Aphasia is a language function disorder that occurs following learning of speaking based on the damages arising as a result of vascular reasons (vein-oriented reasons), traumas or tumors, and that is not caused by a psychiatric problem or an inhibition in the muscular level.
Aphasia may occur due to any kind of focal (forming in a specific location or area) lesion affecting the left hemisphere of the brain. The most common cause of aphasia is the infarction occurring in the left medial (medium) cerebral artery. The other cause, however, is the hemorrhages that occur in the left medial cerebral artery irrigation areas. Temporary ischemic (a decrease in the local blood build-up of an area in the body) attacks, or even migraine can cause temporary speech disorders.
Cerebrovascular events are the prominent reasons of aphasias. In transcortical aphasias, infarctions located in the border areas of the zones irrigated by anterior, medial and posterior arteries appear as the cause of this type of aphasias. Following the cerebrovascular reasons, intracranial tumors, head traumas, some degenerative diseases, and infections affecting the left hemisphere can also be counted as the causes of aphasia.
Prognoses of the patients with infarctions are worse.
Aphasias are classified in two main groups: perisylvian and extra perisylvian aphasias. While Broca and Wernicke, Conduction and Global Aphasia are included in the perisylvian apahasia category, Transcorticalmotor, Transcortical sensory, Transcortical mixed aphasia are included in the extra perisylvian aphasia group.