Browsing by Author "Auno, Sami"

Epilepsy is one of the most common neurological diseases worldwide. Around one-fifth of people with epilepsy are diagnosed with drug-resistant epilepsy. Some of them benefit from epilepsy surgery. Before surgical treatment, the location of the epileptogenic zone (EZ) must be carefully identified to achieve a good surgical outcome. New methods for locating the EZ are constantly being developed. The aim of this study was to investigate whether long-range temporal correlations (LRTC) can be used for non-invasive localization of the EZ in patients with drug-resistant epilepsy. The study involved 10 patients with epilepsy who had previously undergone epilepsy surgery and an MRI. We used the detrended fluctuation analysis (DFA) method to quantify the LRTCs in four different frequency bands in 200 cortical regions based on the patients' individual source reconstructions. We correlated the DFA values with distances from the resection areas and cortical locations of interictal epileptiform discharges (IEDs). In addition, DFA maps were visually inspected by three clinicians to identify the most likely EZs. The study found that DFA maps were significantly correlated with distance from the location of the resection only in the patients with type II focal cortical dysplasia (FCD II) and were associated with IED sites only in the FCD II patients. In addition, visual analysis of the DFA maps showed that in the FCD patients, there was a high interobserver agreement and accuracy in defining the affected hemisphere and lobe. These findings suggest that LRTCs could provide a non-invasive method to identify EZ and facilitate the preoperative evaluation of epilepsy patients.