title: Anti-contactin-associated protein-2 encephalitis: relevance of antibody titres, presentation and outcome.
abstract: To clarify the relevance of titres of IgG antibodies against contactin-associated protein-2 (CASPR2) in diagnosing anti-CASPR2 encephalitis and to describe features and outcomes.
  
  
  
  This was a retrospective analysis of 64 patients with CASPR2 antibodies, categorized independently as 'autoimmune encephalitis' or 'other disease'. Logistic regression methods were performed to identify potential predictors of 'autoimmune encephalitis' in addition to CASPR2 antibodies.
  
  
  
  An upfront CASPR2 antibody serum titre cut-off at ≥1:200 had a diagnostic sensitivity of 85% and a specificity of 81%. Logistic regression analyses indicated that, in addition to titre, encephalitic magnetic resonance imaging (MRI) was a significant predictor of 'autoimmune encephalitis' (Nagelkerke's R2= 0.81, P < 0.001) with high sensitivity (84%) and very high specificity (100%). Patients with CASPR2 antibodies and an estimated probability of >70% of having anti-CASPR2 encephalitis (n = 22) had limbic encephalitis (n = 18, one patient plus ataxia), Morvan syndrome (n = 2) or a hyperkinetic movement disorder (n = 2). Median modified Rankin score (mRS) at diagnosis was 3 (range 1-4). Twenty patients were male; median age was 64 (range 54-75) years; 5/15 patients with cerebrospinal fluid data had intrathecal CASPR2 antibody synthesis, and 12/19 with follow-ups >3 months (median 12 months, range 4-43 months) improved by ≥1 mRS point resulting in a median mRS of 2 (range 0-6; one death; all but one having received immunotherapy); and 2/15 patients with follow-up MRI developed hippocampal atrophy.
  
  
  
  Only higher CASPR2 serum antibody titres indicate anti-CASPR2 encephalitis, and diagnostic accuracy increases if MRI findings are considered. Anti-CASPR2 encephalitis has characteristic features and a favourable outcome with immunotherapy.
authors: Epilepsy Center Bethel, Krankenhaus Mara, Bielefeld, Germany.
authors: C G
authors: CG
authors: Bien
authors: Epilepsy Center Bethel, Krankenhaus Mara, Bielefeld, Germany.
authors: Z
authors: Z
authors: Mirzadjanova
authors: Karl Landsteiner Institute for Clinical Epilepsy Research and Cognitive Neurology, 2nd Neurological Department, General Hospital Hietzing with Neurological Center Rosenhügel, Sigmund Freud University, Vienna, Austria.
authors: C
authors: C
authors: Baumgartner
authors: Epilepsy Center Bethel, Krankenhaus Mara, Bielefeld, Germany.|Department of Neurology, University Hospital Erlangen, Erlangen, Germany.
authors: M D
authors: MD
authors: Onugoren
authors: Swiss Epilepsy Center, Clinic Lengg and Department of Neurology, University Hospital Zurich, Zurich, Switzerland.
authors: T
authors: T
authors: Grunwald
authors: Epilepsy-Center Berlin-Brandenburg, Berlin.
authors: M
authors: M
authors: Holtkamp
authors: Department of Neurology, Center for Research in Clinical Medicine (CCM), HELIOS-Universitätsklinikum Wuppertal, University of Witten/Herdecke, Wuppertal.
authors: S
authors: S
authors: Isenmann
authors: Department of Neurology, Nordwest-Krankenhaus Sanderbusch, Sande.
authors: P
authors: P
authors: Kermer
authors: Department of Neurology, University of Münster, Münster.
authors: N
authors: N
authors: Melzer
authors: Department of Neurology and Clinical Neurophysiology, Klinikum Augsburg, Augsburg.
authors: M
authors: M
authors: Naumann
authors: Department of Psychiatry II Ulm University at Bezirkskrankenhaus Günzburg, Mental Health & Old Age Psychiatry, Günzburg.
authors: M
authors: M
authors: Riepe
authors: Department of Neurology, Evangelisches Krankenhaus Bielefeld, Bielefeld, Germany.
authors: W R
authors: WR
authors: Schäbitz
authors: Department of Neurology 1, Neuromed Campus, Kepler Universitätsklinikum, Linz, Austria.
authors: T J
authors: TJ
authors: von Oertzen
authors: Department of Neurology, Universitätsmedizin Greifswald, Greifswald, Germany.
authors: F
authors: F
authors: von Podewils
authors: Karl Landsteiner-Institute for Neuroimmunological and Neurodegenerative Disorders, Danube Hospital/Donauspital, Vienna, Austria.
authors: H
authors: H
authors: Rauschka
authors: Society for Epilepsy Research, Epilepsy Centre Bethel, Bielefeld, Germany.
authors: T W
authors: TW
authors: May
mesh_terms: D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D004660:Encephalitis / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000276:immunology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008565:Membrane Proteins / Q000276:immunology*; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000276:immunology*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D001323:Autoantibodies; C403049:CNTNAP2 protein, human; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins
keywords: autoimmune encephalitis; autoimmune epilepsy; contactin-associated protein-2 antibodies; outcome