Neuropsychological course of voltage-gated potassium channel and glutamic acid decarboxylase antibody related limbic encephalitis.

BACKGROUND AND PURPOSE

Autoantibodies (abs) to glutamic acid decarboxylase (GAD) and to voltage-gated potassium channels (VGKC) induce distinct courses of limbic encephalitis, related to MRI findings, seizure outcome and cognition.

METHODS

A detailed analysis of the cognitive course of the two forms is presented, spanning a median time interval of 28 months, including parameters of attention, learning and memory in 15 VGKC-ab-positive and 16 GAD-ab-positive patients.

RESULTS

In both groups, the initially significantly impaired attention performance recovered to a putatively premorbid level. In VGKC patients the partially severely impaired learning and memory performance improved under treatment but remained subnormal at last follow-up. By contrast, GAD-ab-positive patients had initially less impaired learning and memory scores but did not show an improvement under treatment.

CONCLUSIONS

The results provide evidence of distinct relations between inductive processes and cognitive outcome in VGKC-ab-positive and GAD-ab-positive subforms of limbic encephalitis, which possibly depend on differences in pathogenic molecular mechanisms and affected cerebral loci.