Intelligence outcomes in 17 patients with developmental and/or epileptic encephalopathy with spike-wave activation in sleep ((D)EE-SWAS) after remission of SWAS

IQ Research
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For children with (D)EE-SWAS (a rare epilepsy syndrome that causes near-continuous abnormal brain activity during sleep), the assumption has often been that once the EEG pattern resolves, the worst is over. This study challenges that assumption and reminds us that remission of a measurable pattern does not always mean recovery of function.

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In this study of 17 patients with a history of (D)EE-SWAS, researchers tracked IQ scores before, during, and after the syndrome’s active phase. The findings show that children experienced an average drop of 22 IQ points while the syndrome was active. But what happened after remission was even more telling. The group split into two trajectories: 9 children showed partial cognitive recovery (gaining an average of nearly 16 IQ points), while 8 children continued to decline (losing an average of 8 more points). The key factor separating these two groups is age at onset. Children whose SWAS began earlier (around age 5 on average) fared significantly worse than those whose SWAS began closer to age 8.

These findings carry real implications for clinical practice. Early identification and intervention in (D)EE-SWAS may be one of the most significant factors in determining a child’s long-term cognitive trajectory. The study also reinforces that cognitive monitoring should not stop when the EEG normalizes. Children who have lived through this syndrome deserve continued neurodevelopmental follow-up, because the brain’s recovery continues long after the seizure activity is gone.

Full study here: Redirecting

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This study is a pretty stark demonstration of how neurodevelopmental timing matters. The 17 patients tracked lost an average of 22 IQ points while the syndrome was active, which is already severe. But after remission the group split into two very different trajectories. Nine children recovered an average of nearly 16 points over time. Eight continued declining, losing another 8 points on average even after the abnormal EEG pattern resolved. The single biggest predictor of which group a child ended up in was age at onset. Earlier onset around age 5 was associated with the worse trajectory, while onset closer to age 8 was associated with partial recovery. The brain is doing a lot of critical structural and functional development in those early years, so disruption during that window appears to leave deficits that do not resolve on their own.

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The practical takeaway is that EEG normalization should not be treated as the finish line for these kids. Cognitive monitoring needs to continue well past seizure remission because the developmental trajectory keeps unfolding for years afterward.