Abstracts

Hypsarrhythmia is an electrographic pattern typically seen in young children with infantile spasms. EEGs of children with hypsarrhythmia were reviewed to determine the relationship between EEG characteristics, age and etiology, and to examine the evolution of these findings over time., In a 4.5 year period, more than 8000 pediatric EEGs were recorded at UT Southwestern/Children[apos]s Medical Center, Dallas. Database review identified 41 patients with 1 or more EEGs showing hypsarrhythmia. Additional medical record review identified associated etiology and neuroimaging findings., Of 41 children with hypsarrhythmia 18 were female, 23 male (M:F ratio 0.7:1). Median age at first EEG with hypsarrhythmia was 8 months (range 0.5 to 132). Etiology was cryptogenic in 11 (26.8%) and symptomatic in 30 (73.2%). 12 children had cortical dysplasia, 9 had hypoxic-ischemic encephalopathy (HIE), 3 had Down Syndrome and 6 had other etiologies (trauma, CMV, mitochondrial, IVH, gliosis). Median age at first diagnosis with hypsarrhythmia did not differ significantly by etiology (cryptogenic: 7 months, dysplasia: 8.5 months, HIE: 9 months). However, 7/12 patients with dysplasia presented at age [underline][gt][/underline]12 months vs. 5/29 without dysplasia (X²⁼6.9, p[underline][lt] [/underline]0.01) and vs. 2/11 cryptogenic patients (X²⁼3.9, p[underline][lt] [/underline]0.05). 37 of 41 initial EEGs with hypsarrhythmia included a sleep sample. Only 5/28 children age [lt]12 months had any identified sleep architecture vs. 4/9 older children (not significant, p[lt]0.2). There was no correlation between sleep architecture and etiology. 8 patients had prior EEGs before their first diagnosis of hypsarrhythmia (3 normal, 5 epileptiform). 23 patients had follow-up EEGs of which 19 were epileptiform, 2 non-epileptiform/slow and 2 normal. Of the 14 EEGs done after [gt]6 months follow-up, 11 were epileptiform (3 focal, 3 generalized, 4 multifocal and 1 hypsarrhythmia), 2 non-epileptiform/slow and 1 normal. Follow up EEGs were epileptiform in 6/6 children with dysplasia vs. 13/17 patients without dysplasia (not significant, p[lt]0.2)., In our sample of children with hypsarrhythmia, older age at diagnosis was significantly associated with presence of cortical dysplasia. 58% of patients with dysplasia were [underline][gt][/underline] age 12 months at first EEG with hypsarrhythmia compared to 17% of children with other etiologies. Limited sample size and short follow up prevented detailed analysis of the characteristics and evolution of hypsarrhythmia, although preservation of sleep architecture tended to be more common in older children. Hypsarrhythmia was transient, and rarely seen after [gt]6 months follow up. However, most children continued to have epileptiform EEGs, including all those with cortical dysplasia. Our findings suggest that older children presenting with hypsarrhythmia should undergo an aggressive search for CNS malformations, and suggest that the risk for persistent epilepsy may be highest in children with cortical dysplasia.,