Surgical treatment of epilepsy in polymicrogyria: A subject-level meta-analysis and decision-making framework

Polymicrogyria (PMG) presents a complex challenge in epilepsy surgery. The optimal surgical strategy and extent of resection, from hemispheric to more limited approaches, remain debated. We aimed to summarize subject-level surgical outcomes and identify factors informing procedure selection.

We conducted a subject-level pooled analysis of 161 patients across 20 retrospective studies, evaluating surgical outcomes (Engel classification), in relation to anatomic extent, surgical procedure, use of intracranial electroencephalography (ICEEG), and other decision-influencing factors.

At ≥12 months follow-up, ~70% of patients achieved seizure freedom (Engel Class I). In our univariate analysis Engel Class I outcomes were associated with shorter epilepsy duration (8.05 vs 11.92 years, p = 0.009). Hemispheric PMG was linked to earlier seizure onset (p = 0.02) and a higher incidence of epileptic encephalopathy with spike-wave activation in sleep (p < 0.0005). Among unilateral non-hemispheric and bilateral PMG cases, seizure-freedom rates were similar between hemispheric and more limited resections, but the latter were associated with a lower incidence of new or worsened motor deficits. Mixed-effects logistic regression (n = 160) showed that hemispheric surgery increased the odds of seizure freedom but without statistical significance (odds ratio [OR] = 3.52, p = 0.055). ICEEG did not significantly influence seizure outcomes but may play a key role in identifying eloquent cortex and guiding safer, tailored resections.

In PMG-related epilepsy, surgical strategy must balance seizure control with preservation of function. ICEEG (especially stereo-EEG [SEEG]) remains a valuable tool for functional mapping and tailored resections.