engleski

Surgical treatment of patients with pharmacoresistant epilepsy

Epilepsy is a chronic condition characterized by an enduring propensity to generate seizures, which are paroxysmal occurring episodes of abnormal excessive or synchronous neuronal activity in the brain. The majority of patients with epilepsy can have their seizures sufficiently controlled by taking antiepileptic medications, but about one third of them eventually are recognized as being pharmacoresistant. Pharmacoresistant patients should have epilepsy surgery considered as a treatment option. Although epilepsy surgery historically has been a matter of some controversy, the tendency over the last few decades is toward an ever increasing acceptance of this treatment modality. The drawbacks of surgery are the risks involved, mainly the risks of hemorrhage, infection, or that of inducing a permanent brain injury. By the improvements achieved both in surgical techniques and in the preoperative evaluation methods over the last 25 years, the risks for such complications are today often acceptably small. The goal of the preoperative evaluation is to determine and delineate the epileptogenic zone, defined as the area needed to be resected to completely abolish the seizures. There is no method available which can determine this area today. Instead the epileptogenic zone is indirectly estimated through determination of other closely related areas, such as the ictal onset zone, the irritative zone, the symptomatogenic zone, and the area of the epileptogenic lesion. Especially the noninvasive part of the preoperative evaluation has had considerable improvements during the last decades. The noninvasive evaluation methods include polygraphic video- encephalography (EEG) monitoring, and neuroimaging techniques such as positron emission tomography (PET), single photon emission computer tomography (SPECT), magnetic resonance imaging (MRI) and magnetoencephalography (MEG). There has also been some refinements of the invasive preoperative evaluation methods, which are including the Wada test, semi invasive video- EEG monitoring (using sphenoidal or foramen ovale (FO) electrodes), and invasive video-ECoG monitoring (using depth electrodes, or the subdural strip or grid electrodes). Today there are good surgical treatment options for the majority of pharmacoresistant patients. Of the many approaches used some are resective neurosurgery, callosotomy, radiosurgery (using gamma knife), multiple subpial transections, and the less invasive method of vagus nerve stimulation.

epilepsy ; pharmacoresistance ; preoperative assessment ; neurosurgery

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