The importance of lateralized and nonlateralized sub-symptoms of visuospatial neglect as predictors of functional outcome after stroke
Abstract: DEGREE OF LICENTIATE IN PSYCHOLOGY Abstract Viken, J. I. (2011). The importance of lateralized and nonlateralized sub-symptoms of visuospatial neglect as predictors of functional dependency after stroke. Department of Psychology, and the Stroke Research Group at the Department of Neuroscience and Physiology, at the Sahlgrenska Academy at Gothenburg University. Visuospatial neglect (VSN) is a disorder which is commonly observed in the acute phase after stroke, especiaIly following right hemisphere damages. Patients who have VSN exhibit impaired awareness and responses to visual stimuli located towards the side opposite the brain lesion ( contralesional side). Previous studies have shown that the presence of VSN is a predictor of functional dependency following stroke. The present paper investigated how different sub-symptoms of VSN are related to functional outcome. The sub-symptoms of VSN were assessed using standard paper and pencil tests of cancellation and visual search, neurological deficits were examined with the Scandinavian Stroke Scale and functional -dependency was measured with the modified Rankin Scale. Scores of~3 at a three months (Study I and II) and at a two years (Study II) follow-up were c1assified as functional dependency. Patients in the current studies were sub-samples from the prospective Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS). Study I inc1uded 375 consecutive stroke patients who were divided into three groups having either lateralized-, nonlateralized-, or no visual inattention. The study examined the course of lateralized and nonlateralized symptoms of inattention across time in relation to functional outcome and neurological symptoms. Compared to the other two groups, participants with lateralized inattention exhibited significantly more severe neurological symptoms, functional dependency and persisting visual inattention, both post-acutely and after three months. Stepwise logistic regressions revealed that post-acute lateralized inattention was an important and independent predictor of functional dependency following right hemisphere damage, but not af ter left hemisphere damage. In Study n a consecutive series of 104 patients with right hemisphere stroke were incIuded. The relative importance of sub-symptoms of VSN as predictors of functional dependency was investigated. Three sub-symptoms of visuospatial neglect (the total number of omissions, asymmetry of omissions and right capture of attention in orientation) and two symptoms related to VSN (visual processing speed and repetitive identification of previously detected targets) were analyzed. The univariate analyses showed that right capture of attention in orientation, asymmetry of omissions and increased processing speed all had strong and significant associations with functional dependency at three months and at two years after stroke. Moreover, stepwise logistic regressions identified right capture of attention as the only significant predictor of dependency at three months whilst increased processing speed was the only significant predictor of dependency at two years. Condusions: When predicting functional outcome following VSN the sub-symptoms of increased processing speed and asymmetry in the orientation of attention are more important than the omissions per se. The development of standardized test methods for these subsymptoms is an important dinical issue since they provide valuable prognostic information over and above the dassification of presence or absence of visuospatial neglect. Keywords: Functional outcome, neglect, recovery, stroke, visual attention, visual search. ISSN 1101-718X ISRN GU/PSYK/A VH-241-SE
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