Agnosia - a disease characterized by the breach of certain kinds of perception that has occurred as a result of
lesion of the cerebral cortex and adjacent subcortical structures.
In case of violation of the projection (primary) cortex occur sensitivity disorders (hearing loss, impaired visual function and pain). In the case where the secondary departments affected cortex, lost the ability to perceive and process information received.
Auditory agnosia is the result of the defeat of the auditory analyzer. If you have damaged the temporal part of the left hemisphere, that is a violation of phonemic hearing, characterized by the loss of the ability to distinguish speech sounds, which can lead to the disorder of the speech in the form of sensory aphasia. This expressive speech of the patient is a so-called "word salad." It may also be violated under the dictation of letters and reading aloud.
If damaged right hemisphere of the patient ceases to recognize absolutely all the sounds and noises. If the front parts of the brain are affected, all processes run with the preservation of auditory and visual systems, but in violation of the general perception of the idea of the situation. Most often this type of auditory agnosia is observed in diseases of psychic nature.
Arrhythmia auditory agnosia characterized by an inability to understand and reproduce a certain rhythm. The pathology manifests itself in lesions of the right temple.
Individual views auditory agnosia can distinguish process that manifests itself a violation of the understanding of speech intonation of others. There is also at pravovisochnom defeat.
Visual agnosia - a violation of the ability to Recognition of objects and their images at full preservation of vision. It occurs when multiple lesions occipital cortex. Visual agnosia is divided into several subspecies:
- Simultaneous agnosia - a violation of the ability to perceive a group of images that form a coherent whole. Thus the patient can distinguish between single and finished image. It developed as a result of the defeat of the area where the joint occipital, parietal and temporal lobes of the brain;
- Color agnosia - is the inability to distinguish colors when saving color vision;
- Alphabetical agnosia - the inability to recognize letters. This pathology is called "acquired literacy." When the safety of the speech, the patients can neither write nor read. Develops in the dominant hemisphere is damaged occipital.
Tactile agnosia - a violation of the recognition of shapes and objects by touch. It appears after defeat
the parietal lobe of the right or left hemispheres. There are several types of agnosia similar nature:
- Subject agnosia - pathology, in which the patient can not determine the size, shape and material of an object, in this case it is able to identify all of its features;
- Tactile agnosia - Recognition of incapacity for letters and numbers being drawn on the arm of a patient;
- Finger agnosia - pathology, characterized by determining a violation of the names of the fingers while touching them with closed eyes of the patient;
- Somatoagnoziya - inability to recognize parts of the body, and their arrangement with respect to each other.
This kind of how spatial agnosia characterized by the inability to recognize spatial images and focus on the spot. In such situations, the patient can not distinguish right from left, confusing layout arrows on the clock and change the letters in the words of places. It manifested in the defeat of the dark of the occipital lobe. Diffuse cortical structures violation may lead to a syndrome in which the patient ignores half the space. In this version of the spatial agnosia he did not notice objects or images located on one side (eg, on the right). During redraw it represents only part of the picture, saying that the other part does not exist.
Among all the other forms of this disease, emit a special kind of agnosia - the so-called anosognosia (Anton-Babinski syndrome). This pathology is characterized by the denial of his disease patients or reduced criticality evaluation. Occurs when the subdominant hemisphere lesions.
Diagnosis, treatment and prognosis of agnosia
Diagnosis agnosia occurs during complex neurological examination, detailed its views revealed by means of special tests.
The treatment for this symptom occurs during the treatment of the underlying disease, and therefore has considerable variability. Just like treatment, prognosis depends on the severity of the underlying pathology. In medical practice, described the cases as spontaneous cure agnosia and prolonged course of the disease, virtually life.