Best Practice Statement for Screening, Assessment and Management of Vision Problems in the First 30 Days after an Acute Stroke

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Subliminal galvanic-vestibular stimulation influences ego- and object-centred components of visual neglect

Neglect patients show contralesional deficits in egocentric and object-centred visuospatial tasks. The extent to which these different phenomena are modulated by sensory stimulation remains to be clarified. Subliminal galvanic vestibular stimulation (GVS) induces imperceptible, polarity-specific changes in the cortical vestibular systems without the unpleasant side effects (nystagmus, vertigo) induced by caloric vestibular stimulation. While previous studies showed vestibular stimulation effects on egocentric spatial neglect phenomena, such effects were rarely demonstrated in object-centred neglect. Here, we applied bipolar subsensory GVS over the mastoids (mean intensity: 0.7. mA) to investigate its influence on egocentric (digit cancellation, text copying), object-centred (copy of symmetrical figures), or both (line bisection) components of visual neglect in 24 patients with unilateral right hemisphere stroke. Patients were assigned to two patient groups (impaired vs. normal in the respective task) on the basis of cut-off scores derived from the literature or from normal controls. Both groups performed all tasks under three experimental conditions carried out on three separate days: (a) sham/baseline GVS where no electric current was applied, (b) left cathodal/right anodal (CL/AR) GVS and (c) left anodal/right cathodal (AL/CR) GVS, for a period of 20. min per session. CL/AR GVS significantly improved line bisection and text copying whereas AL/CR GVS significantly ameliorated figure copying and digit cancellation. These GVS effects were selectively observed in the impaired- but not in the unimpaired patient group. In conclusion, subliminal GVS modulates ego- and object-centred components of visual neglect rapidly. Implications for neurorehabilitation are discussed

Contraversive neglect? A modulation of visuospatial neglect in association with contraversive pushing

Objective: Contraversive pushing (CP) is a neurologic disorder characterized by a lateral postural imbalance. Pusher patients actively push toward their contralesional side due to a misperception of the body's orientation in relation to gravity. Although not every patient with CP suffers from spatial neglect (SN), both phenomena are highly correlated in right-hemispheric patients. The present study investigates whether peripersonal visuospatial functioning differs in neglect patients with versus without CP (NP+ vs. NP+ patients). Method: Eighteen right-hemispheric stroke patients with SN were included, of which 17 in a double-blind case-control study and 1 single case with posterior pushing to supplement the discourse. A computer-based visuospatial navigation task, in which lateralized deviation can freely emerge, was used to quantify visuospatial behavior. In addition, visuospatial orienting was monitored using line bisection. Results: Significant intergroup differences were found. The NP+ patients demonstrated a smaller ipsilesional navigational deviation and more cross-over (contralesional instead of ipsilesional deviation) in long line bisection. As such, they demonstrated a contraversive (contralesionally directed) shift in comparison with the NP+ patients. Conclusions: These findings highlight the similarity between 2 systems of space representation. They are consistent with a coherence between the neural processing system that mainly provides for postural control, and the one responsible for nonpredominantly postural, visuospatial behavior

Efficacy of home-based visuomotor feedback training in stroke patients with chronic hemispatial neglect

Hemispatial neglect is a severe cognitive condition frequently observed after a stroke, associated with unawareness of one side of space, disability and poor long-term outcome. Visuomotor feedback training (VFT) is a neglect rehabilitation technique that involves a simple, inexpensive and feasible training of grasping-to-lift rods at the centre. We compared the immediate and long-term effects of VFT vs. a control training when delivered in a home-based setting. Twenty participants were randomly allocated to an intervention (who received VFT) or a control group (n = 10 each). Training was delivered for two sessions by an experimenter and then patients self-administered it for 10 sessions over two weeks. Outcome measures included the Behavioural Inattention Test (BIT), line bisection, Balloons Test, Landmark task, room description task, subjective straight-ahead pointing task and the Stroke Impact Scale. The measures were obtained before, immediately after the training sessions and after four-months post-training. Significantly greater short and long-term improvements were obtained after VFT when compared to control training in line bisection, BIT and spatial bias in cancellation. VFT also produced improvements on activities of daily living. We conclude that VFT is a feasible, effective, home-based rehabilitation method for neglect patients that warrants further investigation with well-designed randomised controlled trials on a large sample of patients

Action and rehabilitation in hemispatial neglect

Milner and Goodale (1995, 2006) propose a model of vision that makes a distinction between ‘vision for perception’ and ‘vision for action’. Regarding hemispatial neglect, they, somewhat contentiously, hypothesize that this disorder is better explained by damage to a high-level representational structure that receives input from the ventral visual stream, but not from the dorsal-stream. Consequently, they postulate that neglect patients should code spatial parameters for action veridically. Another strong claim of the model is that the dorsal stream’s control of action is designed for dealing with target stimuli in the ‘here and now’, yet when time is allowed to pass and a reaction has to be made on the basis of a visual memory, the ventral stream is required for successful performance. One prediction from this is that neglect patients should be able to perform immediate actions, but should present specific impairments when the action is delayed. In Part I of this thesis the pattern of spared and impaired visuomotor abilities in patients with neglect, as specifically predicted by the perception and action model (Milner & Goodale, 1995, 2006), was investigated. In Chapter 1, the performance of patients with and without neglect after right hemisphere stroke was compared with that of age-matched controls. Participants were asked to point either directly towards targets or halfway between two stimuli (gap bisection), both with and without visual feedback during movement. No neglect-specific impairment was found in timing, accuracy or reach trajectory measures in either pointing or gap bisection. In Chapter 2, I tested whether neglect patients would be unimpaired in immediate pointing, yet show inaccurate pointing in a condition where a delay is interposed between the presentation of the stimulus and the response signal. Similarly to Chapter 1, it was found that neglect patients showed no accuracy impairments when asked to perform an immediate action. Conversely, when pointing towards remembered leftward locations they presented specific accuracy deficits that correlated with neglect severity. Moreover, an initial voxel-based lesion-symptom analysis further revealed that these deficits were associated with damage to occipito-temporal areas which were also mostly damaged in the neglect group. Furthermore, training of grasping the centre of rods (visuomotor feedback training) has been shown to improve neglect (Robertson, Nico & Hood, 1997; Harvey et al., 2003). It is postulated that by using the spared visuomotor abilities in these patients it is possible to ‘bootstrap’ their perceptual deficits through some ‘dorsal-to-ventral recalibration’. Hence, in Part II the immediate and long-term effects of visuomotor feedback training were explored on neglect conventional measures, as well as in daily life tasks. I found that this technique improves neglect symptoms and crucially that these improvements were long lasting, as they were present even after 4-months post-training. Importantly, I also show that the training effects generalize to the patient’s daily lives at follow-up. These findings are very encouraging for the rehabilitation of neglect as this condition has been shown to be the best single predictor of poor recovery after stroke and very difficult to treat

Four Effective and Feasible Interventions for Hemi-inattention Post CVA: Systematic Review and Collaboration for Knowledge Translation in an Inpatient Rehab Setting.

Purpose: To locate, evaluate, and summarize the evidence for effective and feasible interventions to treat hemi-inattention in inpatient rehabilitation settings and ensure knowledge translation with a collaborating clinician Timothy Rich, OTR/L and his team at Harborview Medical Center. Design: Systematic literature review, participatory active research with a collaborating clinician, and knowledge translation. Methods: Included studies that tested effectiveness of mirror therapy (MT), transcutaneous electric nerve stimulation (TENS), limb activation therapy (LAT), and visual scanning therapy (VST). 11 databases were searched to yield 31 articles included in a critically appraised topic (CAT) table. A concise protocol for each intervention was then provided to participating clinicians at an in-service training. A follow-up survey was completed to assess the degree of knowledge translation that had occurred which resulted in a positive response. Conclusion: There is evidence for the effectiveness of VST, TENS, LAT and MT to treat hemi-inattention. Combined interventions were often more effective than when used individually. It is suggested that further research be conducted to address the advisability of a multi-contextual approach to VST in order to maximize generalization to functional tasks in a variety of natural environments

Magnetoencephalography in Stroke Recovery and Rehabilitation

Magnetoencephalography (MEG) is a non-invasive neurophysiological technique used to study the cerebral cortex. Currently, MEG is mainly used clinically to localize epileptic foci and eloquent brain areas in order to avoid damage during neurosurgery. MEG might, however, also be of help in monitoring stroke recovery and rehabilitation. This review focuses on experimental use of MEG in neurorehabilitation. MEG has been employed to detect early modifications in neuroplasticity and connectivity, but there is insufficient evidence as to whether these methods are sensitive enough to be used as a clinical diagnostic test. MEG has also been exploited to derive the relationship between brain activity and movement kinematics for a motor-based brain-computer interface. In the current body of experimental research, MEG appears to be a powerful tool in neurorehabilitation, but it is necessary to produce new data to confirm its clinical utility