[Prognostic value of electroencephalography in non-traumatic comas].

We recorded an EEG within the first few days of coma in 100 patients without history of trauma or drug intoxication, in 50 after cardiac arrest, and in 50 in coma of other, chiefly metabolic etiologies. The EEG findings were classified in 5 categories (I-V) in terms of increasing severity. We were especially interested in the question whether the degree of early EEG disturbances allows prognostic conclusions regarding the clinical fate of patients one month after the beginning of coma. It was found that very severe EEG changes (Grad IV-V) indicate a poor prognosis (death, persistent vegetative state or profound neurological deficits) in over 90% of coma both after cardiac arrest and of other etiologies. An EEG without very severe changes (grade I-III) does not allow definite prognostic conclusions. Depending on the etiology, recovery occurs in 10-33% of cases. The prognostic significance of certain EEG parameters can be summarized as follows: areactivity to external stimuli and the presence of an "alpha-coma" pattern are usually (but not necessarily) associated with a poor outcome. The same applies to coma patients with epileptiform patterns in the EEG and/or suffering from epileptic or myoclonic seizures. One-fourth of patients with triphasic EEG complexes recover completely.