The speech function of most people, including left-handers, is mainly located in the left hemisphere, the posterior upper part of temporal lobe, the lower part of adjacent parietal lobe, the lower lateral part of frontal lobe, and the subcortical communication structure between these parts. The damage of any part of this roughly triangular area (such as infarction, tumor, trauma or degeneration) will hinder some aspects of speech function. Eating-slurring speech (dysarthria).
The dysfunction of receptive (sensory) aphasia lies in the understanding of written language and the recognition of related auditory, visual or tactile signals. There are several subtypes of receptive aphasia, including wernicke's aphasia: patients can speak normal words fluently, often mixed with meaningless words, but they have no understanding of their meaning and relationship. The result is a jumble of speeches or a mixed-word salad. Alexia is
The inferior frontal gyrus (Bullokar area) located in front of facial and lingual motor areas is damaged, resulting in expressive (motor) aphasia. The patient's ability to understand and conceive speech is relatively preserved, but the ability to express speech is hindered. Generally speaking, expressive aphasia will not only hinder oral English (speaking difficulty), but also affect writing (writing difficulty or writing difficulty), which will bring great frustration and disappointment to patients. Named aphasia refers to the inability to say the correct name of an object. It may stem from perception or expression disorder. The rhythm and intonation that add meaning to spoken language are usually influenced by two hemispheres, but sometimes it is only dominated by the secondary hemisphere.
The range of brain patients who can cause speech dysfunction is generally quite large, and rarely only causes simple disorders; Therefore, isolated receptive or expressive aphasia is rare. Extensive frontotemporal lesions cause comprehensive aphasia, which has serious obstacles in understanding and expression.
There have been some formal tests to diagnose aphasia (such as Boston Aphasia Diagnostic Examination), but usually the communication between doctors and patients at the bedside can provide enough clues. The unsmooth and hesitant speech expression (broca aphasia) indicates frontal lobe disorder. Wernicke's aphasia shows that the posterolateral part of the left temporal lobe and the speech area of the inferior parietal lobe are abnormal. Named aphasia reflects the abnormality or degeneration of the posterior part of temporal parietal lobe. While preserving spontaneous Wernicke-like aphasia.
Prognosis and treatment
The recovery of aphasia depends on several factors, including the size and location of the lesion, the degree of speech dysfunction, the patient's age, education level and general health status. The latter three factors have little relationship. Speech function of children under 8 years old can often be restored after severe unilateral hemisphere injury. After the age of 8, most of the speech function recovery occurs in the first three months after illness, but it can still make some progress within one year. As usual, the improvement of understanding ability is better than the improvement of expression ability. In about 15% of the population, the right hemisphere is the main hemisphere for hand use and speech function. Among these people, if a special injury occurs in the left or right hemisphere, it will lead to aphasia, but almost all of them can recover quickly.
There are different opinions on the treatment of aphasia. The existing evidence shows that the patients with the same speech disorder who are systematically treated by experienced speech disorder therapists have better improvement than those who are not treated. Generally speaking, the earlier the speech disorder is treated, the better the effect will be.