Non-fluent aphasias due to anterior cerebral lesions

Abstract

In order to explore the essential deficits which cause the non-fluent speech in aphasic patients with anterior cerebral lesions, recordings of speech samples and neuroimaging data in the transcortical aphasics due to frontal lobe damage were retrospectively reevaluated. Mesial frontal lobe lesions caused transcortical motor aphasia with severe aspontaneity of speech. Dorsolateral frontal lobe lesions were divided into two types. If the lesions spread anteriorly into the anterior portion of frontal lobe such as frontal pole or orbital portion of the inferior frontal gyrus, they caused typical transcortical sensory aphasia with fluent jargon-like speech backed by euphoria, inattention, and disinhibition. In cases with focal dorsolateral frontal lobe damage, some patients showed severe non-fluent speech with much hesitation and discontinuation. Their ability of naming objects were relatively preserved, and therefore, the association between meaning and lexical items was presumed to be spared. They were not able to, however, select one of multiple competitors all of which are properly activated, nor align them in good order. I speculate that severe non-fluent speech is attributable to the impairment of selection and sequencing that are served by dorsolateral frontal lobes.