Factors Influencing the Withdrawal of Antiepileptic Drugs in Adult Patients with Symptomatic Seizures Secondary to Neuronal Surface Antibodies-Associated Autoimmune Encephalitis

PURPOSE: This retrospective study aimed to investigate the relationship between clinical characteristics, seizure outcomes, and the potential factors influencing the withdrawal of antiepileptic drugs (AEDs) in adult patients with symptomatic seizures secondary to neuronal surface antibody (NSAb)-associated autoimmune encephalitis (AE). PATIENTS AND METHODS: Eighty-one patients (age ≥18 years) diagnosed with NSAb-associated AE were included in this retrospective study. After at least 1 year of follow-up, clinical details, magnetic resonance imaging (MRI) findings, electroencephalography (EEG) data, cerebrospinal fluid parameters, and the therapeutic outcomes were analyzed. Patients who needed long-term AEDs to control seizures were divided into two groups (withdrawal ≤1 year and withdrawal >1 year). Multivariable logistic regression analysis was performed to identify the risk factors affecting the AEDs’ withdrawal in patients with seizures secondary to NSAb-associated AE. RESULTS: During the 12-month follow-up after AEDs’ withdrawal, 28 (44.4%) patients among the 63 patients who needed long-term AEDs stopped AEDs within 1 year, while 35 (55.6%) patients continued AEDs treatment. Multivariable logistic regression analysis showed that delayed immunotherapy, status epilepticus (SE), and elevated intrathecal Immunoglobulin G synthesis rate of 24 hours (24-h intrathecal IgG) were independent risk factors for delayed withdrawal in patients with seizure secondary to NSAb-associated AE (odds ratios: 1.129, 6.497, 3.415, P<0.05). The receiver operating characteristics (ROC) curve analysis showed that the area under the curve (AUC) of delayed immunotherapy, SE, and elevated 24-h intrathecal IgG was 0.816 (95% CI=0.711–0.921, P<0.001). CONCLUSION: Delayed immunotherapy, status epilepticus and elevated 24-hour intrathecal IgG synthesis rate are the factors that may influence the decision to delay AEDs’ withdrawal.