MEG (magnetoencephalography) uses a machine to record magnetic fields from the brain. This may show more information than a conventional EEG. It is performed to map brain function and to identify the exact location of the source of epileptic seizures. The exam can also be correlated with an MRI. Unfortunately, preliminary evidence suggests that although MEG has less spatial limitations than surface EEG, it is still not able to localize seizures from HH.