Neurological Syndromes Associated with Antibodies against Neuronal Surface Antigens

Background: Neuronal surface antibodies are associated with numerous neurological symptoms. Better knowledge of these symptoms may improve identification of potential candidates for immunotherapy. Aim: Characterize clinical signs in patients with neuronal surface antibodies positivity. Methods: We detected neuronal surface antibodies in 11/2011-12/2013 in 224 patients (224 in serum and 37 in cerebrospinal fluid). We investigated anti-NMDAR, anti-AMPAR1, anti-AMPAR2, anti-GABA(B)R, anti-LGI1, anti-CASPR2 using cell-based assays for indirect immunofluorescence (Euroimmun AG). We retrospectively analyzed clinical characteristics of patients with positive neuronal surface antibodies in serum or cerebrospinal fluid other than anti-NMDAR positive patients. Results: Neuronal surface antibodies were detected in 11 patients (seven males, median age 58). Six patients had anti-LGI1, four anti-CASPR2 and two anti-AMPAR1 antibodies (one patient had both anti-CASPR2 and anti-AMPAR1 antibodies). Clinical symptoms included chronic epilepsy (n = 5), acute encephalopathy (n = 5) accompanied by epileptic seizures in four patients and one patient presented with cerebellar syndrome and cognitive deficit. Two patients had coincidence of paraneoplastic antibodies (anti-Hu, anti-Ma2). Tumor (small cell lung carcinoma) was diagnosed in one patient (anti-AMPAR1). Eight patients improved following immunotherapy (corticosteroids, IVIG). Early immunotherapy was associated with better outcome. Conclusion: NS-Abs were mostly associated with limbic encephalitis and chronic temporal lobe epilepsy. Immunotherapy had better effect when applied early in the disease course.