Epilepsy is a relatively common brain disorder that can be severely debilitating and sometimes lead to death. Several drugs are available that effectively help to control epileptic seizures. However, about a third of the population of patients with epilepsy have drug-resistant forms where the only known treatment is to remove the brain tissue that initiates the seizures.
Figure 1. A record from the EEG.PL Epilepsy data repository. From “Open Database of Epileptic EEG with MRI and Postoperational Assessment of Foci—a Real World Verification for the EEG Inverse Solutions“. By Piotr Zwolinski, Marcin Roszkowski, Jaroslaw Zygierewicz, Stefan Haufe, Gido Nolte, and Piotr J. Durka. Neuroinformatics Volume 8, December 2010.
A major goal stated in the paper “Open Database of Epileptic EEG with MRI and Postoperational Assessment of Foci—a Real World Verification for the EEG Inverse Solutions” (published December 2010 in Neuroinformatics) is to reduce the need for complicated surgical procedures to figure out the location of the brain tissue responsible for kicking off epileptic seizures. To accomplish this goal the authors report on research to improve the accuracy of epilepsy source localization from scalp electroencephalgram (EEG) recordings using data from their publicly available repository .
The EEG.PL Epilepsy data repository contains records of 23 patients with severe epilepsy between the ages of 1 to 18 years old. All patients were diagnosed with and operated on for drug-resistant epilepsy. In each case, surgery was performed. During surgery electrodes were placed directly on the exposed surface of the brain to collect electrocorticography (ECoG) data, which enabled precise localization of the origin of the seizure activity. If brain tissue was removed, its pathology was extensively examined.
Each EEG.PL Epilepsy data repository record (see Figure 1 above) includes:
- Clinically relevant EEG epochs collected during the pre-surgical period.
- Scanned printouts of EEG epochs containing the epileptogenic structures explicitly marked by the epileptologist.
- Magnetic Resonance Imaging (MRI) brain scans of the patient.
- Identification and structural outline of the epileptogenic zone marked on pre-surgical MRI scans in transverse, sagittal and coronal projections. The placement was verified by ECoG and post-operational results.
- A textual description of each case containing demographic data of each patient, short medical history of epilepsy, essential symptomatology of epileptic fits, additional necessary diagnostic test results, and a concordance report for the epilepsy surgery decision.
The paper under review uses these data to investigate how different computational procedures performed on the EEG data affect the prediction of where the epileptic focus is located in the patient’s brain. For instance, the individual geometry of a patient’s head is an important variable that affects EEG recordings. Using the MRI data included in each EEG.PL Epilepsy data repository record, the patient’s individual head geometry may be taken into account. Algorithms can be used to segment an MR image into volumes representing skin, skull and brain tissues. The EEG.PL Epilepsy data repository appears to be a rich data source that may ultimately benefit patients with epilepsy.