Outcome of limbic encephalitis with VGKC-complex antibodies: relation to antigenic specificity

Area of Science:

• Neurology
• Immunology
• Neuroscience

Background:

• Limbic encephalitis (LE) is often associated with antibodies (Abs) targeting the voltage-gated potassium channel complex (VGKC).
• Key antigens include leucine-rich, glioma inactivated 1 protein (LGI1) and contactin-associated protein-like 2 (CASPR-2).
• Understanding outcomes based on specific antibody targets is crucial for patient management.

Purpose of the Study:

• To correlate clinical outcomes in VGKC-LE patients with the presence of antibodies to LGI1, CASPR-2, or neither.
• To evaluate the long-term effects of specific antibody targets on seizure control, cognitive function, and brain imaging.

Main Methods:

• Retrospective analysis of 18 VGKC-LE patients diagnosed between 2002-2011 at Bonn Epilepsy Centre.
• Patients were categorized based on radioimmunoprecipitation assay results for LGI1-Abs, CASPR-2-Abs, or absence of both.
• Clinical data, neuropsychological assessments, and MRI findings were collected and analyzed.

Main Results:

• Nine patients had LGI1-Abs, three had CASPR-2-Abs, and six had neither.
• Faciobrachial dystonic seizures were specific to LGI1-Ab positive patients.
• While 72% of all patients became seizure-free with methylprednisolone pulses, 7/9 LGI1-Ab(+) patients developed hippocampal atrophy, unlike other groups (p=0.003).
• Memory scores normalized in only 33% of patients, with LGI1-Ab(+) patients exhibiting significantly poorer memory recovery.

Conclusions:

• Most VGKC-LE patients respond well to pulsed intravenous methylprednisolone, achieving seizure freedom.
• LGI1-antibody positive LE is associated with a higher risk of hippocampal atrophy and persistent memory deficits, suggesting permanent neuronal damage.
• Intensified immunotherapy strategies may be necessary to improve long-term cognitive outcomes in LGI1-Ab(+) LE.