Abstracts

Rationale: Surgery is an effective treatment in some patients suffering from medically intractable epilepsy due to focal cortical dysplasia (FCD). However, few studies have focused on seizure outcome in patients with peri-rolandic FCD where surgical resections are usually avoided (or incomplete) due to concerns about post-surgical sensori-motor deficits. Interestingly, balloon cell containing FCD (type IIB) disproportionately localizes to the peri-rolandic area, and there are reports of postoperative seizure worsening in this subgroup of patients. The aim of this study was to evaluate surgical outcomes in patients with peri-rolandic FCD with a focus on type IIB lesions and to address the question of postoperative seizure worsening after an incomplete resection. Methods: We retrospectively reviewed electro-clinical, imaging, and outcome data of patients with pathologically proven FCD who had undergone epilepsy surgery over a 12-year period at Cleveland Clinic Epilepsy Center. Seizure outcomes were compared between patients with rolandic FCD (pre- and/or post central gyrus) and non-rolandic frontal FCD. Exclusion criteria included dual pathology and follow up less than six months. A subgroup analysis was performed for patients with Type IIB lesions and those with rolandic lesions. Results: Seventeen patients with rolandic and 22 patients with non-rolandic FCD were identified. Histopathologically, 12 patients had type IIB FCD; in 8 of them (67%) the lesions were localized in the rolandic region. Mean follow up was 3.7 years (6 months-15 years). At last follow up a seizure free outcome was achieved in 59% of the rolandic subset of patients and 75% in the patients with type IIB FCD. Neurological deficits at last follow up were present in 59% of the rolandic subgroup and 42% of the type IIB subgroup. Residual contralateral weakness was the most common postoperative deficit. Subgroup analysis showed that an incomplete resection, left sided lesions, and postoperative ipsilateral spikes significantly correlate with seizure recurrence in patients with type IIB lesions. Similarly in patients with rolandic lesions an incomplete resection and postoperative ipsilateral spikes on EEG also significantly correlated with seizure recurrence. Three patients (3/8) with rolandic type IIB lesions had worsening postoperatively and presented with status epilepticus; all 3 patients were rendered seizure free following a second complete (more aggressive) surgical resection. Conclusions: Patients with rolandic FCD (including Type IIB subtype) can achieve a good surgical outcome after a complete resection. However, an incomplete surgical resection in rolandic type IIB FCD may lead to acute postoperative seizure worsening suggesting an in situ inhibitory anti-epileptic role for the center of the balloon cell-rich FCD.