Abstracts

Rationale: Intractability to antiepileptic drugs (AEDs) is a common feature of autoimmune epilepsy (AE) and immunotherapy is widely accepted as the first-line. However, AEDs remain the cornerstone of AE therapeutics, and some have documented anti-inflammatory properties. In this project, we explored the pattern of usage and efficacy of AEDs in patients with suspected AE. Methods: This was a retrospective study conducted using the electronic medical record (EMR) and search tool in Mayo Clinic, Rochester. 50 patients with suspected AE and seizures as a main presenting feature were seen at our autoimmune and epilepsy outpatient clinics from 2014 to 2016. Clinical data including demographics, seizure characteristics, type of AED and immunotherapy used, presence of neural antibody, and treatment outcomes were reviewed. Results: Patients ages ranged from 10 - 87 years (mean age, 41.3 y); 26 (52%) were male. Serum and/or CSF autoimmune antibodies were detected in 41 (82%): VGKC (n=16); GAD65 (n=10); ganglionic Ach receptor (n=5); NMDA receptor (n=3); P/Q type calcium channel (n=2); anti-neuronal nuclear (ANNA-1, n=1 and ANNA-2, n=1); TPO (n=1); Anti-Ro (n=1); anti-DS-DNA (n=1). The majority of patients (n=43, 86%) received at least one form of immunotherapy in combination with AEDs while the reminder received AEDs alone. Median number of AEDs used was 2 (range=1-6). Levetiracetam was the most common (n=42) followed by lacosamide (n=18), carbamazepine (n=16), oxcarbazepine (n=11), and lamotrigine (n=11). In addition, 4 patients received VNS therapy, and 3 patients had unsuccessful epilepsy surgeries. The rationale for selecting one AED over the other was not clarified in the EMR. 27 patients (54%) became seizure free: 18 (36%) with immunotherapy, 5 (10%) with AEDs alone, and 4 (8%) with AEDs after failing immunotherapy. Mean follow up = 18.2 months (range= 3-44 months). Initiation of carbamazepine (n=4), lacosamide (n=4), or oxcarbazepine (n=1) resulted in seizure freedom. Regardless of the type of therapy, VGKC antibody positive patients were more likely to become seizure free compared to GAD65 positive and autoimmune antibody negative cases (12/16 vs. 2/10 vs. 2/9 respectively, p=0.018). Conclusions: This retrospective study suggests that the selection of AED therapy in AE is arbitrary. In select patients, AEDs alone were effective in controlling seizures. Although levetiracetam was the most commonly used agent, there was no clear evidence to support its use based on documented efficacy. In contrast, carbamazepine, lacosamide and oxacarbazepine resulted in seizure freedom in a few cases. Prospective studies are needed to clarify AED selection and to elucidate their immunomodulatory properties in AE. Funding: None.