Difference between individuals with left and right hemiparesis in the effect of gluteus medius vibration on body weight shifting.

OBJECTIVE

To test the effect of gluteus medius (GM) vibration on the reduction of asymmetric body weight distribution in individuals with hemiparesis (HP) at two stages of postural recovery.

METHODS

The effects of GM vibration according to the shift of the body weight (%Shift) onto the paretic leg during GM vibration were registered while standing on a force-platform in 40 HP (19 left and 21 right; mean age 54.7±10.6years, mean time after stroke 2.0±1.3months), as soon as they could stand without assistance and 4 to 6 weeks later, and in 40 control subjects (mean age 54.7±10.5years).

RESULTS

Without vibration, baseline body weight (BW) distribution was characterized by underloading of the paretic limb (mean BW on the paretic limb 37.2%±13.1%). At the early stage of balance recovery, % shift toward the paretic limb induced by GM vibration differed significantly between left and right HP (P=0.049) and between left HP and controls (C) (P=0.022) and was related to BW asymmetry (r=0.437, P=0.004). Later, GM vibration reduced asymmetric BW distribution in most HP and no difference was found between left and right HP and between left and C.

CONCLUSION

At an advanced stage of postural recovery, GM vibration could help encourage HP to put weight on the affected limb. Interestingly, a behavioral difference was initially observed between right and left HP that could probably be explained by a different strategy due to the baseline severity of the BW asymmetry.