Focal-onset seizure true Focal seizures Focal seizures are conceptualized as originating within networks limited to one hemisphere. They may be discretely localized or more widely distributed. Focal seizures may originate in subcortical structures. For each seizure type, ictal onset is consistent from one seizure to another, with preferential propagation patterns that can involve the ipsilateral and/or contralateral hemisphere. 2008-03-31T05:27:00Z Partial seizures can be classified as simple (consciousness is maintained) or complex (consciousness is impaired or lost). HP:0007359 Seizure affecting one half of brain HP:0002358 SNOMEDCT_US:29753000 UMLS:C0751495 Partial seizures peter MSH:D012640 human_phenotype Focal seizure Seizures of which initial semiology indicates, or is consistent with, initial activation of only part of one cerebral hemisphere. Focal-onset seizures seizure classification