The evaluation process may include four phases, beginning with the least invasive. This includes procedures described in the Patient Guide to Procedures.
Phase I: The first evaluation phase is a comprehensive investigation that requires approximately a week of continuous audio-visual-electroencephalogram (EEG) monitoring in Yale's six-bed adult epilepsy unit or two-bed pediatric unit. During this time, the patterns of altered behavior and movement, along with the EEG recording during seizures, can help the epileptologists localize the source. Advanced imaging techniques such as magnetic resonance imaging (MRI), PET and SPECT scans along with neuropsychological testing are performed to determine function and pathology.
Phase II: The second phase entails performing an angiogram to study the vascular structures and WADA (intracarotid sodium amytal testing), which determines language dominance and memory assessment useful to surgical planning.
Phase III: If it is necessary to study the brain directly to pinpoint the source of the seizures, the patient may have EEG electrodes surgically implanted either on the surface or within the brain.
Phase IV: Using all the information collected during the prior phases, the interdisciplinary team of specialists is now able to outline for the patient and family whether surgery is possible and what the results might be. If surgery is chosen, neurosurgeons proceed to remove any lesions or damaged brain revealed by the testing process to be the focus of the seizures.