What is agnosia?

Agnosia results in a recognition disorder which can relate to different perceptions (sight, smell, sounds, etc.). This brain disorder affects patients who suffer from brain damage. Discover the definition, diagnosis and treatment of agnosia with Dr Jean-Philippe Delabrousse Mayoux, neurologist.

Agnosia: this recognition disorder

Agnosia may be linked to brain injury or trauma. This neurological disorder prevents the patient from being able to identify or recognize a face, a person, a color, an object or even a sound. Agnosia can be visual, auditory, olfactory and can present itself in a multitude of distinct disorders. Although there is no real treatment, speech therapy and occupational therapy sessions remain very useful.

Thanks to our sensory abilities, we can visualize a shape, recognize a face, a place, a sound, identify a flavor, a smell, or even recognize a texture or the composition of an object or fabric. “Agnosia is defined as the inability to identify an object using at least one of the five senses, without these senses being impaired”explains Dr Jean-Philippe Delabrousse Mayoux, neurologist at the Bergerac Hospital Center.

The different types of agnosia

These gnostic disorders, defined as disturbances of recognition, can take varied manifestations, affecting for example, a single sense or all sensory functions.

We distinguish in particular visual agnosia, when a person finds themselves unable to recognize certain objects, shapes or colors. In this family of brain disorders, let us cite one of the most confusing, prosopagnosia, characterized by the inability to recognize familiar faces. “This can concern the faces of loved ones, but sometimes the person is also unable to recognize their own face. It’s a disorder that can be distressing.”specifies the neurologist.

Agnosia can also be auditory, olfactory, or tactile. “A patient may be able to name an object if shown and name it in a photo, but not be able to identify it if placed in their hand with their eyes closed. adds Dr Jean-Philippe Delabrousse Mayoux.

Furthermore, there are also other subfamilies of agnosia, for example the inability to locate oneself on a map, or to recognize different parts of the body. Anosognosia thus characterizes the inability to be aware of one’s sensory disorders or deficits. “A patient may not be aware of the paralysis of one of his limbs, for example. illustrates the doctor,

Gnosic disorders result from an alteration of certain regions of the brain and in particular associative areas. “These regions of the cortex will connect several brain centers between them and allow the subject to cross-reference information in order to restore a coherent image. continues the specialist.

Causes of agnosia: brain trauma or degenerative disease

While some forms of agnosia are reversible, others are not. It all depends on the cause. Indeed, agnosia can result from a cerebrovascular accident (CVA), a tumor, infectious lesion or brain trauma. “In these situations, depending on the severity of the brain damage, the agnosia may be reversible after a few months, however leaving possible after-effects in these patients.explains the neurologist.

Agnosia can also be correlated with a degenerative disease such as Parkinson’s disease or Alzheimer’s type dementia. In this case, the agnosia is irreversible and may take on new forms of expression and worsen over time. “In Alzheimer’s disease, the aphaso-apraxo-agnosic syndrome combines, for example, disorders that impact language, gesture production as well as gnostic functions., continues the specialist. Each patient being unique, the expression of gnostic disorders will be specific to each.

Diagnosis of agnosia: neurological assessment and examinations

In the presence of these disorders, the doctor is required to establish a clinical and neurological assessment. From different tests, we will check whether there are other forms of alterations as well as an absence of impairment at the language level, for example. “It will then be a matter of identifying the cause: infectious context, recent brain trauma…”, explains the neurologist.

Different medical examinations: scanner, MRI but also brain PET will be considered in order to best observe the functioning of the brain and visualize the brain areas showing less activity.

Management of agnosia: occupational therapy and speech therapy

The management of gnosic disorders mainly involves rehabilitation sessions with an occupational therapist and a speech therapist in order to compensate for brain deficiencies. Remission of disorders varies depending on many factors: the age of the person, the nature and extent of the disorders as well as the cause.

“However, even if agnosia is linked to a degenerative disease, it is important to set up therapeutic monitoring in order to identify the disorders, to clearly explain the situation to caregivers and not to leave the patient isolated.continues the neurologist.