An Update on Apraxia of Speech

Abstract

Purpose of review: Apraxia of speech (AOS) is a motor speech disorder that has long been recognized to occur secondary to acute neurologic insults and, more recently, to neurodegenerative diseases as a harbinger for progressive supranuclear palsy and corticobasal syndrome. This article reviews recent findings regarding the clinic phenotypes of AOS, neuroimaging correlates, and the underlying disease processes.

Recent findings: Two clinical subtypes of AOS map onto two underlying 4-repeat tauopathies. New imaging techniques have recently been applied to the study of progressive AOS. There is no data on the impact of behavioral intervention, although studies of nonfluent/agrammatic primary progressive aphasia that include patients with AOS suggest some benefit in speech intelligibility and maintenance. While recent findings suggest subtypes of AOS exist that are linked to molecular pathology and have important implications for disease progression, further research is needed to assess outcome of behavioral and other types of intervention.

Keywords: Apraxia of speech; Corticobasal syndrome; Degenerative disease; Phonetic; Progressive supranuclear palsy; Prosodic; Tauopathy.

Figure:

[¹⁸F] fluorodeoxyglucose PET (FDG-PET) demonstrating hypometabolism mainly in the right and left premotor and supplementary motor areas. The left hemisphere is slightly more affected than the right hemisphere and there is subtle extension of hypometabolism into left middle and inferior frontal cortex.