Neurogenic Lesions In The Cricothyroid Muscle In Idiopathic Vocal Cord Paresis

Abstract

EMG recordings were made from the cricothyroid muscle in 9 patients with idiopathic vocal cord paresis. In 8 patients the paresis was unilateral; in one it was bilateral. One EMG examination was made in each case at 1-17 months after onset of symptoms, except in 2 cases in which two or three repeated examinations were made at different stages of the disease. The muscle action potentials were compared with those of healthy cricothyroid muscles and with those of the ipsilateral vocal muscle. From the cricothyroid muscle, in 8 patients, potentials typical of reinnervation were encountered among some normal potentials. In one patient, all potentials were of normal type but the interference pattern was incomplete. In the vocal muscle there were signs of conduction block, denervation or reinnervation. The findings show that neurogenic lesions frequently appear both in the cricothyroid and in the vocal muscle in idiopathic vocal cord paresis.