Comparison of Evoked Electromyography of the Larynx to Electrical and Magnetic Stimulation of the Motor Cortex of the Dog

Abstract

The electromyographic and contractile properties of the laryngeal muscles upon stimulation of the laryngeal nerve have been described before. In the present investigation, we used electrical and magnetic stimulation to activate the vocalis muscle in dogs. Stimulation of the vagus nerve at the brain stem exit point resulted in evoked vocalis compound muscle action potential identical in onset latency and configuration to that obtained by the transcranial single-shock magnetic stimulation at high intensity (greater than 80%). Electrical stimulation of the laryngeal representation of the somatomotor cortex resulted in a contralateral evoked vocalis compound muscle action potential. Central delay time for the 10th cranial nerve was calculated by subtracting the latency of the vocalis recorded by stimulation of the vagus nerve as it exited the brain stem from the latency obtained by direct cortical stimulation.