A proposed reinterpretation and reclassification of aphasic syndromes

Background: Different classifications of aphasic disorders have been proposed over the years. During recent decades new approaches to aphasia study have been developed, suggesting that current aphasia classifications can and should be reconsidered. Aims: The purpose of this paper is to attempt to integrate contemporary knowledge about brain organisation of language and to propose a new aphasia classification. Main Contribution: It is emphasised that there are two fundamental forms of aphasia, which are linked to impairments in the lexical/semantic and grammatical systems of language (Wernicke-type aphasia and Broca-type aphasia, respectively). Grammar correlates with the ability to represent actions (verbs) and depends on what is known as Broca's area and its related brain circuits, but it is also related to the ability to quickly carry out the sequencing of articulatory movements required for speaking (speech praxis). Lexical/semantic and grammatical systems not only depend on different brain circuitries, but also on different types of memory and learning (declarative and procedural). Other aphasic syndromes do not really impair language knowledge per se, but rather peripheral mechanisms required to produce language (conduction aphasia and aphasia of the supplementary motor area), or the executive control of the language (extra-Sylvian or transcortical motor aphasia). Conclusions: A new classification of aphasic syndromes is proposed: primary ( or "central'') aphasias (Wernicke's aphasia-three subtypes- and Broca aphasia); secondary (or "peripheral'') aphasias (conduction aphasia and supplementary motor area aphasia); and dysexecutive aphasia (extra-Sylvian-transcortical-motor aphasia), are distinguished.