Accuracy of Conventional Diagnostic Methods for Identifying Structural Changes in Patients with Focal Epilepsy

Epilepsy is a neurological disorder characterized by abnormal firing of nerve impulses in the brain.

This study aims to investigate the frequency of appearance of pathological changes in conventional examination methods (electroencephalography-EEG, brain computerized tomography -CT or brain magnetic resonance imaging - MRI) in patients with epilepsy, and relationship between clinical manifestations and localization of changes in CT or MRI.

In this study we have included 110 patients with focal epilepsy who fulfilled the inclusion criteria out of 557 initially diagnosed patients. Detailed clinical examination together with brain imaging (CT and MRI) and electroencephalography examination was performed. We have evaluated the accuracy of each diagnostic method to localize the epileptic focus. Diagnosis of epilepsy was determined by the ILAE (International League Against Epilepsy) criteria of the year 1989, and classification of epileptic seizures was made according to the ILAE classification 2010.

Electroencephalography presented changes in 60.9% of patients; brain CT in 42.1%, and MRI in 78% of the patients. The results of our study showed that clinical manifestations were not always conveyed with pathological changes in conventional examining methods performed. Of the total of 79 patients with changes in imaging (8 with changes in CT and 71 in MRI), 79.7% presented a clinical picture compatible with the region in which morphological changes were found, while in 20.3% of patients the presented morphological changes were not aligned with the clinical picture.

In patients with epilepsy, conventional examination methods do not always find pathological changes, while clinical manifestations of epilepsy did not always coincide with the location of changes in imaging. Further studies are needed to see if there is clear border between focal and generalized epilepsy.