| A type of developmental and epileptic encephalopathy that presents with drug-resistant seizures between 18 months and 18 years of age (peak onset at 3 to 5 years, onset in second decade is rare). Tonic seizures and at least one other seizure type are mandatory for the diagnosis. Other seizure types include atypical absence seizures, atonic seizures, myoclonic seizures, focal seizures, generalized tonic-clonic seizures, nonconvulsive status epilepticus and epileptic spasms. Development is usually impaired before seizure onset, but over time there is developmental slowing and plateauing with subsequent moderate to severe intellectual disability in 90% of individuals. Behavior disorders (hyperactivity, aggression), autism spectrum disorder, sleep disturbances are common. Neurological examination is often abnormal and related to the underlying etiology. The EEG has diffuse background slowing. Interictal generalized slow spike-and-wave (≤2.5 Hz) and generalized paroxysmal fast activity in sleep (10 Hz or more) are mandatory diagnostic criteria. |
