Abstracts

Rationale: Epileptic spasms (ES) occur outside of West syndrome (WS) well-defined syndromes but have not been well characterized. The aim of this study is to compare etiologic, semiological, electrographic findings and other clinical features of ES in children with WS and children with ES who have never had WS (NoWS). Methods: The video/EEG recordings of consecutive children evaluated in our EMU who were diagnosed as having ES were reviewed and information extracted in a standardized fashion. Results: 102 children had WS from initial onset of epilepsy and at the time of the EMU visit, and 33 children had ES without any history of WS or other specific syndrome. Age at onset was younger in WS versus NoWS (5.5 mo vs 46.7 mo, p<0.0001). Distributions of underlying causes were similar in WS and NoWS (e.g. MCD 15% vs 12%, hypoxic insult 10% vs 12%, unknown cause 19% vs 15%, all p>0.10). Coexistence of other seizure types was more common in NoWS (39% vs 17%, p=0.006). Semiology differed with arms (91% vs 70%, p=0.002) and legs (72% vs 27%, p<0.0001) being involved more often in WS and head (70% vs 43%, p=0.007) involved more often in NoWS. Asymmetry was not significantly more common in WS than NoWS (32% vs 18%, p=0.12). The minimum frequency of clusters per day was similar in WS and NoWS (3.1 vs 3.2 p=0.82); however the minimum number of seizures per cluster was greater in WS (10.3 vs 4.6, p<0.0001). Seizures were more likely to be diurnal only in the NoWS group (27% vs 8%, p=0.004). Interictally, hypsarrythmia was present in 81% of WS and 12% of NoWS EEGs (p<0.0001). Generalized spike discharges were more common in NoWS (24% vs 10%, p=0.03) and discontinuous background was more common in WS (60% vs 36%, p=0.02). One or more normal background features were more commonly seen in NoWS than WS EEGs (76% vs 57%, p=0.05). Ictal findings did not differ significantly between the two groups. Conclusions: There was a substantial proportion of children with ES who did not have WS or other recognizable syndromes. Ictal semiology and clustering varied between WS and NoWS as did certain interictal findings; however, underlying causes and ictal manifestations are similar. This raises questions concerning whether West is a discrete age-limited syndrome or whether differences in how WS vs NoWS manifest simply reflect age-related maturational differences in expression of the same underlying process.