Lateralization of motor innervation in children with intractable focal epilepsy--a TMS and fMRI study.
OBJECTIVE
To correlate hand function with lateralization of motor innervation, as studied with transcranial magnetic stimulation (TMS) and functional magnetic imaging (fMRI), in children with intractable epilepsy and lesions in the vicinity of the motor cortex.


METHODS
In 34 children hand motor function was examined and motor evoked potentials (MEPs) were recorded after TMS of both hemispheres, establishing lateralization of corticospinal innervation. When feasible, patients underwent fMRI using a manual motor task.


RESULTS
Good function of the contralesional hand was associated with early lesions (p=0.02). Lateralization of motor innervation to the contralesional hand correlated with quality of motor function (p=0.001); 83% of children with poor hand function had ipsi- or bilateral innervation, whereas all children with good hand function had pure contralateral control. Mirror movements during movement of the unaffected hand predicted ipsilateral contribution to motor innervation (p=0.006). Fourteen children who had no TMS responses were younger than those with elicitable MEPs (p<0.001). TMS led to a temporary increase of seizure frequency in four children. fMRI results were concordant with TMS.


CONCLUSIONS
Poor function of the contralesional hand is strongly associated with ipsilateral motor innervation. Reorganization in the lesioned hemisphere mainly occurs in early developmental lesions and seems efficient in maintaining good hand function. Clinical examination of hand function has predictive value for the pattern of motor innervation prior to epilepsy surgery, which in older children can further be established by TMS and fMRI.
Koudijs
S M
SM
University Medical Center Utrecht, Room C.03.236, Heidelberglaan 100, P.O. Box 85500, 3508 GA Utrecht, The Netherlands. s.m.koudijs@umcutrecht.nl
Leijten
Frans S S
FS
Ramsey
Nick F
NF
van Nieuwenhuizen
O
O
Braun
K P J
KP
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004828:Epilepsies, Partial / Q000473:pathology* / Q000503:physiopathology*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006225:Hand / Q000294:innervation; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009044:Motor Cortex / Q000098:blood supply* / Q000503:physiopathology*; D010100:Oxygen / Q000097:blood; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult
D010100:Oxygen