The relevance of VGKC positivity in the absence of LGI1 and Caspr2 antibodies
- 3 May 2016
- journal article
- Published by Ovid Technologies (Wolters Kluwer Health) in Neurology
- Vol. 86 (18), 1692-1699
- https://doi.org/10.1212/wnl.0000000000002637
Abstract
Objective: To assess the clinical relevance of a positive voltage-gated potassium channel (VGKC) test in patients lacking antibodies to LGI1 and Caspr2. Methods: VGKC-positive patients were tested for LGI1 and Caspr2 antibodies. Patients lacking both antibodies were matched (1:2) to VGKC-negative patients. Clinical and paraclinical criteria were used to blindly determine evidence for autoimmune inflammation in both groups. Patients with an inconclusive VGKC titer were analyzed in the same way. Results: A total of 1,455 patients were tested by VGKC radioimmunoassay. Fifty-six patients tested positive, 50 of whom were available to be included. Twenty-five patients had antibodies to LGI1 (n = 19) or Caspr2 (n = 6) and 25 patients lacked both antibodies. Evidence for autoimmune inflammation was present in 7 (28%) of the VGKC-positive patients lacking LGI1 and Caspr2, compared to 9 (18%) of the VGKC-negative controls (p = 0.38). Evidence for autoimmune inflammation was mainly found in patients with limbic encephalitis/encephalomyelitis (57%), but not in other clinical phenotypes (5%, p < 0.01). VGKC titers were significantly higher in patients with antibodies to LGI1 or Caspr2 (p < 0.001). However, antibodies to Caspr2 could also be detected in patients with inconclusive low VGKC titer, while many VGKC-positive patients had no evidence for autoimmune inflammation. Conclusions: VGKC positivity in the absence of antibodies to LGI1 and Caspr2 is not a clear marker for autoimmune inflammation and seems not to contribute in clinical practice. No cutoff value for the VGKC titer was appropriate to discriminate between patients with and without autoimmune inflammation.Keywords
This publication has 21 references indexed in Scilit:
- VGKC complex antibodies in epilepsy: Diagnostic yield and therapeutic implicationsSeizure, 2013
- Autoantibodies in Sporadic Creutzfeldt-Jakob DiseaseJAMA Neurology, 2013
- Chronic pain as a manifestation of potassium channel-complex autoimmunityNeurology, 2012
- Paraneoplastic syndromes and autoimmune encephalitisNeurology Clinical Practice, 2012
- Investigations of caspr2, an autoantigen of encephalitis and neuromyotoniaAnnals of Neurology, 2010
- Investigation of LGI1 as the antigen in limbic encephalitis previously attributed to potassium channels: a case seriesThe Lancet Neurology, 2010
- Antibodies to Kv1 potassium channel-complex proteins leucine-rich, glioma inactivated 1 protein and contactin-associated protein-2 in limbic encephalitis, Morvan’s syndrome and acquired neuromyotoniaBrain, 2010
- Potassium channel antibodies in two patients with reversible limbic encephalitisAnnals of Neurology, 2001
- Morvan’s syndrome associated with voltage-gated K channel antibodiesNeurology, 2000
- Acquired neuromyotonia: Evidence for autoantibodies directed against K+channels of peripheral nervesAnnals of Neurology, 1995