loses consciousness, falls, stiffens (the tonic phase), and jerks (clonic phase). Tonic-clonic convulsions usually last for less than 3 minutes but are followed by confusion and tiredness of variable duration (“postictal period”). Generalized tonic-clonic seizures involve both hemispheres from the onset; they occur in patients with idiopathic generalized epilepsies, in some classifications referred to as genetic generalized epilepsies, and have been referred to as primary generalized tonic-clonic seizures. Generalized absence seizures (formerly called “petit mal”) are brief episodes of unconsciousness (4–20 seconds, usually <10 seconds) with no warning and immediate resumption of consciousness (no postictal abnormality). Generalized absence seizures most commonly occur in children with childhood absence epilepsy, a specific idiopathic generalized epilepsy syndrome beginning between 4 and 10 years (usually 5–7 years); most remit by age 12. Other important epilepsy syndromes are infantile spasms (West’s syndrome), Lennox-Gastaut syndrome, juvenile myoclonic epilepsy, and Dravet’s syndrome. The major seizure type in infantile spasms is the epileptic spasm, which consists of a sudden flexion, extension, or mixed extension-flexion of predominantly proximal and truncal muscles. Limited forms, such as grimacing, head nodding, or subtle eye movements, can occur. Myoclonic seizures are sudden, brief (<100 milliseconds), involuntary, single or multiple contractions of muscles or muscle groups of variable topography (axial, proximal limb, distal limb). Myoclonus is less regularly repetitive and less sustained than is clonus.