Time-variant connectivity pattern estimation during multiple epileptic seizure onsets

Epilepsy is a neurological disorder characterized by recurrent seizures, i.e. abnormal synchronous activity of neurons in the brain. The brain region responsible for the epileptic activity is called the epileptogenic region. In most cases epilepsy can be cured by using anti-epileptic drugs. However, approximately 25% of the patients cannot be cured through medication or by medical treatment, they suffer from so-called refractory epilepsy. This can be treated by surgically removing the epileptic focus. The possibility for this surgery is examined during the presurgical evaluation [1]. Therefore, the precise and accurate location of the epileptic region is of utmost clinical relevance. Intracranial ElectroEncephaloGraphy (iEEG) is the recording of brain activity at a high temporal resolution through electrodes placed within the brain and is used to help locating the epileptic focus during the presurgical evaluation. Functional connectivity estimates the statistical dependence between spatially remote neurophysiological events and provides insight about the propagation pattern of information flow between signals. The aim of this study is to identify and detect the functional connectivity pattern through iEEG-analysis during multiple epileptic seizure onsets of the same patient to locate the epileptic focus more accurately.