Electroencephalography in Epilepsy Evaluation

PURPOSE OF REVIEW Epilepsy is a heterogeneous disorder that is often associated with abnormal electroencephalogram (EEG) findings. This article provides an overview of common EEG findings in epileptic disorders. The physiologic basis of EEG and intracranial EEG studies is also discussed.

RECENT FINDINGS EEG is widely used in clinical practice. Because of the paroxysmal nature of seizure disorders, interictal epileptiform discharges, such as spikes and sharp waves, are often used to support the diagnosis of epilepsy when a habitual seizure is not captured by EEG. Interictal and ictal EEG findings also underlie the classification of seizures and epilepsy. Continuous critical care EEG monitoring has become an invaluable study in the diagnosis and treatment of subclinical seizures and nonconvulsive status epilepticus. Intracranial EEG with subdural or intraparenchymal electrodes is warranted when localization of the seizure focus and mapping of eloquent brain areas are required to plan epilepsy surgery.

SUMMARY The EEG is a key tool in the diagnosis of epilepsy. Interictal and ictal EEG findings are crucial for the confirmation and classification of seizure disorders. Intracranial EEG monitoring is also indispensable for planning surgery for some patients.

Address correspondence to Dr Mohamad Z. Koubeissi, George Washington University, Department of Neurology, 2150 Pennsylvania Ave NW, Washington, DC 20037, [email protected].

RELATIONSHIP DISCLOSURE: Dr Chen reports no disclosure. Dr Koubeissi serves on the editorial boards of Epilepsy Currents and Functional Neurology and as the surgery and device editor of Epilepsy.com. Dr Koubeissi has received personal compensation for serving on the speakers’ bureaus of Sunovion Pharmaceuticals Inc and UCB SA, and has received publishing royalties from Springer for his book, Epilepsy Board Review.

UNLABELED USE OF PRODUCTS/INVESTIGATIONAL USE DISCLOSURE: Drs Chen and Koubeissi report no disclosures.