Clinical and Electroencephalographic Correlates of Acute Encephalopathy

Abstract

The term encephalopathy encompasses a wide variety of syndromes caused by a large number of different toxic, metabolic, and degenerative derangements. Despite advances in intensive medical care and new diagnostic procedures, encephalopathy remains a frequent and underrecognized critical medical condition with high morbidity and mortality. Electroencephalography (EEG) enables rapid bedside electrophysiological measurements of brain dysfunction and complements clinical and neuroimaging assessment of encephalopathic patients. Both progressive slowing of EEG background activity with increasing cerebral compromise and decreased EEG reactivity to external stimuli provide important diagnostic and prognostic information. The aim of this review was to provide an overview of the diagnostic and prognostic value of EEG in encephalopathic patients.

Impairment of GABAergic system contributes to epileptogenesis in glutaric acidemia type I

“…Because theta waves are related to learning and cognition, the decrease in theta power could be responsible for the intellectual impairment and behavior alteration observed in untreated GA‐I symptomatic patients and in animal models with GA‐I . Changes in normal EEG patterns such as intermittent delta waves are closely related, with many types of encephalopathies and epilepsy . The predominance in delta oscillations observed in the Gcdh −/− ‐ Lys mice during the wake state could be related to the progressive encephalopathy and epilepsy in GA‐I patients.…”

“…2 Changes in normal EEG patterns such as intermittent delta waves are closely related, with many types of encephalopathies and epilepsy. 31,32 The predominance in delta oscillations observed in the Gcdh À/À -Lys mice during the wake state could be related to the progressive encephalopathy and epilepsy in GA-I patients.…”

Electroencephalographic patterns of lithium poisoning: a study of the effect/concentration relationships in the rat

“…Characteristics of rat encephalopathy were identified according to the usual definitions in humans . Triphasic waves were defined as positive sharp transients of >70 μV amplitude (up to 250−300 μV) preceded and followed by negative waves of lower amplitude.…”

Which EEG patterns in coma are nonconvulsive status epilepticus?

“…Intermittent rhythmic delta activity occurring most often over the frontal regions, occasionally also posteriorly, is found in more superficial stages of coma (i.e., obtundation, somnolence, and sopor) and deep midline lesions affecting the thalamocortical projections [3,[26][27][28][29][30]. They may also be found in patients with epilepsy but clearly do not represent an ictal pattern [31] (Fig.…”

“…Clinical and "electrographic" seizures are robust predictors of poor outcome in patients with critical illness [10,29,39,46,[128][129][130][131][132][133]. The semiology of seizures in comatose patients is rarely generalized tonic-clonic; rather, it is more often focal clonic, or myoclonic, inconspicuous, and limited to only some parts of the body, face, or eyes [134].…”