Mount Sinai Researchers Use Sensory Mapping to Define Sensitivity Variations in Human Voice Box
Study Could Lead to Better Diagnosis and Treatment of Diseases Affecting the Larynx
In a first-of-its-kind study, Mount Sinai researchers have used sensory mapping to discover that the posterior part of the larynx (closest to the swallowing tract) is the main area of the voice box to protect the airway from potentially dangerous swallowed or inhaled substances. This novel finding can potentially help doctors better understand and manage diseases affecting the larynx and lead to new, targeted treatments. The results of this study have been published in the June online edition of The Laryngoscope.
“The human voice box ('larynx') is arguably one of the most life-sustaining organs in the body, yet there is still much we don’t know about its basic functions. This study sheds light on a critical protective function of the larynx that we have not had definite proof of until now,” explained author Catherine Sinclair, MD, FRACS, Assistant Professor of Otolaryngology at the Icahn School of Medicine at Mount Sinai. “Understanding this aspect of basic larynx physiology is essential to help us diagnose laryngeal disease, manage it appropriately, and create new therapies.”
Dr. Sinclair, along with Sedat Ulkatan, MD, Director of Intraoperative Neurophysiology at Mount Sinai West, and Maria Tellez, MD, Neurophysiologist at Mount Sinai West, started this research to find out if different areas of the human larynx had different abilities to elicit a protective airway reflex termed the “laryngeal adductor reflex” (LAR), which is an involuntary protective response to stimuli in the larynx. This is important because many conditions affecting the larynx, including cancer, reflux, laryngomalacia ('soft larynx' in infancy), and laryngospasm (uncontrolled contraction of the larynx), likely impair or over activate our ability to elicit the LAR, which in turn can impair airway protection, putting patients at increased risk of aspiration and pneumonia.
Researchers analyzed 10 patients while under general anesthesia. All had normal laryngeal function. The team used a probe to deliver a low-intensity electric stimulus to different areas of the larynx and recorded whenever this stimulus was able to elicit the LAR and cause vocal cord contraction. They discovered that stimulation of the back part of the larynx produced vocal cord contraction in all patients. No other areas of the larynx produced consistent results. This proved that the back of the larynx is a highly sensitive area and the one to most easily elicit the LAR. Before this study, it was widely known that if patients had the back part of their voice box removed or affected by certain diseases, they had a more difficult time protecting their airway. The research showed at a physiological level why that is the case. Researchers also found that the vocal folds themselves do not elicit a reflex to low-intensity stimulations.
“This knowledge is essential to facilitate our accurate diagnosis and treatment of a variety of upper-airway diseases. These results will allow us to refine existing and develop new techniques for the diagnosis of diseases such as aspiration, dysphagia, and laryngospasm,” said Dr. Sinclair. “The study results may also give us insight into unexplainable diseases including sudden infant death syndrome (SIDS). We hope to use the results of this study to develop new diagnostic tests for laryngeal diseases.”
“This study will help to transform our current understanding of the protective function of the larynx, conceivably opening new exploration opportunities in various human respiratory disorders such as SIDS and patients with high risk of aspiration undergoing general anesthesia,” said Dr. Ulkatan. “We will be able to explore new diagnostic tests and possibly some therapeutic neuromodulation due to the new groundbreaking physiologic principles uncovered in this research,” added Dr. Tellez.
About the Mount Sinai Health System
The Mount Sinai Health System is New York City's largest integrated delivery system, encompassing eight hospitals, a leading medical school, and a vast network of ambulatory practices throughout the greater New York region. Mount Sinai's vision is to produce the safest care, the highest quality, the highest satisfaction, the best access and the best value of any health system in the nation. The Health System includes approximately 7,480 primary and specialty care physicians; 11 joint-venture ambulatory surgery centers; more than 410 ambulatory practices throughout the five boroughs of New York City, Westchester, Long Island, and Florida; and 31 affiliated community health centers. The Icahn School of Medicine is one of three medical schools that have earned distinction by multiple indicators: ranked in the top 20 by U.S. News & World Report's "Best Medical Schools", aligned with a U.S. News & World Report's "Honor Roll" Hospital, No. 12 in the nation for National Institutes of Health funding, and among the top 10 most innovative research institutions as ranked by the journal Nature in its Nature Innovation Index. This reflects a special level of excellence in education, clinical practice, and research. The Mount Sinai Hospital is ranked No. 18 on U.S. News & World Report's "Honor Roll" of top U.S. hospitals; it is one of the nation's top 20 hospitals in Cardiology/Heart Surgery, Gastroenterology/GI Surgery, Geriatrics, Nephrology, and Neurology/Neurosurgery, and in the top 50 in six other specialties in the 2018-2019 "Best Hospitals" issue. Mount Sinai's Kravis Children's Hospital also is ranked nationally in five out of ten pediatric specialties by U.S. News & World Report. The New York Eye and Ear Infirmary of Mount Sinai is ranked 11th nationally for Ophthalmology and 44th for Ear, Nose, and Throat. Mount Sinai Beth Israel, Mount Sinai St. Luke's, Mount Sinai West, and South Nassau Communities Hospital are ranked regionally.