THE EFFECTS OF SIDE OF LESION ON THE ATTENTIONAL REQUIREMENTS OF STANDING AND WALKING IN INDIVIDUALS POST-STROKE.

Wellmon R, Pierce S, Palmer C, Arnone J, Billerman C, Lynch K, Nangle A. MossRehab Hospital, Philadelphia, PA and Widener University, Chester, PA.

Purpose: The purpose of this study was to examine the attentional requirements of standing and walking for individuals diagnosed with a unilateral cerebral vascular accident (CVA).

Background: Individuals post-CVA experience mobility dysfunction for a variety of reasons. A decrease in the capacity to allocate attentional resources across multiple sources of information may limit ambulation potential and increase the risk of injury. The effects of a stroke on central nervous system tissue structures can cause a diminution in the capacity to allocate attentional resources that may be hemispheric specific.

Subjects: Thirty-two adults admitted to a free standing acute inpatient rehabilitation facility were assigned to one of two groups - left CVA (n=14, mean age = 62.9±13.6 yrs), right CVA (n=18, mean age = 62.7±12.8 yrs). Subjects post-CVA achieved modified independence in ambulation prior to participating in the study. Two additional groups consisting of elderly, non-disabled adults (n=18, mean age = 68.3±10.3 yrs) and young, non-disabled (n=18, mean age = 25.9±2.6 yrs) adults also participated in the study. Non-disabled adult subjects were all independent in community ambulation.

Methods: A dual-task voice reaction time (VRT) paradigm was used to examine the attentional requirements of sitting, standing, and walking for each of the groups. The dual-task approach documents attentional cost by examining changes in performance on a secondary task while the subject is actively engaged in completing a primary task. The primary tasks in this study were standing and walking on a level surface. The secondary task was verbally responding to an auditory stimulus by saying the letter "B". In addition, gait velocity, while walking on a level surface, and balance performance using the timed up-and-go test were examined.

Analysis: A 4 (group) x 3 (task) ANOVA with repeated measures on the last factor was used to examine between and within group differences in VRT. A one-way ANOVA was used to examine differences in gait velocity and performance on the timed up and go test. Results: Non-disabled young and elderly adults had significantly faster VRT for standing and walking when compared to the groups post-CVA. No significant differences were found in VRT based either on the side of the lesion for the groups post-CVA or between the non-disabled young and elderly adult groups. Individuals post-CVA walked significantly slower and took significantly longer to complete the timed up-and-go test.

Conclusions: When performing functional activities, participants post-stroke incurred an increased attentional demand as evidenced by slower VRT when compared to the two groups of non-disabled subjects. In the current study, the location of the lesion was not a factor affecting the allocation of attentional resources for the subjects post-stroke. Non-disabled elderly adults demonstrated similar attentional abilities when standing and walking as young adults, which discounts age as a source for the increase in attentional demand. The increase in attentional demand may be due in part to the effects of the central nervous system lesion. In addition, impairments in multiple organ systems, such as those responsible for balance and motor function, may have affected task automaticity. Subjects post-stroke may have had to consciously think about maintaining balance when standing and walking because of the resultant impairments. This will cause an increase in the attentional demands of task performance.

Funding Source: Moss Rehabilitation Research Institute and Widener University.

Paper presented at the 2003 Annual Conference & Exposition of the American Physical Therapy Association, Washington, DC.