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Aphasia: Causes, Symptoms, Diagnosis, Treatment
Medical expert of the article
Aphasia is a disorder or loss of speech function - a violation of active (expressive) speech and its understanding (or its nonverbal equivalents) as a result of the defeat of speech centers in the cerebral cortex, basal ganglia or white matter containing the conductors connecting them. The diagnosis is made on the basis of clinical symptoms, data of neuropsychological and visualization (CT, MRI) studies. The prognosis depends on the nature and extent of the lesion, as well as on the age of the patient. Specific treatment of aphasia is not developed, but active correction of speech disorders contributes to a more rapid recovery.
Speech functions are mainly associated with the posterior upper sections of the temporal lobe, adjacent lower parts of the parietal lobe, lower lateral sections of the frontal lobe, and subcortical connections between these areas, usually in the left hemisphere, even in left-handed regions. Damage to any part of this conditionally united area of the brain (in case of an infarct, tumor, trauma or degeneration) leads to certain disturbances in the speech function. Prosody (stresses and intonation of speech, which gives it significance) is a function of both hemispheres, but sometimes violations are noted with isolated dysfunction of the subdominant hemisphere.
Aphasia should be distinguished from violations of speech development and from dysfunction of motor conducting paths and muscles that provide articulation of speech (dysarthria). Aphasia, to some extent conditionally, is divided into sensory and motor.
Sensory (receptive or aphasia Wernicke) aphasia is the inability to understand words or recognize auditory, visual or tactile symbols. It is caused by the defeat of the posterior regions of the temporal lobe of the brain of the dominant hemisphere and is often combined with alexia (a violation of the understanding of written speech). With expressive (motor or aphasia Broca) aphasia remain relatively intact understanding and understanding of speech, but the ability to speech formation is impaired. Motor aphasia is caused by a lesion of the posterior-inferior part of the frontal lobe. In this case, often noted agraphy (a disorder of the letter) and a violation of reading aloud.
Symptoms of aphasia
Patients with aphasia Wernicke fluently speak normal words, often including meaningless phonemes, but do not realize their meanings or relationships. As a result, verbal confusion or "verbal okroshka" arises. Patients with aphasia Wernicke, as a rule, know that their speech is incomprehensible to others. Wernicke's aphasia usually accompanies the narrowing of the right visual field, since the visual pathway passes near the affected area.
Patients with Broca's aphasia can understand and interpret words relatively well, but their ability to pronounce words is broken. Usually, the disease affects speech formation and writing (agraphy, dysgraphy), making it difficult for patients to communicate. Broca's aphasia can be combined with anomie (inability to name objects) and impaired prosodic (intonational components).
Diagnosis of Aphasia
Verbal communication usually makes it possible to identify the presence of coarse aphasia. The research conducted to identify specific disorders should include the study of spontaneous speech, naming, repetition, understanding, speech formation, reading and writing. Spontaneous speech is assessed by the following indicators: fluency, the number of spoken words, the ability to initiate speech, the presence of spontaneous mistakes, pauses for word selection, doubts, verbosity and prosody. Initially aphasia Wernicke can be mistaken for delirium. However, aphasia Wernicke - isolated verbal disorder in the absence of other signs of delirium (flickering consciousness, hallucinations, inattention).
A formalized cognitive study conducted by a neuropsychologist or speech therapist can reveal more subtle levels of dysfunction and help in planning treatment and assessing the available recovery potential. The specialists have a wide choice of different formal tests for the diagnosis of aphasia (for example, "Boston Aphasia Diagnosis", "Western Block of Aphasia Testing", "Boston Tests", "Nominative Test", "Test of Action Names", etc. ).
CT or MRI (with or without angiography) is performed to determine the nature of the lesion (infarct, hemorrhage, volumetric education). Further studies are conducted to clarify the etiology of the disease in accordance with the previously described algorithm.
Prognosis and treatment of aphasia
The effectiveness of treatment has not been reliably established, but most clinicians believe that attracting a professional speech therapist in the earliest stages of the disease gives the best results: the earlier treatment is begun, the more chances of success.
The degree of recovery also depends on the size and location of the lesion, the degree of speech disorders and, to a lesser extent, on the age, education level and general health of the patient. Virtually all children under the age of 8 years of speech function is restored completely after severe damage to any of the hemispheres. At a later age, the most active recovery occurs within the first three months, but the final stage can last up to 1 year.