Diagnosis and Surgical Treatment of Intractable Epilepsy

Abstract

To determine the localization of the epileptic focus, noninvasive evaluation that includes an analysis of the seizure characteristics, repeat EEGs, and imaging diagnosis should first be performed. If these noninvasive studies are not helpful in determining the distribution of epileptogenic areas, then invasive intracranial EEG monitoring becomes necessary, and for this purpose three types of electrodes, depth, subdural, and epidural, have been used. In this regard, the subdural recording method has become the most widely employed method internationally. The use of surgery for treating intractable epilepsy can be divided into two types : resective surgery or disconnective surgery. Resective srugery includes lesionectomy, cortical excision, and lobectomy. Subpial resec-tion, which is used when performing cortical excision, was conceived by Horsely and still constitutes the basic technique in the surgical treatment of epilepsy. The use of temporal lobectomy was established during the 1950's, but now, a more selective resection of the mesial temporal structures, under the guidance of a surgical microscope, is empolyed. A Iateral temporal approach (anteromedial temporal lobectomy) is one of these temporal methods of surgery. This procedure has several advantages, which include an easy orientation of the anatomical structures and a minimal risk of postoperative neurological deficits, such as speech disturbance or visual field defects. Disconnective surgery involves corpus callosotomy, multiple subpial transection (MST), and/or functional hemispherectomy. The use of corpus callosotomy for cases of epilepsy began in 1940 and has proven very effective for the control of drop attacks. We describe the technical aspects of temporal lobectomy and corpus callosotomy in detail and provide illustrative drawings.