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Otolaryngology Residency Program

Laryngeal Pacing for Vocal Cord Paralysis

                                                                           

Dr. David Zealear, has led research efforts employing  functional electrical stimulation as a new method of treating laryngeal paralysis.   Within recent years, renewed interest has arisen for this research as a potentially useful treatment for patients with bilateral vocal fold paralysis, a life-threatening problem. When both sides of the larynx are paralyzed, the patient can no longer open his vocal folds for ventilation, so a tracheotomy must be made in the neck or the vocal fold surgically resected to restore breathing through the mouth, which destroys the voice and impairs swallowing. Dr. Zealear introduced a new, more physiological approach to treatment termed “laryngeal pacing”. It involves stimulation of the laryngeal muscles to open the vocal folds during inspiration. During non-inspiratory phases, the vocal folds passively relax back to the midline to allow normal voice production and swallowing. In order to bring laryngeal pacing into the clinical arena, Dr. Zealear has led animal studies to determine parameters effective for stimulation of denervated muscle. In 1994, Dr. Zealear conducted the first trial of laryngeal pacing in a patient using an external device, which prompted a biomedical company (Medtronic, Inc.) to initiate FDA trials with an implantable laryngeal pacemaker.   Serving as principal investigator on the project, Dr. Zealear directed the first successful implant of a laryngeal pacemaker in the United States in 1996. Ultimately, seven patients were implanted worldwide with this device. Results were promising, and a new generation pacemaker is currently under investigation (St. Jude Medical—Neuro Division). A human trial with this new device is currently underway.

             
 During Dr. Zealear’s studies of laryngeal muscle stimulation, he became interested in the possibility that electrical stimulation may effect the manner in which regenerating motor neurons reconnect to the muscle. Studies have previously shown that when muscles of the head and neck become paralyzed from nerve injury, the nerve regeneration is often faulty, so that the rewiring of muscles becomes criss-crossed. In this instance the patient cannot make meaningful movements and remains paralyzed. Dr. Zealear’s studies have now proven conclusively that electrical stimulation of a paralyzed denervated muscle increases the chances that it becomes rewired correctly, so that the brain regains natural control over the muscle. These results may have significance to other nerve-muscle systems of the body and provide a means for patients with various types of paralysis to regain the capacity to move again in a coordinated fashion.           

 

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