How Inhibition Relates to Impulsivity after Moderate to Severe Traumatic Brain Injury

Impulsive behaviors and poor inhibition performances are frequently described in patients with traumatic brain injury (TBI). However, few studies have examined impulsivity and associated inhibition impairments in these patients. Twenty-eight patients with moderate to severe TBI and 27 matched controls performed a stop-signal task designed to assess prepotent response inhibition (the ability to inhibit a dominant or automatic motor response) in a neutral or emotional context and a recent negative task to assess resistance to proactive interference (the ability to resist the intrusion into memory of information that was previously relevant but has since become irrelevant). Informants of each patient completed a short questionnaire designed to assess impulsivity. Patients showed a significant increase in current urgency, lack of premeditation, and lack of perseverance when retrospectively compared with the preinjury condition. Group comparisons revealed poorer prepotent response inhibition and resistance to proactive interference performances in patients with TBI. Finally, correlation analyses revealed a significant positive correlation between urgency (the tendency to act rashly when distressed) and prepotent response inhibition in patients with TBI. This study sheds new light on the construct of impulsivity after a TBI, its related cognitive mechanisms, and its potential role in problematic behaviors described after a TBI. (JINS, 2013, 19, 1-9

Increasing upper limb training intensity in chronic stroke using embodied virtual reality: a pilot study.

Technology-mediated neurorehabilitation is suggested to enhance training intensity and therefore functional gains. Here, we used a novel virtual reality (VR) system for task-specific upper extremity training after stroke. The system offers interactive exercises integrating motor priming techniques and embodied visuomotor feedback. In this pilot study, we examined (i) rehabilitation dose and training intensity, (ii) functional improvements, and (iii) safety and tolerance when exposed to intensive VR rehabilitation. Ten outpatient stroke survivors with chronic (>6 months) upper extremity paresis participated in a ten-session VR-based upper limb rehabilitation program (2 sessions/week). All participants completed all sessions of the treatment. In total, they received a median of 403 min of upper limb therapy, with 290 min of effective training. Within that time, participants performed a median of 4713 goal-directed movements. Importantly, training intensity increased progressively across sessions from 13.2 to 17.3 movements per minute. Clinical measures show that despite being in the chronic phase, where recovery potential is thought to be limited, participants showed a median improvement rate of 5.3% in motor function (Fugl-Meyer Assessment for Upper Extremity; FMA-UE) post intervention compared to baseline, and of 15.4% at one-month follow-up. For three of them, this improvement was clinically significant. A significant improvement in shoulder active range of motion (AROM) was also observed at follow-up. Participants reported very low levels of pain, stress and fatigue following each session of training, indicating that the intensive VR intervention was well tolerated. No severe adverse events were reported. All participants expressed their interest in continuing the intervention at the hospital or even at home, suggesting high levels of adherence and motivation for the provided intervention. This pilot study showed how a dedicated VR system could deliver high rehabilitation doses and, importantly, intensive training in chronic stroke survivors. FMA-UE and AROM results suggest that task-specific VR training may be beneficial for further functional recovery both in the chronic stage of stroke. Longitudinal studies with higher doses and sample sizes are required to confirm the therapy effectiveness. This trial was retrospectively registered at ClinicalTrials.gov database (registration number NCT03094650 ) on 14 March 2017

Could local dynamic stability serve as an early predictor of falls in patients with moderate neurological gait disorders? A reliability and comparison study in healthy individuals and in patients with paresis of the lower extremities.

Falls while walking are frequent in patients with muscular dysfunction resulting from neurological disorders. Falls induce injuries that may lead to deconditioning and disabilities, which further increase the risk of falling. Therefore, an early gait stability index would be useful to evaluate patients in order to prevent the occurrence of future falls. Derived from chaos theory, local dynamic stability (LDS), defined by the maximal Lyapunov exponent, assesses the sensitivity of a dynamic system to small perturbations. LDS has already been used for fall risk prediction in elderly people. The aim of the present study was to provide information to facilitate future researches regarding gait stability in patients with neurological gait disorders. The main objectives were 1) to evaluate the intra-session repeatability of LDS in patients and 2) to assess the discriminative power of LDS to differentiate between healthy individuals and neurological patients. Eighty-three patients with mild to moderate neurological disorders associated with paresis of the lower extremities and 40 healthy controls participated in the study. The participants performed 2×30 s walking wearing a 3D accelerometer attached to the lower back, from which 2×35 steps were extracted. LDS was defined as the average exponential rate of divergence among trajectories in a reconstructed state-space that reflected the gait dynamics. LDS assessed along the medio-lateral axis offered the highest repeatability and discriminative power. Intra-session repeatability (intraclass correlation coefficient between the two repetitions) in the patients was 0.89 and the smallest detectable difference was 16%. LDS was substantially lower in the patients than in the controls (33% relative difference, standardized effect size 2.3). LDS measured in short over-ground walking tests seems sufficiently reliable. LDS exhibits good discriminative power to differentiate fall-prone individuals and opens up the possibility of future clinical applications for better prediction of fall risk in neurological patients

How inhibition relates to impulsivity after moderate to severe traumatic brain injury

Impulsive behaviors and poor inhibition performances are frequently described in patients with traumatic brain injury (TBI). However, few studies have examined impulsivity and associated inhibition impairments in these patients. Twenty-eight patients with moderate to severe TBI and 27 matched controls performed a stop- signal task designed to assess prepotent response inhibition (the ability to inhibit a dominant or automatic motor response) in a neutral or emotional context and a recent negative task to assess resistance to proactive interference (the ability to resist the intrusion into memory of information that was previously relevant but has since become irrelevant). Informants of each patient completed a short questionnaire designed to assess impulsivity. Patients showed a significant increase in current urgency, lack of premeditation, and lack of perseverance when retrospectively compared with the preinjury condition. Group comparisons revealed poorer prepotent response inhibition and resistance to proactive interference performances in patients with TBI. Finally, correlation analyses revealed a significant positive correlation between urgency (the tendency to act rashly when distressed) and prepotent response inhibition in patients with TBI. This study sheds new light on the construct of impulsivity after a TBI, its related cognitive mechanisms, and its potential role in problematic behaviors described after a TBI