Speech in Glossectomy Assessed by Tagged-MRI

Johns Hopkins University, Baltimore MD

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Abstract

This proposal describes a pathway to independence program for Emi Murano, M.D., Ph.D. The research component of the program is focused on the use of MRI and physiological modeling to help improve the management of glossectomy surgery for the treatment of oral tongue cancer. Oral cancers have the 7th highest incidence in the country;among them, oral tongue cancer has shown a recent 5 to 6-fold increase in incidence in younger adults ages 20 to 44 years and a twofold increase in older adults (Shiboski, 2005). Although the mortality rate of oral tongue cancer is not considered high, its morbidity is significant - causing speech, mastication and swallowing problems, which affect quality of life. The aims of this application are threefold. The first aim is to examine the effects of glossectomy surgery on tongue deformation strategies. These effects will be studied using a unique combination of detailed data on internal tongue deformation from tagged-cine-MRI and anatomy from high-resolution MRI and diffusion tensor imaging. The clinical goal of this work is to provide objective measurements of tongue function following surgical treatment. The second aim is to use the MRI data from glossectomy patients and normal controls to explore the occurrence of areas of internal rigidity and deformation in the tongue and how they interact with speech motor control. This investigation will be guided by a view of the tongue as a muscular hydrostat and hypotheses about the use of rigidities as a novel way of reducing the complexity of control strategies. The third aim is to simulate glossectomy tongue motion using a physiological/biomechanical model. These simulations, with subject-specific versions of the model, will be used to test our hypotheses, with the ultimate goal of providing a tool for exploring options for surgical management by surgeons, therapists and patients. This work will provide the following new knowledge: (1) Relations between surgical variables and outcomes such as tongue motion and speech quality, (2) Information about patterns of tongue rigidity and how they may constitute a mechanism for reducing the complexity of the motor control, (3) Model-based predictions of the effects of muscle resection and tongue motion during speech post-surgery.