Newey CR and Sarwal A
Limbic encephalitis may occur as an infectious, paraneoplastic, or autoimmune phenomenon. One such cause
of limbic encephalitis is voltage gated potassium channel antibodies (VKGC). Hyponatremia with new cognitive
decline may be one of the presenting symptoms. The exact mechanism of hyponatremia is unknown though findings
consistent with syndrome of inappropriate antidiuretic hormone (SIADH) are observed. We retrospectively reviewed
all cases admitted to an academic medical center with a diagnosis of limbic encephalitis (848 adults between 2004
to 2010) and found six cases of VGKC antibody associated limbic encephalitis. Three of the six cases had SIADH
that completely or partially resolved with a combination of water restriction and immunotherapy. The reversibility of
hyponatremia and limbic encephalitis with immunomodulation suggests an antibody-mediated cause. We further
review available literature for association of hyponatremia and VGKC limbic encephalitis and propose mechanisms of
for the hyponatremia in autoimmune encephalitis