Aphasia and dysphasia are language associated conditions. Specific regions of the brain control the understanding, written and spoken language. Frontal lobe and temporal lobe of the brain contains two of these key areas. According to these anatomical and functional relationships, neuroscientists divide aphasia and dysphasia into many sub categories. In essence, aphasia and dysphasia are two levels of severity of the same condition. In medical terminology, the prefix “a” means an absence while the prefix “dys” means an abnormal. For example, amenorrhea means a lack of menstruation while dysmenorrhea means abnormal menstruation.
Aphasia is a total disruption of understanding and forming language. The area close to the left temporal lobe in the pre-motor cortex of the left frontal lobe is the Brocha’s area. Damage to this area disrupts speech production. This is called expressive aphasia because the patients can understand speech well enough. Only verbal expression is disordered. They produce very short meaningful phrases with great difficulty. Often they know of their mistakes and are frustrated by it. There is right sided weakness in patients with expressive aphasia because the same brain area is important for controlling movements of the right side of the body too.
An area on the temporal lobe close to the parietal lobe is called Wernicke’s area. This area is responsible for understanding spoken and written language. Damage to this area causes receptive aphasia. This is called receptive aphasia because the patients can formulate sentences without any grammatical errors, but they cannot convey the meaning. Only the reception of meaning is disordered, but their expression is normal. Understanding written and spoken language is very difficult for them. They tend to add unnecessary words into sentences and create new words. They are usually unaware of their mistakes. These people do not have associated body weakness because, the Wernicke’s area is nowhere near the areas responsible for gross motor functions.
Conduction aphasia is a rare form of aphasia. Patients cannot repeat what was specifically said, but understanding, talking, and writing are normal. Trans cortical motor aphasia is due to damage to anterior superior frontal lobe. Patients have very short halting speech with good language understanding. Essentially, its symptoms are similar to expressive aphasia except normal repetition ability. Stroke is the commonest cause of this aphasia. Trans cortical sensory aphasia has similar symptoms as receptive aphasia, except for normal repetition ability. Anomic aphasia features a total disruption of naming. Global aphasia includes both expressive and receptive disorders.
Stroke, brain tumors, progressive neurological conditions like Alzheimer’s disease and Parkinsonism, intra-cerebral bleeding, and encephalitis are known causes of aphasia.
What is the difference between Aphasia and Dysphasia?
• There is only one difference between aphasia and dysphasia. Aphasia means a total disruption while dysphasia means a moderate disruption.
• When the above mentioned conditions are very severe to the point of total loss of speech the term aphasia is used.
• When the conditions are of moderate severity, without total speech disruption, dysphasia is used.
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