Research: Limbic and Motor System Interactions in Laryngeal Function

Director: Douglas J. Van Daele, MD (douglas-van-daele@uiowa.edu)
Research Assistant: Steven Udelhofen, BSE (steven-udelhofen@uiowa.edu)

The neurolaryngology laboratory is dedicated to furthering our understanding of the neural control of the larynx. To this end, we are investigating the neuroanatomic connections between areas of the midbrain and cortex to the brainstem that have not typically been associated with motor control of the larynx. Evidence from animal studies has shown direct connections from frontal lobe structures to the facial nucleus that may play a role in the focal dystonia blepharospasm. Using neural tracers, we are searching for similar connections to brainstem regions associated with control of the larynx. Once the anatomic connections are more clearly identified, we will be better able to interpret functional neuroimaging studies in humans with normal and abnormal voicing patterns.

In addition, our laboratory is interested in the changes in muscle physiology that accompany denervation and occur after radiation treatments. Most previous investigators have used immunostaining with SDS-PAGE techniques to identify changes in fiber type. We have begun using quantitative real-time PCR to better understand the fiber type switching that occurs in response to change in neural input. We will then attempt to expand that technique for use in post-radiated tissue in order to compare changes in fiber type. Post-radiation therapy techniques can then be devised around re-arrangement of muscle fiber types.

Physical therapists are well versed in the benefits of neuromuscular electrical stimulation (NMES) for denervated tissue. Increasingly speech pathologists have begun using NMES to treat swallowing disorders. This has been an area of extreme controversy within the speech pathology community. There are several possible mechanisms for NMES to work including increasing sensory input, augmenting muscle activity through enhancement of muscle fiber type, brainstem retraining, and recruitment of motor units. A long-term interest of our lab is to study the changes in upper airway physiology associated with application of electrical stimulation.