Spontaneous recovery from visual inattention 12 months after right hemisphere stroke

Visual inattention is a frequent neuropsychological disorder after right hemisphere (RH) stroke and is known to have a negative impact on functional abilities of patients. Visual inattention is related to both lateralized attentional deficits and non-lateralized difficulties in visual processing. The aim of this thesis was to study spontaneous recovery from visual inattention during a 12-month follow-up focusing on visual reasoning abilities, visual reasoning speed, and initial rightward bias. The study group consisted of 25 patients who were admitted to Tampere University Hospital due to a first-ever RH stroke. The presence of visual inattention was examined using the Behavioral Inattention Test (BIT) and the starting point (SP) analysis of its three cancellation tasks. Based on the results patients were divided into two groups and their SPs were measured along with those of a healthy control group (HC). Sixteen patients (64%) exhibited visual inattention (the VIN+ group) and nine (36%) did not (the VIN- group). Visual reasoning abilities were assessed using the Picture Completion task from the Wechsler Adult Intelligence Scale Revised (WAIS-R). At 12 months, laterality of the stimuli and the performance time on the first 12 items were also taken into account. Results showed that the VIN+ group performed poorer than the VIN- group in the visual reasoning task in the acute phase. Their performances improved during the first six months after stroke so that at six and 12 months there were no differences between the patient groups. The visual reasoning performance of the VIN- group did not change during the follow-up period. When the performances of the patients were compared to the HC s, the number of patients performing within normal range was higher in the VIN- group at each examination. During the acute phase there were significant differences between the SPs of the groups in the cancellation tasks. The VIN+ group showed pathological SPs located on the right side that shifted towards the left during the first six months after stroke. There were no differences in SPs between the patient groups at six or 12 months. When visual reasoning speed was measured one year after stroke, the VIN+ group spent significantly more time finding the left-sided than the right-sided stimuli. The VIN+ group showed spontaneous recovery from visual inattention during the first six months after stroke. Their visual reasoning abilities improved and the initial rightward bias decreased. However, visual inattention in the acute phase had long-standing effects: The VIN+ group exhibited slow visual processing on the left-sided stimuli even 12 months after stroke. In order to detect visual inattention and start rehabilitation in optimal time, this study suggests that the SP analysis should be used as a standard procedure along the conventional tests when assessing the presence of visual neglect and visual inattention