Successful return to professional work after neglect, extinction, and spatial misperception - Three long-term case studies.

Spatial neglect is a frequent, disabling syndrome and is associated with a poor rehabilitation outcome. Return to work seems almost impossible and has not been reported so far. Here, three cases with extensive right-hemisphere lesions after stroke are reported, who all showed residual left visuospatial neglect, left visual extinction on double simultaneous stimulation (DSS), and marked spatial-perceptual deficits. After early inpatient rehabilitation all three patients received specific, successive neuropsychological therapy as outpatients in four domains: (1) Optokinetic stimulation with pursuit eye movements and saccadic eye-movement training to reduce left-sided neglect and improve visual exploration; (2) Anti-extinction training to reduce left-sided visual extinction; (3) Spatial-perceptual feedback training to improve spatial-perceptual disorders and visuoconstruction; and (4) Job-related visual and cognitive treatments. All three cases were treated in sequential single-subject baseline designs. Significant improvements were obtained in all treated domains during therapy, which persisted at follow up. After a period of graded vocational re-integration, all three patients worked successfully in their prior job, two part-time (50%), one full-time (100%). These results show that return to professional (paid) work is possible despite initially severe neglect, hemianopia, visual extinction, and spatial-perceptual disorders after stroke.

Effects of repetitive galvanic vestibular stimulation on spatial neglect and verticality perception-a randomised sham-controlled trial.

Recent evidence shows that bipolar galvanic vestibular stimulation (GVS) with the cathode on the left (CL) or right (CR) mastoid ameliorates spatial neglect, extinction and verticality perception transiently and partly permanently. However, no randomised controlled trial evaluated the long-term effects of repetitive GVS in comparison to sham-GVS on exploration and verticality perception. To compare the effects of CL-GVS, CR-GVS and Sham-GVS on spatial exploration and verticality perception in right-hemispheric stroke patients with left neglect we conducted a randomised controlled trial with minimisation. Twenty-four patients completed 10-12 training sessions on a daily basis, 5 days/week. The CL-and CR-GVS group received 20 min of stimulation at 1.5 mA, the Sham-GVS group only 30 s of CL-GVS. Simultaneously, all patients performed a standard therapy of smooth pursuit eye movement training (SPT) followed by visual scanning training (VST). Outcome measures (Neglect test, visuo-tactile search task, subjective visual and tactile vertical) were assessed before and immediately after the intervention and at 2- and 4-week follow-ups. Our results show that neither our standard therapy nor the combination of standard therapy and GVS improved neglect symptoms significantly. The reasons for our non-significant results are discussed.

The Effects of a Novel Treatment for Hemianopic Dyslexia on Reading, Symptom Load, and Return to Work.

Reading disorders are frequent in homonymous hemianopia and are termed hemianopic dyslexia (HD). The existing treatment methods have shown improvements in reading speed, accuracy, and eye movements during reading. Yet, little is known about the transfer effects of such treatments on functional, reading-related tasks of daily life, e.g., reading phone numbers, finding typing errors or text memory. In addition, little is known about the effects on symptom load and return to work. Here, we examined a new reading therapy entailing three different methods-floating text, rapid serial visual presentation (RSVP) of single words, and the moving window technique-and evaluated their efficacy. Twenty-seven chronic HD patients were treated in a baseline design with treatment-free intervals before and after a treatment period of several months. HD was assessed with a battery of reading tests and a questionnaire about subjective symptom load at four time-points. Patients received all three reading therapies over several weeks. The results show significant and stable improvements during treatment within all measures. Approximately 63% of treated patients returned to work after the therapy. We concluded that our novel HD treatment led to widespread and lasting improvements in reading performance, generalized to functional reading tasks and reduced symptom load, and the majority of patients were able to return to work.

Minor adverse effects of galvanic vestibular stimulation in persons with stroke and healthy individuals.

OBJECTIVE: Galvanic vestibular stimulation (GVS) induces polarity-specific activations in the vestibular nerves and upstream in the vestibular and parietotemporal cortices as well as sub-cortical regions. This makes it an attractive technique for cognitive neuromodulation. However, systematic studies regarding adverse effects of GVS are unavailable. Thus, this study assessed adverse effects during and after sub-sensory GVS (mean: 0.6 mA) and GVS with 1.5 mA. METHODS: Two hundred and fifty-five GVS sessions delivered to 55 persons with stroke and 30 healthy individuals were analysed using a 34-item-questionnaire including potential symptoms and rating scales for adverse effects. RESULTS: The most frequent symptoms during and after GVS were slight itching (mean: 10.2%) and tingling (mean: 10.7%) underneath the electrodes. Healthy individuals and persons with stroke did not differ in their incidence and rated intensity of adverse effects, nor did persons with or without unilateral spatial neglect. Adverse effects were found more frequently with GVS with 1.5 mA as with sub-sensory GVS. Participants were unable to differentiate real from sham conditions during sub-sensory GVS. Importantly, neither seizures nor vertigo or nausea were observed. CONCLUSION: Sub-sensory GVS and GVS with 1.5 mA induce very few and mild adverse effects in healthy and persons with stroke and are safe when safety guidelines are followed.

Scanning your body is different from performing body movements: a double dissociation between body representational neglect and apraxia.

Body representational neglect (BRN) and apraxia can be found after left hemisphere (LH) lesions. Additionally, both disorders recruit knowledge about certain body parts, their position in space, and their spatial relationship to each other. Hence, the present study examined whether BRN and apraxia can be functionally dissociated at the behavioral and neural level. 23 LH lesioned patients were examined with a standardized body neglect test (Vest test) and a standardized test of apraxia (imitation of meaningless gestures). At the behavioral level BRN and apraxia showed a double dissociation. Moreover, these deficits were associated with specific brain lesions: while BRN was related to lesions in Brodmann areas 6 and 44 and frontal white matter, apraxia was linked to lesions in the superior longitudinal fasciculus and parietal and central white matter. The results are discussed as indicating dissociable representations of the human body within the left cerebral hemisphere.

Combination of pursuit eye movement training with prism adaptation and arm movements in neglect therapy: a pilot study.

OBJECTIVE: The aim of the present study was to determine if a combination of pursuit eye movement training to optokinetic stimulation (OKSP) and prism adaptation leads to greater improvement of neglect symptoms than a single application of OKSP. Additionally, the effect of ipsilesional arm movements during OKSP was tested. METHODS: Ten patients with left-sided neglect due to unilateral right-sided vascular brain lesions were studied between 2 and 4.5 months after their stroke. Each patient received 4 different single-session treatments (each lasting 30 minutes): visual scanning treatment (control condition), OKSP, OKSP in conjunction with wearing base-left prisms inducing a shift of the visual field to the right by 10 degrees, and OKSP in conjunction with the right to the left side. Severity of visuospatial neglect was assessed before and directly after each treatment with 4 standard neglect tests. RESULTS: Visual scanning training improved neglect symptoms only slightly. Single OKSP stimulation led to significant improvements in all tests. OKSP in conjunction with prism adaptation was superior to the control condition in the cancellation task. The treatment condition requiring arm movements aggravated neglect symptoms in all tests. A comparison between treatments indicates best improvements may be achieved with OKSP without any additional treatment. CONCLUSIONS: The present results give evidence that OKSP significantly reduces symptoms of visuospatial neglect within 1 treatment session. The results suggest that patients should be prevented from performing ipsilesional movements during OKSP.

Inhibitory and facilitatory location priming in patients with left-sided visual hemi-neglect.

In visual search for pop-out targets, reaction times are facilitated when the target on the current trial appears at a previous target location, and inhibited when it appears at a previous distractor location, relative to when it appears at a previously empty (neutral) location (Maljkovic and Nakayama, Perception and Psychophysics 58:977-991, 1996). However, while normal subjects are able to positively/negatively tag selected target/rejected distractor locations to guide search on the next trial, patients with visual hemi-neglect may have a (uni- or bilateral) deficit in these functions that may contribute to their disturbed visual scanning behavior. To examine this, using a pop-out search task, the present study assessed cross-trial facilitatory and inhibitory priming in 14 patients with left-sided visual hemi-neglect and in 14 age-, education-, and IQ-matched control subjects. The group of neglect patients did show significant facilitatory and inhibitory priming. However, while control subjects exhibited balanced effects of facilitation and inhibition, inhibition was relatively reduced in magnitude in neglect patients. In particular, inhibition was virtually absent in two patients with lesions affecting superior regions of the frontal cortex, putatively encroaching on the frontal eye field of the right hemisphere. These findings provide neuropsychological evidence that facilitatory and inhibitory priming effects are based on dissociable mechanisms, consistent with Geyer et al. (Journal of Experimental Psychology: Human Perception and Performance 33:788-797, 2007).

Task-dependent modulation of neglect dyslexia? Novel evidence from the viewing position effect.

Spatial neglect may involve neglect dyslexia resulting in a failure to identify words or parts of words in the contralesional hemispace. The present study explored a well-documented dissociation in neglect dyslexics' word processing, i.e. impaired reading aloud in the presence of good lexical decision performance for the same stimuli. To investigate whether this dissociation is also reflected in the visuo-spatial characteristics of word processing, a well-established paradigm of word processing in normal readers (technique of variable viewing positions, [Nazir, T., Heller, D., Sussmann, C., 1992. Letter visibility and word recognition: The optimal viewing position in printed words. Perception and Psychophysics, 52, 315-328]) was combined with a word naming and a lexical decision task. Compared to previous studies of neglect dyslexia, the present study additionally entailed tachistoscopical displays of word stimuli in different viewing positions. The word stimuli varied orthogonally along the two linguistic dimensions of word frequency (lexical manipulation) and syllable number (sublexical manipulation). Participants were sixteen patients with left-sided visual neglect and an age-matched control group. We expected the dissociation in neglect dyslexia to be reflected in task-specific effects in naming and lexical decision. This was partly confirmed by an interaction of task demands with viewing-position-specific results. Interestingly these results pointed to a task-dependency in word processing not only in neglect patients but also in normal readers, when equal error rates were experimentally obtained between control and neglect participants. Together with the finding of a task-specific effect of syllable number in the neglect group, the present results suggest that task demands modulate the degree of neglect dyslexia from early stages of visual word processing.

Line bisection as an early method to assess homonymous hemianopia.

Horizontal line bisection task is a common clinical task well known to most neuropsychologists. Typically, patients with visuospatial neglect show a reliable ipsilesional deviation in the bisection of long lines. Less well known in the English literature is the typical line bisection error observed in hemianopic patients who show the opposite deviation. In fact, this contralesional deviation in bisection was well known in the old German scientific literature. In 1894, more than 110 years ago, the German physician Dr. D. Axenfeld published a short case report about line bisection as a "simple method to diagnose hemianopia". His paper is one (if not the first) historical report, describing the "typical hemianopic line bisection error". At the time of its publication, it was a very popular paper in the German scientific community frequently cited by subsequent researchers. Between 1900 and 1920, Axenfeld's observation motivated several further studies using bisection by well-known researchers such as Best, Liepmann, Wilbrand, Poppelreuter and Fuchs. Surprisingly, most of today's clinical and cognitive studies use experimental modifications of line bisection in neglect patients and healthy subjects, often without realizing that this task was originally devised for the assessment of hemianopic patients. Consequently, the hemianopic line bisection error was "neglected" for many decades until its recent "rediscovery". The present paper has three aims. First, Axenfeld's classical report is translated. Second, interpretations arising from early bisection studies (around 1900-1930) in hemianopic patients are summarized and framed within contemporary science. Finally, we attempt to explain why this formerly well-known clinical phenomenon was forgotten later for nearly a century.

Spatial remapping in visual search: Remapping cues are provided at attended and ignored locations.

We experience the world as stable and continuous, despite the fact that visual input is overwritten on the retina with each new ocular fixation. Spatial remapping is the process that integrates selected visual information into successive (continuous) representations of our spatial environment, thereby allowing us to keep track of objects, and experience the world as stable, despite frequent eye (re-)fixations. The present paper investigates spatial remapping in the context of visual pop-out search. Within standard instances of the pop-out paradigm, reactions to stimuli at previously attended locations are facilitated (faster and more accurate), and reactions to stimuli at previously ignored locations are inhibited (slower and less accurate). The mechanisms that support facilitation at previously attended locations, and inhibition at previously ignored locations, serve to enhance the efficiency of visual search. It is thus natural to expect that information about which locations were previously attended to or ignored is stored and remapped as a concomitant to successive representations of the spatial environment. Using variants of the pop-out paradigm, we corroborate this expectation, and show that information concerning the prior status of locations, as attended to or ignored, is remapped following attention shifts, with some degradation of information concerning ignored locations.

The capacity of attention and simultaneous perception of objects: a group study of Huntington's disease patients.

Using a whole report-paradigm based on [Bundesen, C. (1990). A theory of visual attention. Psychological Review, 97, 523-547; Bundesen, C. (1998). A computational theory of visual attention. Philosophical Transactions of the Royal Society of London B, Biological Sciences, 353, 1271-1281] theory of visual attention (TVA), [Finke, K., Bublak, P., Dose, M., Müller, H. J., & Schneider, W. X. (2006). Parameter-based assessment of spatial and non-spatial attentional deficits in Huntington's disease. Brain, 129, 1137-1151] demonstrated profound reductions in perceptual processing speed and visual working memory (WM) storage capacity in Huntington's disease (HD) patients. A comparably severe impairment of visual processing capacity has previously been reported for two simultanagnosia patients [Duncan, J., Bundesen, C., Olson, A., Humphreys, G., Ward, R., Kyllingsbaek, S., van Raamsdonk, M., Rorden, C., & Chavda, S. (2003). Attentional functions in dorsal and ventral simultanagnosia. Cognitive Neuropsychology, 20, 675-702]. To investigate whether such a deficit does also prevail in HD, the simultaneous perception of visual objects was tested in 10 HD patients under free viewing conditions and without time constraints. Objects were presented under four different conditions: (i) single, (ii) multiple adjacent, (iii) multiple embedded, and (iv) multiple overlapping. The dependent measure was the percentage of identification failures. Performance was compared to that of 15 healthy subjects matched for age, education, gender and general mental ability. For HD patients, the percentage of errors in the various testing conditions was examined for correlations with the TVA parameters of visuo-perceptual processing speed and WM storage capacity. These parameters were estimated using verbal whole report of briefly presented letters. TVA permits the two parameters to be estimated mathematically independently and relatively unaffected by any motor deficits present in HD. The identification error rate was substantially increased in HD patients, compared to control subjects, in the overlapping-figures subtest. This deficit was significantly and negatively correlated with processing speed, whereas there was no correlation with WM storage capacity. These results demonstrate the presence of deficits in simultaneous perception in HD, related to a severe reduction in perceptual processing speed. The results are discussed with respect to a dopamine mediated decline of cortical cholinergic activation, diminishing the number of visual objects that can be simultaneously represented within the visual processing system.

Contralesional Trunk Rotation Dissociates Real vs. Pseudo-Visual Field Defects due to Visual Neglect in Stroke Patients.

In stroke patients, the clinical presentation of visual field defects (VFDs) is frequently accompanied by visual neglect, i.e., the inability to attend and respond to the contralesional space. However, the diagnostic discrimination between the lack of reactions to contralesional stimuli due to VFDs or visual neglect is challenging during clinical examination. This discrimination is particularly relevant, since both clinical pictures are associated with different therapeutic approaches and outcomes. The aim of this study was to systematically investigate the effectiveness of trunk rotation toward the contralesional side-a manipulation dissociating the coordinate system of the trunk from that of the head and eyes-in disentangling real VFDs from "pseudo-VFDs" that occur due to visual neglect. Twenty patients with a left-sided VFD after a right-hemispheric stroke (10 additionally showing visual neglect in neuropsychological testing, VFD + neglect; 10 without neglect, VFD) were tested with Goldmann perimetry in both standard and trunk rotation conditions. In the standard condition, both VFD and VFD + neglect patients showed a conspicuous narrowing of the left visual field. However, trunk rotation triggered strikingly different patterns of change in the two groups: it elicited a significant increase in visual field extension in the VFD + neglect group, but left visual field extension virtually unchanged in the VFD group. Our results highlight contralesional trunk rotation as a simple, viable manipulation to effectively and rapidly disentangle real VFDs from "pseudo-VFDs" (i.e., due to visual neglect) during clinical examination.

Rotation or translation of auditory space in neglect? A case study of chronic right-sided neglect.

Egocentric models of neglect explain the lateralised omission of stimuli in neglect patients by an ipsilesional shift of a subjective reference frame. However, they differ in the direction of shift (rotation around the midsagittal plane versus translation in front/back space). We tested this hypothesis in a patient (AJ) with persistent right-sided neglect following a left temporo-parieto-occipital and hypoxic lesion and in six age-matched healthy subjects. AJ showed visual neglect in line bisection, size matching, reading and visual search. Auditory localization was tested by using two different psychophysical techniques based on binaurally simulated stimuli for the horizontal plane in front and back space. Eye position was continuously monitored during stimulus presentation in all subjects. AJ revealed a significant ipsilesional, leftward shift of his auditory subjective median plane (ASMP) in front space (mean: -22.6 degrees), and a rightward shift of the ASMP in back space (+14.5 degrees). This pattern of results was replicated with a different psychophysical technique in a retest 10 months later. The rotational shift of AJ's ASMP contrasted with normal performance in the healthy subjects. Monaural hearing deficits can not account for these differential findings as all subjects (including AJ) performed normally. In conclusion, a rotation of the egocentric spatial reference frame may occur in the auditory modality for right-sided neglect.

Modified pen grip in the treatment of Writer's Cramp.

Writer's Cramp (WC) is a focal, action-related dystonia, which induces hypertonic co-contractions and severely impairs handwriting. One behavioral treatment approach is the handwriting training developed by Mai and Marquardt (1999), [Mai, N., & Marquardt, C. (1999). Schreibtraining in der neurologischen Rehabilitation. In EKN-Materialien für die Rehabilitation. Dortmund: Borgmann] which includes among various motor exercises the use of a modified pen grip (stabilized between index and middle finger). This pen grip has proven particularly successful in clinical practice. The current study aims at elucidating the immediate effects of the modified pen grip on writing in 23 WC patients and 11 healthy controls. All participants wrote a sentence with their usual and also with the modified pen grip. Movement and pressure were recorded with a digitizing tablet. Pressure, movement time for the whole sentence, script size and writing fluency were analyzed. When writing with their usual pen grip, pressure in the WC patients was elevated, and writing speed was decreased compared to healthy controls. Changing over to the modified pen grip reduced the pressure significantly in WC patients and controls, but left other aspects of their writing unaffected. This shows that the use of the modified pen grip is an effective way to normalize pen pressure in WC patients, thereby providing the best conditions for the training of speed and fluency.

Clinical and Psychometric Evaluations of the Cerebral Vision Screening Questionnaire in 461 Nonaphasic Individuals Poststroke.

BACKGROUND: Cerebral vision disorders (CVDs) are frequent after brain damage and impair the patient's outcome. Yet clinically and psychometrically validated procedures for the anamnesis of CVD are lacking. OBJECTIVE: To evaluate the clinical validity and psychometric qualities of the Cerebral Vision Screening Questionnaire (CVSQ) for the anamnesis of CVD in individuals poststroke. METHODS: Analysis of the patients' subjective visual complaints in the 10-item CVSQ in relation to objective visual perimetry, tests of reading, visual scanning, visual acuity, spatial contrast sensitivity, light/dark adaptation, and visual depth judgments. Psychometric analyses of concurrent validity, specificity, sensitivity, positive/negative predictive value, and interrater reliability were also done. RESULTS: Four hundred sixty-one patients with unilateral (39.5% left, 47.5% right) or bilateral stroke (13.0%) were included. Most patients were assessed in the chronic stage, on average 36.7 (range = 1-620) weeks poststroke. The majority of all patients (96.4%) recognized their visual symptoms within 1 week poststroke when asked for specifically. Mean concurrent validity of the CVSQ with objective tests was 0.64 (0.54-0.79, P < .05). The mean positive predictive value was 80.1%, mean negative predictive value 82.9%, mean specificity 81.7%, and mean sensitivity 79.8%. The mean interrater reliability was 0.76 for a 1-week interval between both assessments (all P < .05). CONCLUSION: The CVSQ is suitable for the anamnesis of CVD poststroke because of its brevity (10 minute), clinical validity, and good psychometric qualities. It, thus, improves neurovisual diagnosis and guides the clinician in the selection of necessary assessments and appropriate neurovisual therapies for the patient.

Assessing neglect dyslexia with compound words.

OBJECTIVE: The neglect syndrome is frequently associated with neglect dyslexia (ND), which is characterized by omissions or misread initial letters of single words. ND is usually assessed with standardized reading texts in clinical settings. However, particularly in the chronic phase of ND, patients often report reading deficits in everyday situations but show (nearly) normal performances in test situations that are commonly well-structured. To date, sensitive and standardized tests to assess the severity and characteristics of ND are lacking, although reading is of high relevance for daily life and vocational settings. METHOD: Several studies found modulating effects of different word features on ND. We combined those features in a novel test to enhance test sensitivity in the assessment of ND. Low-frequency words of different length that contain residual pronounceable words when the initial letter strings are neglected were selected. We compared these words in a group of 12 ND-patients suffering from right-hemispheric first-ever stroke with word stimuli containing no existing residual words. Finally, we tested whether the serially presented words are more sensitive for the diagnosis of ND than text reading. RESULTS: The severity of ND was modulated strongly by the ND-test words and error frequencies in single word reading of ND words were on average more than 10 times higher than in a standardized text reading test (19.8% vs. 1.8%). CONCLUSION: The novel ND-test maximizes the frequency of specific ND-errors and is therefore more sensitive for the assessment of ND than conventional text reading tasks. (PsycINFO Database Record

Extra-powerful on the visuo-perceptual space, but variable on the number space: Different effects of optokinetic stimulation in neglect patients.

We studied the effects of optokinetic stimulation (OKS; leftward, rightward, control) on the visuo-perceptual and number space, in the same sample, during line bisection and mental number interval bisection tasks. To this end, we tested six patients with right-hemisphere damage and neglect, six patients with right-hemisphere damage but without neglect, and six neurologically healthy participants. In patients with neglect, we found a strong effect of leftward OKS on line bisection, but not on mental number interval bisection. We suggest that OKS influences the number space only under specific conditions.

Holmes and Horrax (1919) revisited: impaired binocular fusion as a cause of "flat vision" after right parietal brain damage - a case study.

The complete loss of binocular depth perception ("flat vision") was first thoroughly described by Holmes and Horrax (1919), and has been occasionally reported thereafter in patients with bilateral posterior-parietal lesions. Though partial spontaneous recovery occurred in some cases, the precise cause(s) of this condition remained obscure for almost a century. Here, we describe a unique patient (EH) with a large right-sided occipito-parietal hemorrhage showing a complete loss of visual depth perception for several months post-stroke. EH could well simultaneously describe multiple visual objects - hence did not show simultanagnosia - but at the same time was completely unable to estimate their distance from him. In every 3-D visual scene objects appeared equidistant to him, thus experiencing a total loss of depth perception ("flat vision"). Neurovisual assessments revealed normal functions of the eyes. EH showed bilateral lower field loss and a severely impaired binocular convergent fusion, but preserved stereopsis. Perceptual re-training of binocular fusion resulted in a progressive and finally complete recovery of objective binocular fusion values and subjective binocular depth perception in a far-to-near-space, gradient-like manner. In parallel, visual depth estimation of relative distances improved, whereas stereopsis remained unchanged. Our results show that a complete loss of 3-D depth perception can result from an isolated impairment in binocular fusion. On a neuroanatomical level, this connection could be explained by a selective lesion of area V6/V6A in the medial occipito-parietal cortex that has been associated with the integration of visual space coordinates and sustained eye-positions into a cyclopean visual 3-D percept.

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: 0.7mA) 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 20min 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.

Subliminal galvanic-vestibular stimulation recalibrates the distorted visual and tactile subjective vertical in right-sided stroke.

Stroke of the right cerebral hemisphere often causes deficits in the judgement of the subjective visual vertical (SVV) and subjective tactile vertical (STV) which are related to central vestibular functioning. Clinically, deficits in the SVV/STV are linked to balance problems and poor functional outcome. Galvanic Vestibular Stimulation (GVS) is a non-invasive, save stimulation technique that induces polarity-specific changes in the cortical vestibular systems. Subliminal GVS induces imperceptible vestibular stimulation without unpleasant side effects. Here, we applied bipolar subliminal GVS over the mastoids (mean intensity: 0.7 mA, 20 min duration per session) to investigate its online-influence on constant errors, difference thresholds and range values in the SVV and STV. 24 patients with subacute, single, unilateral right hemisphere stroke were studied and assigned to two patient groups (impaired vs. normal in the SVV and STV) on the basis of cut-off scores from healthy controls. Both groups performed these tasks under three experimental conditions on three different days: a) sham GVS where electric current was applied only for 30s and then turned off, b) left-cathodal GVS and c) right-cathodal GVS, for a period of 20 min per session. Left-cathodal GVS, but not right-cathodal GVS significantly reduced all parameters in the SVV. Concerning STV GVS also reduced constant error and range numerically, though not significantly. These effects occurred selectively in the impaired patient group. In conclusion, we found that GVS rapidly influences poststroke verticality deficits in the visual and tactile modality, thus highlighting the importance of the vestibular system in the multimodal elaboration of the subjective vertical.