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

To demonstrate that Visual Midline Shift Syndrome (VMSS) following a cerebrovascular accident (CVA) can be corrected with yoked prisms.

This randomized study describes how the use of yoked prisms affects visual midline and documents the influence of yoked prisms on improving postural orientation.

Evaluation of VMSS and its correlation with postural lean during ambulation were studied in 30 post-CVA subjects and 30 controls.

Yoked prisms were used to treat VMSS by correcting posture and balance.

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.

Yoked prisms are an effective means of treating VMSS in this population and may be useful in other neurological syndromes with visuo-spatial involvement.