Neural Basis of Coexisting Swallowing and Communication Disorders after Stroke

Johns Hopkins University, Baltimore MD

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Abstract

DESCRIPTION (provided by applicant): Sharing a conversation over a meal is one of the most common ways we have of interacting with family and friends. Neurologic diseases, most prominently stroke, can cause speech, language, and swallowing deficits which have a great impact on how we interact with others and limit how we participate in society. Since communication and swallowing can be affected, separately or together, in patients with neurologic disease the extent of overlap or relatedness in the brain networks controlling these functions is of paramount importance. The main research goal of this proposal is to identify the neuro-anatomical locations associated with the coexistence of specific types of speech, language and/or swallowing disorders, as opposed to those that are only relevant to one, and to determine the role of acute stroke severity and volume in the development of dysfunction. The main training goal is to acquire focused training in high level MRI image analysis (including voxel based analysis), neuroscience, cognitive neuropsychology of language, and communication disorders. To achieve the research goals we propose the following: 1) to determine if the coexistence of swallowing, speech and language dysfunction is associated with distinct neuro-anatomical locations; and 2) To identify associations and dissociations between specific types of aphasia, types of motor speech deficits (dysarthrias and apraxia of speech), and affected swallowing stages (oral, pharyngeal and esophageal). Using acute stroke as a focal injury model we will determine which of these functions are affected in a particular case and identify associations between deficits and specific areas of dysfunctional tissue identified on MRI (diffusion and perfusion imaging). We hypothesize that dysphagia and dysarthria will be associated with unilateral focal brain lesions in several subcortical and brainstem locations, but aphasia and apraxia of speech (with or without dysarthria) co-occur only with posterior frontal tissue dysfunction. Understanding these brain-function relationships is critical for early diagnosi and treatment of stroke patients, particularly for the use of therapies such as tDCS which must target specific neural structures. Furthermore, if neural networks involved in specific speech, language, and swallowing behaviors are shared, interventions for one may result in improvements in the other. More broadly, understanding the brain-function relationships between each of these functions is a step towards developing a full understanding of the neural control of speech, language, and swallowing and will be foundational for the diagnosis and management of these problems.