Idiopathic epilepsy with generalized tonic–clonic seizures only versus idiopathic epilepsy with phantom absences and generalized tonic–clonic seizures: One or two syndromes?
Version of Record online: 4 JUL 2008
Wiley Periodicals, Inc. © 2008 International League Against Epilepsy
Volume 49, Issue 12, pages 2050–2062, December 2008
How to Cite
Koutroumanidis, M., Aggelakis, K. and Panayiotopoulos, C. P. (2008), Idiopathic epilepsy with generalized tonic–clonic seizures only versus idiopathic epilepsy with phantom absences and generalized tonic–clonic seizures: One or two syndromes?. Epilepsia, 49: 2050–2062. doi: 10.1111/j.1528-1167.2008.01702.x
- Issue online: 1 DEC 2008
- Version of Record online: 4 JUL 2008
- Accepted May 8, 2008; Early View publication July 4, 2008.
- Typical absences;
- Absence status epilepticus;
- Video EEG;
- Generalized spike wave;
- Breath counting
Purpose: To define the relationship between two syndromes of idiopathic generalized epilepsy (IGE) with apparently similar phenotypes: The form with generalized tonic–clonic seizures only (IGE-GTCS) and that with phantom absences (IGE-PA).
Methods: We compared the electroclinical features of 33 consecutive patients with GTCS and generalized spike wave (GSW); 18 had only GTCS and were diagnosed as IGE-GTCS, and 15 had hitherto unnoticed mild absences on the electroencephalography (EEG) and were diagnosed as IGE-PA. All patients were subjected to the same diagnostic workout, including video EEG during hyperventilation with breath counting (HBC). Patients with a clinical history of absences or myoclonic seizures were excluded.
Results: PA were easily identified with the first or second EEG in 14 of 15 patients with IGE-PA and always with sleep-deprived EEGs; conversely, PA did not occur in the IGE-GTCS patients despite using more EEGs. GTCS were twice as frequent in the IGE-GTCS group and tended to occur on awakening, whereas episodes of absence status affected twice as many patients with IGE-PA. The hereditary risk was 30% in the IGE-GTCS and 6.7% in IGE-PA. GSW had a strong polyspike component in IGE-PA and were briefer in IGE-GTCS. There is no evidence for a maturational influence on the duration of GSW in either syndrome.
Conclusion: Our findings clearly indicate that IGE-GTCS and IGE-PA are two distinct IGE syndromes and emphasize the role of PA for patients' diagnosis and management and for syndromic classification. They also appear to validate HBC as a simple, sensitive, and pragmatic method for the clinical identification of typical absences.