Infantile spasms in tuberous sclerosis complex: Prognostic utility of EEG

Abstract

To assess cognitive and epilepsy outcomes in tuberous sclerosis complex (TSC) patients with a history of infantile spasms (IS), in relation to spasm history, electroencephalography (EEG) characteristics, genetic mutation, and treatment history. The authors conducted a retrospective review of 45 children and adults with TSC and a history of IS. EEG reports from the time of spasms were evaluated for all patients, and EEG tracings were accessible and evaluated for 20 patients. Clinical outcome was unfavorable for the majority of patients. However, 33% had experienced at least one year of seizure freedom at follow-up, and 24% of those tested had IQs above 70. Hypsarrhythmia severity scores varied widely, with some EEGs severely hypsarrhythmic and others essentially normal. Lower IQ was significantly associated with higher hypsarrhythmia severity scores on EEG report, the presence of background disorganization on EEG report, the absence of normal sleep patterns on EEG, and a lower degree of treatment success on vigabatrin. A relationship between poor cognitive outcome and poor epilepsy outcome was confirmed. The correlation between poor epilepsy outcome and a greater degree of background disorganization on EEG approached significance, as did the association between subsequent intractable epilepsy and an older age at IS cessation. A greater than expected ratio of TSC2 to TSC1 patients was observed across this IS population. Early detection and successful treatment portend a more favorable outcome in TSC patients with IS. Although EEG findings in these patients vary, specific characteristics may serve as clinically useful prognostic markers.