Modifying postural adaptation following a CVA through prismatic shift of visuo-spatial egocenter

Abstract

OBJECTIVE: To demonstrate that Visual Midline Shift Syndrome (VMSS) following a cerebrovascular accident (CVA) can be corrected with yoked prisms. RESEARCH DESIGN: This randomized study describes how the use of yoked prisms affects visual midline and documents the influence of yoked prisms on improving postural orientation. METHODS AND PROCEDURES: Evaluation of VMSS and its correlation with postural lean during ambulation were studied in 30 post-CVA subjects and 30 controls. EXPERIMENTAL INTERVENTIONS: Yoked prisms were used to treat VMSS by correcting posture and balance. OUTCOMES AND RESULTS: Over 50% of post-CVA subjects showed positive visual midline shift (p < 0.001; 95% confidence interval [CI], 0.660.93 for right CVAs and p = 0.001; 95% CI, 0.61-0.93 for left CVAs). A statistically significant proportion of those with a positive shift showed a decrease in shift utilizing yoked prisms (p < 0.001; 95% CI, 0.73-0.97 for right CVAs and p = 0.001; 95% CI, 0.07-0.39 for left CVAs). Additionally, over 50% of CVA subjects developed lean or drift away from hemiparesis and many subjects showed increased weight-bearing on the hemiparetic side with yoked prisms. CONCLUSIONS: Yoked prisms are an effective means of treating VMSS in this population and may be useful in other neurological syndromes with visuo-spatial involvement.