Abstracts

Rationale: West Syndrome is an age dependent epileptic encephalopathy characterized by infantile spasms, hypsarrhythmia and developmental delay. It is commonly seen in infants from 3 to 6 months. It can be preceded by neonatal seizures. We reviewed the EEGs of children with hypsarrhythmia to identify patients whose seizure onset was at or before the first month of life, the relationship between electrographic features and etiology, and the evolution of these findings over time. Methods: Methods. In a 8.5 year period, more than 15000 pediatric EEGs were recorded at UT Southwestern/Children's Medical Center, Dallas. On a database retrospective review we identified 95 patients with 1 or more hypsarrhythmic EEG s. 32 patients had a seizure onset at or before the first month of life (neonatal onset). Additional medical record review identified etiology and electroclinical findings. Results: Of 95 children with hypsarrhythmia. 32 had a seizure onset at or before the first month of life. 17 were male and 15 female (ratio 0.8:1). Etiology was symptomatic in 29/32 (90.6%) vs 41/63 (65%) of children with a latter seizure onset (p= 0.0072). 18/32 (62%) children had hypoxic-ischemic encephalopathy, 5/32 (17%) had cortical dysplasia and 6/32 (20.6%) had other etiologies. There were 5 (16%) patients where hypsarrhythmia was first identified between 0-1 months, and 27 (84%) patients presented hypsarrhytmia after this age (2 to 84 months) . In EEG s were sleep was recorded, 50% of those with neonatal onset had some preserved normal architecture vs 65% of latter onset. 10/32 patients had an interictal EEG prior the diagnosis of hypsarrhythmia; of these 10/10 showed epileptform abnormalities. 9/32 patients had follow up EEG at least 6 months after hypsarrhythmia was identified. None of these was normal versus the latter onset group were 6/26 were normal. 22/32 of the patients had spasms only, 6/32 had spasms and other seizure type, 4/32 had other seizure types without spasms. Conclusions: In our sample of children with hypsarrhythmia, the age of presentation was similar for children with neonatal seizures and those who have latter onset. Symptomatic etiologies were significantly more common among the neonatal seizure onset group. These children tended to have more severe disruption of background EEG (loss of all sleep architecture). None in the neonatal onset sample had a normal EEG at follow up or prior the hypsarrhythmic pattern was identified, compared to 23% of the children with a latter age of seizure onset who had normal follow up EEG's. In despite of the etiology, a seizure onset during the neonatal period in patients with hypsarrhythmia, may be associated to a more severe electroclinical outcome.