Several aspects of speech disorders caused by frontal lobe damage

Abstract

  The underlying mechanisms of speech and language disorders due to the frontal lobe damage were considered, according to the three levels of verbal processing, that is motor speech disturbances, neurobehavioral and linguistic disturbances. Although error inconsistency has traditionally been considered an important characteristic of apraxia of speech (AOS) , it may be difficult to differentiate between AOS and other types of dysarthria by this criterion. Damage to white matter bundles such as the frontal aslant tract might play an important role as a major cause of the disturbance in speech initiation and spontaneity. Two cases with progressive non-fluent aphasia were presented. They were not able to construct a sentence from the given two words. Besides to word finding difficulty in running speech, and an inability to select one among many verbal expressions, the deficits of generating sentences might be one of major origins of non-fluent speech in aphasia due to frontal lobe damage.