Which of the following EEG finding is charecteristic of absence seizures?

The electroencephalogram (EEG) of absence seizures shows a characteristic 3Hz spike-and-wave pattern during the seizures. The spells of seizures are characterized by brief loss of consciousness without loss of postural tone. It is associated with eye blinking or a slight head turning. Several hundred such spells occur daily, leading to impaired school performance and social interactions. These spells are characteristically inducible by hyperventilation. Ref: Clinical Neurology By Roger P. Simon, 7th Edition, Chapter 8 ; Adams and Victor's Principles of Neurology By Allan H. Ropper, 9th Edition, Chapter 16