The role of magnetoencephalography in pediatric epilepsy surgery.

INTRODUCTION: Magnetoencephalography (MEG) is a new diagnostic imaging and brain mapping device that has been recently used in the context of pediatric epilepsy, epilepsy surgery, and neuronavigation. PRINCIPLES OF MAGNETOENCEPHALOGRAPHY: MEG allows for the placement of magnetic spike sources on a conventional magnetic resonance imaging scan, the so-called magnetic source imaging, so that the localization of epileptiform activity in a child can be determined. Considerable effort is placed on analyzing the configuration and number of spike waves by MEG that relate to a primary epileptiform discharge. Such MEG spike clusters are corroborated now by intraoperative invasive subdural grid monitoring that show good correlation in the majority of cases. Another important role of MEG relates to the mapping of critical regions of brain function using known paradigms for speech, motor, sensory, visual, and auditory brain cortex. FUTURE APPLICATIONS: When linked to standard neuronavigation devices, MEG brain mapping can be extremely helpful to the neurosurgeon approaching nonlesional epilepsy cases or lesional cases where the safest and most direct route to the surgical disease can be selected. As paradigms for brain mapping improve and as MEG software upgrades become more sensitive to analyzing all types of spike sources, MEG will play an increasingly important role in pediatric neurosurgery, especially for the child with intractable epilepsy.