Epilepsy Diagnosis, Evaluation and Presurgical Planning

Seizures occur when one or more parts of the brain receive a burst of abnormal electrical signals that temporarily interrupt normal electrical brain function. Although types of seizures vary in severity, even the most severe generalized seizures that sweep through the entire brain at once usually originate in a single area of the brain. Our specialists use advanced imaging studies both in diagnosis and presurgical planning to pinpoint areas of the brain where seizures arise and map out the entire brain, millimeter by millimeter, to show us precisely which brain functions occur in each section of the brain. Individual treatment decisions and prognosis are determined based on the analysis of integrated results of multiple tests including:

EEG Monitoring

The state-of-the-art BWH EEG Lab is an official training site for EEG technologists through Caritas Laboure College. Under the direction of Barbara Dworetzky, MD, and chief technologist, Paul Dionne, our laboratory performs approximately 2,000 EEGs per year, 500 continuous monitoring studies, has a fully networked neurology-neurosurgery ICU with intensive monitoring capabilities and offers full evoked potential studies. The following studies are performed here:

• Video EEG monitoring: a procedure that records the brain’s continuous electrical activity by means of electrodes to the scalp and synchronizes it with video. It is indicated for patients with recurrent spells suspected of being seizures.
• EEG with polysomnography: This is a complete EEG conducted along with a simultaneous sleep study that provides overnight epilepsy monitoring and measures various parameters of sleep cycles and stages of sleep. This test is performed at the Sleep Laboratory, located at the Brigham and Women's Faulkner Hospital.
• Intracranial EEG monitoring: This is an invasive procedure that provides the most precise information available regarding seizure location, when routine scalp EEG monitoring is unable to localize the seizure focus for those patients interested in pursuing surgery as treatment for epilepsy.

Functional Brain Mapping

At BWH, we use advanced functional neurosurgical techniques and advanced brain mapping techniques when planning and performing surgery. Functional magnetic resonance imaging (fMRI), diffusion, diffusion tensor imaging (DTI), magnetoencephalography (MEG) and ictal SPECT, are used together to noninvasively localize seizure activity and identify areas of the cortex of the brain that are related to critical function, including language, motor skills and memory. These techniques are being combined with intraoperative electrocortical stimulation and phase II epilepsy monitoring using intracranial electrophysiologic studies to perform more complete and precise surgery, while preserving neurological functions.

Other Functional Imaging

A Positron Emission Tomography (PET) scan allows specialists to see changes in brain metabolism using the uptake of glucose with a radioactive atom in it. A PET scan is used to identify areas of hypometabolism (decreased glucose uptake), which may be associated with a seizure. PET scans are sometimes combined with CT scans (PET-CT) so that doctors can see detailed images of the brain and glucose uptake simultaneously. Single Photon Emission Computed Tomography (SPECT) scans enable specialists to look at blood flow in the brain.

Wada Testing

Named after Juhn Wada, a Japanese-Canadian neurologist, this test is used to determine which side of the brain is most responsible for language and short-term memory.