Analysis Of High Frequency Oscillatory Signals In Epileptic Scalp And Intracranial EEG

Epilepsy is a chronic nervous system disease caused by excessive discharge of brain neurons.More than 30% of patients with epilepsy are drug-refractory epilepsy.One method for treating refractory epilepsy is through surgical removal of the epileptogenic area.Studies have shown that high-frequency oscillations（HFOs）of EEG are an effective biomarker in the epileptic region.At present,clinicians mainly analyze the patient’s imaging data and EEG based on experience to determine the location of the epileptogenic zone.Stereotactic EEG has been studied to detect intracranial HFOs,but this method is invasive.In this paper,the simultaneous EEG of the intracranial and scalp was analyzed,and the possibility of localizing the epileptogenic zone using HFOs of scalp EEG was studied.The main research contents are as follows:First,acquire the EEG signals from patients with epilepsy.The scalp EEG data were collected by the scalp EEG acquisition system.The intracranial EEG data were collected by intracranial implanted electrode,and the simultaneous EEG were studied.Second,the simultaneous EEG from patients with epilepsy were preprocessed and HFOs were extracted.The data were subjected to bipolar processing,and the Ensemble Empirical Mode Decomposition（EEMD）method was used to preprocess the intracranial and extracranial EEG data.Using the improved HFO detection algorithm,combined with complex wavelet transformation and power analysis methods,those data were analyzed from multiple characteristics such as amplitude,frequency,number of continuous waves,and waveform similarity.HFOs in EEG data were extracted.Finally,the correlation analysis of the HFOs of intracranial and extracranial EEG was carried out,the Pearson correlation coefficient between the extracranial HFO and the intracranial HFO was calculated,and the relative position distribution of the extracranial electrode and the intracranial electrode was calculated,and the electrode position distribution was analyzed.The results showed that some intracranial HFOs could be transmitted to the scalp and can be detected.The corresponding HFO can be detected in the scalp when the actual distance between the scalp electrode and the intracranial electrode is within 70 mm.And as the frequency decreases,the number increases.In this paper,the relationship between electrode depth and signal transmission efficiency is also calculated.The results show that the corresponding HFO can be detected on the scalp when the electrode depth is within 60 mm.And as the frequency decreases,the number increases.The results of this study show that there are partial intracranial HFO signals that can be transmitted to the scalp and can be detected,which provides a basis for the clinical application of scalp HFO to the treatment of epilepsy patients.It provides some help for solving problems such as low clinical manual testing efficiency and SEEG testing that causes great trauma to patients.