Left-hand somatosensory stimulation combined with visual scanning training in rehabilitation for post-stroke hemineglect: A randomised,double-blind study

The aim of this randomised, double-blind study was to investigate the therapeutic effectiveness of left-hand electrical stimulation for patients with post-stroke left visuo-spatial neglect. This approach was hypothesised to enhance activation of the right hemisphere attention system and to improve visual exploration of extrapersonal space. Participants (n = 40) in the study were in a relatively early stage of recovery from their first right hemisphere stroke, and were randomly assigned to the experimental (E) or control (C) group. Group E received conventional visual scanning training combined with electrostimulation of the left hand, while Group C received scanning training with sham stimulation. Their visuo-spatial neglect was assessed twice, prior to the rehabilitation programme and on its completion, using cancellation tests and a letter-reading task. The effect of electrostimulation on hemineglect was assessed following a single administration and after a month-long rehabilitation programme.

Although the immediate effect of stimulation was poor, after a month-long rehabilitation period we found significantly greater improvement in Group E patients than in Group C patients. Interestingly, the presence of hemisensory loss did not weaken the observed effect. Therefore, we claim that contralesional hand stimulation combined with visual scanning was a more effective treatment for hemineglect rehabilitation than scanning training alone.     

Laterality of motor response in visuo-spatial neglect: a case study

We report a case of severe visuo-spatial neglect consequent upon right hemisphere stroke. At time of testing, the patient had a left visual field deficit and a very mild left hemiparesis. Star cancellation and line bisection performed with the right hand revealed profound left neglect; tested with the left hand, performance was only slightly impaired. The results are compatible with recent accounts of differential hemispheric activation provoked by lateralized pre-motor programming.     

Efficacy of visuo-spatial training in right-brain damaged patients with spatial hemineglect and attention disorders

Several rehabilitative approaches have been used to reduce neglect disorders. Some studies tried to demonstrate that hemineglect can be ameliorated by using tasks promoting attentional activation towards the neglected hemispace (Robertson et al., 1995, 2001). As a consequence, a functional link between level of attention and disorders of space exploration has been proposed. For this reason we tried to explore the possible role of attentional deficits on the efficacy of a standard neglect treatment based on visuo spatial rehabilitation. In this study we then examined the performances of a selected group of seven right brain damaged patients, suffering from both severe hemineglect and attentional deficits (of both phasic and tonic components of attention), to several tasks before and after a visuo-spatial training (VST) whose efficacy has been already demonstrated (Pizzamiglio et al., 1992). Results showed that VST induces a significant remission of hemineglect symptoms independently from disorders of attention. Moreover, after visuo-spatial rehabilitation, no improvement of attentional deficits is detectable.     

Transcutaneous electrical stimulation of the neck muscles and hemineglect rehabilitation

In four patients with left visuo-spatial hemineglect and right brain- damage, the therapeutic effects of Transcutaneous Electrical Nervous Stimulation (TENS) of the left neck muscles, associated with a non-specific treatment, and of a specific rehabilitation paradigm were investigated. The two treatments were given for an 8-week period each. TENS had positive effects on hemineglect in two out of four patients, whereas the specific treatment produced a major improvement of the disorder in all four cases. The suggestion is made that an effective treatment of neglect requires a paradigm comprising a range of visuo-spatial exploratory tasks of increasing complexity and a systematic feedback as to the success of the patients' performance. This is the case of the specific treatment. By contrast a procedure confined to a sensory stimulation, which produces a short-term improvement in the range of minutes, does not have comparable long-term effects. ? 1996 Elsevier Science Ireland Ltd. All rights reserved.     

Using real-time fMRI neurofeedback to restore right occipital cortex activity in patients with left visuo-spatial neglect: proof-of-principle and preliminary results

Hemineglect is common after right parietal stroke, characterised by impaired awareness for stimuli in left visual space, with suppressed neural activity in the right visual cortex due to losses in top-down attention signals. Here we sought to assess whether hemineglect patients are able to up-regulate their right visual cortex activity using auditory real-time functional magnetic resonance imaging (rt-fMRI) neurofeedback. We also examined any effect of this training procedure on neglect severity. Two different neurofeedback methods were used. A first group of six patients was trained to up-regulate their right visual cortex activity and a second group of three patients was trained to control interhemispheric balance between their right and left visual cortices. Over three sessions, we found that the first group successfully learned to control visual cortex activity and showed mild reduction in neglect severity, whereas the second group failed to control the feedback and showed no benefit. Whole brain analysis further indicated that successful up-regulation was associated with a recruitment of bilateral fronto-parietal areas. These findings provide a proof of concept that rt-fMRI neurofeedback may offer a new approach to the rehabilitation of hemineglect symptoms, but further studies are needed to identify effective regulation protocols and determine any reliable impact on clinical symptoms.     

Good recovery in visual scanning in a patient with persistent anosognosia.

A patient with hemineglect disturbance (N.G.) due to a right hemispheric lesion was admitted to rehabilitative training which featured the use of procedures devised in a previous study (Pizzamiglio et al., 1990) both in a standard way and with the addition of optokinetic stimulation. This latter paradigm produces an automatic reaction which favors the spatial orienting of the patient toward his (left) neglected side. N.G. showed good recovery in visual scanning and, by the end of training, reached a level of recovery similar to other neglect patients. However, his recovery was particularly slow and no change was observed in his attitude toward the visual disturbance. The conclusion is reached that recovery in visual scanning also can be obtained in patients with persistent anosognosic disturbances. Stimulations such as the optokinetic condition which influence patients' behavior at an automatic level may play an important role in this recovery. CBF studies obtained before and after training showed a CBF improvement mainly in the right temporoparietal regions, behind the lesion, and in the left frontal cortex. The implications of these findings on various theoretical interpretations of the hemineglect disturbance are briefly discussed.     

Experiences of combined visual training and arm activation in the rehabilitation of unilateral visual neglect: A clinical study

This study reports a rehabilitation training for unilateral visual neglect combining a visual training programme and arm activation. Four cases of left visual neglect are presented with differing arm use. Neglect impairment was assessed using seven neuropsychological tests at weekly intervals for nine weeks: three weeks before, during and after the treatment period. In addition, one patient was followed over a longer time period. The treatment consisted of both a visual training programme and simultaneous arm activation. Considerable improvement in three of the four patients was observed in article reading. Moreover, all patients showed some improvement on three cancellation tests, whereas there was no improvement on other tests. In particular, the patients who had full hand or shoulder movement showed improvement in their performance. These results point out the usefulness of combined visual training and arm activation in the rehabilitation of visual neglect.     

Hemispheric activation vs spatio-motor cueing in visual neglect: a case study

We report a case of mild visuo-spatial neglect consequent upon right-hemisphere stroke. At the time of testing, the patient had a complete left visual field deficit but only a very slight left hemiparesis. Under conventional testing conditions, line bisection performed with the right hand showed more severe left neglect than when performed with the left hand. This pattern of performance could, however, be modified, both quantitatively and qualitatively, by changing the starting position of the patient's hand when bisecting horizontal lines. The results suggest that spatio-motor cueing has a more profound effect upon task performance than does differential hemispheric activation per se. We also provide a demonstration that, in a normal subject, the starting position of the hand is likewise a crucial determinant of task performance. In this case, however, there is also an interaction between the hand (and hence hemisphere) deployed and the position of that hand in space.     

Effects of passive tactile and auditory stimuli on left visual neglect

Patients with left-sided visual neglect fail to copy the left part of drawings or the drawings on the left side of a sheet of paper. Our aim was to study the variations in copying drawings induced by passive stimulation in patients with left-sided visual neglect. No stimulation at all, tactile unilateral and bilateral, binaural auditory verbal, and nonverbal stimuli were randomly applied to 14 patients with right-hemisphere strokes. Only nonverbal stimuli decreased the neglect. As nonverbal stimuli mainly activate the right hemisphere, the decrease in neglect suggests right-hemispheric hypoactivity at rest in these patients. The absence of modification of neglect during verbal stimulation suggests a bilateral hemispheric activation and the persistence of interhemispheric imbalance. Our results showed that auditory pathways take part in the network involved with neglect. Passive nonverbal auditory stimuli may be of interest in the rehabilitation of patients with left visual neglect.     

Hemianopia, hemianesthesia, and spatial neglect: a study with evoked potentials.

We recorded somatosensory or visual evoked potentials (SEPs, VEPs) to stimuli contralateral and ipsilateral to the lesion in three right-brain-damaged patients with left spatial hemineglect and in three left-brain-damaged patients without evidence of neglect, as assessed by visual exploratory tasks. All patients had contralateral homonymous hemianopia or hemianesthesia. The three neglect patients showed normal SEPs or VEPs to stimuli delivered to the left half-field or to the left hand, without conscious perception and verbal report of the stimulation. By contrast, the three left-brain-damaged patients without neglect showed no recognizable cortical evoked response to contralateral visual or somatosensory stimuli. In all patients, the cortical evoked responses to ipsilateral stimulation were normal. In patients with spatial hemineglect, hemianopia and hemianesthesia may be manifestations of the neglect syndrome (visual and somatosensory hemi-inattention), rather than representing primary sensory deficit. Visual and somatosensory hemi-inattention may be due to defective access to the neural processes subserving conscious perception by information that has undergone early sensory processing.     

Adding transcutaneous electrical nerve stimulation to visual scanning training does not enhance treatment effect on hemispatial neglect: a randomized,controlled, double-blind study

Background: Left-sided transcutaneous electrical nerve stimulation (TENS) increases right hemispheric activity, which may improve the rehabilitative outcome of hemispatial neglect.

Objective: To examine the behavioral effect of electrical stimulation of the nerve afferents of the left hand during early neuropsychological rehabilitation of post-stroke patients with hemispatial neglect.

Methods: This randomized, controlled, double-blind study included 29 patients (enrolled in the experimental or control group) with left hemispatial neglect after right hemispheric stroke. For 3 weeks, patients received 15 therapeutic sessions involving TENS (active or sham) with a mesh glove applied on the entire left hand during the first 30 minutes of a 45-minute conventional visual scanning training (VST). Signs of hemispatial neglect were assessed using a psychometric test before and after treatment.

Results: Univariate analysis of covariance revealed that differences between the control and experimental groups were not significant after treatment (F(1, 22)?=?0.294, P?=?0.593) when adjusted for pre-treatment scores and time since stroke onset. This suggested that electrical stimulation failed to mitigate the severity of hemispatial neglect symptoms.

Conclusion: Our study did not provide evidence of the effectiveness of TENS when added to VST during early rehabilitation for patients with post-stroke hemispatial neglect. Other techniques (applied alone or together) should be sought to improve recovery in this population.     

Spatial neglect

Unilateral spatial (hemi-)neglect or (hemi-)inattention are clinical terms used to describe a number of different clinical symptoms which have in common the patient's failure to attend to, respond adequately to, or orient voluntarily to people or objects in the contralesional space. Unilateral spatial neglect is most often observed following brain lesions affecting the right hemisphere, and in particular the right inferior parietal cortex (angular and supramarginal gyrus) and right temporoparietal junction. Importantly, the term hemineglect cannot be meaningfully used if the target behavior is explained by primary sensory or motor deficits only. Typically the patient's deficit is supramodal: patients with hemineglect fail to respond to novel or meaningful stimuli irrespective of whether they are presented in the visual, auditory, and somesthetic (somatosensory) domain. As adequate perception and spatial representation of both the body and the outside world are mandatory for almost all activities of daily living, hemineglect is known to limit the degree of active participation in rehabilitation programs and is thus commonly associated with poor functional recovery and less successful social reintegration. A number of new promising behavioral and pharmacological treatments may help to ameliorate neglect in the future.     

Visuo-spatial neglect: a systematic review of current interventions and their effectiveness

Left visuo-spatial neglect is a well-recognized predictor of poor functional outcome following right hemisphere stroke. Over the past 60 years, 18 different methods have been described and evaluated aimed at reducing the effects of this impairment. Although there are some grounds for optimism particularly in terms of short-term impairment-based effects, the range and degree of disability borne by many patients remain high and the clinical effectiveness of the different methods viewed in terms of long-lasting functional improvement (i.e. improvement of disabilities or handicap) is not clear. A systematic review of the available clinically relevant literature, using comparative and stringent levels of evidence, indicates that visual scanning training (VST), trunk rotation (TR) or repeated neck muscle vibrations (NMV) when associated with an extensive training program, mental imagery training, video feedback training and prism adaptation (PA) can be recommended for the rehabilitation of patients with left neglect. More studies however are needed to determine the optimal paradigm of limb activation (LA) eliciting a sustained functional improvement. Sensory stimulations alone and Fresnel prisms do not appear to be functionally relevant. For the other methods, the actual literature is not sufficient to conclude whether or not a long-term functional improvement can be achieved.     

Right-sided neglect in a left-hander: evidence for reversed hemispheric specialization of attention capacity

Severe hemi-spatial neglect, anosognosia, contralateral hypokinesia, aprosodia, and visual-spatial constructive difficulties--typically seen in right-handers with right hemisphere lesions--were observed in a left-handed patient with an acute left frontal cortical and subcortical infarct. There was no evidence of accompanying aphasia and the neglect syndrome gradually resolved over a 2-week period. The assumption by the left hemisphere of a classic right hemisphere attention, visuo-spatial and prosodic superiority may represent a case of reversed hemispheric specialization.     

Abstracts presented at the joint meeting of the British Neuropsychological Society (BNS) and the Societa Italiana di Neuropsicologia (SNIP), 25-27 April 2001, London Zoo,Regent’s Park,London, UK

Visual neglect has classically been associated with right hemisphere injury in parietal, frontal, or temporal cortex, in the basal ganglia or in the thalamus. More recently, visual neglect has been associated with injury extended into fronto-parietal white matter tracts. However, in most published cases white and gray matter injuries were associated. We present the anatomo-clinical study of a patient presenting with severe acute left visual neglect due to ischemic infarct limited to the right cerebral hemisphere white matter. Magnetic resonance diffusion tensor imaging tractography was instrumental to accurately localize the injury to the right arcuate fasciculus that is a component of the large-scale networks controlling visuo-spatial attention. These results add to a growing appreciation that neglect may result from disruption of a distributed attentional network.     

Is judgement of line orientation selectively impaired in right brain damaged patients?

The judgement of line orientation test (JLOT) is widely used to assess visuo-spatial processing. Most neuropsychological studies have shown that on this task right hemisphere damaged (RHD) patients are significantly more impaired than left hemisphere damaged (LHD) patients, suggesting a dominant role of the right hemisphere in discriminating line orientation. To investigate whether other factors can affect performance on JLOT, a modified version of the test, consisting of the 30 original test items and their mirror images, was employed. In Experiment 1 normal participants were more accurate in discriminating the left lines of the original items, and the right lines of the mirror-reversed items, thus indicating that in original JLOT the stimulus arrays comprise lines on the left side that are easier to judge than lines on the right. In Experiment 2, RHD patients with visual neglect were significantly more impaired than patients without neglect, who performed similarly independently from the side of the lesion. Among patients without neglect, however, LHD patients were more accurate than RHD patients without neglect with the original items, but produced more errors than RHD patients without neglect when faced with the mirror-reversed items. Overall, the results of the present study suggest that the greater impairment on standard JLOT shown by RHD patients has to be interpreted as the by-product of the presence of visual neglect, which is more frequent following right hemisphere damage, and of the uneven distribution of the stimulus lines, which are easier to discriminate in the left space. The clinical and theoretical implications of the results are discussed.     

The assessment of visuo-spatial neglect after acute stroke.

Forty four consecutive patients with acute hemispheric stroke and forty seven elderly controls with no neurological disease were assessed for visuo-spatial neglect, using a modified neglect test battery. Neglect was found to be equally common in patients with right hemisphere and left hemisphere stroke three days after stroke (72% versus 62%). It was more severe in those with a right hemisphere stroke and resolved more frequently in those with a left hemisphere stroke. The battery was validated against an occupational therapist's assessment of neglect on self-care tasks. The inter-observer reliability was good and it was possible to monitor changes over time with the battery.     

Relationship between the Head Deviation Angle and Hemineglect in Patients with Right Hemisphere Stroke

Background: Patients with hemineglect have been reported to have abnormal head posture. We attempted to determine the extent to which the angles are correlated with the severity of hemineglect. Methods: In a prospective, single-center, cross-sectional study on 40 patients with single right hemisphere stroke, we evaluated left hemineglect severity using the line bisection and line cancellation tests. Head deviation angles were measured at admission and discharge using a head device containing 3 graduated discs that determined the angles of head deviation in the sagittal, coronal and transverse planes. Results: Head angles in the transverse and coronal planes differed significantly between the left hemineglect and non-hemineglect groups. Scores obtained from the line bisection and line cancellation tests correlated with these angles. Furthermore, improvement in left hemineglect after rehabilitation training corresponded to a reduction in the angles. Conclusion: Stroke patients with hemineglect exhibited significant head deviations in the transverse and coronal planes. Deviation angles correlated with hemineglect test scores.     

Extinction of auditory stimuli in hemineglect: Space versus ear

Unilateral extinction of auditory stimuli, a key feature of the neglect syndrome, was investigated in 15 patients with right (11), left (3) or bilateral (1) hemispheric lesions using a verbal dichotic condition, in which each ear received simultaneously one word, and a interaural-time-difference (ITD) diotic condition, in which both ears received both words lateralised by means of ITD. Additional investigations included sound localisation, visuo-spatial attention and general cognitive status. Five patients presented a significant asymmetry in the ITD diotic test, due to a decrease of left hemispace reporting but no asymmetry was found in dichotic listening. Six other patients presented a significant asymmetry in the dichotic test due to a significant decrease of left or right ear reporting, but no asymmetry in diotic listening. Ten of the above patients presented mild to severe deficits in sound localisation and eight signs of visuo-spatial neglect (three with selective asymmetry in the diotic and five in the dichotic task). Four other patients presented a significant asymmetry in both the diotic and dichotic listening tasks. Three of them presented moderate deficits in localisation and all four moderate visuo-spatial neglect. Thus, extinction for left ear and left hemispace can double dissociate, suggesting distinct underlying neural processes. Furthermore, the co-occurrence with sound localisation disturbance and with visuo-spatial hemineglect speaks in favour of the involvement of multisensory attentional representations.     

Crossed right hemisphere syndrome following left thalamic stroke

In most right-handed people, language and motor functions are more reliant on systems of the left hemisphere while several non-linguistic visuo-spatial and attentional processes depend more on the right hemisphere. The rare exceptions to these rules provide important clues as to what functions co-lateralise, and are thus crucial for models of cerebral specialization. Here we report on the case of a patient, who, after a lesion restricted to the left thalamic region, showed signs normally associated with right hemispheric injury including motor impersistence, visuo-spatial dysfunction and poor comprehension of facial expression. Language abilities were spared and no signs of apraxia were present, in spite of his right hand, foot and eye preference, a pattern normally associated with conventional cerebral dominance. In spite of his other right hemispheric signs, the patient showed no signs of hemi-spatial neglect. The patient's pattern of spared and impaired abilities is compared and contrasted with other rare cases of crossed right hemisphere syndrome.