Volumetría y electroencefalografía digital en pacientes con epilepsia del lóbulo temporal medial farmacorresistente sometidos a cirugía

Abstract

To assess the value of volumetric measurement by means of magnetic resonance imaging (MRI) and interictal electroencephalogram (EEG) in pre- and post-operative assessment of patients with medication-resistant medial temporal lobe epilepsy (MTLE) who were submitted to surgery. We evaluated 12 volumetric studies carried out using MRI and 24 digital EEG records for six patients suffering from complex partial seizures that were resistant to medical treatment and had their origin in the temporal lobe. A volumetric analysis was performed using MRI to study the epileptogenic region and the frequencies at which interictal epileptiform discharges (IED/minute) appeared before, at six months and at one year after surgery were calculated; a correlation was observed between the volumetric analysis and the irritative and epileptogenic region. The volumes of both the ipso and contralateral hippocampuses were smaller in comparison to the increased frequency of the IED in the mesial regions. The inferior temporal lobes and the parahippocampal cortex have reduced volumes ipsolateral to the epileptogenic region. At six months after performing the temporal lobectomy, the IED frequency decreased with respect to the pre-operative IED. A negative correlation was found between the resected volume of the parahippocampal cortex and the inferior temporal lobe, and the post-operative IED frequency at one year. In patients with medication resistant MTLE the volumes of other structures in the medial temporal lobe are diminished, in addition to the hippocampus, and they are seen to have a smaller volume on the side that is ipsolateral to the epileptogenic region. There is a relation between the volume of the resected hippocampus and the post-operative IED frequency in patients with MTLE who successfully underwent a temporal lobectomy. Volumetric analysis of the epileptogenic lesion using MRI provides localising information that is valuable in the pre-operative assessment of patients with medication resistant MTLE who are submitted to surgery.