Diagnosis, clinical indication, and pending problems in surgical treatment for intractable epilepsy

Abstract

The treatment strategy for epilepsy depends on an accurate diagnosis and precise understanding of the pathophysiology of the disease. The diagnosis of epilepsy itself must be based on the combination of the patient’s clinical information (medical history, ictal symptoms and their change), neurological findings, EEG, and imaging study of CT/MRI. In some cases, long-term video-EEG monitoring, capable of recording ictal EEG and symptoms simultaneously, is essential to discriminate non-epileptic seizures. Although the primary care of epilepsy starts with medical treatment, surgical treatment has been expanding its indication for medically intractable epilepsy, along with the development of more precise imaging techniques. Also, to obtain good seizure control after epilepsy surgery, it is essential to identify the epileptogenic area to resect. Since there exist no single modality of non-invasive pre-surgical examination up to today, we usually combine multiple modalities for finding clues to the epileptogenic area. In the case that some discrepancies were found among these modalities, and/or that the border between the epileptogenic and functional areas was not clearly identified, invasive EEG with intracranial electrodes is necessary for recording ictal brain activity directly from the cerebral cortex. Pre-surgical evaluation, commonly evaluated with intracranial subdural electrodes, has practical limitation inside, according to many clinical reports. On the other hand, application of stereotactic electroencephalography (SEEG) with depth electrodes has been reported more frequently in the last several years. In addition to this, the concept of epilepsy, whereby an abnormal intracranial neural network corresponds to the cause of disease, has been proposed and reported. clinical trials based on this concept have been applied for therapeutic intervention to obtain relief of symptoms and good seizure control.