Abstracts

Rationale: There are some preliminary reports showing voltage gated potassium channel (VGKC) complex antibodies in patients with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS), but the clinical and laboratory characteristics of VGKC complex antibody positive MTLE-HS patients have not been investigated in a consecutive large series. Our aim was to elucidate the clinical and laboratory clues for detection of VGKC complex antibodies in this prototype of frequent, drug-resistant epilepsy syndrome. Methods: Consecutive patients diagnosed with MTLE fulfilling the MRI criteria for HS were enrolled. The sera of 111 patients and various control groups (80 subjects) were tested for neuronal autoantibodies against uncharacterized VGKC complex antigens by RIA, as well as against the subtypes of contactin-associated protein-like 2 (CASPR-2) and leucine-rich glioma inactivated 1 (LGI1) by cell-based assays, after ethic approval and signed consents. The clinical and laboratory features of all VGKC-seropositive versus seronegative groups were compared and binary logistic regression analysis was performed to explore the differentiating variables. Results: We found antibodies against CASPR-2 in eleven, uncharacterized VGKC-complex antigens in four patients out of 111 MTLE-HS patients and in none of the control subjects. The history of status epilepticus (p=0.001), diagnosis of psychosis (p=0.009), unexplained remission (p=0.009), cognitive dysfunction (p=0.01) and PET/SPECT findings in temporal plus extratemporal regions (p=0.03) were found significantly more frequent in the VGKC-seropositive group. Binary logistic regression analysis disclosed that status epilepticus (adjusted-odds ratios?=?0.050- 0.805, p=0.023), psychosis (adjusted-odds ratios?=?0.016-0.549, p=0.009) and cognitive dysfunction (adjusted-odds ratios?=?0.054-0.968, p=0.045) were statistically significant variables to differentiate between VGKC-complex seropositive group versus seronegative group. EEG features including ictal recordings and post-operative seizure freedom did not differ between the VGKC-complex group and seronegative group. Conclusions: This is the first systematic study screening VGKC-complex antibodies (13.5%) in a large consecutive series of patients with MTLE-HS and showed some differentiating features. The presence of these VGKC auto-antibodies might be markers of unknown immunopathological processes in MTLE pathogenesis. Their significance and potential benefits in selection of patients who would response to early immune treatment possibilities need to be further scrutinized. Funding: None