Abstracts

Rationale: Determining the clinical efficacy of a new anti-seizure drug (ASD) being added to a patient’s regimen is often a lengthy and risky process. Currently, there are no metrics available to accurately predict ASD response in a relatively short amount of time following its initiation. Therefore, we seek to determine whether the efficacy of a newly started ASD can be predicted in a clinically meaningful amount of time using detection outputs from an intracranial responsive neurostimulator. Methods: Patients implanted with an intracranial responsive neurostimulator (RNS; Neuropace, Inc) device and receiving care at a single center were identified for analysis. Medical records were reviewed to identify all ASD changes patients had undergone since device implantation. Daily detection outputs in the form of “episode starts” and “long episodes” were averaged and compared at varying time points before and after ASD initiation. Ratios of detection counts before and after each medication change were then compared with medication response outcomes. Medication success or failure was retrospectively determined on an individual basis based on provider documentation of improvement in seizures, whether or not the provider and patient chose to continue the medication long term, and patient-reported clinical efficacy (seizure diaries). Results: 21 ASD changes identified from 20 patients met inclusion criteria for a clinically relevant time-point analysis in which detection counts were averaged three months before and one week after initiation of a new ASD. A significant difference between long episode ratios was found between medication successes and failures (p=0.0048). If mean long episode count decreased over the first week by at least 10% (11 instances), then medication was effective in all but two instances (PPV=81.82%). If mean long episode count increased over the first week by at least 10% (5 instances), then medication was ineffective in all but one instance (NPV=80.00%).  Conclusions: In this small cohort of patients with an implanted RNS device, changes in long episode detections within the first week following start of a new ASD accurately predicted long-term ASD efficacy. Funding: None.