Prognostic value of spectral analysis of electroencephalogram in patients with severe head injury

: To determine the prognostic value of electroencephalogram (EEG) in patients with severe head injury, fifteen adult patients were examined for three months after trauma. All patients (age: 16-74 years old) remained comatose (Glasgow Coma Scale: less than 8) for more than 72 hours. Ten out of 15 cases were surgically treated. Barbiturates were not used in any patient for the sake of controlling the increased intracranial pressure. Three months after trauma, the clinical outcome of each patient was evaluated using Glasgow Outcome Scale (GOOD: good recovery/moderate disability, POOR: severe disability/persistently vegetative/dead). EEG was examined repeatedly for 3 months after trauma; 56 EEG recordings were performed on 15 cases. Each EEG recording was never for less than 12 hours and EEG was recorded from the bilateral parietal electrodes. Using EEG TREND MONITOR (NIHONKODEN), the spectral analysis of EEG was performed in five frequency bands (delta, theta, alpha-1, alpha-2, beta) and the EEG power of each frequency band was shown as the percentage of total EEG power (% FREQ BAND). The findings of each % FREQ BAND was classified into the following four groups. 1) slow-monotonous: The EEG power was comprised invariably and almost exclusively of low frequency bands (i.e. delta and theta), and the "slow-fast constant" which is the power of slow waves (delta and theta) divided by the power of fast waves (alpha-1, alpha-2, and beta) was stable.(ABSTRACT TRUNCATED AT 250 WORDS)