Vision does not always help stroke survivors compensate for impaired limb position sense.

BACKGROUND

Position sense is commonly impaired after stroke. Traditional rehabilitation methods instruct patients to visualize their limbs to compensate for impaired position sense.

OBJECTIVE

Our goal was to evaluate how the use of vision influences impaired position sense.

METHODS

We examined 177 stroke survivors, an average of 12.7 days (+/- 10 days (SD)) post-stroke, and 133 neurologically-intact controls with a robotic assessment of position sense. The robot positioned one limb (affected) and subjects attempted to mirror-match the position using the opposite limb (unaffected). Subjects completed the test without, then with vision of their limbs. We examined three measures of position sense: variability (Var), contraction/expansion (C/E) and systematic shift (Shift). We classified stroke survivors as having full compensation if they performed the robotic task abnormally without vision but corrected performance within the range of normal with vision. Stroke survivors were deemed to have partial compensation if they performed the task outside the range of normal without and with vision, but improved significantly with vision. Those with absent compensation performed the task abnormally in both conditions and did not improve with vision.

RESULTS

Many stroke survivors demonstrated impaired position sense with vision occluded [Var: 116 (66%), C/E: 91 (51%), Shift: 52 (29%)]. Of those stroke survivors with impaired position sense, some exhibited full compensation with vision [Var: 23 (20%), C/E: 42 (46%), Shift: 32 (62%)], others showed partial compensation [Var: 37 (32%), C/E: 8 (9%), Shift: 3 (6%)] and many displayed absent compensation (Var: 56 (48%), C/E: 41 (45%), Shift: 17 (33%)]. Stroke survivors with an affected left arm, visuospatial neglect and/or visual field defects were less likely to compensate for impaired position sense using vision.

CONCLUSIONS

Our results indicate that vision does not help many stroke survivors compensate for impaired position sense, at least within the current paradigm. This contrasts with historical reports that vision helps compensate for proprioceptive loss following neurologic injuries.