Abstracts

Rationale: The term Lennox-Gastaut syndrome (LGS) is traditionally used to depict children with severe epilepsy with multiple seizure types, intellectual disability, and EEG showing generalized slow spike-wave complexes. The phenotype may be seen in various conditions including neonatal hypoxia ischemia, genetic neurometabolic conditions, or early focal brain lesions. The prognosis for seizure control and developmental outcome is generally considered to be grim. Experience at Cleveland Clinic indicates that children with LGS phenotype and an early focal brain lesion may benefit from epilepsy surgery. We aim to examine seizure outcome and its predictors after resective epilepsy surgery for LGS in children. Methods: We reviewed all LGS phenotype patients under 18 years of age who underwent resective epilepsy surgery at Cleveland Clinic between 06/01/2002 and 06/31/2012. LGS phenotype patients who were treated with only corpus collosotomy or vagus nerve stimulation were excluded. Results: Of 880 consecutive pediatric patients who underwent epilepsy surgery from 2002 to 2012, 36 LGS phenotype patients were identified who underwent focal, lobar, or multilobar resection (n=15) or hemispherectomy (n=21). Underlying etiologies of the epilepsies included malformation of cortical development (n=13), perinatal cerebral infarction, hemorrhage, or hypoxia ischemia (n=14), or focal cerebral encephalomalacia due to trauma or infection (n=7). The brain lesions or injuries were congenital (n=17), perinatal (n=10) or acquired at 2 months to 3 years (median 6 months) of age (n=9). Age at surgery was 0.25 to 18 (median 7) years of age. Preoperative seizure burdens were high, typically many per day. In the absence of predominantly focal features on EEG, surgical planning was based primarily on MRI. No patients were studied with invasive electrodes prior to surgery. At 6 months to 6.6 years (median 34 months) follow-up, 19 patients (52.8%) were seizure-free (Engel class Ia). In the seizure recurrent group, 2 had late remission 2 years after surgery and 5 became almost seizure-free (Engel class II) with an average of 9 seizures per month (>90% improvement). An additional 10 patients had significant seizure reduction (Engel class III) with 50-90% improvement. Overall, at last follow-up, 24 patients (66.7%) were either seizure-free or had major improvement (Engle I to II). Using survival analysis, the chance of seizure freedom was 60.1% (95% confidence interval (Cl) = 52.1-68.1%) at 12 months, 51% (95% Cl = 42-60%) at 24months, 40.8% (95% Cl = 30.8-50.8%) at 30 months and above. On multivariate analysis, bilateral PET abnormalities (risk ratio = 11.3, 95% Cl=2.31-71.0) predicted seizure recurrence. Conclusions: Resective epilepsy surgery can be an effective treatment option for LGS phenotype patients with an early focal brain lesion. The florid generalized slow spike wave complexes and EEG seizures in these patients do not contraindicate epilepsy surgery, which is based largely on MRI findings. For preoperative counseling, bilateral PET abnormalities appear to be a risk factor for poor outcome.