Peri-Personal Space Tracing by Hand-Blink Reflex Modulation in Patients with Chronic Disorders of Consciousness

The assessment of awareness in patients with chronic Disorders of Consciousness (DoC), including Unresponsive Wakefulness Syndrome (UWS) and Minimally Conscious State (MCS), is challenging. The level of awareness impairment may depend on the degree of deterioration of the large-scale cortical-thalamo-cortical networks induced by brain injury. Electrophysiological approaches may shed light on awareness presence in patients with DoC by estimating cortical functions related to the cortical-thalamo-cortical networks including, for example, the cortico-subcortical processes generating motor responses to the perturbation of the peri-personal space (PPS). We measured the amplitude, latency, and duration of the hand-blink reflex (HBR) responses by recording electromyography (EMG) signals from both the orbicularis oculi muscles while electrically stimulating the median nerve at the wrist. Such a BR is thought to be mediated by a neural circuit at the brainstem level. Despite its defensive-response nature, HBR can be modulated by the distance between the stimulated hand and the face. This suggests a functional top-down control of HBR as reflected by HBR features changes (latency, amplitude, and magnitude). We therefore estimated HBR responses in a sample of patients with DoC (8 MCS and 12 UWS, compared to 15 healthy controls -HC) while performing a motor task targeting the PPS. This consisted of passive movements in which the hand of the subject was positioned at different distances from the participant's face. We aimed at demonstrating a residual top-down modulation of HBR properties, which could be useful to differentiate patients with DoC and, potentially, demonstrate awareness preservation. We found a decrease in latency, and an increase in duration and magnitude of HBR responses, which were all inversely related to the hand-to-face distance in HC and patients with MCS, but not in individuals with UWS. Our data suggest that only patients with MCS have preserved, residual, top-down modulation of the processes related to the PPS from higher-order cortical areas to sensory-motor integration network. Although the sample size was relatively small, being thus our data preliminary, HBR assessment seems a rapid, easy, and first-level tool to differentiate patients with MCS from those with UWS. We may also hypothesize that such a HBR modulation suggests awareness preservation.

Robotic gait training in multiple sclerosis rehabilitation: Can virtual reality make the difference? Findings from a randomized controlled trial

Gait, coordination, and balance may be severely compromised in patients with multiple sclerosis (MS), with considerable consequences on the patient's daily living activities, psychological status and quality of life. For this reason, MS patients may benefit from robotic-rehabilitation and virtual reality training sessions. Aim of the present study was to assess the efficacy of robot-assisted gait training (RAGT) equipped with virtual reality (VR) system in MS patients with walking disabilities (EDSS 4.0 to 5.5) as compared to RAGT without VR. We enrolled 40 patients (randomized into two groups) undergoing forty RAGT±VR sessions over eight weeks. All the patients were assessed at baseline and at the end of the treatment by using specific scales. Effect sizes were very small and non-significant between the groups for Berg Balance Scale (-0.019, CI95% -2.403 to 2.365) and TUG (-0.064, 95%CI -0.408 to 0.536) favoring RAGT+VR. Effects were moderate-to-large and significant for positive attitude (-0.505, 95%CI -3.615 to 2.604) and problem-solving (-0.905, 95%CI -2.113 to 0.302) sub-items of Coping Orientation to Problem Experienced, thus largely favoring RAGT+VR. Our findings show that RAGT combined with VR is an effective therapeutic option in MS patients with walking disability as compared to RAGT without VR. We may hypothesize that VR may strengthen RAGT thanks to the entrainment of different brain areas involved in motor panning and learning.