types is also made by evaluation of the vocal folds. METHODS: Electrodes were percutaneously placed int o the thyroarytenoid muscles of 10 adult canines. Amplitude of electro myographic activity was measured and compared during vagal stimulation before and after large-scale laryngeal movements. Signal consistency over time was examined. Animals were killed and vocal fold injury was graded and compared histologically RESULTS: Waveform morphology did no t consistently differ between electrode types. The variability of elec tromyographic amplitude was greater for the hooked-wire electrode (p < 0.05), whereas the mean amplitude measures before and after large-sca le laryngeal movements did not differ (p > 0.05). Inflammatory respons es and hematoma formation were also similar. CONCLUSIONS: Waveform mor phology of electromyographic signals registered from both electrode ty pes show similar complex action potentials. There is no difference bet ween the hooked-wire electrode and the concentric needle electrode in terms of electrode stability or vocal fold injury in the thyroarytenoi d muscle after large-scale laryngeal movements.