The initial events of the seizure often offer the best clue for determining the seizure type as well as the anatomical location of the origin of the seizure. The duration of the seizure is determined by timing the onset of the seizure to the beginning of the postictal state. Most seizures last less than three minutes. Absence seizures usually last less than 30 seconds. Consciousness is unaffected during a simple partial seizure and is altered, though not necessarily lost, during a complex partial seizure.
Loss of consciousness occurs in all generalized seizures, except for myoclonic seizures.
For purposes of classification, consciousness is defined as the ability to react in a meaningful and appropriate way to external stimuli. With complete loss of consciousness, the patient has amnesia for the event and no response, or an altered response, to stimuli. Changes in motor activity Alteration in motor activity may be manifested as minimal impairment with continuation of ongoing activity. Patterned, convulsive muscle activity may occur, as in tonic-clonic seizures. Complex reactive movements involving postures and coordinated movements similar to normal, purposeful, goal-directed activity may occur, but these movements are incomplete or inappropriate and often appear forced.