Plasticity in spatial neglect: recovery and rehabilitation.
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Humans↗
Biomedical subjects
G Kerkhoff
Publications and source records attributed to G Kerkhoff.
Construction and psychometric properties of a novel test for body representational neglect (Vest Test).
PURPOSE: Multimodal spatial neglect manifests itself also in nonvisual modalities such as audition, touch and body representation. Yet, quantitative tests for the diagnosis of nonvisual neglect are still quite rare. The purpose of the present paper was to develop and evaluate a novel, simple and sensitive test for the assessment of body representational neglect (BRN) in patients with left or right cerebral hemispheric lesions. METHODS: The vest test covers the front part of the trunk. The blindfolded subject wears the vest and is instructed to pick up all objects from the 24 pockets of the vest (12 on each side) as quickly as possible using the ipsilesional, nonparetic hand. Two samples of healthy control subjects (each N=25) using either their left or their right hand performed the test in identical way to obtain normative data for patients searching with their left hand (i.e. left hemisphere stroke patients) versus their right hand (i.e. right hemisphere stroke patients). The test can be performed within 5~minutes, even with aphasic or apractic stroke patients. RESULTS: Psychometric evaluations in a sample of 50 patients with unilateral stroke (25 leftsided, 25 rightsided) show high objectivity, high internal consistency (Cronbach's alpha=0.96), good retest-reliability (0.79 after 1 week in neglect patients) and good validity as compared with two other measures of BRN or multimodal neglect. Patient examples show that BRN as assessed with the vest test allows the detection of qualitatively and quantitatively different patterns of BRN, and shows double dissociations from visual neglect and from apraxia in left hemisphere stroke patients. Details of the test including instructions and cut-off values are given for users in the appendix of this article. CONCLUSIONS: In conclusion, the vest test is a sensitive, quick and reliable test for BRN which complements the assessment of visuo- and audiospatial neglect and allows to measure recovery (spontaneous or treatment-induced) in patients with BRN. Furthermore, it can help to improve our knowledge about the multisensory coding of our body and the surrounding space in the human brain.
Activities of Daily Living↗
Repetitive optokinetic stimulation induces lasting recovery from visual neglect.
PURPOSE: To evaluate whether repetitive optokinetic stimulation with active pursuit eye movements leads to substantial and greater recovery from visual neglect as compared to conventional visual scanning training. METHODS: Two groups of five patients with leftsided hemineglect were consecutively collected and matched for clinical and demographic variables as well as neglect severity. One group received five treatment sessions of repetitive optokinetic stimulation (R-OKS) within one week, while the other group received the same amount of conventional visual scanning training (VST) using identical visual stimuli and setup. All patients were treated in a single-subject baseline design with treatment-free intervals before (14 days) and after specific neglect therapy (14 days). Dependent variables were the improvements in digit cancellation, visuoperceptual and visuomotor line bisection and visual size distortion during treatment. The transfer of treatment effects was assessed by a paragraph reading test. RESULTS: The results showed superior effects of OKS treatment in all five patients which generalized across all tasks administered and remained stable at follow-up. In contrast, no significant improvements were obtained after VST training in any of these tasks, except in line bisection. CONCLUSION: We conclude that the presentation of moving visual stimulus displays with active smooth pursuit eye movements can be more efficient than conventional visual scanning training using static visual displays.
Adult↗
Visuospatial neglect in near and far space: dissociation between line bisection and letter cancellation.
The differential performance on a line bisection and a cancellation task in near and far space was studied. A group of 10 patients with severe left-sided visuospatial neglect and a group of 10 right-brain damaged patients without neglect were examined. The stimuli were presented at a distance of 60 cm (near space) and 160 cm (far space), respectively, and corrected for visual angle. In the line bisection task, patients were asked to point to the estimated line centre with a pencil (near space) or a stick (far space). In the cancellation task, patients pointed to all target stimuli they could detect using either a pencil (near space) or a stick (far space). Most patients with left hemineglect showed a more prominent neglect in far space as compared to near space for the line bisection task, whereas no difference of performance between near and far space was found in the control patients. In contrast, no group showed a distance effect in the cancellation task. The observation that only line bisection is influenced by the distance of the stimulus suggests that line bisection and cancellation are processed differentially. It is proposed that line bisection requires an allocentric reference system focusing attention on objects, whereas cancellation tasks are based on an egocentric reference system responsible for visuospatial attention. Our results indicate that distance changes perception within the allocentric but not within the egocentric system.
Adult↗
[Prognostic value of noninvasive coronary plaque burden quantification in patients with risk factors].
Non-invasive quantitative indices of atherosclerosis are promising new parameters for an improved prognostic stratification of patients with risk factors that aim at individualized risk factor assessment and modification. In a recently published ACC/AHA consensus document, further data on the diagnostic and prognostic value of coronary calcified plaque quantification were strongly encouraged prior to its use in the general population. In this present work we summarize data published since, which contribute significantly to the prognostic value of fast CT-based noninvasive coronary calcified plaque quantification. It is a measure of atherosclerostic disease activity and is hence an index for the likelihood of future cardiovascular events. Current data indicate that noninvasive quantification of coronary atherosclerosis has incremental prognostic value beyond conventional single risk factor assessment. However, it is not clear yet whether it has a significant value beyond quantitative combined risk assessment using complex risk prediction models such as Framingham charts. Results from ongoing prospective trials such as the MESA study in the US and the Heinz Nixdorf Recall study in Germany will clarify some of the pending issues. In addition, it is still unclear, at what stage of the disease process, which of the available imaging tools will provide optimal diagnostic and prognostic value for the individual patient.
Adult↗
[A "late" scimitar syndrome. Diagnostic contribution of cardiac computed tomography].
A 51-year-old female hospitalized with a non-specific colitis, presented a crescent-like shadow in the right lower lung accompanied by a reduced right lung volume on a routine chest x-ray. There was no family history of congenital heart disease. The initially performed, noninvasive, contrast enhanced cardiac CT (electron-beam tomography [EBT]) proved the suspected diagnosis of a partial, anomalous pulmonary, transdiaphragmatic vein drainage (APVD) in combination with a hypoplastic right lower lobe and dextrocardia. These findings are in accordance with scimitar syndrome. Regarding to the clinical situation with symptoms like slowly progressive dyspnea on exertion and low exercise tolerance for the last 2 years and an invasively documented left-to-right shunt ratio >50% (Qp:Qs = 2.6 : 1) surgical repair was recommended. The anomalous vein was connected to the left atrium creating a "neo-septum". On a postoperative checkup after 9 months the patient is without any medication, symptoms during moderate activity are relieved, exercise tolerance was substantially better and noninvasive imaging visualized the corrected drainage of the anomalous vein to the left atrium.
Anastomosis, Surgical↗
Neck muscle vibration induces lasting recovery in spatial neglect.
OBJECTIVES: To evaluate whether neck muscle vibration is an effective technique for neglect rehabilitation, with lasting beneficial effects. METHODS: The effects of differential treatment of visual exploration training alone or in combination with neck muscle vibration were evaluated in a crossover study of two matched groups of 10 patients suffering from left sided neglect. Each group received a sequence of 15 consecutive sessions of exploration training and combined treatment. The effects of treatment were assessed with respect to different aspects of the neglect disorder such as impaired perception of the egocentric midline, exploration deficits in visual and tactile modes, and visual size distortion. The transfer of treatment effects to activities of daily living was examined by a reading test and a questionnaire of neglect related everyday problems. All variables were measured six times: three baseline measurements, two post-treatment measurements, and one follow up after two months. RESULTS: The results showed superior effects of combination treatment. A specific and lasting reduction in the symptoms of neglect was achieved in the visual mode, which transferred to the tactile mode with a concomitant improvement in activities of daily living. The improvement was evident two months after the completion of treatment. In contrast, isolated exploration training resulted in only minor therapeutic benefits in visual exploration without any significant transfer effects to other tasks. CONCLUSIONS: Neck muscle vibration is a decisive factor in the rehabilitation of spatial neglect and induces lasting recovery when given as a supplement to conventional exploration training.
Activities of Daily Living↗
The effects of magnetic stimulation and attentional cueing on tactile extinction.
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Adult↗
Spatial processing of spoken words in aphasia and in neglect.
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Adult↗
Spatial hemineglect in humans.
The paper reviews the main findings of studies of hemispatial neglect after acquired brain lesions in people. The behavioral consequences of experimentally induced lesions in animals and electrophysiological studies, which shed light on the nature of the disorder, are briefly considered. Neglect is behaviorally defined as a deficit in processing or responding to sensory stimuli in the contralateral hemispace, a part of the own body, the part of an imagined scene, or may include the failure to act with the contralesional limbs despite intact motor functions. Neglect in humans is frequently encountered after right parieto-temporal lesions and leads to a multicomponent syndrome of sensory, motor and representational deficits. Relevant findings relating to neglect, extinction and unawareness are reviewed and include the following topics: etiological and anatomical basis, recovery; allocentric, egocentric, object-centered and representational neglect; motor neglect and directional hypokinesia; elementary sensorimotor and associated disorders; subdivisions of space and frames of reference; extinction versus neglect; covert processing of information; unawareness of deficits; human and animal models; effects of sensory stimulation and rehabilitation techniques.
Awareness↗
Repetitive peripheral magnetic stimulation alleviates tactile extinction.
Despite its frequency in right brain damaged patients crucial mechanisms of tactile extinction are still obscure and treatments are unavailable. Recent PET observations suggest a hypometabolism in the primary and secondary somatosensory cortex of the lesioned hemisphere in patients with tactile extinction. Functional and morphological investigations have shown that the sensorimotor cortex has a remarkable capability of reorganization when the sensory inflow is changed. Repetitive peripheral magnetic stimulation (RPMS) applied in patients suffering from central paresis alleviates sensorimotor as well as cognitive deficits by the induction of proprioceptive inflow, thereby activating plasticity in the CNS. Based on the observation of reduced metabolic activity in patients suffering from tactile extinction we applied RPMS to explore the effects of peripheral sensory stimulation on tactile extinction. Fourteen right-hemisphere lesioned patients with tactile extinction were randomly allocated to an experimental and a control group. The experimental group received one single RPMS treatment of the left forearm as well as a condition of attentional cueing known to improve visual extinction. The control group, with comparable tactile extinction scores, neither received RPMS nor verbal cueing, but was tested twice to evaluate possible learning or test repetition effects. In the experimental group RPMS led to a significant reduction of left-sided extinctions in the recognition of different tactual surfaces, but had no effect on ipsilesional errors. In contrast, attentional cueing had no significant effect on left-sided extinction errors but unexpectedly increased right-hand extinction errors slightly but significantly. The control group showed stable extinction scores of the left- and right-hand stimulus across two measurements, thus ruling out learning or test repetition effects. These results show that sensory inflow is an important modulatory factor in tactile extinction. Furthermore, multiple RPMS may prove a promising way for the rehabilitation of patients with this disorder.
Adult↗
Neurovisual rehabilitation: recent developments and future directions
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Journal Article↗
Multiple perceptual distortions and their modulation in leftsided visual neglect.
There is an ongoing debate concerning the perception and neural representation of space in neglect. Four experiments are here reported designed to further investigate the nature of perceptual distortions and their modifiability in patients with neglect. In Experiment 1 it was found that neglect patients, in contrast to left- or right-hemisphere lesioned control patients and normal subjects, show similar distortions of perceived visual space when judging the extension of horizontal distances (space distortion) as compared to the horizontal size of objects (size distortion). Similar deficits were present in most neglect patients in a newly developed space bisection task. These results attest that neglect patients have perceptual distortions related to within-object (size) and between-object (distance) spatial processing in their horizontal plane. Objects were oversized by 33% and distances by 19% horizontally in neglect patients, whereas all control groups showed nearly veridical spatial coding (deviations<5%). In Experiment 2 the modifiability of these distortions was tested by the use of slow visual background motion. Leftward, coherent background motion transiently restored normal horizontal size and distance coding in neglect patients, whereas rightward motion aggravated the deficit significantly in the distance task, but not in the size task. None of the other subject groups showed any influence of background motion on spatial judgments. Experiment 3 evaluated possible effects of simultaneous vs successive stimulus presentation in perceptual distortions, thus modulating attentional factors. Neglect patients performed significantly better - although not normal - with a successive presentation of the spatial stimuli (2 s, 10 s delay) as compared to the simultaneous condition in the size judgment task, but not in the distance task. In contrast, this manipulation had no effects in any of the control groups. Experiment 4 reports more detailed results of subject J.S., a neglect patient with a right mediotemporal lesion, who showed a marked horizontal size distortion, but normal horizontal distance judgments. Despite some fluctuation in J.S.'s size judgments he showed a significant overestimation of horizontal object size by +22% to +40% across several test blocks and testing sessions. Thus, performance fluctuations due to attentional or other reasons cannot fully account for J.S.'s dissociation in size vs distance judgments. He thus shows that the visual coding of horizontal spatial extension within an object can be dissociated from that of the spatial extension between objects along the horizontal plane. Finally, performance in the three spatial tasks (used in Experiment 1) was found to correlate significantly with three typical tests of spatial neglect (line bisection, cancellation, copying, r=0.42-0.77), thereby indicating a significant relationship to the neglect syndrome.Together, the results of the four experiments are interpreted in support of multiple spatial-perceptual distortions in visual neglect, which are influenced by visual motion and attention. Perceptual distortions relating to objects and space between objects are present in most neglect patients, but may dissociate, as in case J.S. It is argued that these might reflect the existence of several, partially overlapping and diverging neural maps for the representation of different spatial attributes in the horizontal plane. Furthermore, it is hypothesized that these perceptual distortions constitute an important element of the spatial-perceptual deficits encountered in the syndrome, contribute to its severity, but are not the key deficit of the disorder.
Aged↗
Neurovisual rehabilitation: recent developments and future directions.
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Brain Damage, Chronic↗
Contrasting spatial hearing deficits in hemianopia and spatial neglect.
Spatial hearing deficits have been described in widely differing pathologies, including bilateral temporal or unilateral parietal lesions, hemispherectomy, spatial neglect and right-sided cortical lesions without neglect. However, the topography of spatial hearing deficits after cortical lesions is only poorly understood, unlike that of vision and touch. We investigated the auditory subjective straight ahead (SSA) with a new technique of binaural sound source simulation using broad-band single pulses which were filtered with head-related transfer functions and delivered with a 5 degree resolution over headphones in front space. Normal subjects showed quite accurate judgments of the SSA, with a small but significant shift to the left of centre (-1.7 degrees) in the horizontal plane. Hemineglect without a scotoma, produced a large ipsilesional deviation of the auditory SSA (+22 degrees), while two hemianopic subjects, both without neglect, showed the opposite deviation of their perceived auditory SSA towards their contralesional, blind hemifield (+10 vs -28 degrees). Two control patients with unilateral lesions, both without neglect and without hemianopia, produced normal judgments of their auditory SSA (-3.0 degrees, +3.8 degrees). These results suggest at least two contrasting influences on directional spatial hearing after unilateral cortical lesions: hemianopia vs hemispatial neglect. The results are interpreted in favour of multisensory convergence of visual and auditory information in directional spatial hearing.
Acoustic Stimulation↗
Visual background motion reduces size distortion in spatial neglect.
Patients with visual neglect show deficits in horizontal size perception in their neglected hemispace, as previously reported. The present study examined whether this size distortion can be modulated by visual background motion to the left or right while the patient performs a visual size judgment task. Six neglect patients and six normal subjects were investigated with a psychophysical size judgment task. All neglect patients showed a significant perceptual underestimation of horizontal bars in their left hemispace expressed as an overestimation of horizontal object size in the baseline (no motion) condition. Slow visual motion of background stimuli towards the right, ipsilesional side aggravated the deficit slightly, but not significantly, whereas leftward background motion completely normalized the size distortion (in four cases) or even led to an overcompensation (in two cases). This facilitatory effect was specific as it was obvious for the constant errors in the size judgments, but not in their accuracy as reflected by unchanged difference thresholds. These results suggest that coherent background motion restores temporarily the disturbed perception and representation of horizontal object size in spatial neglect.
Adult↗
[Balint syndrome and associated disorders. Anamnesis--diagnosis--approaches to treatment].
Balint syndrome is a combination of symptoms including simultanagnosia, a disorder of spatial and object-based attention, disturbed spatial perception and representation, and optic ataxia resulting from bilateral parieto-occipital lesions. Fixation and ocular exploration of space are severely impaired, as are reading, writing, drawing and orientation as well as movement in space. Low-level visual impairments may be associated and difficult to evaluate but are not a necessary element of Balint syndrome. This review summarizes the relevant facts of the etiology, localization of lesions, and the core features as well as frequently associated disorders of the syndrome. Instructions for the examination of patients are given and approaches for the management and treatment outlined. Models of attention and space representation are described for the explanation of this multifaceted and exciting syndrome. Finally the key features of the syndrome are summarized in a table at the end of the paper.
Agnosia↗
Effects of unilateral brain damage on grip selection, coordination, and kinematics of ipsilesional prehension.
To determine whether the left and right hemispheres play specific roles in goal-directed movements, prehension with the ipsilesional hand was tested in patients with unilateral brain damage. The task required that subjects rotate the hand while reaching for a bar that was presented in different orientations in the frontal plane, thus making high demands on visuospatial processing. The grasped bar had to be put into a hole: under one task condition the placement of the bar was specified, while under another it was not. The constrained task required that the subject anticipate the placing action when planning the initial prehensile movement. Grip selection, reaction times, kinematics of the transport movement, and coordination of hand rotation during transport were assessed in ipsilesional movements of 22 patients with either left or right brain damage (LBD and RBD) and in control subjects. Patients in both groups exhibited performance deficits; however, impairment characteristics differed profoundly between the groups. RBD patients showed prolonged reaction time and degraded kinematics in the unconstrained task, whereas LBD patients performed relatively well when only the orientation of the bar varied, but slowly and frequently incoordinated when the subsequent action was specified. Our findings emphasize the dominant role of the right hemisphere in processing visuospatial aspects of goal-directed movements, whereas the left hemisphere subserves non-spatial aspects of preplanning under increased task demands. Correlations of the patient's performance with results from clinical tests showed that neither deficits in visuospatial perception of RBD patients nor apraxia of LBD patients could account for the observed abnormalities in the use of the ipsilesional hand.
Adult↗