Agnosia is a neuropsychological symptom based on a disorder of information processing in the brain. Functional deficits in certain brain areas may be the cause. Therapies for this disorder are often based on compensatory strategies.
What is agnosia?
In medicine, agnosia is used to describe a rare neuropsychological symptom whereby information processing in the brain no longer functions properly. The term agnosia comes from the Greek, meaning “not knowing,” and is also used that way in philosophy. In medicine, however, agnosia is used to describe a rare neuropsychological symptom according to which information processing in the brain no longer functions properly. The phenomenon occurs after bi- or unilateral lesions of certain brain regions. The affected person is able to perceive all objects around him through his sensory organs. However, he is not able to assign or name them correctly. The objects are therefore no longer recognized by him, although there are no sensory defects, cognitive disorders or attention deficits. Sigmund Freud introduced the term agnosia in medicine, referring exclusively to the inability to assign the objects seen, although the visual faculty is present. According to Freud, however, this also includes cortical blindness and soul blindness. Cortical blindness is blindness due to a functional failure of the visual cortex in the brain despite healthy eyes. The soul blindness is characterized by the fact that the objects can be seen, but can no longer be assigned. Today, the term agnosia has been expanded to include failures of all sensory modalities.
Causes
The causes of agnosia lie in the destruction of certain brain areas responsible for corresponding information processes. These lesions may be caused by strokes, brain injuries, brain tumors, infections in the meninges and brain, or severe mental illness. If the rearmost part of the cerebrum in the area of the occipital lobe is damaged, visual agnosia may result. This is because visual information processing takes place there. If there is damage in the posterior temporal lobe area, auditory agnosia often results. If the parietal lobe is damaged, autotopagnosia often occurs. In this case, the affected patient can no longer localize skin stimuli on his or her own body.
Diseases with this symptom
- Stroke
- Brain tumor
- Meningitis
- Early summer meningoencephalitis
- Brain abscess
- Multi-organ failure
- Blood poisoning
- Anxiety disorder
- Polytrauma
- Lymphoma in the brain
- Depression
- Post-traumatic stress disorder
- Trauma
- Septic_shock
- Pituitary adenoma
Diagnosis and course
There are different forms of agnosia, which the doctor can easily assign. The type of agnosia already gives the doctor clues as to which brain regions are affected. For this purpose, he performs various tests that relate to specific sensory areas. In general, there is a classification into visual, acoustic, tactile or spatial agnosia. In addition, there are autotopagnosia and anosognosia. Visual agnosia can again be divided into different subtypes. So-called prosopagnosia is a disorder of facial perception. The patient does not recognize familiar persons by their face. Recognition takes place, for example, by voice or gait. Apperceptive agnosia also belongs to this group. In this case, the affected person can perceive individual elements, but cannot put them together to form an overall object. In associative agnosia, the patient recognizes the entire object in shape and form, but cannot make sense of its function. In color agnosia, the colors can no longer be recognized. Acoustic agnosia is characterized by the fact that the affected person hears sounds but cannot put them together into words or sentences. The inability to orient oneself in space is called spatial agnosia. In tactile agnosia, objects that are palpated cannot be assigned. The inability to recognize functional failures of one’s own body parts or organs is called anosognosia.In this case, the patient perceives the failed body parts as functional and wants to use them accordingly. In the process, falls may occur.
Complications
Agnosia can be a trigger for various complications. Depending on the severity and cause of agnosia, severe motor impairments and sensory organ dysfunction occur. The sense of balance, for example, is sometimes severely disturbed by the neuropsychological symptom, which can lead to falls and similar injuries. The eyes and ears are also affected and function only to a limited extent or not at all in those affected. The complications that follow can exacerbate the main symptoms of agnosia. In addition, intellectual performance is usually severely impaired and can only be partially restored by occupational therapy. Further complications occur in agnosia mainly due to consequential damage such as autotopagnosia. This makes it impossible for affected persons to localize skin irritations or injuries on their own body, which often leads to an intensification of existing diseases. Last but not least, the emotional state of those affected is also a risk factor. Agnosia can lead to severe mental and physical disabilities and thus place an enormous psychological burden on the patient. Complications are rare during the actual therapy. Although permanent damage often occurs, the occupational therapy used does not pose any major risks to those affected. Only in the case of drug treatment, for example, in the treatment of psychological secondary symptoms necessary, further complications can occur in some cases.
When should one go to the doctor?
As soon as relatives or the affected person himself or herself notice that he or she is suffering from a failure to recognize objects or people, a doctor should be consulted immediately and as soon as possible. Since the sensory organs are usually not damaged, there is a risk that therefore perhaps initial symptoms are not immediately recognized or the hope that the disorder will soon disappear. In agnosia, the eyes and ears continue to function. Nevertheless, the failure to recognize objects is an elementary disorder of perception and should be taken very seriously. The meaninglessness of visual impressions in a diseased person indicates brain damage, which should be examined more closely as soon as possible. In addition, there is an increased risk for the affected person to suffer further damage when coping with everyday life. If the disorder causes the inability to recognize a car, walking across the street is to be classified as life-threatening. Only through an intensive medical examination, the agnosia can be diagnosed and appropriate medical measures are initiated. The so-called soul blindness involves lesions in the brain. Therefore, the non-recognition of objects is to be understood as an immediate warning signal. Spontaneous recovery or presence of temporary effects of the limitation is unfortunately not expected.
Treatment and therapy
There is no specific treatment for agnosia. If a lesion has occurred in a specific area of the brain, such as from a stroke, improvement may occur on its own after some time. However, this depends on the size and location of the damage and the age of the patient. After the first three months, most of the improvement occurs. Even after that, processes often take place that attenuate the loss. However, permanent disabilities must be assumed in most cases. The physician can only arrange compensatory measures to overcome the failures. Thus, in the course of occupational therapy, an attempt is made to compensate for the corresponding agnosia as best as possible by using other functions that are still available. During occupational therapy treatment, the patient can learn to make greater use of other features to recognize people and objects. For example, in agnosia, the patient does not recognize the face of a person he knows. However, to identify that person, the individual may rely on other characteristic features such as voice, posture, or gait. The learning process may be so successful that the lack of facial recognition no longer plays any role at all and may even go unnoticed. Occupational therapy can of course be applied to all forms of agnosia.This takes advantage of the fact that, as a rule, only selective failures occur in the brain’s information processing system.
Outlook and prognosis
As a rule, the patient’s perception is severely disturbed by agosnia. This mainly affects the recognition of faces of different people. Patients then try to match people based on their voice or gait. However, agosnia can also affect other areas of life. These include colors or shapes, for example, which are equally unrecognizable. This leads to a strong restriction of everyday life for the patients. For example, some professions cannot be performed due to agosnia. Unfortunately, there is no treatment for agosnia. However, exercises can be performed that compensate for the affected weaknesses and replace them with other ways of perception. Therefore, agosnia does not result in a reduced life expectancy in most people. For treatment, mainly methods from occupational therapy or speech therapy are used. In complicated cases, certain organs can also fail completely. These include, for example, the ears or the eyes. This can lead to a very severe restriction of everyday life for the patient. These patients are then dependent on the help of other people.
Prevention
Agnosia cannot be prevented. There are congenital and acquired forms. The congenital forms are often genetic conditions or prenatal developmental disorders. The acquired forms are caused by diseases such as strokes or other brain-organic disorders. For all forms of agnosia, there are no prophylactic measures.
Here’s what you can do yourself
Agnosia is not a common symptom of disease, but for those who suffer from it, it is a very big problem. The terms soul deafness and soul blindness used in German indicate how complex and serious the disorder of hearing, sight or touch can be. Because the symptom occurs so individually, it is absolutely necessary in treatment – especially in self-help – to be patient-specific. Although agnosia is generally incurable, the impairments can be more or less compensated for by special forms of training. In prosopagnosia, for example, the aim is to enable patients to identify people by means of recognition features other than the face (posture, gait, voice, clothing, hairstyle, etc.). Sometimes it is simple-seeming measures that help – such as writing and arithmetic exercises. Which exercises should be carried out should be discussed with the therapist or the doctor. In general, conversation or occupational therapies are indispensable in the treatment. Through learning processes and memory formation, targeted exercises create new neurons and synapses in the brain, which can bring about an improvement in performance. Much depends on the circle of friends and family in the treatment. It is advisable to ensure the social integration of the affected person, to reduce his risk of injury in everyday life, and to give him peace of mind through a confident demeanor.
