VGKC complex antibodies in epilepsy: diagnostic yield and therapeutic implications

In a significant number of patients developing epilepsy in adult life, the aetiology of their seizures remains unclear. Antibodies directed against the voltage gated potassium channel complex (VGKC Ab) have been identified in various cohorts of patients with epilepsy, although the role of these antibodies in epilepsy pathogenesis is not fully known.

We reviewed the notes of 144 patients with unexplained adult onset epilepsy who had been tested for VGKC Abs. We collected data on their clinical syndrome, investigation results and response to treatment.

We identified 6 (4.2%) patients who had titres of >400 pM. One of the six patients was positive for LGI1 and another for CASPR2 subunit antibodies. All patients were given immunotherapy and experienced improvement in seizure control. No patient had the clinical syndrome of limbic encephalitis.

Patients with otherwise unexplained epilepsy and positive VGKC Abs are a heterogeneous group. In our cohort there was an overall favourable response to immunotherapy but further prospective studies are needed to determine the significance of these antibodies and the optimum treatment regimen for patients.