EEG Patterns of Diffuse Anoxic Coma in Adults

ABSTRACT.

A previously designed EEG scale in anoxic coma divided abnormalities into five major grades: 1—near normal, 2—theta activity dominant, 3—delta activity dominant, 4—burst suppression pattern, and 5—isoelectric EEG. The prognostic accuracy of this scale was 83%. After inclusion of all variabilities of EEG in anoxic coma, such as alpha pattern coma, theta pattern coma and others, a revised scale has been introduced. This scale is based on dominant frequencies, their amplitudes, persistence, and reactivity. This scale was applied retrospectively to EEG records performed 24–36 hours after onset in 72 patients who had arrested cardiac or respiratory function for more than 7 minutes. The scale divides EEG patterns in anoxic coma into: benign, uncertain, and malignant with regard to survival. The predictive accuracy was 98.4%. There was a significant relationship between EEG patterns and outcome. A similar relationship was found between fatal outcome and duration of arrest of the vital function. The number of survivors decreased with age. No correlation was found between EEG patterns and neuropathological findings.

KEY WORDS.:

• Adults
• alpha coma
• burst suppression
• diffuse anoxic coma
• EEG
• electrocerebral silence
• spindle coma
• theta coma