TY - CHAP M1 - Book, Section TI - Secondarily Generalized Seizures A1 - Chung, Steve S. A1 - Horne, Kent A2 - Sirven, Joseph I. A2 - Stern, John M. PY - 2011 T2 - Atlas of Video-EEG Monitoring AB - In clinical practice, epileptic seizures with focal onset and subsequent generalized motor involvement are referred to as secondarily generalized seizures.1,2 However, generalized motor manifestations do not necessarily imply that the entire or even bilateral cerebral cortex is producing the epileptic discharges.3 Focal seizures arising from the supplementary motor cortex or basal ganglia also can produce clinical signs of generalized motor activity.4 Conversely, bilateral and widely spread ictal electroencephalographic (EEG) patterns can be found in patients with minimal or subtle motor activity during a secondarily generalized seizure (Case 11-1).5 Thus, the operational definition of secondary generalization in the era of video-EEG monitoring (VEM) should be focal onset of an epileptic seizure with generalized or bilateral ictal electrographic propagation.6 According to the classification by the International League Against Epilepsy (ILAE), there are three different types of secondarily generalized seizures: tonic-clonic seizures, absence seizures, and epileptic spasms (Table 11-1).1,7,8 Differences in clinical presentation and EEG findings of these seizure types are compared in Table 11-2. Although partial onset seizures do not commonly progress to secondarily generalized seizures, more than 60% of patients with partial seizures may experience tonic-clonic seizures.9 Not all secondarily generalized convulsions progress from complex partial seizures, and up to 20 to25% of them are directly evolved from simple partial seizures, which suggests multiple cortical and subcortical routes of spread are possible for secondary generalization.10 SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/29 UR - neurology.mhmedical.com/content.aspx?aid=1103049178 ER -