Suspected limbic encephalitis and seizure in cats associated with voltage-gated potassium channel (VGKC) complex antibody.

J Vet Intern Med. 2013 Jan-Feb;27(1):212-4.

Pakozdy A, Halasz P, Klang A, Bauer J, Leschnik M, Tichy A, Thalhammer JG, Lang B, Vincent A.

Clinical Department for Companion Animals and Horses, Clinic for Small Animals Internal Medicine, University of Veterinary Medicine, Vienna, Austria. akos.pakozdy@vetmeduni.ac.at

Abstract

BACKGROUND:

Treatment-resistant complex partial seizures (CPS) with orofacial involvement recently were reported in cats in association with hippocampal pathology. The features had some similarity to those described in humans with limbic encephalitis and voltage-gated potassium channel (VGKC) complex antibody.

HYPOTHESIS/OBJECTIVES:

The purpose of this pilot study was to evaluate cats with CPS and orofacial involvement for the presence of VGKC-complex antibody.

ANIMALS:

Client-owned cats with acute orofacial CPS and control cats were investigated.

METHODS:

Prospective study. Serum was collected from 14 cats in the acute stage of the disease and compared with 19 controls. VGKC-complex antibodies were determined by routine immunoprecipitation and by binding to leucine-rich glioma inactivated 1 (LGI1) and contactin-associated protein-like 2 (CASPR2), the 2 main targets of VGKC-complex antibodies in humans.

RESULTS:

Five of the 14 affected cats, but none of the 19 controls, had VGKC-complex antibody concentrations above the cut-off concentration (>100 pmol/L) based on control samples and similar to those found in humans. Antibodies in 4 cats were directed against LGI1, and none were directed against CASPR2. Follow-up sera were available for 5 cats in remission and all antibody concentrations were within the reference range.

CONCLUSION AND CLINICAL IMPORTANCE:

Our study suggests that an autoimmune limbic encephalitis exists in cats and that VGKC-complex/LGI1 antibodies may play a role in this disorder, as they are thought to in humans.

Copyright © 2012 by the American College of Veterinary Internal Medicine.

PMID: 23278981

Akos Pakozdy-1

Figure 1.

The voltage-gated potassium channel (VGKC) is composed of alpha (α) and beta (β) subunits and is complexed to other proteins including CASPR2 and ADAM 22/23. Leucine-rich, glioma inactivated 1 (LGI) is a neuronally secreted protein that binds to ADAM. Mutations in the gene encoding LGI1 have been found in around 50% of patients with autosomal dominant lateral temporal epilepsy (ADLTE) or autosomal dominant partial epilepsy with auditory features (ADPEAF), whilst autoantibodies to LGI1 have been detected in patients with faciobrachial dystonic seizures. We have detected autoantibodies in the serum of cats with treatment-resistant complex partial seizures with orofacial involvement, which bind to LGI1 too. No antibodies that bound CASPR2 were detected.

Akos Pakozdy-2

Figure 2.

Epileptic seizure is originating from the temporal lobe in a cat with LGI1 limbic encephalitis. Orofacial automatisms, such as hypersalivation, facial  twitching, mastication and licking, are characteristic ictal signs of this epileptic condition.

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