Functional MRI correlates of lower limb function in stroke victims with gait impairment.
OBJECTIVE
Although knowledge concerning cortical reorganization related to upper limb function after ischemic stroke is growing, similar data for lower limb movements are limited. Previous studies with hand movement suggested increasing recruitment of motor areas in the unlesioned hemisphere with increasing disability. We used ankle movement as a lower limb analog to test for similarities and differences in recovery patterns.


METHODS
Eighteen subjects were selected with chronic residual gait impairment due to a single subcortical ischemic stroke. Functional MRI scans were obtained at 3.0 T during active and passive ankle dorsiflexion in the patients (8 females, 10 males; mean age, 59.9+/-13.5 years; range, 32 to 74 years) and 18 age-matched healthy control subjects.


RESULTS
We observed substantial neocortical activity associated with foot movement both in the patients with stroke and in the healthy control subjects. Our primary finding was increased cortical activation with increasing functional impairment. The extent of activation (particularly in the primary sensorimotor cortex and the supplementary motor area of the unlesioned hemisphere) increased with disability. The changes were most prominent with the active movement task.


CONCLUSIONS
Using ankle movement, we observed increased activation in the unlesioned hemisphere associated with worse function of the paretic leg, consistent with studies on movement of paretic upper limbs. We interpret this finding as potentially adaptive recruitment of undamaged ipsilateral motor control pathways from the supplementary motor area and (possibly maladaptive) disinhibition of the ipsilateral sensorimotor cortex.
Enzinger
Christian
C
Department of Neurology, Medical University of Graz, Auenbruggerplatz 22, A-8036 Graz, Austria. chris.enzinger@meduni-graz.at
Johansen-Berg
Heidi
H
Dawes
Helen
H
Bogdanovic
Marko
M
Collett
Jonathan
J
Guy
Claire
C
Ropele
Stefan
S
Kischka
Udo
U
Wade
Derick
D
Fazekas
Franz
F
Matthews
Paul M
PM
D000328:Adult; D000368:Aged; D001931:Brain Mapping / Q000379:methods; D003337:Corpus Callosum / Q000502:physiology; D004525:Efferent Pathways / Q000473:pathology / Q000503:physiopathology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D007866:Leg / Q000294:innervation / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000473:pathology / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology; D009433:Neural Inhibition / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology; D010291:Paresis / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D020127:Recovery of Function; D020521:Stroke / Q000150:complications / Q000473:pathology / Q000503:physiopathology*