Density spectral array, evoked potentials, and temperature rhythms in the evaluation and prognosis of the comatose...

Glasgow Coma Scale (GCS), density spectral array (DSA), EEG, BAEP and circadian temperature rhythm were studied in comatose patients in order to determine level of arousal and appraise the prognostic capability of these combined measures. Subjects were 29 comatose patients in the neurosurgical ICU at the Rambam Medical Center suffering from head trauma, vascular disorders or metastatic growth. Results show that best prognostic capabilities were for DSA, GCS and BAEP, in that order. As a single parameter physiological response to a sound stimulus (increase in EMG, change in EEG frequency and appearance of sharp waves or k-complex) was the single best predictor for outcome, with significant response rates for the good, deficit, vegetative and death outcomes at 83%, 57%, 37% and 18%, respectively. Rectal temperature was analysed for 24 h circadian periodicity. Daily acrophases were found to shift forward or backward on the level of about 2-7 h a day with fluctuations about a stable or unstable mean. The absence of 'free-running rhythms' associated with environmental isolation studies might reflect an ability to respond to environmental Zeitgerbers while unconscious. Temperature oscillations as well as 24 h rhythms were found even in the most severely brain-damaged patients, reflecting the resilience of the circadian oscillators in the brain to trauma.