Utility of the scalp-recorded ictal EEG in childhood epilepsy

Purpose: To evaluate the usefulness of the scalp-recorded ictal EEGs in dia gnosing childhood epilepsy. Methods: We analyzed the ictal EEGs of 259 seizures in 183 patients who vis ited the department of child neurology, Okayama University Medical School. during the past 6 years. Results: We divided all seizures into the following four categories, accord ing to the diagnostic usefulness of ictal EEGs in determining the seizure t ype: 1. (a) Ictal EEGs confirmed the diagnosis of the seizure type based on seizure symptoms (101 seizures): (b) Ictal EEGs aided in the classificatio n of the seizure type based on the seizure symptoms (101 seizures): (c) Ict al EEGs corrected errors in the classification (37 seizures): and (d) Ictal EEGs revealed previously unreported/undocumented seizure type (20 seizures ). 2. Of the 37 misdiagnosed seizures (group C), 11 were nonepileptic seizu res misdiagnosed as epileptic seizures, eight were complex partial seizures (CPS) misdiagnosed as the other seizure types, and 10 were other seizure t ypes misdiagnosed as CPSs. 3. Of the 20 previously unreported/undocumented seizures (group D), nine were myoclonic seizures, five were absence seizure s, five were CPS, and one was tonic spasms. 4. Seventy-two patients had CPS . Among them, 11 patients showed no epileptic spikes in their interictal EE G recordings. Therefore, ictal recordings confirmed the diagnosis of epilep sy. Conclusions: Ictal EEG recording is a very useful diagnostic tool not only for determining seizure types, but also for uncovering the existence of the unsuspected seizure types. It supplies the physician with useful informati on for the classification and the treatment of epilepsy. In particular, ict al EEGs are useful in diagnosing patients with CPS.