Abstracts

Rationale: Infantile spasms (IS) may be preceded by either provoked or unprovoked seizures of other types. The aims of this study were to (i) describe the other seizure types prior to onset of infantile spasms, and (ii) describe the clinical features of this cohort including age of onset of spasms, primary cause of epilepsy, and development. Methods: Pediatric Epilepsy Research Consortium (PERC) is a multicenter initiative of US pediatric epilepsy centers. Since 2012, there has been a continuous prospective observational study to evaluate the clinical features and management of newly-diagnosed IS. Results: There were a total of 249 new onset infantile spasm cases enrolled. Acute provoked neonatal seizures occurred in 11/249 (4%) cases of infantile spasms. There were 30/249 (12%) cases treated with anticonvulsants at some earlier time, but stopped prior to development of infantile spasms. Ongoing epilepsy in 86/249 (35%) cases required maintenance anticonvulsants at the time of infantile spasm onset. The mean age of spasm onset with and without prior epilepsy was 9.1±5.4 months and 7.5±3.5 months, respectively (p=0.02). Seizure types present at or prior to the onset of infantile spasms were both generalized (tonic (n=24), myoclonic (n=16), tonic-clonic (n=9), myoclonic-tonic (n=2), and atonic / drop attack (n=2)) and focal (focal motor (n=15), arrest/staring/blinking seizures (n=14), and clonic (n=11)). Specific etiologies may be classified as associated with abnormal neuroimaging (hypoxic ischemic encephalopathy (n=9), infarction/stroke (n=7), periventricular leukomalacia/intraventricular hemorrhage (n=6), trauma (n=6), congenital anomaly (n=4), tuberous sclerosis (n=3), lissencephaly (n=3), tumor (n=2), malformation of cortical development (n=2), heterotopia (n=1), agenesis/dysplasia of the corpus callosum (n=1), and schizencephaly (n=1)) or more likely a structurally normal brain (genetic/chromosomal (n=9), metabolic disorder (n=4)). Development in prior epilepsy cases (n=86) at baseline and at 3 months follow up after onset of infantile spasms was assessed for motor and cognitive measures (Table1). Conclusions: This study describes the seizures associated with development of infantile spasms. Both generalized and focal seizure types preceded infantile spasms with similar frequency. Infants with prior diagnosis of epilepsy developed infantile spasms later than those without pre-existing unprovoked seizures. Abnormal neuroimaging was common in cases where a specific cause could be determined. Degree of developmental delay at onset of infantile spasms was generally abnormal in patients with a history of epilepsy which may make assessment of this outcome after treatment more difficult to assess in this cohort.