Procedure May Lead to Better Treatment for Children with Vocal Cord Paralysis

Newswise — The human larynx is essential for breathing and vocalizing, and when damaged, an emergency tracheotomy may be necessary to ensure survival. Vocal cord paralysis (laryngeal paralysis) is the second most common congenital irregularity of the larynx, accounting for 15-20 percent of all cases. The most common treatment for laryngeal paralysis is a tracheotomy, a surgical hole placed in the windpipe below the larynx that allows airflow to the lungs.

Prolonged tracheostomy often leads to a multitude of severe challenges for both patient and family, and is by no means an ideal treatment. Children undergoing this procedure are generally tracheostomy-dependent for at least three years before surgery can be performed to remove the tube (decannulation), resulting in development problems and increased caregiver burden. Surgery to remove the tube is traditionally done inside the larynx and, because of the child's smaller anatomy, can be risky as it causes scaring and swelling of the airway, which could compromise airflow.

A new study proposes that manipulating a structure outside the larynx is a safe and effective alternative that may allow tracheostomy-dependent children to be free of their breathing tube earlier in life. The study authors, Brian Rotenberg, BSc, MD, Sam Daniel, MD, FRCS, and Vito Forte, MD, FRCS, of the Hospital for Sick Children in Toronto, Ontario, Canada, propose that removal of the cricothyroid muscle (CTM - muscles of the larynx affecting the vocal cords), adjacent to the larynx, will indirectly widen the paralyzed glottis (the space between the vocal cords). This action restores voice and airflow through the larynx and eliminates the need for a tracheotomy tube. Results of their study will be presented in the study titled, "Pediatric Laryngeal Paralysis: A New Proposed Surgical Therapy" at the Mid Winter Meeting of the Association for Research in Otolaryngology (www.aro.org) being held February 22-26, 2004, at the Adam's Mark Hotel, Daytona Beach, FL.

Methodology: A prospective study was conducted using a piglet animal model to simulate laryngeal paralysis (LP) and evaluate the proposed treatment's outcome. The laryngeal structure of piglets is closely related to that of human children. The cricothyroid muscles (CTMs) of 11 piglets with LP were removed. Animals acted as their own controls. Outcome measures consisted of serial inspiratory (breathing in) and expiratory (breathing out) airflow resistance measurements taken (1) with no intervention (as a baseline control); (2) after recurrent laryngeal nerve (RLN) sectioning; and (3) after CTM removal. Several animals were awakened to asses their clinical responses to the interventions. The paired Student t-test was used for statistical analysis. Results: Inspiratory airflow resistance was significantly increased by RLN sectioning and then significantly decreased after subsequent CTM removal. Clinical responses to the interventions mirrored the measured findings.

Conclusion: Removal of the CTM significantly reduces inspiratory airway resistance in piglets with LP. This effect is seen as a measurable decrease in laryngeal airflow resistance as well as in clinical observations of piglets' perioperative behaviors. The relevance of this animal study may be that for the young human patient, this procedure is easily undertaken, is safe, and potentially avoids the pitfalls and complications of current intralaryngeal surgical procedures. These findings suggest that this procedure warrants further investigation to assess its potential in treating intractable pediatric LP and/or hastening tracheotomy removal.