Poster C96, Sunday, March 26, 5:00 – 7:00 pm, Pacific Concourse
Neurobehavioural characteristics of limbic encephalitis associated with voltage-gated potassium channel complex antibodies.
Clare Loane1, Adriana Roca-Fernandez1,2, Carmen Lage-Martinez1,3, Samrah Ahmed1, Christopher R Butler1; 1Memory Research Group, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK., 2Oxford Multiple Sclerosis and Neuromyelitis Group, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK., 3Cognitive Disorders Unit, Hospital Universitario Marques de Valdecilla, Santander, Spain.
Limbic encephalitis associated with antibodies to the voltage-gated potassium channel complex (VGKC-LE) often results in memory impairment with accompanying hippocampal damage thus could provide an opportune human model of hippocampal amnesia. However, comprehensive characterisation of the neurobehavioural profile of VGKC-LE patients is currently lacking. A group of VGKC-LE patients (n =17) and matched healthy controls underwent clinical interview, extensive neuropsychology testing as well as structural magnetic resonance imaging (MRI) and resting-state functional MRI (rs-fMRI). Manual delineation of medial temporal lobes (MTL) structures and FreeSurfer cortical parcellation were employed to investigate atrophy patterns. Seed-based connectivity analysis investigated aberrant functional connectivity of the anterior and posterior memory networks. We confirm long-term cognitive impairment is confined to the memory domain. Structural MRI analyses confirms focal hippocampal atrophy with no evidence for a consistent reduction of other sub-cortical or cortical regions. No significant association between hippocampal atrophy measures and memory performance was detected. Reduced functional connectivity was evident from anterior hippocampi to each contralateral temporal pole. Functional connectivity between left anterior hippocampus and right temporal pole was significantly correlated with WMS-IV Word List delayed recall scores (r = -0.584; p = 0.05) in patients. We have demonstrated that VGKC-LE patients present with persistent memory impairment and focal hippocampal atrophy. However, the presence of hippocampal atrophy alone does not clearly explain the memory deficits. Instead, our data strongly suggest that a functional disturbance at rest is a contributory factor and could explain inconsistencies currently existing in the hippocampal amnesia literature.
Topic Area: LONG-TERM MEMORY: Episodic