LIMITATIONS OF ELECTROMYOGRAPHY AND MAGNETIC STIMULATION FOR ASSESSING LARYNGEAL MUSCLE CONTROL

The development of new phonosurgical techniques has increased the leve l of interest in the field of neurolaryngology. This field requires va lid techniques for determining if muscle activation is normal. Larynge al electromyography is being used more frequently to assess muscle inn ervation and synkinesis. Further, magnetic stimulation has been introd uced as a noninvasive technique for nerve stimulation. Technical limit ations that affect the clinical utility of both these techniques are r eviewed: 1) difficulties obtaining selective and accurate electromyogr aphic laryngeal muscle recordings. 2) normal variation in movement and muscle activation patterns within and between normal individuals when producing the same speech syllables, and 3) variation in laryngeal mu scle response latencies between and within normal subjects during peri pheral magnetic stimulation. Given the normal variation in laryngeal e lectromyography and magnetic stimulation response latencies, these tec hniques may not yet be reliable or accurate for assessing reinnervatio n or synkinesis following recurrent laryngeal nerve injury.