Amnestic aphasia
Amnestic aphasia is a variant of aphatic disorder in which the nominative function of speech breaks down. It is characterized by visual amnesia, forgetting the names of objects, speech pauses and difficulties in choosing words, verbal paraphasias. Diagnostics involves a neurological examination (cerebral MRI, MRA, ultrasound of the arteries of the head and neck), neuropsychological and speech therapy testing. Therapeutic and corrective work in aphasia includes etiopathogenetic pharmacotherapy, speech therapy, neurocorrection.
General information about Amnestic aphasia
Amnestic (nominative, anomalous) aphasia is accompanied by difficulties in visual recognition and verbal designation of objects. It was singled out in a separate form by the Soviet neuropsychologist A.R. Luria in 1973, pointing out that in this case, the only central defect is the difficulty in naming objects. Later, amnestic aphasia was excluded from the neuropsychological classification, since it is rare in its pure form, usually serving as a symptom of acoustic-mnestic or semantic aphasia. In modern aphasiology, amnestic aphasia is again considered as an independent unit – its frequency among all forms is 4.2-7.5%.
The reasons
Amnestic disorders occur with local lesions of the posterior-lower parts of the temporal cortex and the parieto-occipital regions of the left hemisphere (20, 21, 37, and 40 of Brodmann’s field). The causes of amnestic aphasia in most cases are:
- cerebral infarction in the pool of the posterior cerebral artery;
- open head injury ;
- intracerebral hematoma ;
- tumors of the cerebral hemispheres (meningioma, astrocytoma, glioblastoma );
- encephalitis of various etiologies;
- progressive dementia (Alzheimer‘s, Binswanger’s, Pick’s);
- brain surgery.
Predisposing (background) factors are hypertension, cerebral atherosclerosis, hypercholesterolemia, angiopathy, family history, exogenous intoxication.
Symptoms of amnestic aphasia
Acoustic-mnestic aphasia
Patients lose the ability to retain the auditory row in memory within 3 or more elements, to perceive the expanded text by ear. Comprehension of both situational and other forms of speech suffers. Simple verbal instructions are usually available, multi-step instructions are not. The patient often asks again, asks to speak more slowly, to repeat what he has heard.
Expressive speech is dominated by short sentences, verbal paraphasias. There are frequent pauses associated with the search for the desired word, perseveration. There are difficulties in naming, especially the recollection of proper names, geographical names, various dates, telephone numbers suffers. A retelling of texts is difficult.
Optical-mnestic aphasia
With this type of amnestic aphasia, visual recognition of familiar objects is impaired, and a word perceived by ear does not evoke visual images. There are difficulties in depicting objects from memory; in the process of drawing, patients miss important characteristic details, do not complete significant details. At the same time, copying and sketching is good.
There are also difficulties with sorting items into categories: vegetables, clothes, furniture. Written speech is impaired by the type of literal, verbal or one-sided optical alexia (patients do not see the left half of the text).
Amnestic aphasia
Forgetting the names of objects is a defining violation. Patients cannot find the right word to denote well-known things, replace the forgotten word with a description of the object or its purpose. So, for example, about a pencil, a patient says “this is … what they draw or write with.” However, when prompted for the first syllable, he manages to remember the word he was looking for. Amnestic aphasia classification symptoms
The phrase is pronounced slowly, interrupted by pauses, during which the patient selects the right word. The time between question and answer increases (latency period). Spontaneous oral speech is replete with verbal paraphasias. Written speech (reading aloud, writing under dictation), as a rule, is preserved. However, cases have been described when amnestic aphasia was combined with alphabetic agnosia and optical alexia. Spontaneous writing also suffers, which is due to a decrease in nouns and the predominance of verbs in oral speech.
Classification
Amnestic aphasia is multifactorial and heterogeneous. Depending on the dominant lesion of the auditory, visual, or associative zones, it can occur in three types:
- acoustic-mnestic: the leading defect is the inferiority of auditory-speech memory;
- optical-mnestic: central defect – optical amnesia and agnosia;
- actually amnestic: the main problem is a violation of the naming function.
Pathogenesis of Amnestic aphasia
The pathogenetic mechanism of amnestic aphasia is still completely unclear. Some researchers note that the 37th cytoarchitectonic field according to Brodman accumulates auditory and visual stimuli (overlap zone), therefore, its defeat leads to the dissociation of the visual image of the word and its verbal designation.
There is an opinion linking amnestic aphasia with damage to the deep structures of the temporal cortex. In this case, the connection between the cortical auditory analyzer and the hippocampus, which is responsible for the function of memorizing and storing information, is disrupted. From the point of view of the neuropsychological approach (Luria A.R.), nominative aphasia is the result of a violation of the operation of selecting words stored in the patient’s memory.
Diagnostics of Amnestic aphasia
In amnestic aphasia, understanding of speech, articulation, the function of reading and writing are preserved, therefore, nominative difficulties are often attributed to age-related “memory problems”. A comprehensive instrumental, psychological, and speech therapy examination helps to identify the aphatic nature of the disorders:
- Diagnostics of the causes of aphasia. To clarify the etiology of speech disorders and localize the lesion focus instrumental studies are called. Cerebral CT or MRI is indicated for all patients. With cerebrovascular pathology, it is possible to conduct an ultrasound of the brachiocephalic vessels, MR-angiography. Lumbar puncture and blood tests help in establishing the causes.
- Neuropsychological examination. When conducting special diagnostic tests in the neuropsychological status of patients with amnestic aphasia, various forms of agnosia (visual-object, optical-spatial, letter), optical amnesia can be detected. There is a decrease in the volume of memorization and productivity of word reproduction, the difficulty of drawing from memory.
- Speech diagnostics. Conducted by a speech therapist-aphasiologist. Includes the study of expressive and receptive speech, auditory-speech memory, reading, writing. Amnestic aphasia is characterized by word search when naming objects, verbal paraphasias, weakness of acoustic and visual traces, speech pauses, and sometimes reading difficulties.
Correction of amnestic aphasia
Medical rehabilitation
Active drug treatment is carried out in the acute period of stroke, TBI, neuro infections. Patients with neurodegenerative pathologies require constant pharmacological support. Taking into account the main problem, against the background of which amnestic aphasia developed, hypotensive, nootropic, antioxidant, deaggregant, vitamin preparations can be used. From the methods of physical rehabilitation, personalization of the head and SHVZ, magnetotherapy, electrophoresis, and micro polarization is later connected. According to indications, psychotherapy sessions are recommended.
Logotherapy
Correctional exercises for amnestic aphasia are aimed at restoring the correlation of visual-object images with the word. For this, the categorical and situational connections of objects are updated, as well as their signs, qualities, functions. In the classroom, pictures and real objects, articulatory-graphic supports, pictograms are used. Applied exercises and techniques:
- memorizing word lines by ear with a gradual increase in the number of words from 3-5 to 10;
- training of visual memory (games “What is gone”, “What has changed”);
- reading pictures with signatures;
- Search for items by name;
- classification of objects;
- comparison of real objects with drawn ones;
- compilation of stories based on plot pictures and retelling of texts;
- solving crosswords.
Regular sessions with a speech therapist, conducted against the background of drug treatment, allow you to restore the optical image of various objects, build up the subject vocabulary, and expand the volume of auditory-speech memory.
