Paroxysmal attacks of impaired consciousness, occasionally accompanied by spasm or twitching of cephalic muscles, which usually 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., various stereotyped movements, usually of the face or hands; 6) absence with atypical features, e.g., bizarre motor activity.

Origin: L. Absentia

(05 Mar 2000)