Objective Right hemisphere stroke may cause an ipsilesional attention bias and left hemispatial neglect. Computerized time-limited tasks are more sensitive than conventional paper-pencil tests in detecting these spatial attention deficits. However, their frequency in the acute stage of stroke, the neuroanatomical basis and functional relevance for patients’ everyday life are unclear. Method A realistic visual search task is introduced, in which eye movements are recorded while the patient searches for paperclips among different everyday objects on a computer display. The “Desk task” performance of 34 acute right hemisphere stroke patients was compared to established paper-pencil tests for neglect and the Posner reaction time task, and finally correlated to structural brain lesions. Results Most of the patients, even those without clinical neglect signs and with normal paper-pencil test performance, exhibited a clear ipsilesional attention bias in the Desk task. This bias was highly correlated to the left-right asymmetry in the Posner task and to neglect-related functional impairment scores. Lesion-symptom mapping revealed task-specific differences: deficits in the Desk task were associated with lesions of the superior temporal gyrus, contralesional unawareness in the Posner task with ventral frontal cortex lesions and paper-pencil cancellation bias with damage to the inferior parietal lobe. Neglect behavior was further associated with distinct fronto-parietal white matter tract disconnections (ILF, SLF, Arcuate). Conclusions Results from the novel Desk task indicate a functional relevance of spatial attention deficits in right brain damaged patients, even if they are “subclinical”. This should be considered especially in patients without obvious clinical neglect signs.

Background and Purpose-Right hemisphere stroke patients frequently experience spatial neglect, a severe lack of awareness for contralesional hemispace. Although neglect counts among the strongest predictors for poor functional outcome after stroke, there is no established therapy, particularly not for the acute stage. Methods-In a randomized controlled trial, we compared the combined treatment of hemifield eye patching and repetitive optokinetic stimulation in acute stroke patients with neglect to the spontaneous course. Outcome measures were a neuropsychological test battery for neglect as well as scales of functional independence and clinical impairment.Outcomes were assessed at baseline (day 1), post treatment (day 8), and at 1-month follow-up (day 30). Results-Final analysis included 21 acute right hemisphere stroke patients with neglect (23 enrolled, 2 lost to follow-up) allocated either to the treatment (1 week hemifield eye patching and daily sessions of optokinetic stimulation, n=11) or the control group (no neglect-specific treatment, n=10). At baseline, both groups did not differ in neuropsychological test performance, clinical impairment, or functional disability. At the post treatment session, both groups had improved in all these measures, and results were stable or further improved at follow-up. However, there was no significant difference in this change between the treatment and the control group. Conclusions-An early intervention of combined hemifield eye patching and optokinetic stimulation in acute stroke patients with spatial neglect has no additive effect to the spontaneous remitting course of the disorder.

Objective. Leftward optokinetic stimulation (OKS) is a promising therapeutic approach for right-hemisphere stroke patients with left hemispatial neglect. We questioned whether the putative neural basis is an activation of frontoparietal brain regions involved in the control of eye movements and spatial attention. Methods. We used functional magnetic resonance imaging to investigate brain activations during OKS in acute right-hemisphere stroke patients (RHS, n = 19) compared with healthy control subjects (HC, n = 9). Based on neuropsychological testing we determined the ipsilesional attention bias in all RHS patients, 11 showed manifest hemispatial neglect. Results. In HC subjects, OKS in either direction led to bilateral activation of the visual cortex (V1-V4), frontal (FEF) and supplementary (SEF) eye fields, intraparietal sulcus (IPS), basal ganglia, and thalamus. RHS patients’ activations were generally reduced compared with HC. Nevertheless, leftward OKS bilaterally activated the visual cortex (V1-V4), FEF, SEF, IPS, and thalamus. The neural response to OKS was negatively correlated with patients’ behavioral impairment: The greater the individual attention bias/neglect the weaker the brain activations. Conclusion. In RHS patients, leftward OKS activates frontoparietal regions (FEF, IPS) that are spared from structural brain damage and functionally involved in both oculomotor control and spatial attention. This may provide a neural basis for the known therapeutic effects of OKS on hemispatial neglect. In acute stroke stages, reduced activation levels correlating with neglect severity indicate functional downregulation of the underlying dorsal attention network. Therefore, chronic RHS patients with less severe neglect after recovery of network disturbances may be more suitable candidates for OKS rehabilitation.

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