Motor outcome after subcortical stroke: MEPs correlate with hand strength but not dexterity.
OBJECTIVE
Motor evoked potential (MEP) amplitude and threshold are predictors of functional outcome in the early stages after stroke, and improvement in these parameters usually accompanies motor recovery. The aim of this study in patients with subcortical stroke was to determine whether there is a correlation between MEP amplitude and threshold and the degree of recovery of strength and dexterity in the affected hand.


METHODS
MEP amplitude and threshold were measured on the affected and unaffected sides in 23 patients who had suffered a subcortical ischaemic stroke up to 23 years previously. Grip strength was measured using a hand-held dynamometer and dexterity was assessed using a modification of the McCarron test battery.


RESULTS
Grip strength correlated with both MEP amplitude and threshold (r=0.49 and r=-0.54, respectively, P<0.05), whereas the McCarron score for motor dexterity did not correlate significantly with either of these MEP parameters.


CONCLUSIONS
Grip strength and dexterity correlate differentially with MEP parameters of excitability and conduction in the corticospinal pathway after recovery in patients with subcortical stroke. Grip strength is dependent on restoration of corticospinal excitability and conduction whereas additional factors such as cortical reorganization may underlie recovery of motor dexterity.
Thickbroom
Gary W
GW
Centre for Neuromuscular and Neurological Disorders, University of Western Australia, QEII Medical Centre, Nedlands, Australia. gthickbr@cyllene.uwa.edu.au
Byrnes
Michelle L
ML
Archer
Sarah A
SA
Mastaglia
Frank L
FL
D000328:Adult; D000368:Aged; D002540:Cerebral Cortex / Q000502:physiology*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009048:Motor Skills / Q000502:physiology*; D018709:Statistics, Nonparametric; D020521:Stroke / Q000503:physiopathology*