Conventional and Quantitative EEG in the Diagnosis of Delirium Among the Elderly
Delirium has long been recognized as symptomatic of serious underlying illness
in the elderly, and an early diagnosis is critical. Delirium is often
undiagnosed, misdiagnosed, or mistaken for other disorders, and so it is
vital that assessment for this disorder not only be accurate, but ideally
be able to distinguish “organic” from “functional” causes
of acute mental status changes, and differentiate Delirium from Dementia,
as well as provide a reliable indicator of severity of illness. Electroencephalogram
(EEG) with quantitative analysis (QEEG) offers considerable use not
only in confirming the clinical diagnosis of an organic syndrome, but also
in distinguishing Delirium from Dementia. This can be accomplished due
to the specific EEG variables, which differentiate encephalopathy from normal,
or “functional” states from specific variables distinguishing
Delirium from Dementia. Variables found best able to distinguish delirious
from non-delirious individuals include the amount of theta activity, relative
power in the delta frequency band, and the brain map rating (Jacobson, Leuchter,
and Walter, 1993). The clinical use of EEGs and QEEGs to determine the
presence of Delirium is extremely useful, as the presence of Delirium necessitates
an immediate, costly, and possibly invasive work-up for precipitating causes. EEGs
and QEEGs are completely non-invasive, and whether an individual is currently
undergoing neuroleptic treatment does not affect the results in terms of
detection of Delirium.