EEG Findings in Acute Carbon Monoxide Intoxication (Clinical and Prognostic Significance of EEG)

ABSTRACT

To determine the clinical and prognostic significance of EEG study in acute carbon monoxide intoxication, the EEGs of 107 patients, whom the study was performed relatively early in the course of intoxication, were analyzed and compared with the clinical courses and CT brain scans retrospectively. The final outcome of the patients consisted of 78 cases of recovery, 20 cases of prolonged coma and 9 cases with delayed neurologic sequeles. Statistically, there was no evidence of the age and sex influencing the clinical outcome or EEG finding. The EEG abnormalities depended upon the level and duration of unconsciousness, showing more abnormal EEG in the patient with deeper and longer coma. Many serial EEGs revealed almost parallel improvement to the clinical recovery but not always. Usually the EEG abnormality had the tendency to persist a little longer than the clinical. The patterns and grades of EEG abnormalities were also important to provide the prognostic significance. Almost all of the patients revealing, rarly in the course, some normal alpha background or high amplitude regular 1.5-2.5 Hz slow waves which looked like triphasic wave would be recovered soon or later. The irregular geneeralized delta slow waves, not responding to the outer stimuli suggested poor prognosis and prolonged coma. The abnormal CT brain scan such as low density in basal ganglia and/or white matter also showed some prognostic value, but not that of EEG studies. The development of delayed neurologic sequeles, however, could not be predicted by EEG or CT brain scan.