Patterns of hemispheric compromise in primary progressive apraxia of speech: From clinical profiling to differential diagnosis.

In this issue of European Journal of Neurology, Robinson et al. present a novel study on primary progressive apraxia of speech. The authors describe different clinicopathological profiles in patients with left-dominant, right-dominant, and bilateral atrophy of the supplementary motor area and lateral premotor cortex. This commentary discusses the importance of this evidence to understand individual differences among these patients, distinguish them from those with nonfluent variant primary progressive aphasia, and reflect on the relations between motor speech deficits and underlying pathology.