Title : Choroid plexus dysfunction and impaired cerebrospinal fluid flow in long COVID: A multimodal MRI and biomarker study
Abstract:
Background
Long COVID (Post-COVID Syndrome, PCS) is characterized by persistent neurological symptoms such as fatigue, cognitive impairment, and autonomic dysfunction. Our previous research revealed significant structural and functional abnormalities in the brainstem and cerebellar peduncles, including volume reduction, impaired white matter integrity, and decreased cerebrospinal fluid (CSF) flow velocity. Notably, regions surrounding the fourth
ventricle and cerebellar peduncles-critical for CSF circulation-were especially aBected, supporting the “Broken Bridge Syndrome” hypothesis.
Recent Advances in Choroid Plexus Research: Scientific Rationale
A recent systematic review (Annual Review of Pathology: Mechanisms of Disease, 2025)6 has highlighted the central role of the choroid plexus (ChP) in viral infections and the development of chronic neurological disorders. The ChP serves as a gateway and reservoir for neurotropic viruses, is associated with persistent neuroinflammation, and is implicated in barrier dysfunction and the pathogenesis of chronic CNS symptoms. Further, the ChP is increasingly recognized as a key orchestrator of neuroimmune processes and a promising therapeutic target.
Novelty and Innovation
This study introduces several novel aspects that advance the field beyond current literature:
• Mechanistic Link Between ChP Dysfunction and CSF Flow in Long COVID:
While ChP enlargement and inflammation have been described in neuroinflammatory and neurodegenerative conditions, the explicit mechanistic relationship between ChP dysfunction and impaired CSF flow in Long COVID has not been systematically investigated. Our protocol is the first to directly address this gap by integrating advanced
CSF flow quantification with ChP imaging and biomarker analysis67.
• Advanced Multimodal Imaging Approaches:
We will employ state-of-the-art MRI techniques, including high-resolution T1-weighted imaging for ChP volumetry, phase-contrast MRI for CSF flow, and the latest
developments in quantitative ChP contrast enhancement mapping (e.g., ΔT1 mapping, as recently applied in multiple sclerosis research)35. These methods allow for sensitive, reproducible, and non-invasive assessment of ChP structure and function, as well as blood-CSF barrier integrity.
• Integration of Organoid Models and Translational Imaging:
Building on recent advancements in ChP organoid research and functional imaging4, our study will leverage imaging protocols validated in 3D ChP organoid models to inform in vivo data interpretation and provide a translational bridge from bench to bedside.
• Artificial Intelligence for ChP Segmentation:
We will utilize and validate deep learning-based segmentation tools for the ChP, which have shown accuracy comparable to manual segmentation and enable robust,
automated analysis in large datasets and across imaging centers5.
• Comprehensive Biomarker Correlation:
The study will uniquely correlate ChP imaging findings with a broad panel of inflammatory and autoantibody biomarkers, cognitive testing, and clinical symptom profiles, providing a holistic view of ChP involvement in Long COVID pathophysiology.
• Potential for New Diagnostic and Therapeutic Strategies: By elucidating the role of the ChP as both a mediator of neuroinflammation and a regulator of CSF dynamics, this research may identify new imaging biomarkers and
therapeutic targets for intervention in Long COVID and related chronic CNS conditions6.
Objectives
Primary Objective:
• To compare choroid plexus volume, morphology, and CSF flow dynamics between Long COVID patients and healthy controls using advanced MRI techniques.
Secondary Objectives:
• To correlate ChP and CSF flow parameters with cognitive performance, autoantibody profiles, and inflammatory markers.
• To investigate the relationship between ChP dysfunction, brainstem/cerebellar changes, and clinical symptom severity.
Methods
Study Design
• Type: Prospective case-control study, employing multimodal imaging and biomarker analysis.
• Setting: University Medical Center Hamburg-Eppendorf, Department of Neuroradiology. Participants
• Inclusion Criteria: Adults (18–65 years) with Long COVID according to NICE/WHO
criteria (>12 weeks of symptoms), laboratory-confirmed SARS-CoV-2 infection.
• Exclusion Criteria: Pre-existing CNS disorders or severe psychiatric illnesses.
• Controls: Age- and sex-matched healthy volunteers.
Imaging Protocol
• MRI Scanner: 3T Siemens Skyra
• Sequences:
o High-resolution T1-weighted MPRAGE for ChP volumetry.
o Phase-contrast MRI for CSF flow quantification (aqueduct, fourth ventricle).
o ΔT1 mapping for ChP contrast enhancement and blood-CSF barrier assessment3.
o DTI for white matter integrity analysis.
o 3D reconstructions using FreeSurfer and Horos.
• Analysis: Automated and AI-supported segmentation and volumetry of the ChP, CSF flow measurement, comparison of brainstem and cerebellar peduncle volumes. Biomarker and Clinical Assessment
• Blood/CSF: Autoantibody panels (β2, M2, anti-adrenergic, anti-muscarinic), cytokines (IL-6, IL-1β, IL-8), and standard inflammatory markers.
• Cognitive/Clinical: MoCA, Trail Making Test, autonomic function (heart rate variability, blood pressure variability).
Statistical Analysis
• Group Comparisons:
Independent t-tests or Mann-Whitney U tests.
• Correlations: Pearson or Spearman coeBicients.
• Multivariate Regression: Adjustment for age, sex, and COVID-19 severity.
• E/ect Sizes: Hedges’ g for imaging metrics.
Ethics and Dissemination
• Ethics: Approved by the Ethics Committee of the University Medical Center Hamburg- Eppendorf.
• Data Availability: Anonymized data available upon reasonable request.
• Dissemination: Results will be submitted to BMC Medical Imaging and presented at international conferences.
Impact
This study will be the first to systematically assess the mechanistic link between choroid plexus dysfunction and impaired CSF flow in Long COVID, integrating cutting-edge imaging, AI-driven analysis, translational organoid models, and comprehensive biomarker profiling. The findings may yield novel diagnostic markers and therapeutic targets for Long COVID and other chronic neuroinflammatory disorders.
Key References
1. Annual Review of Pathology: Mechanisms of Disease (2025). Choroid Plexus Pathophysiology.6
2. ISMRM 2025. Novel IVIM approach for ChP structure and perfusion assessment.1
3. medRxiv (2025). Quantitative ChP contrast enhancement and tissue injury in MS.3
4. Springer (2025). 3D ChP organoid imaging and functional analysis.4
5. J Magn Reson Imaging (2023/2024). AI-based ChP segmentation and validation.5
6. ISMRM 2025. ChP morphology and CSF flow dynamics.7
7. PMC (2025). ChP volume as a neuroimaging marker in Alzheimer’s continuum.8
