Imaging correlates of motor recovery from cerebral infarction and their physiological significance in well-recovered patients.
We studied motor representation in well-recovered stroke patients. Eighteen right-handed stroke patients and eleven age-matched control subjects underwent functional Magnetic Resonance Imaging (fMRI) while performing unimanual index finger (abduction-adduction) and wrist movements (flexion-extension) using their recovered and non-affected hand. A subset of these patients underwent Transcranial Magnetic Stimulation (TMS) to elicit motor evoked potentials (MEP) in the first dorsal interosseous muscle of both hands. Imaging results suggest that good recovery utilizes both ipsi- and contralesional resources, although results differ for wrist and index finger movements. Wrist movements of the recovered arm resulted in significantly greater activation of the contralateral (lesional) and ipsilateral (contralesional) primary sensorimotor cortex (SM1), while comparing patients to control subjects performing the same task. In contrast, recovered index finger movements recruited a larger motor network, including the contralateral SM1, Supplementary Motor Area (SMA) and cerebellum when patients were compared to control subjects. TMS of the lesional hemisphere but not of the contralesional hemisphere induced MEPs in the recovered hand. TMS parameters also revealed greater transcallosal inhibition, from the contralesional to the lesional hemisphere than in the reverse direction. Disinhibition of the contralesional hemisphere observed in a subgroup of our patients suggests persistent alterations in intracortical and transcallosal (interhemispheric) interactions, despite complete functional recovery.
Nair
Dinesh G
DG
Department of Neurology, Palmer 127, Beth Israel Deaconess Medical Center/Harvard Medical School, 330, Brookline Avenue, Boston, MA 02215, USA.
Hutchinson
Siobhan
S
Fregni
Felipe
F
Alexander
Michael
M
Pascual-Leone
Alvaro
A
Schlaug
Gottfried
G
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002544:Cerebral Infarction / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009048:Motor Skills; D020127:Recovery of Function; D050781:Transcranial Magnetic Stimulation