Robotic rEhabilitation sCenario fOr patieNts With NeglECT

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.

MOTORE is a planar end-effector robot for upper limb rehabilitation. In the literature, studies on the efficacy of this device in improving speed, strength, and spasticity of the upper limbs are available. However, no evidence is available regarding its use in treating hemi-inattention in post-stroke patients.

For this reason, this study aims to extend the use of the MOTORE device to the cognitive domain by creating a new virtual reality scenario for the robot. The scenario will consist of a sequential visual stimuli exercise with intra-session adaptive difficulty, designed to guide the patient's attention toward the neglected side of space through the combined use of visual and auditory stimuli and motor requests. The new scenario will be evaluated for usability with plegic post-stroke patients suffering from left hemi-inattention.

The novelty of the current study lies in the application of a multisensory approach, using auditory and visual stimuli, along with movement supported by the robot, to direct the patient's attention to the stimulus placed on the side of space affected by hemi-inattention.

Inclusion criteria

• Presence of a diagnosis of right hemispheric stroke
• Presence of a diagnosis of hemi-inattention (Apple test)
• Presence of left hemiplegia (Fugl-Meyer Assessment Upper Limb ≤58)
• Adjusted Montreal Cognitive Assessment <20
• Written informed consent

Exclusion criteria

• Presence of cognitive decline prior to the event
• Presence of previous stroke events
• Presence of osteoarticular rigidity (e.g., ankylosis, functional limitations with traumatic or degenerative origin) or spasticity in the affected upper limb (Modified Ashworth Scale ≥3 on shoulder, elbow, or wrist)
• Inability to maintain a sitting position
• Presence of severe visual disabilities
• Recent injection of botulinum toxin in the upper limb or planned injection of botulinum toxin during the study period
• Orthopaedic, neurological, or psychiatric disorders that could interfere with the study procedures and motor or cognitive assessments
• Unstable fractures of the upper limb
• Severe osteoporosis
• Skin lesions on the upper limb