Abstract Details

Title Hippocampal, Fornix, Uncinate, and Amygdala Degeneration in Amyotrophic Lateral Sclerosis: the Pathological Substrate of Memory Impairment

Topic Neuromuscular and Clinical Neurophysiology (EMG)

Presentation(s) S18 - Neuromuscular and Clinical Neurophysiology (EMG): Neuroimaging, Outcome Measures, and Biomarkers (1:48 PM-2:00 PM)

Poster/Presentation
Number 005

Objective The comprehensive evaluation of mesial temporal lobe structures; hippocampal subfields, amygdala, fornix, uncinate fasciculus, and perforant pathway zone in ALS compared to disease controls and healthy controls.

Background Hippocampal involvement is a recognized post-mortem feature of ALS based on both macroscopic observations and pTDP-43 patterns. Memory impairment in ALS however is under recognized and seldom screened for. Radiologically, the involvement of specific hippocampal subfields and their white matter connectivity patterns are poorly characterized in vivo.

Design/Methods 50 well-characterized ALS patients, 18 patients with Alzheimer’s disease and 40 healthy controls were included in a prospective multimodal neuroimaging study. Study participants underwent comprehensive neuropsychological profiling including detailed memory assessments. A multimodal approach was implemented to characterize mesial temporal lobe pathology in the three study groups. Total hippocampal volumes, amygdala volumes and total intracranial volume were estimated. Hippocampal segmentation was performed to estimate subfield volumes. Vertex analyses were undertaken to characterize shape deformations and morphometry was carried out to identify disease-specific grey matter signatures. White matter tractography was performed for the fornix, uncinate fasciculus and perforant pathway zone to generate tract-wise fractional anisotropy, axial diffusivity, and radial diffusivity values.

Results Patients with ALS and AD have divergent hippocampal signatures. The Cornu Ammonis 2/3 subfield and the hippocampus-amygdala transition area are the most affected regions in ALS in contrast to AD, where the presubiculum and subiculum are the most vulnerable regions. Tractography reveals considerable fornix and perforant pathway pathology in both patient groups. Mesial temporal lobe structures in ALS have a selective and disease-specific vulnerability profiles and their white matter projections exhibit concomitant degeneration.

Conclusions Our combined grey and white matter analyses indicate a connectivity-based, network-defined involvement of interconnected temporal lobe structures as opposed to the contiguous involvement of adjacent structures. Our imaging findings underline the importance of screening for memory deficits and personalised management strategies in ALS.

Authors/Disclosures
Peter Bede, MD, PhD (Academic Unit of Neurology) PRESENTER	Dr. Bede has nothing to disclose.
	No disclosure on file
Michail Rentzos, PhD	No disclosure on file
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Foteini Christidi, PhD	No disclosure on file

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