Functional-Magnetic Resonance Imaging and Transcranial Magnetic Stimulation in a Case of Schizencephaly

Byun, Woo Mok; Han, Bong Soo; Lee, Jae Kyo; Chang, Yongmin

Abstract

PURPOSE
This study was to present the functional brain mapping of both functional magnetic resonance imaging(MRI) and transcranial magnetic stimulation(TMS) in a case of schizencephaly.
MATERIALS AND METHODS
A 28-year-old man, who had left hemiplegia and schizencephaly in right cerebral hemisphere, was examed with both functional MRI and TMS. Motor function of left hand was decreased whereas right hand was within normal limit. For functional MRI, gradient-echo echo planar imaging(TR/TE/alpha=1.2 sec/90 msec/90) was employed. The paradigm of motor task consisted of repetitive self-pased hand flexion-extension exercises with 1-2 Hz periods. An image set of 10 slices was repetitively acquired with 15 seconds alternating periods of task performance and rest and total 6 cycles( three ON periods and three OFF periods) were performed. In brain mapping, TMS was performed with the round magnetic stimulator(mean diameter; 90mm). The magnetic stimulation was done with 80% of maximal output. The latency and amplitude of motor evoked potential(MEP)s were obtained from both abductor pollicis brevis(APB) muscles.
RESULTS
Functional MRI revealed activation of the left primary motor cortex with flexion-extension exercises of healthy right hand. On the other hand, the left primary motor cortex, left supplementary motor cortex, and left premotor areas were activated with flexion-extension exercises of left hand. In TMS, magnetic evoked potentials were induced in no areas of right cerebral hemisphere, but in 5 areas of left cerebral hemisphere from both abductor pollicis brevis. Latency, amplitude, and contour of response of the magnetic evoked potentials in both hands were similar.
CONCLUSION
Functional MRI and TMS in a patient with schizencephaly were successfully used to localize cortical motor function. Ipsilateral motor pathway is thought to be secondary to reinforcement of the corticospinal tract of the ipsilateral motor cortex.