Stroke is the leading cause of disability among adults, and more than 60% of stroke
survivors have motor deficits, particularly related to the upper limb. Stroke
rehabilitation usually involves intensive motor training aimed to promote adaptive
plasticity, by reducing motor deficits and developing new motor learning strategies. It
has recently been proposed that the systematic use of action observation (AO) followed by
imitation (Action Observation Therapy - AOT) is an effective way to improve motor
functions and to promote upper limb recovery in patients with motor disorders. During a
typical AOT session, a series of daily life actions (e.g., grasping a key and inserting
it into a lock) are practiced for about 2/5 weeks (with a frequency of 3-5 daily sessions
per week). During each rehabilitation session, patients are instructed by the therapist
to observe a specific action performed by an actor, presented as a short video-clip on a
monitor, and afterwards to reproduce the previously observed action with the paretic
limb. In each video, a single motor act is usually presented as observed from different
perspectives (e.g., subjective, front or side view). This therapy is based on the neural
model of the Mirror Neuron System (MNS), originally discovered in the monkey premotor and
parietal cortex, formed by visuomotor neurons that become active both when a monkey
performs a goal-directed motor act and when it simply observes the same o a similar motor
act performed by the experimenter. A comparable MNS has also been identified in humans
using different electrophysiological and neuroimaging techniques. In humans, the two main
nodes of the MNS are the inferior parietal lobule (IPL) and the ventral premotor cortex
(PMv), plus the caudal part of the inferior frontal gyrus (IFG).
AOT is considered particularly useful for activating the motor system in those conditions
in which intensive motor training is not feasible, because of the severity of the
impairment of motor functions or due to the presence of pain, inflammation, muscle
fatigue. In the last years, new Virtual Reality-based (VR) rehabilitation treatments have
been introduced, in order to present rehabilitation exercises in more practical and
friendly setting. These treatments are generally well accepted by the patients because
they offer several advantages: relatively low cost (in particular for semi-immersive
versions), engaging environment, real-time personalization of exercises and greater
adaptability to the patient's clinical features and progress, as well as possibility to
record motor performance and to acquire and provide feedback to the patient in real time.
Furthermore, VR exercises usually require a minimal therapist supervision, thereby
facilitating home-based form of rehabilitation.
Several studies support the application of VR methods in the rehabilitation of the
hemiplegic upper limb in patients with stroke. Recent literature reviews provided
evidence for improvement of upper limb motor function and daily life activity after
VR-based training, as compared to vicarious standard interventions. However, clinical
evidence based on rigorous RCT on the effect of combined use of observation of actions
followed by their immediate imitation in a VR environment (AO+VR therapy) are lacking,
especially in the case of rehabilitation applied during the chronic phase after the
stroke.
The main hypothesis is that, for the recovery of motor function of hemiplegic stroke
patients, the combined rehabilitation treatment (AO+VR therapy) is more effective than a
control treatment (Control Observation - CO) based on observation of videos without motor
content (e.g., environmental natural scenes ), followed by the execution of actions in VR
(CO+VR control therapy),.
In sum, the planned trial will examine the following hypotheses:
AO+VR is an effective tool to promote upper limb control in paretic stroke patients,
and its effects are higher than CO+VR control treatment.
motor performance, cognitive level, and structural brain damage assessed before
treatment are correlated to the degree of improvement determined by the AO+VR
intervention;
AO+VR intervention determines, as compared to CO+VR control treatment, plastic
functional changes of the MNS activity.