The Electroencephalogram in Altered States of Consciousness
Neurologic Clinics August 1, 1985 Richard P. Brenner 56 citations
Electroencephalography (EEG) can help evaluate patients with altered states of consciousness. Diffuse slowing of background rhythms and triphasic waves suggest metabolic dysfunction, especially hepatic. Generalized fast activity may indicate drug intoxication. Abnormalities such as PLEDs or focal continual PDA support a diagnosis of supratentorial lesion, while a normal EEG in a comatose patient suggests a brain-stem lesion. The EEG may also reveal nonconvulsive status epilepticus. Certain patterns have prognostic implications but are not specific to a single cause. For example, burst suppression or diffuse alpha pattern coma can occur in hypoxia or drug intoxication; with hypoxia the prognosis is extremely poor, but complete recovery often follows drug ingestion. If the cause is unknown, sequential records are needed for prognosis.