Abstracts

Rationale: Electroencephalography (EEG), as a routine tool in clinical settings, has been utilized to characterize and localize the epileptic origin. In recent years, high-density EEG based source imaging has emerged to play an important role in localizing active brain regions and studying functional brain networks. Pediatric patients, which represent an important subgroup of epilepsy patients, usually have a variety of seizure characteristics and are less likely to achieve favorable surgical outcome. The development of noninvasive methods to accurately localize epileptogenic zones will significantly benefit these patients in their pre-surgical planning. The aim of this study is to investigate the feasibility of a novel noninvasive seizure imaging technique to image epileptogenic zones in pediatric patients.Methods: Dense array scalp EEG with 128 channels was recorded in four pediatric patients (2M/2F, ages 8-17). A dynamic seizure imaging approach (Yang et al., 2011) was utilized to image the seizure sources with high spatial-temporal resolution. A patient-specific boundary element head model, together with a cortical current density source model was used to improve the spatial resolution. Seizure components with ictal time-frequency features were extracted and their distributed sources over the cortex were integrated to image spatial-temporal activities. All of the patients suffered from medically intractable epilepsy and had resective surgery removing seizure onset zone. We evaluated the seizure imaging results by comparing them with the intracranial recordings and surgical outcome of the patients.Results: All patients were rendered seizure free with at least one-year follow up after surgery. In the group of patients studied, the sources from the noninvasive EEG imaging approach were co-localized well with the surgical resection. In 3 out of the 4 patients, the maximal source activation was located inside the resected area. The source maximum of the remaining patient was within 15 mm distance to the resected area. Among the 3 patients who underwent intracranial monitoring, 2 patients had source imaging results overlapping with the seizure onset zone identified from intracranial recording.Conclusions: Dense array EEG and the seizure source imaging approach were applied in a group of four pediatric patients. The source imaging results were consistent with the intracranial recording and surgical resection. The results demonstrate the feasibility of imaging seizure onset zone using this novel, noninvasive EEG technique. It also indicates the potential application of this seizure imaging approach as a noninvasive tool in providing additional information for pre-surgical planning of pediatric epilepsy patients.