1.8 Applied Electrophysiology
87
Topographic Quantitative
Electroencephalography (QEEG)
Unlike standard EEG interpretation, which relies on wave-
form recognition, QEEG involves a computer analysis of data
extracted from the EEG. Findings are compared with a large
population database of subjects without any known neurologi-
cal or psychiatric disorder as well as QEEG profiles that may
be characteristic of some defined diagnostic group. In QEEG,
Table 1.8-4
Electroencephalography (EEG) Alterations
Associated with Medical Disorders
Seizures
Generalized, hemispheric, or focal
spike, spike-wave discharge, or both
Structural lesions
Focal slowing, with possible focal spike
activity
Closed head injuries Focal slowing (sharply focal head
trauma)
Focal delta slowing or more widespread
slowing (subdural hematomas)
Infectious disorders
Diffuse, often synchronous, high
voltage slowing (acute phase of
encephalitis)
Metabolic and endo-
crine disorders
Diffuse generalized slowing of wake
frequencies
Triphasic waves: 1.5 to 3.0 per second
high-voltage slow waves, with each
slow wave initiated by a blunt or
rounded spike-like transient (hepatic
encephalopathy)
Vascular patho-
physiology
Slowed alpha frequency and increased
generalized theta slowing (diffuse
atherosclerosis)
Focal or regional delta activity (cerebro-
vascular accidents)
Table 1.8-3
Electroencephalography (EEG) Alterations
Associated with Medication and Drugs
Drug
Alterations
Benzodiazepines
Increased beta activity
Clozapine (Clozaril)
Nonspecific change
Olanzapine (Zyprexa)
Nonspecific change
Risperidone (Risperdal)
Nonspecific change
Quetiapine (Seroquel)
No significant changes
Aripiprazole (Abilify)
No significant changes
Lithium
Slowing or paroxysmal activity
Alcohol
Decreased alpha activity; increased
theta activity
Opioids
Decreased alpha activity; increased
voltage of theta and delta waves;
in overdose, slow waves
Barbiturates
Increased beta activity; in withdrawal
states, generalized paroxysmal
activity and spike discharges
Marijuana
Increased alpha activity in frontal
area of brain; overall slow alpha
activity
Cocaine
Similar to marijuana
Inhalants
Diffuse slowing of delta and theta
waves
Nicotine
Increased alpha activity; in with-
drawal, marked decrease in alpha
activity
Caffeine
In withdrawal, increase in amplitude
or voltage of theta activity
Figure 1.8-4
Diffuse slowing in a 67-year-old patient
with dementia. Six- to seven cycles per
second (cps) activity predominates over
the parieto-occipital regions. Although
reactive to eye closure, the frequency
of this rhythm is abnormally slow.
(Reprinted from Emerson RG, Walesak
TS, Turner CA. EEG and evoked poten-
tials. In: Rowland LP, ed.
Merritt’s Text-
book of Neurology.
9
th
ed. Baltimore:
Lippincott Williams & Wilkins; 1995:68,
with permission.)
the analog-based electrical signals are processed digitally and
converted to graphic, colored topographical displays. These
images are sometimes called “brain maps.” Color Plate 1.8-5
illustrates topographic QEEG images of a patient with a closed
head injury.
QEEG remains primarily a research method, but it holds considerable
clinical potential for psychiatry, mainly in establishing neurophysiologi-
cal subtypes of specific disorders and for identifying electrophysiological
predictors of response. Examples of some of the more promising results
of QEEG research include the identification of subtypes of cocaine
dependence and the subtype most likely to be associated with sustained
abstinence; identification of subtypes of obsessive–compulsive disorder
(OCD) that predict clinical responsiveness or lack of responsiveness
to selective serotonin reuptake inhibitors (SSRIs); and the differentia-
tion between normals, attention–deficit disorder and attention-deficit/
