An Electroencephalographic Classification for Coma

Abstract

Background:The assessment of thalamocortical function in comatose patients in the intensive care unit (ICU) can be difficult to determine. Since the electroencephalogram (EEG) affords such assessment, we have developed an EEG classification for comatose patients in our general ICU. Methods: One hundred EEGs were classified in a blinded fashion by two EEGers, using our method and that of Synek. Interobserver agreement was assessed using kappa score determination. Results: Kappa scores were 0.90 for our system and 0.75 for the Synek system. (The Kappa score represents the inter-rater agreement that is beyond chance; 0.90 is almost perfect agreement, while 0.75 is substantial agreement). Conclusion: Our system for classifying EEGs in comatose patients has a higher interobserver reliability than one that was previously published. This EEG classification scheme should be useful in clinical electrophysiological research involving ICU patients, allowing for internal consistency and comparisons among centres. RESUME: Une classification electroencephalographique du coma. Introduction: II peut etre difficile d'eValuer la fonction thalamocorticale chez les patients comateux a l'unite de soins intensifs (USI). Comme cette evaluation peut etre faite au moyen de l'electroencephalogramme, nous avons developpe une classification EEG pour les patients comateux a notre USI generale. Methodes: Deux electeoencephalographistes ont classify cent EEGs a l'aveugle, en utilisant notre methode et celle de Synek. La concordance interobservateur a et6 evaluee au moyen de la cote kappa. Resultats: Les cotes kappa etaient de 0.90 pour notre systeme et de 0.75 pour le systeme Synek. (La cote kappa represente la concordance interobservateur au-dela de la chance; 0.90 est une concordance presque parfaite, alors que 0.75 est une bonne concordance). Conclusion: Notre systeme de classification des EEGs chez les patients comateux a une plus grande fiabilite interobservateur qu'une autre classification deja publi6e. Cette methode de classification EEG devrait etre utile en recherche clinique electrophysiologique chez des patients de l'USI, en tenant compte de la concordance interne et de la comparaison intercentres.Can. J. Neurol. Sci. 1997; 24: 320-325 Neurological disease in the setting of the intensive care unit (ICU) has a variable prognosis from full recovery to death. More than 10% of patients in general ICUs suffer serious central nervous system complications that add to their morbidity and mortality.1 Assessment of illness severity is an important component of the management of such cases. There are a number of standardized assessment scales for measuring the severity of illness, which is related to outcome: APACHE (Acute Physiology and Chronic Health Evaluation), APACHE II or APACHE III, the Sepsis Severity Score, Simplified Acute Physiology Score II (SAPS II) and the Mortality Prediction Model (MPM) 2 "6 The APACHE scales use the Glasgow Coma Scale as part of the acute physiology evaluation while other scales incorporate clini...

Electroencephalography (EEG) and Unconsciousness

“…"; the following patterns are suggested to be prognostically malignant if persistent: grade 3 abnormality with small amplitude, diffuse, irregular delta activity; grade 4 ("burst suppression pattern"), in particular when epileptiform discharges are present and with "low-output EEG"; and grade 5 ("isoelectric EEG"); fatal outcome is also common with the "nonreactive type of alpha pattern coma" and the recently reported "theta pattern coma." (Young et al , 1997). Table 5 lists the Young EEG Classification System.…”

The Prognostic Value of the EEG in Postanoxic Coma

“…The recordings were interpreted in a blind way by the same board-certified neurologist, specialized in electroencephalography. The EEG abnormalities were, if possible, categorized, using the EEG classification system proposed by Synek [20] and Young et al [21] ( Table 1). The EEG classifications were divided into four prognostic categories, optimal, benign, malignant, and fatal, using the prognostic table of Synek [22].…”

“…Evolution of Coma After One Month 80.8% of the patients with a vegetative state after 30 days (GOS 2) were dead (GOS 1; 95% CI = 60.7-93.5) after Table 1 Synek-and Young-classification, according to [20,21] Synek-classification (1988) I. Regular (Fig.…”

Metabolic encephalopathies

“…Additional support in the assessment of hypoxic/ anoxic coma can be gained to a certain extent from electroencephalography with graded classification [12,13,14]. Important criteria are the burst-suppression pattern and the development of alpha-coma in the deeply comatose patients.…”