Paroxysmal attacks of impaired consciousness, occasionally accompanied by
spasm or twitching of
cephalic muscles, which generally can be brought on by hyperventilation; depending on the
type and severity of the absence, the
EEG may
show an
abrupt onset of a 3/sec
spike and
wave pattern as in
simple absence, or in
atypical cases, a 4/sec
spike and
wave or faster
spike complexes. The
clinical states accompanying these
EEG abnormalities may be classified as: 1)
absence with no overt manifestations, e.g.,
simple absence;
epileptic absence; subclinical absence; 2)
absence with
clonic movements, e.g., myoclonic absence; 3)
absence with
atonic states, e.g.,
atonic absence; 4)
absence with
tonic contractions, e.g.,
hypertonic muscular contraction; 5)
absence with automatisms, e.g., different stereotyped movements, generally of the
person or hands; 6)
absence with
atypical parameters, e.g., bizarre
engine activity.
Origin: L. Absentia