Agnosia is a disturbance in the perception of sensory stimuli when the sensory organs, such as the eye and the ear, are completely functioning properly. There are many forms of agnosia, some of them can significantly affect everyday functioning - for example, prosopagnosia, in which the patient does not recognize the faces of people he knows. The appearance of any form of agnosia must not be underestimated - the cause of its occurrence may even be a brain tumor.

The termagnosiacomes from Greek and means ignorance or ignorance. It was introduced into the medical language in 1891 by Sigmund Freud. The simplest explanation for agnosia is a condition in which the perception of stimuli from the environment is disturbed, despite having properly functioning sensory organs. In the case of agnosia, the disorders concern not only the organs receiving experiences from the environment, but the brain centers responsible for the registration and processing of the sensory stimuli reaching them. Agnosia, due to its possible causes, can occur in people of any gender and age.

Agnosia: causes

Agnosia can be caused by any conditions that cause damage to the cortical centers of the brain. The most common causes of agnosia are:

  • head injuries
  • tumors of the central nervous system
  • intracranial bleeding
  • dementia
  • neurodegenerative diseases
  • brain hypoxia
  • poisoning (e.g. carbon monoxide)
  • stroke
  • central nervous system infections (e.g. encephalitis)

Agnosia: types

There are 3 main types of agnosia, concerning the different senses:visual agnosia , auditory agnosia and sensory agnosia. Within these categories, further sub-types of agnosia are listed - the patient's problem may be related to receiving only one specific type of stimuli.

  • prosopagnosia (impaired facial recognition),
  • achromatopsia (unable to identify colors),
  • akinetopsy (disturbance of vision of moving objects),
  • spatial agnosia (not recognizing one's surroundings),
  • simultanagnosia (ability to focus on only one thingobject at the same time - seeing e.g. a table, the patient is not able to recognize the color of the walls in the room or other objects located in it at the same time),
  • alexia (unable to recognize texts and letters).

Another type of disorder isauditory agnosia . In its course, patients may not be able to recognize the speech they hear, and there is also a form of auditory agnosia in which patients do not perceive more complex sounds, such as music. A specific type of this form of agnosia is cortical deafness, in which patients do not hear any sounds when the hearing organ is fully functioning. The third type of neurological disorders in question issensory agnosia . In her case, the problem mainly concerns recognizing the shape of objects, both those that are known to the patient and those that are completely new to the patient. At the same time, patients are able to recognize the weight or size of the objects they touch. The main representative of this type of agnosia is astereognosia, in which the patient cannot recognize objects just by touching them. There are other types of agnosia that are hard to attribute to one particular type of sensory experience. Such problems are:

  • autotopagnosia (inability to identify specific parts of one's own body),
  • anosognosia (the patient's unawareness or even denying the existence of any disease disorders, one of the forms of anosognosia is the blind patient's denying that he or she simply cannot see),
  • emotional agnosia (the inability to recognize the so-called body language of other people or infer about their emotions based on the observation of the face).

Agnosia: diagnostics

The type of agnosia in the patient plays a fundamental role in diagnosing diseases in patients experiencing agnosia. This is due to the fact that on the basis of the type of agnosia, it is possible to infer where in the brain there was any damage. For example, visual agnosia are usually caused by defects in the occipital lobes, while auditory agnosia can be caused by damage to the parietal lobes of the brain. Neuroimaging plays an unquestionable role in the diagnosis of agnosia. By means of such examinations as computed tomography or magnetic resonance imaging of the head, it is possible to visualize e.g. tumors within the brain, but also ischemic changes caused by a stroke. In search of the cause of agnosia, it is also important to conduct a medical interview with the patient.

Agnosia: treatment

Agnosia itself is actually a symptom, not a disease - a treatmentit is subject to the condition that caused the agnosia. The specific therapy depends on the cause of the agnosia - if it is cancer, then interventions will be undertaken focusing on its treatment, while in the case of central nervous system infection, the patient will be given appropriate drugs to allow the infection to resolve. its occurrence (this may be the case in brain infections) and it may persist in the patient for a longer period of time (e.g. in a situation where it was caused by a stroke). In patients experiencing long-term agnosia, various exercises can be used, allowing them to achieve a better level of functioning - as an example, speech therapy in patients with various forms of auditory agnosia.

Category:

Neurology