CSF findings in patients with voltage gated potassium channel antibody associated limbic encephalitis

Recently, a new subtype of limbic encephalitis (LE) has been described, serologically characterized by the presence of antibodies against voltage gated potassium channels (VGKC, to be called VGKC-LE). Only little is known about CSF findings in this new disorder. Here we report the results of 29 lumbar punctures in 17 patients with VGKC-LE. Slight pleocytosis, mainly consisting of lymphocytes and monocytes, and elevated total protein concentrations were present in 41 and 47%, respectively. Intrathecal immunoglobulin (Ig) synthesis as defined by the presence of CSF-specific oligoclonal IgG bands, an increased IgG index, or an elevated IgG, IgA, or IgM ratio, was not detected in any of the patients, but dysfunction of the blood–CSF barrier was found in 35%. CSF findings were normal in 23%. Conclusions: Unlike paraneoplastic LE, VGKC-LE is not frequently associated with intrathecal Ig production or markedly elevated white cell counts. Thus, normal CSF findings do not preclude the disease. VGKC-Ab should, therefore, be determined whenever LE is clinically suspected, irrespective of the presence or absence of inflammatory CSF changes.