Analysis of Deep Coma and Brain Death Based on Phase Synchronization with EEG

Electroencephalography (EEG) has the advantages of non-invasive, real-time and high temporal resolution. It has been considered one of the most reliable methods for diagnosing deep coma and brain death patients in clinical practice. Phase synchronization (PS) method can be applied to detect the information flow and information exchange among different brain regions. In this paper, we aim to provide the diagnostic reference of deep coma patients and brain death patients based on EEG data and determine some potential clinical practice standards by using PS method. We first calculate the phase locking value (PLV) between the channel pairs located on the forehead among three types of patients (deep coma patients, brain death patients, and a patient from deep coma to brain death). Then the PLV differences between the two types of patients were analyzed based on different frequency bands, where the significance of the results was verified by the significant test (one-way ANOVA). Finally, the difference coefficient d is used to measure the degree of PS for two types of patients in different frequency bands. The results showed that the degree of PS in deep coma patients was significantly higher than that in brain death patients. This difference was more pronounced in the low frequency bands (delta, theta, alpha and low beta), and the difference was most prominent in the alpha frequency band.