Clinical Associate Professor of Pediatrics BC Children's Hospital, University of British Columbia Vancouver, British Columbia, Canada
Rationale: Infantile spasms (IS) are one of the most significant seizure types in Trisomy 21 (T21), resulting from secondary causes, such as infarcts from congenital heart disease or without other identifiable etiology. The latter group often respond to treatment with relatively low risk of subsequent epilepsy. Similarly, in the general population, 20% have IS with normal development at onset and no identifiable etiology (previously termed “idiopathic”) and are expected to have more favorable outcome than other IS patients. Vigabatrin or steroids are first-line therapies for IS, and although some have noted the possibility that children with T21 respond best to steroids, controlled trials have not been carried out.The study objective is to determine if there are differences in treatment response, relapse rates and subsequent epilepsy between patients with and without T21 with no identifiable etiology when vigabatrin is used as first-line treatment. Methods: Patients with IS were identified via the neurophysiology database. Charts were reviewed and patients treated with vigabatrin as first-line therapy were divided into two groups: 1) T21 and IS with no secondary seizure etiology 2) IS and normal development at onset with no identified etiology. Clinical features of the 2 groups were compared, including time from onset of IS to treatment, treatment of IS, time from treatment to resolution of IS, development of subsequent epilepsy, neuro-imaging findings and EEG results. Results: Over a 28-year period, 24 children with T21 and IS were identified and compared to 40 children in the control group. There was no significant difference in age of onset or time between onset and treatment. However, children with T21 were more difficult to control; the median number of anti-seizure medications used was 3 vs.1 in the T21 and control groups respectively. The T21 group was more likely to have a relapse of spasms [10 (412vs. 4 (10%), p = 0.004)]. One patient with T21 had 2 relapses after 3 and 13 months of treatment. Relapses were often delayed in the T21 group, with a mean of 8 months after spasms cessation compared to three months in the control group. The T21 group also had a higher subsequent risk of epilepsy [11 (46%) vs. 8 (20%), p = 0.003]. Four of the T21 developed Lennox-Gastaut syndrome, compared to one in the control group. Conclusions: Close long-term observation of patients with T21 and IS is important as they had a higher risk of relapse; often delayed and a higher risk of subsequent epilepsy. Our results differ from previous studies using steroids as first-line treatment, where it has been demonstrated that the groups have similar treatment response1,2 and T21 patients having a lower risk of subsequent epilepsy.2 Therefore, our results are suggestive that vigabatrin as first-line treatment in T21 and IS may be less favorable than steroids.
Armstrong D, Said RR. Outcomes of high-dose steroid therapy for infantile spasms in children with trisomy 21. J Child Neurol. 2019;34(11):646-52.
Beatty CW, Wrede JE, Blume HK. Diagnosis, treatment, and outcomes of infantile spasms in the Trisomy 21 population. Seizure. 2017;45:184-8.
Funding: Please list any funding that was received in support of this abstract.: No funding was received for this study.