Hemianopia

Cognitive rehabilitation of hemianopia through multisensory stimulation

AvDesk is a multisensory telerehabilitation device, the result of a collaboration with IRCCS Stella Maris. For more than 10 years, work has been underway on a compensatory rehabilitative treatment that appears to yield excellent results in subjects with both hemianopia and neglect.

The device offers a cognitive rehabilitation treatment and is capable of enhancing visual skills through audiovisual stimuli.

What is hemianopia and what are the symptoms?

This issue arises following lesions related to traumatic events, most frequently due to vascular dementia, in the primary visual cortices—areas designated for processing visual information. The number of patients with hemianopia following a stroke is surprising: 25,000 new cases (60% of the total).

The therapy is designed to rehabilitate patients, both children and adults, who present a visual field deficit resulting from neurological diseases.

What are the causes of hemianopia?

The main causes of this problem are:

  • thrombosis
  • stroke (catch up on our meeting series "Cerebral stroke: let's clarify")
  • aneurysms
  • compression of the optic pathways
  • brain tumors
  • cerebral ischemia

Cognitive rehabilitation treatment

Through the stimulation of multisensory neurons (audio/visual type), eye movements are trained in the direction where the patient has the visual field deficit or neglect. The subject must demonstrate having perceived the light target (red light) by interacting with a button and directing their eyes toward the source of the sound.

The neurorehabilitation process is aimed at increasing the patient's saccadic movement, which is the response time to audiovisual stimuli. This type of approach exploits the mechanisms of neural plasticity, naturally present in the brain, and the integration of multisensory elements. In this way, a progressive reinforcement of compensatory functions is achieved (such as the implementation of adequate oculomotor strategies).

The multisensory neurons, which are particularly active in the first years of life before falling into a sort of "hibernation," respond better to a multisensory stimulus (auditory and visual). These types of audiovisual neurons are located in the superior colliculus, an area that remains preserved from damage even in the case of lesions such as a cerebral stroke.

Hemianopia: multisensory rehabilitation

In the webinars we organize throughout the year, Dr. Tinelli, a child neuropsychiatrist and Head of the Vision Laboratory at IRCCS Stella Maris, presented the applicability of the multisensory approach also in children with hemianopia due to acquired rather than congenital lesions. Subjects with congenital lesions have a spontaneous reorganization due to the great brain plasticity present at birth; conversely, children with acquired lesions exhibit behavior more similar to that of adults: difficulties in visual exploration tasks, reading, recognizing people, etc.

In a study from a few years ago, several hemianopic children with congenital and acquired lesions were subjected to a battery of visual exploration tests with the aim of identifying a target. In subjects with congenital lesions, reaction times are similar on both the ipsilesional and contralesional sides (the side of the visual field deficit); this does not occur in children with acquired lesions, where reaction times on the hemianopic side are double those of the healthy side.

Research developments

Subsequent studies have made it possible to understand that in children with congenital lesions and hemianopia, blindsight or visione cieca develops, unlike what happens in children with acquired lesions. To demonstrate this, psychophysical forced choice techniques were used.

At this point in the study, the main challenge was to figure out how to help hemianopic children with acquired lesions. Consequently, the rehabilitative treatment based on the stimulation of multisensory neurons was successfully applied. The duration of the treatment is short (2-3 weeks), so with good initial motivation, it is often possible to achieve excellent results even in children.

The founding principles underlying this type of rehabilitation are such that they expand the application opportunities of this treatment to other types of visual and cognitive deficits.

Clinical evidence

The effectiveness of audiovisual stimulation in the rehabilitation of hemianopia has been documented by over 20 years of peer-reviewed literature. Below is a selection of representative studies:

For the complete scientific literature, please consult the dedicated page.

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