Location of the primary motor cortex in schizencephaly

BACKGROUND AND PURPOSE: Functional reorganization of the brain can result f rom congenital brain disorders as well as from brain infarction, The purpos e of our study was to use functional MR imaging to determine whether reorga nization of brain function occurs in patients with schizencephaly. METHODS: Four patients with schizencephaly (three right-handed, one ambidex trous) presented with seizures. Associated lesions included agenesis of the corpus callosum (n = 1) and absence of the septum pellucidum (n = 1), Func tional MR imaging was performed in each patient using a single-section fast low-angle shot (FLASH) blood oxygen level-dependent (BOLD) technique at 1. 5 T in a standard head coil. The motor cortex was initially identified on a n axial T1-weighted anatomic image. Thirty consecutive images were obtained during a motor task consisting of repetitive finger-to-thumb opposition Th e percentage of change in increased signal intensity was calculated for the primary motor area, An ipsilateral activation index was used to compare th e affected with the unaffected hemisphere. RESULTS: The percentage of change in increased signal intensity in the area of activation ranged from 4.8% +/- 0.9 to 9.2% +/- 1.2 (mean, 5.6% +/- 15) , The ipsilateral activation index in the affected hemisphere was 0.00 to 0 .38, whereas that in the unaffected hemisphere was 15.4 to infinity. The di fference in the ipsilateral activation index between each hemisphere was co nsidered significant. CONCLUSION: Our results showed increased activation in the unaffected hemis phere in patients with schizencephaly, which may reflect functional reorgan ization of the motor area in patients with this congenital disorder.