Motor strokes: the lesion location determines motor excitability changes.
OBJECTIVE
The purpose of this research was to investigate the impact of lesion location on motor excitability and motor performance.


METHODS
We studied patients with pure motor strokes in 4 different brain areas: motor cortex lesions (n=7), striatocapsular lesions (n=13), lacunar lesions of the internal capsule (n=13), and paramedian pontine lesions (n=10). Motor performance tests included the 9-hole-peg test and grip strength recordings. Motor excitability was determined by transcranial magnetic stimulation. Motor thresholds, stimulus-response curves, silent periods, motor cortical inhibition, and facilitation were investigated.


RESULTS
The 4 groups were clinically similar but showed major differences in motor excitability. Only motor cortex lesions had a loss of intracortical inhibition in the affected hemisphere. In the internal capsule lesion group and the pontine lesion group, stimulus-response curves were depressed on the affected side. All of the subcortical lesions showed a prolongation of the silent period in the paretic side. Motor thresholds were predominantly elevated in the lesioned hemisphere of patients with internal capsule or pontine lesions. Motor performance was correlated with silent period duration in internal capsule lesions and with motor thresholds in internal capsule and pontine lesions.


CONCLUSIONS
Motor cortex lesions exhibited deficient inhibitory properties. In contrast, subcortical lesions displayed an enhancement of inhibition. Internal capsule and pontine lesions affecting the corticospinal tract on different levels particularly impaired neuronal recruitment. Our results suggest that the lesion location determines a specific pattern of motor excitability changes.
Liepert
Joachim
J
Department of Neurology, University Medical Center Eppendorf, Hamburg, Germany. liepert@uke.uni-hamburg.de
Restemeyer
Cordula
C
Kucinski
Thomas
T
Zittel
Simone
S
Weiller
Cornelius
C
D000368:Aged; D001479:Basal Ganglia / Q000473:pathology / Q000503:physiopathology; D020520:Brain Infarction / Q000175:diagnosis* / Q000503:physiopathology*; D003342:Corpus Striatum / Q000473:pathology / Q000503:physiopathology; D004056:Differential Threshold; D005260:Female; D006801:Humans; D020772:Internal Capsule / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000473:pathology* / Q000503:physiopathology*; D009048:Motor Skills; D009460:Neurologic Examination; D011149:Pons / Q000473:pathology / Q000503:physiopathology; D011595:Psychomotor Agitation; D018709:Statistics, Nonparametric