Dynamic course of intracortical TMS paired-pulse responses during recovery of motor function after stroke.
BACKGROUND
Recovery of motor function after stroke may be associated with changes in inhibitory and facilitatory circuits within the motor cortex.


OBJECTIVE
We explored such changes longitudinally after stroke, using transcranial magnetic stimulation (TMS).


METHODS
Subjects (N = 27) with a single cerebral infarction affecting movement of either hand were studied at <10 days poststroke, 1 month, and 6 months. Age-matched control subjects (N = 9) were studied at 2 times.


RESULTS
In contrast to previous studies, paired-pulse inhibition was increased in patients with a subcortical stroke compared to control subjects. After a cortical stroke, paired-pulse facilitation was also increased. Stroke location affected the time course of inhibition. Subcortical stroke resulted in increased inhibition initially that decreased over time, whereas cortical stroke had no significant effect on inhibition and a more immediate and lasting effect on facilitation.


CONCLUSIONS
The time course of a decline in inhibition based on TMS after subcortical stroke followed the gain in motor recovery. Increased facilitation in cortical stroke patients is more likely to represent the effect of early cortical circuit disruption and may not play a role in subacute changes in motor function.
Wittenberg
George F
GF
Department of Neurology, Wake Forest University Health Sciences, Winston Salem, NC, USA. GWittenb@GRECC.U.Maryland.edu
Bastings
Eric P
EP
Fowlkes
Allison M
AM
Morgan
Timothy M
TM
Good
David C
DC
Pons
Timothy P
TP
D000368:Aged; D002544:Cerebral Infarction / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology; D020127:Recovery of Function / Q000502:physiology*; D020521:Stroke / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation