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

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.

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.

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.

Smooth Pursuit "Bedside" Training Reduces Disability and Unawareness During the Activities of Daily Living in Neglect: A Randomized Controlled Trial.

UNLABELLED: Background Neglect is associated with disability, unawareness, poor long-term outcome, and dependence from caregivers. No randomized trial has evaluated the effects of smooth pursuit eye movement training (SPT) and visual scanning training (VST) at the bedside on these variables. Objective To compare the effects of SPT and VST in postacute stroke at 1 month with left neglect. METHODS: We carried out an assessor-blinded, randomized controlled trial. The 24 participants were randomly allocated to either SPT or VST (n = 12 each). They received 20 treatment sessions lasting 30 minutes each at the bedside over 4 weeks. Outcome measures included the Functional Neglect Index (FNI) based on 4 tasks: find objects on a tray, stick bisection, picture search, and gaze orientation. In addition, the Unawareness and Behavioral Neglect Index (UBNI) with 6 items about unawareness and 4 about neglect in activities of daily living, the Help index (required assistance in 10 functional activities), the Barthel Index, and the rehabilitation phase were rated by treatment-blinded assessors. Outcome measures were obtained before and immediately after the end of the interventions and at a 2-week follow-up. Results Significantly greater improvements were obtained after SPT versus VST treatment in the FNI and UBNI, and there were continued improvements selectively in the SPT group 2 weeks later. Conclusions SPT accelerates recovery from functional neglect and reduces unawareness significantly. Bedside neglect treatment using SPT is effective and feasible early after stroke.

Perceptual relearning of binocular fusion after hypoxic brain damage: four controlled single-case treatment studies.

OBJECTIVE: Hypoxic brain damage is characterized by widespread, diffuse-disseminated brain lesions, which may cause severe disturbances in binocular vision, leading to diplopia and loss of stereopsis, for which no evaluated treatment is currently available. The study evaluated the effects of a novel binocular vision treatment designed to improve binocular fusion and stereopsis as well as to reduce diplopia in patients with cerebral hypoxia. METHOD: Four patients with severely reduced convergent fusion, stereopsis, and reading duration due to hypoxic brain damage were treated in a single-subject baseline design, with three baseline assessments before treatment to control for spontaneous recovery (pretherapy), an assessment immediately after a treatment period of 6 weeks (posttherapy), and two follow-up tests 3 and 6 months after treatment to assess stability of improvements. Patients received a novel fusion and dichoptic training using 3 different devices designed to slowly increase fusional and disparity angle. RESULTS: After the treatment, all 4 patients improved significantly in binocular fusion, subjective reading duration until diplopia emerged, and 2 of 4 patients improved significantly in local stereopsis. No significant changes were observed during the pretherapy baseline period and the follow-up period, thus ruling out spontaneous recovery and demonstrating long-term stability of treatment effects. CONCLUSIONS: This proof-of-principle study indicates a substantial treatment-induced plasticity after hypoxia in the relearning of binocular vision and offers a viable treatment option. Moreover, it provides new hope and direction for the development of effective rehabilitation strategies to treat neurovisual deficits resulting from hypoxic brain damage.

Perceptual Relearning of Binocular Fusion and Stereoacuity After Brain Injury.

BACKGROUND: Brain lesions may disturb binocular fusion and stereopsis, leading to blurred vision, diplopia, and reduced binocular depth perception for which no evaluated treatment is currently available. Objective The study evaluated the effects of a novel binocular vision treatment designed to improve convergent fusional amplitude and stereoacuity in patients with stroke or traumatic brain injury (TBI). Methods Patients (20 in all: 11 with stroke, 9 with TBI) were tested in fusional convergence, stereoacuity, near/far visual acuity, accommodation, and subjective binocular reading time until diplopia emerged at 6 different time points. All participants were treated in a single subject baseline design, with 3 baseline assessments before treatment (pretherapy), an assessment immediately after a 6-week treatment period (posttherapy), and 2 follow-up tests 3 and 6 months after treatment. Patients received a novel fusion and dichoptic training using 3 different devices to slowly increase fusional and disparity angles. Results At pretherapy, the stroke and TBI groups showed severe impairments in convergent fusional range, stereoacuity, subjective reading duration, and partially in accommodation (only TBI group). After treatment, both groups showed considerable improvements in all these variables as well as slightly increased near visual acuity. No significant changes were observed during the pretherapy and follow-up periods, ruling out spontaneous recovery and demonstrating long-term stability of binocular treatment effects. Conclusions This proof-of-principle study indicates a substantial treatment-induced plasticity of the lesioned brain in the relearning of binocular fusion and stereovision, thus providing new, effective rehabilitation strategies to treat binocular vision deficits resulting from permanent visual cortical damage.

Smooth pursuit eye movement training promotes recovery from auditory and visual neglect: a randomized controlled study.

BACKGROUND: No treatment for auditory neglect and no randomized controlled trial evaluating smooth pursuit eye movement therapy (SPT) for multimodal neglect are available. OBJECTIVE: To compare the effects of SPT and visual scanning therapy (VST) on auditory and visual neglect in chronic stroke patients with neglect. METHODS: A randomized, prospective trial was conducted. Fifty patients with left auditory and visual neglect were randomly assigned. Twenty-four patients completed SPT therapy and 21 patients VST. Five patients (4 VST, 1 SPT) were lost. Each group received 1-hour sessions of neglect therapy for 5 consecutive days totaling 5 hours. Outcome measures in visual neglect (digit cancellation, visuoperceptual- and motor line bisection, paragraph reading) and auditory neglect (auditory midline) were assessed twice before therapy, thereafter, and at 2-week follow-up. The SPT group practiced smooth pursuit eye movements while tracking stimuli moving leftward. The VST group systematically scanned the same but static stimuli. Both groups were divided into subgroups, and effects were separately investigated for mild and severe neglect. RESULTS: Both groups did not differ before therapy in clinical/demographic variables or neglect severity (auditory/visual). After treatment, the SPT group showed significant and lasting improvements in all visual measures and normal performance in the auditory midline. Neither visual nor auditory neglect impairments changed significantly after VST. Moreover, the treatment effect sizes (Cohen's d) were considerably higher for visual and auditory neglect after SPT versus VST, both for mild and severe neglect. CONCLUSIONS: Repetitive contralesional, smooth pursuit training induces superior, multimodal therapeutic effects in mild and severe neglect.

Now You Feel both: Galvanic Vestibular Stimulation Induces Lasting Improvements in the Rehabilitation of Chronic Tactile Extinction.

Tactile extinction is frequent, debilitating, and often persistent after brain damage. Currently, there is no treatment available for this disorder. In two previous case studies we showed an influence of galvanic vestibular stimulation (GVS) on tactile extinction. Here, we evaluated in further patients the immediate and lasting effects of GVS on tactile extinction. GVS is known to induce polarity-specific changes in cerebral excitability in the vestibular cortices and adjacent cortical areas. Tactile extinction was examined with the Quality Extinction Test (QET) where subjects have to discriminate six different tactile fabrics in bilateral, double simultaneous stimulations on their dorsum of hands with identical or different tactile fabrics. Twelve patients with stable left-sided tactile extinction after unilateral right-hemisphere lesions were divided into two groups. The GVS group (N = 6) performed the QET under six different experimental conditions (two Baselines, Sham-GVS, left-cathodal/right-anodal GVS, right-cathodal/left-anodal GVS, and a Follow-up test). The second group of patients with left-sided extinction (N = 6) performed the QET six times repetitively, but without receiving GVS (control group). Both right-cathodal/left-anodal as well as left-cathodal/right-anodal GVS (mean: 0.7 mA) improved tactile identification of identical and different stimuli in the experimental group. These results show a generic effect of GVS on tactile extinction, but not in a polarity-specific way. These observed effects persisted at follow-up. Sham-GVS had no significant effect on extinction. In the control group, no significant improvements were seen in the QET after the six measurements of the QET, thus ruling out test repetition effects. In conclusion, GVS improved bodily awareness permanently for the contralesional body side in patients with tactile extinction and thus offers a novel treatment option for these patients.

The frequency and significance of the word length effect in neglect dyslexia.

Neglect patients often omit or misread initial letters of single words, a phenomenon termed neglect dyslexia (ND). Omissions of whole words on the contralesional side of the page during paragraph reading are generally considered as egocentric or space-based errors, whereas misreading of the left part of a word can be viewed as a type of stimulus-centred or word-based, neglect-related error. The research of the last decades shed light on several effects of word features (such as written word frequency, grammatical class or concreteness) that modulate the severity of ND. Nevertheless, almost all studies about those modulating factors were case studies and some of them have not been replicated yet. Therefore, to date we do not know how relevant such effects of different word stimuli are for a population of ND patients. Knowing their incidence would improve our theoretical understanding of ND and promote the development of standardized ND assessments, which are lacking so far. In particular, case studies have shown that ND error frequency increases systematically with word length (word length effect, WLE) while other single case studies found contrary results. Hence, the existence of the WLE in ND is unsettled and its incidence and significance in stroke patients is unknown. To clarify this issue we evaluated the relation between word length and the extent (number) of neglected or substituted letters within single words in ND (neglect dyslexia extent, NDE) in a group of 19 consecutive ND patients with right hemisphere lesions. We found a clear WLE in 79% (15 of 19) of our ND patients, as indicated by significant correlations between word length and NDE. Concurrent visual field defects had no effect on the WLE in our sample, thus showing no influence of early visual cortical processing stages on the WLE in neglect dyslexia. In conclusion, our results suggest a clear relationship between word length and reading errors in ND and show that the WLE is a frequent phenomenon in ND.

Effects of feedback-based visual line-orientation discrimination training for visuospatial disorders after stroke.

BACKGROUND: Patients with right or more rarely left parietotemporal lesions after stroke may have profound visuospatial disorders that impair activities of daily living (ADL) and long-term outcome. Clinical studies indicate improvements with systematic training of perception. Studies of perceptual learning in healthy persons suggest rapid improvements in perceptual learning of spatial line orientation with partial transfer to nontrained line orientations. OBJECTIVE: The authors investigated a novel feedback-based perceptual training procedure for the rehabilitation of patients after stroke. METHODS: In an uncontrolled trial, 13 participants showing profound deficits in line orientation and related visuospatial tasks within 12 to 28 weeks of onset performed repetitive feedback-based, computerized training of visual line orientation over 4 weeks of treatment. Visual line-orientation discrimination and visuospatial and visuoconstructive tasks were assessed before and after training. RESULTS: The authors found (a) rapid improvements in trained but also in nontrained spatial orientation tests in all 13 participants, partially up to a normal level; (b) stability of the obtained improvements at 2-month follow-up; (c) interocular transfer of training effects to the nontrained eye in 2 participants suggesting a central, postchiasmatic locus for this perceptual improvement; and (d) graded transfer of improvements to related spatial tasks, such as horizontal writing, analog clock reading, and visuoconstructive capacities but no transfer to unrelated measures of visual performance. CONCLUSIONS: These results suggest the potential for treatment-induced improvements in visuospatial deficits by feedback-based, perceptual orientation training as a component of rehabilitation after stroke.

Line bisection error predicts the presence and severity of neglect dyslexia in paragraph reading.

Cancellation tasks and line bisection tasks are commonly used to diagnose spatial neglect after right hemisphere lesions. In such tasks, neglect patients often show leftsided omissions of targets in cancellation tests as well as a pathological rightward deviation in horizontal line bisection. However, double dissociations have also been reported and the relation between performance in both tasks is not clear. Another impairment frequently associated with the neglect syndrome are omissions or misread initial letters of single words, a phenomenon termed neglect dyslexia (ND). Omissions of whole words on the contralesional side of the page are generally considered as egocentric or space-based errors, whereas misreadings of the left part of a word in ND can be viewed as a type of stimulus-centered or word-based, perceptual error. As words, sentences and horizontal lines have a similar spatial layout in the sense that they all are horizontally aligned, long stimuli with a canonical left-right orientation (with a defined beginning on the left and an end on the right side), we hypothesized a significant association between the horizontal line bisection error (LBE) in neglect and the extent (number) of neglected or substituted letters within single words in ND (neglect dyslexia extension, NDE). To this purpose, we computed Center-of-Cancellation (CoC) scores in a cancellation task as well as Center-of-Reading (CoR) scores in an experimental paragraph reading test. We found that the CoR was a better indicator for egocentric word omissions than the CoC in a group of 17 patients with left visuospatial neglect. Furthermore, the LBE predicted the severity of ND, indicated by highly significant correlations between the LBE and the extent of the neglected letter string within single words (NDE; r=0.73, p<0.001) as well as between the LBE and the frequency of ND errors (r=0.61; p=0.009). In contrast, we found no significant correlation between the CoC and the severity of ND. These results indicate two different pathological mechanisms being responsible for contralesional spatial neglect and ND. In conclusion, the LBE is a more sensitive predictor of the presence and severity of the reading disorder in spatial neglect than conventional cancellation tasks.

Optokinetic stimulation affects word omissions but not stimulus-centered reading errors in paragraph reading in neglect dyslexia.

Patients with right hemisphere lesions often omit or misread words on the left side of a text or the initial letters of single words, a phenomenon termed neglect dyslexia (ND). Omissions of words on the contralesional side of the page are considered as egocentric or space-based errors, whereas misread words can be viewed as a type of stimulus-centered error where the left part of a single perceptual entity (the word) is neglected. Previous patient studies have shown that optokinetic stimulation (OKS) significantly modulates many facets of the neglect syndrome, including the subjective body midline, line bisection and size distortions. An open question is whether OKS can also influence omissions and stimulus-centered errors in paragraph reading in ND. The current study compared the influence of OKS on both types of reading errors using controlled indented paragraph reading tests in a group of 9 right-hemisphere lesioned patients with ND, 7 patients without ND and 9 matched healthy controls. Leftward OKS significantly reduced omissions on the left side of the text in ND. In contrast, the pattern of stimulus-centered reading errors remained unchanged. In conclusion egocentric manipulations like OKS only appear to influence space-based attentional processes evident as omissions in paragraph reading but have no impact on stimulus-centered attentional processes evident as word-based errors during paragraph reading in ND.

A long-lasting improvement of tactile extinction after galvanic vestibular stimulation: two Sham-stimulation controlled case studies.

Sensory extinction is frequent and often persistent after brain damage. Previous studies have shown the transient influence of sensory stimulation on tactile extinction. In the present two case studies we investigated whether subliminal galvanic vestibular stimulation (GVS) modulates tactile extinction. GVS induces polarity-specific changes in cerebral excitability in the vestibular cortices and adjacent cortical areas in the temporo-parietal cortex via polarization of the vestibular nerves. Two patients (DL, CJ) with left-sided tactile extinction due to chronic (5 vs. 6 (1/2) years lesion age) right-hemisphere lesions (right fronto-parietal in DL, right frontal and discrete parietal in CJ) were examined. Both showed normal tactile sensitivity to light touch and yielded 90-100% correct identifications in unilateral tactile stimulations for both hands. In Baseline investigations without GVS and Sham-GVS both showed stable left-sided tactile extinction rates of 40-55% (DL) and 49-72% (CJ). In contrast, one session of right-cathodal GVS (intensity: 0.6 mA, duration: 20 min) permanently improved tactile identification of identical stimuli, while a second session with left-cathodal GVS significantly reduced left-sided extinction rates for different stimuli in DL. Patient CJ's left-sided tactile extinction was significantly improved by left-cathodal GVS (0.5 mA, 20 min) for different stimuli, while right-cathodal GVS induced a significant reduction for identical materials. In contrast, Sham-stimulation was ineffective. Improvements remained stable for at least 1 year (DL) resp. 3 weeks (CJ). Control experiments ruled out improvements in tactile extinction merely by retesting. In conclusion, chronic tactile extinction may be permanently improved by GVS in a polarity-specific way.

Effects of head rotation on space- and word-based reading errors in spatial neglect.

Patients with right hemisphere lesions often omit or misread words on the left side of a text or the beginning letters of single words which is termed neglect dyslexia (ND). Two types of reading errors are typically observed in ND: omissions and word-based reading errors. The prior are considered as space-based omission errors on the contralesional side of the page, while the latter can be viewed as a kind of stimulus- or word-based reading errors where leftsided parts of a single perceptual entity (the word) are neglected. The head, trunk and eyes are part of a hypothetical egocentric reference frame that is aligned around our body and divides space into a left and right hemispace. Previous neglect studies have shown that head- and trunk-orientation significantly influence contralesional neglect. An open question is whether such egocentric manipulations also influence omissions and word-based errors in paragraph reading in ND. The current study investigated in a sample of right-hemisphere lesioned patients with ND vs. without ND and matched healthy control subjects the influence of head-rotation (HR) on both types of reading errors using controlled indented paragraph reading tests. Passive leftward HR significantly reduced omission errors on the left side of the text in ND, but had no effect on word-based reading errors. In conclusion egocentric manipulations like HR only appear to influence space-based attentional processes in neglect evident as omissions in paragraph reading but have no impact on those attentional processes involved in word identification evident as word-based errors in paragraph reading.