UNILATERAL HEMISPHERIC DYSGENESIS ASSOCIATED WITH GENERALIZED ATYPICAL ABSENCE SEIZURES
Abstract number :
2.384
Submission category :
Year :
2003
Submission ID :
3862
Source :
www.aesnet.org
Presentation date :
12/6/2003 12:00:00 AM
Published date :
Dec 1, 2003, 06:00 AM
Authors :
Howard L. Kim, John Kuratani, Marcio Sotero de Menezes, Jong M. Rho Neurology, University of California at Irvine College of Medicine, Irvine, CA; Neurology and Pediatrics, Children[apos]s Hospital and Regional Medical Center, University of Washington Sch
Atypical absence seizures (AAS) represent a common and often medically refractory generalized seizure type associated with a wide variety of diffuse CNS pathologies. We report 3 pediatric patients whose epilepsies were dominated by frequent AAS in which uni-hemispheric dysgenesis was identified by brain MRI studies.
During a retrospective chart review, three patients with uni-hemispheric abnormalities and AAS were identified. All patients obtained high-resolution head MRI studies and long-term video-EEG (LTM) monitoring using scalp electrodes.
Three patients had epilepsies consisting exclusively of AAS (age of onset, 6 months to 7 years), and had varying degrees of mental retardation and spastic hemiparesis contralateral to the smaller hemisphere. Brain MRI studies did not show clear evidence of neuronal migration defects. Interictal EEG recordings revealed irregular, 2.0- to 2.5-Hz generalized slow spike-wave complexes, independent multifocal sharp waves, and underlying slow EEG background activity bilaterally. Ictal EEG recordings captured numerous atypical absence seizures (with atonic features, but no distinct atonic or tonic seizures) associated with generalized slow spike-wave complexes. One patient became seizure-free on sodium valproate and clonazepam (43 month follow-up). The other 2 patients underwent an anterior-2/3 corpus callosotomy, after which they became seizure-free for up to 4 months; one of these later underwent a right functional hemispherectomy, ultimately becoming seizure-free off medications (3 year follow-up). In this latter case, surgical pathology revealed diffuse cortical dysplasia.
An unusual epileptic syndrome, characterized by uni-hemispheric dysgenesis, hemiparesis, and atypical absence seizures (HHA), has been identified in three patients with varying degrees of developmental delay. Although some of their electro-clinical features superficially resembled those seen in the Lennox-Gastaut syndrome, there was an absence of other distinct seizure types. We conclude that HHA may represent a clinically novel nosologic entity; however, further study is required.