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 a., the EEG may show an abrupt onset of a 3-sec spike and wave pattern as in simple a., 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) a. with no overt manifestations, e.g., simple a.; epileptic a.; subclinical a.; 2) a. with clonic movements, e.g., myoclonic a.; 3) a. with atonic states, e.g., atonic a.; 4) a. with tonic contractions, e.g., hypertonic muscular contraction; 5) a. with automatisms, e.g., various stereotyped movements, usually of the face or hands; 6) a. with atypical features, e.g., bizarre motor activity. [L. absentia]
- simple a. a brief clouding of consciousness accompanied by the abrupt onset of 3-sec spikes and waves on EEG. SYN: pure a..
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ab·sence (abґsens) 1. absence epilepsy. 2. absence seizure.Medical dictionary. 2011.