EEG Monitoring In Predicting Outcome Of Comatose Patients

Backgrounds:Coma is the most severe unconsciousness, with a variety of causes including diffuse metabolic disturbances, structural lesions and status epilepticus. Electroencephalogram (EEG) is always necessary for the assessment of comatose patients, because of its advantage in monitoring the cortical function. EEG can also predict the clinical prognosis. Previous study had found out a scale for hypoxic ischemic encephalopathy (HIE) patients, according to their EEG patterns. While some of the EEG patterns remain unclear in prognosis. It still needs for further study that whether the classification is suitable or not for more coma cases than HIE. The preservation of sleeping patterns was thought to be relative with good outcome, but controversial. This study conducted EEG monitoring in comatose patients to find out the prognostic significance of EEG, and seek for the relationship between sleeping patterns and outcome.Methods:Glasgow Coma Scale (GCS) and long-term EEG were conducted in comatose patients for the first time, with the clinical information recorded. GCS and regular EEG were reviewed every week after the first record, till the end of follow-up or the hospital discharge. Outcome was confirmed as recovered, maintained and dead. EEG findings were classified by Synek scale. EEG and GCS results were analysed respectively with outcome by Fisher test and Spearman relativity test. Statistical significance was taken as P<0.05.Results:Total16cases met including criteria. Neither significant difference (P=0.744) nor relativity [Spearman (GCS)=0.178, P=0.539] was showed between GCS scores and outcome. EEG correlated significantly with outcome [Spearman (EEG)=-0.713, P=0.005], although with no significant difference (P=0.062). Only1case had sleeping pattern preserved and maintained till the end, while another uncertain but finally recovered. Periodic epileptiform discharge was found in1patient, and NCSE could not be excluded in this patient. Conclusions:EEG correlates with the outcome of comatose patients, and it is valuable as a predicting factor. Although no significant difference has been showed between EEG and outcome, the enlargement of sample size is necessary for more precise consequence. The relationship between sleeping patterns and outcome remains unclear. NCSE should be considered in comatose patients with epileptiform discharge. The usage of GCS or EEG alone sometimes has limitation. It requires more detailed EEG scale, frequent monitoring and prolonged follow-up period in further study.