P86. Epilepsy associated with autoimmune encephalitis with DPPX and aquaporin-4 antibodies

Abstract

Various new antibodies (abs) that target surface neuronal antigens have been recently discovered. This has led to a new interpretation of Autoimmune Encephalitis (AE). These Encephalitis syndromes are less often associated with cancer and respond well to treatment with immunotherapy in comparison to encephalitis associated with antibodies against intracellular structures. Literature describes 4 cases of AE with auto-abs against neuronal surface protein dipeptidyl-peptidase-like protein-6 (DPPX), a subunit of the Kv4.2 potassium channels. All patients exhibited similar symptoms including subacute onset of progressive cognitive dysfunction, agitation, myoclonic jerks, resting tremor, hyperreflexia and seizures. Pleocytosis (11–117/μl) in cerebrospinal fluid (CSF) withintrathecal production of IgG or oligoclonal bands (OCBs) was confirmed. 3 patients developed severe diarrhoea andweight loss. MRIs of brain revealed nonspecific white matter changes (Boronat et al., 2013; Suchecki et al., 2014). 3 new cases of DPPX auto-abs associated with progressive encephalomyelitis withrigidity and myoclonus were published in 2014(Balint, 2014). Guiding symptoms were cerebellar ataxia with hyperreflexia andtrunk stiffness. We present a 65years old female patient with initial progressive affective dysfunction, loss of drive and interests andshort-term memorydysfunction. Later on, dyscognitive seizures and resting tremor with fluctuating myoclonic jerks evolved. At admission to the hospital patient had almost no recollection of the last three months. MRI showednonspecific changes in white matter. EEG demonstrated pronounced IRDAs. In CSF 4 white blood cells with intrathecal production of IgG und OCBs were detected.Additionally Hashimoto-thyroiditis was observed.With a cell-based assay and immunofluorescence DPPX-abs in serum (titer 1:3,000,000) and CSF (1:200) were detected. Further serum analysis revealed positive aquaporin-4-abs (titer 1:375). Due to seizures and myoclonic jerks levetiracetam was started. On prolonged oral prednisolon therapy (100mg daily over 3months, currently reduced to 50mg daily) patient achieved progressive improvement of neurologic impairments. In rehabilitation immunosuppression with azathioprine had been started. As a result of this treatment, patient remains stable. A tumor search was inconclusive. In summary, recently described abs against DPPX were evaluated as a cause of patient's symptoms. Moreover, aquaporin-4-abs, which are held specific for neuromyelitis optica, were detected before any evidence of NMO and may be interpreted along with Hashimoto-thyroiditis as a propensity to autoimmune diseases. It is possible that aquporin-4-abs are presentyears before the NMO onset. Cooccurrence of these two rare abs with focus on central nervous system has not yet been described. Reports of coexistence of NMO and autoimmune diseases, which affect the peripheral nervous system (e.g. Myasthenia gravis ) or diseases of rheumatic origin (e.g. Sjogren-Syndrome) were already published.