Distinguishing among motor speech disorders is important: The role of speech pathology in neurologic diagnosis

The contribution that distinguishing among motor speech disorders (MSDs) can make to the localization and diagnosis of neurological disease is frequently ignored by medicine and, at the least, underappreciated by speech-language pathology. This is of no small consequence because speech abnormalities can be the presenting or most prominent sign of neurologic disease. This chapter addresses the relationship between the differential diagnosis of acquired MSDs and the localization and diagnosis of neurologic disease. It highlights the clinical reality of the relationship through five case studies and a summary of the specific lessons they provide that illustrate the sometimes crucial importance of recognizing the meaning of speech signs in clinical diagnostic settings. The chapter reviews foundations on which such clinical contributions have been built, and a few examples of recent studies of dysarthria or apraxia of speech associated with neurodegenerative disorders (paraneoplastic cerebellar degeneration, tauopathies) that are helping to refine those abilities. Finally, it offers some thoughts about how future clinical practice and training, and clinical and more basic research, can improve the contributions that MSD diagnosis can make to medical diagnostic efforts in clinical practice.