New York Eye and Ear Infirmary
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Spasmodic Dysphonia

Principal Investigator: Rick Roark, Ph.D.

Enrollment: Open 

Objective: Spasmodic dysphonia is a symptomatic term used to identify a neurogenic disorder affecting voice and speech due to moderate to severe spasming of vocal fold musculature during phonation, otherwise referred to as spastic laryngeal dystonia. The disorder has been studied by many investigators; however the principal causative factors and extent of the involved neural mechanisms remain unknown. Our research team is applying the technology of Vector Laryngeal EMG to examine motor unit firing rate and recruitment patterns of thyroarytenoid muscle in persons with spasmodic dysphonia.

Overview: Faculty in the Department of Otolaryngology have long taken an interdisciplinary approach to the study of this complex neurological disorder/ This team includes a bioengineer, physicians, biostatistician and speech scientists. Analysis techniques that include simultaneous recording of multiple laryngeal and supralarygneal musculature, and analysis of recorded myoelectric signals using  time-frequency transforms, wavelets, principal components analysis, and statistical pattern recognition using state space parameterization were pioneering efforts among the first in the field of medical research. The development of vector laryngeal EMG had its beginning stimulus in the need to glimpse up the neural pathways due to inexplicable patterns noted in frequency phenomena observed in the muscle activities of spasmodic dysphonia patients.

Departmental Co-Investigators are Steven Schaefer, M.D., James CL Li, M.D., Lucian Sulica, M.D. and Craig Zalvan, M.D.

Eligibility: Research subjects are being recruited for this study. If you are a physician encountering patients with recent-onset spasmodic dysphonia, please contact Dr. Roark for participation details.

Contact Information: Rick Roark, Ph.D., (212) 979-4200

Funding: Funding for this research has been provided by the National Institutes of Health, the National Science Foundation, and the Hascoe Foundation.

Selected Publications & Presentations:

Roark, RM., Dowling EM, DeGroat RD, Watson BC, Schaefer SD. Time-Frequency analysis of thyroarytenoid myoelectric activity in normal and spasmodic dysphonia subjects, Journal of Speech and Hearing Research 1995, 38:289-303. [Abstract]

Roark RM, Li JC-L, Schaefer SD, Adam A, De Luca CJ. Multiple Motor Unit Recordings of Laryngeal Muscles: The Technique of Vector Laryngeal EMG. Laryngoscope 2002, 112:2196-2201. [Abstract]


Preliminary Results:

In the top figure, the "power content" of  thyroarytenoid muscle is analyzed in both frequency and time, whereby high-frequency phenomena is observed during and before spasmodic events at 3.5 and 5 seconds. The bottom figure is the same information plotted in the form of a two-dimensional "contour" plot. Whereas spasm had heretofore been viewed as principally an "amplitude" event, this study determined that investigations of the firing rate and recruitment of lower motoneurons of affected laryngeal musculature should be examined to determine the specific lower motor neural behavior of this disorder.

Related Information: Other Research Projects in Neurolaryngology




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