Agnosia: introduction
Described for the first time by Lissaeur around the end of the nineteenth century, agnosia designates the inability or difficulty in recognizing objects, people, shapes or anyhow stimuli, through one or more sensory channels.
Agnosia represents a very complex cognitive dysfunction, sustained by an immediate or progressive damage to some brain reasons related to the sensitivity and perception of external stimuli.
Diagnosis
Considering the brain disorder, it is advisable to make a differential diagnosis with pathologies apparently similar to agnosia, such as anomia: in the latter condition, the patient is able to recognize the object, but not to remember its name. At first glance, these two pathologies could be confused or misinterpreted: in this regard, the differential diagnosis helps to distinguish them.
The diagnosis of agnosia, often difficult to interpret, must be carried out through some targeted tests, which allow not only to identify the disorder, but also to define its severity.
The diagnosis is performed in order to recall a visual and / or verbal stimulus to the patient, subsequently evaluating the possible correspondence between the two stimuli. In other patients, the diagnosis is made only on visual evidence.
Among the various diagnostic tests, the following are mentioned:
- Bottom-up (or periphery-to-center test): type test decision-making-object, where the agnostic patient is subjected to a series of questions regarding images. He must establish whether the object depicted in the image belongs to reality or is an imaginary object.
- Riddoch and Humphreys hippograph test: the subject is questioned on the possible existence or otherwise of the figures represented in the drawings.
- Test of the figures with missing parts: the agnostic is presented with some incomplete images and must choose which of the proposed alternatives is more suitable to complete the first image.
- Verbal tests (top down, or from the center to the periphery): for example, the patient is asked to perform a drawing, without having a sample to copy (production of visual images). Among the verbal tests we also remember the test of description of the shape of a given object or image.
- Evocation test of the gesture through which an object is used: the specialist mimes an object, and the patient must choose which image is the most suitable to represent the object.
- Object colorage test: the agnostic, placed in front of figures without a colored background, must color the white spaces with the most suitable color. An agnostic patient is not able to attribute semantic characters to the objects under examination. (Eg leaf → green)
Rehabilitation
Fortunately, agnosia is not a very frequent phenomenon; however, when it occurs, the rehabilitation treatment can be particularly complex and difficult, even more so when the patient is affected by anosognosia and has difficulty in recognizing himself. some precautions are recommended, such as: reminding the patient where he is at that given moment, paying attention to the surrounding environment; remind the agnostic for what purpose a given object or tool is used; pay particular attention to some parts of the body not recognized by the patient (through a mirror, for example); again, subject the patient to a series of practical, useful rehabilitation exercises to the recognition of the object in question [taken from The rehabilitation of the hemiplegic: multimedia manual of evaluation and recovery of motor functions, By Giuliano Dolce, Ruggero Prati, Lucia F. Lucca]
Agnosias like disease in its own right they are quite rare, since they are often connoted within more complex and articulated cerebral deficits. Unfortunately, the complete recovery of the agnostic patient is rather unlikely: nevertheless, the symptoms can be alleviated through targeted rehabilitation.
Other articles on "Agnosia: diagnosis and treatment"
- Agnosia
- Agnosia in Brief: Summary of Agnosia
