Clinical and electroencephalogram characteristics of children with late-onset epileptic spasms

Abstract：Objective To analyze the clinical and electroencephalogram (EEG) characteristics, therapeutic response and long-term prognosis of the children with late-onset epileptic spasms. Methods The clinical data, EEG features and response to different treatment protocols in 59 children with late-onset epileptic spasms were retrospectively reviewed. Thirty-seven of them were followed up for 13 ~ 90 months and the age at last contacting ranged from 2 years 6 months to 12 years 2 months (median 60 months). Results The onset age of epileptic seizures ranged from 12 to 98 months (median 22 months). The first seizure type was epileptic spasms in 36 cases (60.0%) and other seizure type in 23 children (39.0%). Epileptic spasms were the only seizure type during entire period in 20 patients (33.9%). There were also partial seizures in 17 cases (28.8%) and other generalized seizures in 22 patients (37.3%) during the course of disease. The EEG appeared classic hypsarrhythmia in 14(23.7% ) , unilateral hypsarrhythmia in 2 (33.4% ) and no hypsarrhythmia in 43 patients (72.9%). Twenty-two patients (37.3%) presented with focal or unilateral clinical image and/or EEG abnormal. Forty-four patients were symptomatic epilepsies and the predominant diseases included perinatal brain injury, central nervous system infection and brain malformation. Fourteen patients (23.7%) met the criteria of late-onset West syndrome, 7 patients (11.9% ) were diagnosed with Lennox-Gastaut syndrome. Fifty patients were responsible to ACTH therapy, including seizure-free in 32% of them. But recurrent rate was 61.5%. In 37 patients who were followed up, 46% maintained seizure free under taking the anti-epileptic drugs at the last follow up. Psychomotordevelopment delay was observed in over 80% of patients who were followed up, 16% of them had severe regression. Multivariate regression with Cox analysis showed that etiologies, seizure types, phenotypes of epilepticspasms, and response to ACTH therapy all had no correlation with the long-term outcome of the seizure or psychomotor development. Conclusion Epileptic spasms not only occur in West syndrome or infantile spasms, but also in the children beyond infantile period. Late-onset epileptic spasms may be caused by varied severe encephalopathy and it is usually accompanied with partial or other generalized seizures. Most cases do not present typical hypsarrhythmia on EEG. Similar to infantile spasms, most late-onset epileptic spasms are drug resistant and had a very poor outcome. ACTH therapy is still the first line therapeutic drug for such a catastrophic disease.