Neuroimaging

A key role of neuroimaging is to identify structural lesions underlying epilepsy. Absolute indications for neuroimaging include focal epilepsy, a focal neurological deficit, failure to respond to first-line antiseizure medications, and seizure recurrence after a period of seizure freedom. Detecting a structural lesion concordant with the electro-clinical syndrome improves the chances for a positive outcome following epilepsy surgery. Magnetic Resonance Imaging (MRI) is the primary imaging modality, but even with a dedicated epilepsy protocol, a lesion is not detected in a third of people with focal epilepsy. Novel contrasts and machine learning post-processing methods can increase the detection of subtle brain abnormalities. [ 18 F]FDG PET can show glucose metabolism abnormalities when MRI has been normal or non-contributory. Ictal and interictal SPECT imaging of cerebral perfusion may help focus localisation. Task-based functional MRI may be used to map eloquent functions before surgery and to predict the risk of neurological deficits after surgery.