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The EEG in metabolic encephalopathy and coma
1Department of Neurology, Johns Hopkins Bayview Medical Center, 4940 Eastern Avenue, Baltimore, MD 21224, U.S.A. pkaplan@jhmi.edu
Summary
Electroencephalography (EEG) patterns correlate with coma depth and prognosis, especially after cardiorespiratory arrest. Specific EEG findings can suggest certain causes like hepatic or renal insufficiency.
Area of Science:
- Neurology
- Neurophysiology
- Clinical Electrophysiology
Background:
- Early research by Fischgold and Mathis, and Pamela Prior established correlations between coma depth and EEG patterns.
- Specific EEG patterns like alpha coma, spindle coma, and triphasic waves are associated with various conditions, including endocrine disorders.
Purpose of the Study:
- To review the utility of electroencephalography (EEG) in assessing patients with stupor and coma.
- To explore the correlation between EEG patterns, etiology, and prognosis in coma patients.
Main Methods:
- Review of case reports and series linking specific EEG patterns to clinical conditions.
- Analysis of EEG reactivity and patterns in relation to coma severity and outcome.
Main Results:
- EEG correlations with prognosis are most reliable in cases of cardiorespiratory arrest (CRA) due to anoxic-ischemic insult.
- Certain EEG patterns suggest specific etiologies: triphasic waves (TWs) with hepatic/renal insufficiency, and spindle coma with brainstem dysfunction.
- EEG is valuable for differentiating organic from psychiatric conditions and excluding nonconvulsive status epilepticus (NCSE).
Conclusions:
- EEG provides a useful, though not always specific, guide to the etiology and degree of brain dysfunction in coma.
- EEG is a critical tool for prognosis, particularly in post-anoxic coma, and for clinical decision-making.