Collaborative Development of a Virtual Reality Scenario, Integrated Into a Robotic Upper Limb Rehabilitation Device, for the Treatment of Unilateral Spatial Negligence (NSU) Through Mutisensory Stimulation: Feasibility and Usability Pilot Study

Stroke in the right hemisphere can provoke both motor and cognitive symptoms. Hemi-inattention is a cognitive deficit typical of right hemispheric damage, with an incidence ranging from 12% to 95%. This deficit can manifest as difficulty in detecting and responding to stimuli from the left side of space, without any motor or sensory impairments that could justify the deficit. Hemi-inattention is usually associated with lesions in the inferior and superior parietal areas and, sometimes, in parts of the frontal area and the white matter connecting the parietal to the prefrontal areas. Hemi-inattention significantly compromises patients' quality of life and can negatively impact both motor and cognitive rehabilitation outcomes.

According to the theory of premotor spatial attention, brain attention and motor circuits are closely connected. Thus, it is possible to hypothesize that somatosensory activation in the contralesional space could stimulate the neural networks responsible for spatial representation and the conscious perception of stimuli. Some studies have attempted to verify this hypothesis by developing ad-hoc rehabilitation programs based on these theoretical principles. These studies can be divided into:

Studies investigating upper limb active mobilization, which require the activation of residual motor capabilities Studies investigating upper limb passive mobilization. It is widely accepted that hemi-inattention is a multisensory deficit, i.e., involving several sensory channels, and that a rehabilitation program based on joint stimulation of different channels can be effective.

Robot-assisted rehabilitation for the upper limbs, especially in hemiparetic patients, has gained growing interest in recent years, given the possibility of intensive treatment while still ensuring patient safety [8-9]. However, few studies have focused on the use of robotic devices, whose training modality often involves serious games, on cognitive aspects, particularly on hemi-inattention.

Even though preliminary and based on small sample sizes, these studies suggest a potential advantage of integrated cognitive and motor intervention for the rehabilitation of the upper limb and hemi-inattention. Indeed, the use of serious games and virtual reality scenarios can promote a synergistic effect of motor and cognitive stimulation. Furthermore, robotic rehabilitation can offer additional advantages, such as the "game effect," the ability to adapt the exercise difficulty level to the patient's performance, and the possibility of providing real-time feedback to the patient.