Size Doesn’t Matter: Cortical Stroke Lesion Volume is Not Associated with Upper Extremity Motor Impairment and Function in Mild, Chronic, Hemiparesis

Why would you even expect lesion size to make a difference in upper extremity hemiparesis? Its so blatently obvious that you have to look at location.
http://www.archives-pmr.org/article/S0003-9993%2813%2900031-2/abstract

Abstract 

Objective

To determine: (a) the relationship between lesion volume and upper extremity (UE) motor impairment using the UE section of the Fugl-Meyer (FM); and (b) the relationship between lesion volume and UE functional outcomes using the Arm Motor Ability Test (AMAT) Functional Ability (FA) and Time scales.

Design

Secondary, retrospective analysis of randomized controlled trial data

Setting

Not applicable

Participants

139 subjects with chronic stroke (83 males; mean age of all subjects = 56.7 + 11.2 years; mean time since stroke onset = 59.6 + 65.6 months; 90 subjects with right hemiparesis) and stable, active, distal UE movement.

Intervention

Data were collected related to subjects’ lesion volum and UE movement prior to their participation in a multicenter randomized controlled trial.

Main Outcome Measures

The FM and the AMAT.

Results

Neither age nor lesion volume was related to FM performance. The p-value for the regression coefficient of lesion volume was 0.045 in the AMAT FA model and 0.016 in the AMAT Time model. Lesion volume accounted for only an additional 1.7% (AMAT FA) to 3.1% (AMAT Time) of the variability in motor function, and was not clinically meaningful.

Conclusions

Data suggest no relationship between lesion volume and UE impairment, and a small, clinically insignificant relationship between lesion volume and UE motor function. Stroke affects metabolic changes in intact regions, and causes diffuse structural loss in anatomically remote regions from the infarction. These other factors may account for variance in motor outcomes following stroke.