Electroencephalography in the differential diagnosis of dementia

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In this short clinically oriented review, the value of
electroencephalography (EEG) in the diagnostic evaluation
of cognitive decline is discussed, based on the
recommendations of the European and Dutch guidelines.
In general, an EEG with diffuse slowing with or
without focal abnormalities argues for the presence of
an underlying neurodegenerative illness and against
subjective memory complaints or a psychiatric illness
such as a depression. The value of an EEG in the differential
diagnosis between the most common causes of
dementia is dependent on the specific clinical problem.
One of the clinical problems in which EEG has the highest
yield is the distinction between the two most common
dementia types, i.e. Lewy Body Dementia (DLB)
and Alzheimer’s Disease (AD): severe slowing of the
background rhythm with a peak frequency in the theta
frequency band (4 - 8 Hz) accompanied by frontal intermittent
rhythmic delta activity (FIRDA) gives strong
EEG support for DLB, whereas a diagnosis of AD is more
likely when the EEG is normal or when only mild diffuse
slowing is found. Furthermore, a normal EEG in an early
onset dementia gives support for the diagnosis frontotemporal
lobar degeneration. In addition, EEG is very
useful when a metabolic, toxic or infectious encephalopathy
is suspected. An EEG should be performed in
subacute disease courses, with auto-immune encephalitis
or Creutzfeldt-Jakob disease as possible causes, or
when (temporal lobe) epilepsy is suspected. In conclusion,
EEG is most valuable in a specific differential diagnosis
together with the clinical context and other
diagnostic tests. Distinct EEG patterns can then help to
make one of the diagnoses a more or less likely cause of
the patient’s symptoms.
Original languageEnglish
Pages (from-to)173
Number of pages182
Publication statusPublished - 2016

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