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Contains fulltext : 87495.pdf (Publisher’s version ) (Closed access) Asymmetry in performance and an association with non-lateralized attention are often mentioned as two important aspects of the clinical manifestation of visuospatial neglect. Both these aspects were investigated in 21 left (LH) and 24 right hemisphere (RH) stroke patients and in 20 healthy subjects. The letter and star cancellation subtests of the Behavioural Inattention Task (BIT) and a computerized visual reaction time task (CVRT) with stimuli presented either left, central or right in extrapersonal space were administered. In LH patients, the calculation of BIT asymmetry scores allowed a better distinction between patients with and without neglect than raw omission scores. However, in RH patients, raw and asymmetry scores led to similar classifications. In the CVRT, raw and asymmetry scores for the number of omissions also produced identical classifications. Thus, the computation of asymmetry scores for omissions did not substantially refine the diagnosis of neglect. On the other hand, more patients were classified as neglect patients by using CVRT reaction time (RT) asymmetry scores than by using BIT or CVRT omission scores. Ipsilesional RT's were chosen as a measure of general, non-lateralized attention. The ipsilesional RT's of the LH and RH patients did not differ from the healthy subjects' lateral RT's. However, within the RH group, patients with both RT asymmetries and BIT scores above cut-off level showed longer ipsilesional RT's than patients with defective RT asymmetries but normal BIT scores. This supports the idea of an interaction between lateralized and non-lateralized attentional components in neglect, in which the presence of general attentional deficits exacerbates the severity of neglect symptoms. RT tasks may contribute to the detection of asymmetries in visuospatial attention in patients with subclinical neglect symptoms, who might compensate for their lateralized deficit in paper-and-pencil tasks employing intact general attention. 01 mei 2010

This study presents measures of unilateral deficits on the Rey Figure copy that may be easily incorporated into the scoring system described by Lezak (1983, 1995), extending previous research that reported similar indices using the Denman (1984) scoring system. One hundred and eight subjects participated. Indices of unilateral inattention on the Rey Figure were compared to criterion measures on the Letter Cancellation Test. Left-side omissions on the Rey Figure were greater among right-CVA neglecting subjects (n = 36) than among non-neglecting right-CVAs (n = 32), left-CVAs (n = 20), and controls (n = 20). In addition, right-CVA subjects with neglect omitted significantly more items and evidenced much poorer accuracy of reproduction on the left versus the right side of the figure, whereas no unilateral differences were noted among the other groups. When using the Lezak-Osterrieth system, an asymmetric error profile containing two or more left-sided omissions indicates a strong likelihood of negle...

A patient with severe left hemi-inattention was found to be influenced by neglected stimuli in free drawing tasks. He was presented 64 sheets of paper: 32 had geometric figures on the left side and 32 on the right side. The patient was asked what he saw and invited to draw a subject of his choice on the sheet of paper. The patient always denied seeing anything when the figures were on the left side, while he identified the figures on the right side. Four judges examined the patient's drawings and all of them agreed that 11 drawings were influenced by neglected stimuli and none by non-neglected ones. The drawings he made were similar but not the exact reproduction of neglected figures. This finding confirms that visual processing can proceed without awareness in a patient with hemi-inattention.

The psychometric characteristics of two semi-structured scales for evaluation of the extrapersonal and personal hemi-inattentive disorder in situations similar to those of everyday life are analysed. The scales were administered to 73 RBD patients (55 resulted hemi-inattentive on standard diagnostic tests) and to 26 control subjects. Results showed a high level of interjudge and internal consistency for both instruments. Asymmetrical performances were very rare in control subjects. For the Extrapersonal Scale, asymmetry was detected in most neglect patients while it was rare in patients without neglect. For the Personal Scale, about half of hemi-inattentive patients and 25% of patients without hemi-inattention displayed asymmetrical performance. These findings are consistent with the idea that the Personal Scale measures a different dimension than both the Extrapersonal Scale and standard tests for neglect. In a similar vein, the Extrapersonal, but not the Personal, Scale was correlated with stan...

We investigated how perceptual and semantic relationships between the left and right half of chimeric stimuli influence overt and covert visual processing by asking eight right brain damaged (RBD) patients with hemispatial neglect to identify complete, half-, and chimeric drawings. Chimeric stimuli belonged in one of four categories defined according to the perceptual and semantic relatedness between the two compounding hemi-figures. Thus, the hemi-figures could be related both perceptually and semantically, only perceptually, only semantically, or neither perceptually nor semantically. Although patients often appeared to base their report on the right part of the chimerics, the number of errors was minimal when conflicts between the two hemi-figures were maximal. Moreover, perceptual conflicts, which mainly affect the perception of the shape, appeared to influence the performance more than semantic conflicts. Since the analysis of shape incongruency is probably accomplished at early levels of information processing, the result suggests that preattentive analysis is largely spared in the experimental patients and that, in our task, bottom-up factors more than top-down factors modulate the expression of left neglect.

Drawing tasks, both free and copied, have achieved a central position in neuropsychological testing of patients with unilateral cerebral dysfunction by virtue of their sensitivity to different kinds of organic brain disorders and their ability to provide information on lateralized brain damage. In the drawings of patients with right hemispheric damage, visuospatial neglect is revealed by the omission of details on the side of the drawing contralateral to the hemispheric lesion. Patients with unilateral cerebral damage, particularly those with left hemispheric damage, also demonstrate a tendency to place their drawings on the side of the page ipsilateral to the cerebral lesion, a phenomenon which has been termed visuospatial hemi-inattention. It has been reported previously that brief external application of alternating pulsed electromagnetic fields (EMFs) in the picotesla (pT) range intensity improved visuoperceptive and visuospatial functions and reversed neglect in Parkinsonian patients. The present communication concerns four fully medicated elderly nondemented Parkinsonian patients (mean age: 74.7 +/- 4.6 yrs; mean duration of illness: 7.7 +/- 5.2 yrs) in whom application of these EMFs produced reversal of visuospatial hemi-inattention related to left hemispheric dysfunction. These findings support prior observations demonstrating that pT EMFs may bring about reversal of certain cognitive deficits in Parkinsonian patients.

Contrasting hypotheses have been proposed about the functional equivalence between waking saccades and REMs. Patients with left visual hemi-inattention showed dissociation between the direction of waking saccades and that of REMs. REMs directed toward the left were virtually absent, while waking inspective saccades directed in both lateral directions were present, but confined to the right hemispace. It is concluded that: a) the cortical areas regulating attention are relevant in the production of REMs; b) two separate attentional mechanisms have to be considered in relation to the hemi-inattentive syndrome, one is involved in the cognitive control of visual exploration and plays little or no role in the modulation of REMs, the other deals with REMs during sleep and with reflex-like orienting responses to peripheral stimuli during waking.

A series of stroke patients (n = 31) were assessed at four stages: 4 weeks, 8 weeks, 12 weeks and 18 months post-trauma. Significant recovery was noted at 8 weeks, although a trend towards recovery continued throughout the assessment phases. Patients presenting with hemi-inattention at the 4-week assessment achieved significantly poorer levels of functional ability at the final assessment although in some cases the inattention had resolved on neuropsychological tests.

The hemi-inattention syndrome was studied in 15 right-handed adults, 12 men and 3 women. One patient had a pontic-mesencephalic lesion, 3 had right hemisphere damage, 7 had left-hemisphere lesion and 4 had bilateral lesions. All lesions were confirmed by CT-scan. Different criteria of hemi-inattention were used. All patients presented extinction, inattention and in 13 visuomotor akinesia; 5 of the left and all of the right and bilateral lesion patients presented spatial neglect. CT-scans were superimposed. The posterior parietal region was the most important in producing contralateral hemi-inattention. Results are discussed with relation to the literature and the educational factor and cerebral asymmetry are discussed with regard to hemi-inattention.

Twenty right brain-damaged patients and two left brain-damaged patients who showed neglect in the early stage of a stroke were reexamined at a mean time of 10.5 months. In four patients neglect was still as severe as on the initial examination and visual scanning was limited to the right space or even to its rightmost portion. Available CT scan findings suggest that in some patients thalamic lesions may play a critical role in the persistence of neglect. All the other patients improved with passage of time, but minor signs of hemi-inattention could still be demonstrated in the great majority of them.

The ability to maintain steady fixation for short periods of time was found to decrease as the severity of visual hemi-inattention increased in right-hemisphere stroke patients and matched normal control subjects. Performance was best in the central area of the visual-spatial field and worst in peripheral areas. It is suggested that the paradigm employed reveals the manifestation of a “general” inattention phenomenon that shares the same underlying mechanism as hemi-inattention.

Ten patients undergoing left ventrolateral thalamotomy (LVLT) and 11 patients undergoing right ventrolateral thalamotomy (RVLT) for Parkinsonian or essential tremor performed a test of visual searching for parallel lines before and after surgery. On average RVLT caused impairment of searching only on the left side. LVLT affected searching on both sides, with the impairment being slightly more marked on the right side. The tendency to initiate searching from the side ipsilateral to the lesion increased after VLT. The results indicated that unilateral VLT caused hemi-inattention in visual searching, which deficit is possibly related to the transient motor neglect usually observed in the extremities contralateral to VLT.

Deficits in visual discrimination were examined in 30 combat soldiers with head wounds, 20 of whom had unilateral lesions (10 right and 10 left) of the posterior cerebral hemispheres and 10 of whom had frontal lobe wounds, left, right or bilateral. Seven of the patients with posterior lesions, but none with frontal lesions, showed visual spatial disorientation as demonstrated by a shift in the peak of the stimulus generalization gradient of an experimentally conditioned sensory discrimination. The peak shift occurred to the side opposite the cerebral lesion in all cases, and the deficit did not occur when the task was presented as a match to sample.