Selective Visual Neglect Research, Literature Review Example

Spatial neglect is considered a complex invalidating syndrome clinically, most commonly suffered by those patients who are with right brain damage. Spatial neglect is reported often immediately after the right hemispheric lesions of the Middle Cerebral Artery (MCA) that works in damaging the frontal-parietal subcortical-cortical network subserving space awareness and representation. Collecting the evidence, however, presents that neglect can also result into the Posterior Cerebral Artery (PCA) lesions that do not straightforwardly influence this network of parietal–frontal nature (Doricchi et.al. 2003). The purpose of the study was to find out the effect of selective visual neglect in right brain damaged patients with splenial interhemispheric disconnection. Using two patients as a case study, the study endeavored to prove for the first time that PCA lesion selectively affects the splenium of the corpus callosum and the adjacent right primary visual cortex hence provoking severe neglect restriction to the visual domain. The sampling technique used in the study was stratified sampling in which patients with specific characters were chosen for the study. The sample size used in the study comprised of two patients. Patient 1, MP a right-handed 76-year-old housewife admitted to a rehabilitation hospital after suffering from severe Auxilium Vitae and Volterra twenty-five days after a right hemisphere ischemia was induced by embolic stroke. Patient 2, MB a right-handed 81-year-old retired clerk, who was admitted to the same rehabilitation hospital after suffering from severe right hemisphere hemorrhage (Orsini, et.al. 1987).

In regards to the methods used in the study, the research study used experimental research design in which three experiments were performed in relation to the topic of study. First and firstmots, Perceptual-visual neglect in which the patient’s visual neglect peripersonal space was thoroughly assessed through Line Bisection Task (Tomaiuolo, & M & Oliva, 2010). To effectively achieve the required results of the study, Patient 1 performed the Line Bisection Task using the right hand while Patient performed the task using both right and left hand. Line cancellation additionally was performed by the two patients in the sample study using their right hands. The Letter Cancellation task is another method of data collection used in the study which the patients performed with their right hand. In collecting data related to Visual neglect for the extra personal space, the researchers asked patients to indicate as well as name pictures attached to the walls of a testing room (3 m 9 3 m.). The other experiment done in the study was Personal-body neglect in which the researchers assessed neglect for personal-body space through the Fluff Test. The test was done in two separate sessions thus one in blindfolded condition while the other in free vision (Zoccolotti & Judica, 1991). During the two tests all the patients were required to reach and remove 2 9 4 cm paper strips attached to their body with their ipsilesional right-hand. Data was collected depending on the ability of the patient to reach the three targets attached to their individual right hand side leg, left leg and left leg and left arm. Since the test primarily concentrated on the personal body neglect, no target was actually attached on the patient’s right arm. This was excluded from the task. The other experimental data collection method used in the study was Representational-topographical neglect in which, neglect for space representation test was done. All the patients were asked to mentally visualize Familiar Square within their hometown. For accuracy and reliability the topographic descriptions given by the patients were evaluated with the maps provided by healthy relatives living within the same towns as the patients. Lastly, Neuroanatomical investigation was done in which MRI brain scan for each patient was obtained 4 months past stroke onset.

The results of the study for Behavioral investigation for MP Patient 1 indicated that the patient suffered from severe chronic neglect for the Visual peripersonal and Visual extra personal space. In the bisection assessment performed in relation to contralesional neglect as well as hemianopia caused dramatic shift in the bisection long 20 cm lines on the rightward and short 2cm lines on left bisection. As far as the cancellation assessment is concerned, the results indicated extreme severe neglect among the two patients. In regards to the Letter cancellation assessment task with target letters interspersed among the distracters, the findings indicated that only two targets were canceled which reflects weaker asymmetry Line cancellation among the two patients. In the representational assessment between the patients no visual neglect was observed in the sample study. In the second experiment Anatomical investigation, the results findings indicated patient 1 localized damage in the right hemisphere as well as a clear damage of the posterior portion of splenium of the corpus callosum was present. The results findings for patient two in this experiment indicated that the visual neglect suffered was equally the same as that one of patient one. The results indicated that the two patients suffered from severe chronic neglect for the Visual peripersonal and Visual extra personal space (Cocchini eet.al. (2001). Patient 2 showed localized lesion in the right hemisphere. In the two patients matter lesions proved evident as a result of contiguous parietal as well as temporal areas observed to be adjacent to the patient’s posterior horn of the lateral ventricle.

In conclusions the study indicated that callosal damage has a significant effect on the right side of the splenium in patient one while callosal fibers and concomitant left hemianopia in patient one and two caused damage to the right primary visual cortex. Both patient one and two developed severe spatial neglect exclusively restricted to the visual domain. On other hand the study indicated that no spatial neglect was found for the Personal-body and the Representational-imagery space. The findings from the empirical study indicated that brain lesions tends to deprive intact parietal and frontal attentional areas from particular sensory inputs which in normal cases if damaged can only result to spatial neglect which limited to specific brain sensory modalities.

Reference

Tomaiuolo, F., Bresci, M & Oliva, M. (2010).Selective visual neglect in right brain-damaged patients with splenial interhemispheric disconnection. Publisher: Springer

Doricchi F, Tomaiuolo F. (2003). The anatomy of neglect without hemianopia: a key role for parietal-frontal disconnection? NeuroReport 14:995-998.

Orsini A, et.al. (1987). Verbal and spatial immediate memory span: normative data from 1355 adults and 1112 children. Ital Journal Neurol Science 8(6):539–548

Zoccolotti P, Judica A. (1991). Functional evaluation of hemi neglect by means of a semi structured scale: personal extrapersonal differentiation. Neuropsychol Rehabil 1:33–34.

Cocchini N, et.al. (2001). The Fluff Test: a simple task to assess body representation neglect. Neuropsychol Rehabil 11:17–31