The relevance of VGKC positivity in the absence of LGI1 and Caspr2 antibodies.

Abstract

Editors' Note: Critiquing the article by van Sonderen et al., “The relevance of VGKC positivity in the absence of LGI1 and Caspr2 antibodies,” Lilleker et al. share their own experience with patients with focal epilepsy and voltage-gated potassium channel (VGKC) antibodies who responded to immunosuppression, although some of these patients were negative for LGI1 and Caspr2. They also point to published criteria for recognizing neuronal surface antibody syndromes, which include response to immunosuppression as a feature supporting a definite diagnosis. Furthermore, they add that the study sample was small and lacked testing for antibodies directed against other components of the VGKC complex. Commenting on the same article, Yeo et al. stress the idea of identifying additional antibodies that could be directed toward other components of the VGKC complex, and that positive and negative tests should be interpreted in the appropriate clinical context. Responding, van Sonderen et al. defend their article, noting that response due to or after treatment can be difficult to discriminate, as is prediction of natural history. They add that despite the small sample size, power was sufficient to detect the value of clinical evaluation with appropriate ancillary testing. They also note that clinical phenotype was important to fulfill autoimmunity criteria, while a positive VGKC test was not. For instance, the risk for autoimmunity is high in patients …