Abstracts

Rationale: Lennox-Gastaut Syndrome (LGS) is among the most severe epileptic encephalopathies and is characterized by multiple drug-resistant seizure types, cognitive impairment and slow-spike-and wave EEG pattern. As etiologies of LGS are heterogeneous, the clinical presentation of people with LGS varies significantly. There is little available literature characterizing the burden of the various seizure types in people with LGS despite this information being crucial for management strategies. We therefore analyzed the occurrence and frequency of individual seizure types in people with LGS who later underwent implantation of a vagus nerve stimulator captured in the VNS Therapy Outcomes registry which comprises more than 7000 patients in total. Methods: Case report forms in the VNS Therapy Outcomes registry were searched for patients with a diagnosis of LGS. A propensity score method (PSM) was employed to match subjects LGS patients with LGS to those with non-LGS drug resistant epilepsy (DRE) 1:2 using the following matching variables: age at implant, age at diagnosis and gender. Overall seizure frequency and occurrence and frequency of individual seizure types were assessed at [pre-implantation] baseline.  Results: A total of 7383 (808 LGS and 6575 non LGS) patients were evaluated for eligibility. 564 (69.8%) patients with LGS and 1128 (17.2%) patients with non-LGS DRE went into the PSM analysis set. Despite the median age at VNS implant being significantly lower in the LGS population (15) than in the non LGS DRE population (28) the median number of prior [failed] antiepileptic drug (AED) treatments was the same (4). Median total monthly seizure frequency was more than double in the LGS PSM population than in the non-LGS DRE population:90 (IQR, 28-312) vs 40 (IQR, 10-150) p<0.001 Wilcoxon test). All assessed seizure types were significantly more frequent in the LGS PSM population than in the non-LGS DRE population.  Conclusions: This analysis suggests that seizure burden in LGS patients who later undergo VNS implantation is more than double than that in non-LGS patients. Furthermore this analysis offers insight into the occurrence and frequency of individual seizure types affecting people with LGS. Funding: No funding