Objective: We try to discover changes in CSF dynamics and regional brain activation due to pre and post CSF drainage with 7T fMRI and 3T Cine MRI.

Background: Normal pressure hydrocephalus (NPH) is not uncommon neurodegenerative disease sharing the symptoms of dementia and parkinsonism. Conventional treatment of NPH is cerebrospinal fluid (CSF) drainage or ventriculoperitoneal shunt however, we don’t know the mechanism and after effect of CSF drainage yet.

Method: NPH patients were enrolled who aged 60~80, Evan’s ratio > 0.3 and showed triad of NPH. Evaluation items before and after CSF drainage were cognitive test like mini-mental state examination (MMSE), Clinical Dementia Rating (CDR), Montreal Cognitive Assessment (MoCA), Frontal Assessment Battery (FAB) and, gait parameters such as 10m gait, time up and go (TUG) and time up and go-cognition (TUG-cog). Patients follow the motor task such as stomping feet during 7T fMRI scan. And then participants synchronized the heart rate and CSF pulse by attaching portable EKG during 3T Cine Phase-Contrast MRI. Normal control groups also had 7T fMRI and 3T Cine-MRI.

Results: 6 NPH patients and 3 healthy individuals were enrolled. The mean age of the NPH group was 72.0 ± 7.0 years, with a mean disease duration of 2.6 ± 2.3 years and a mean Evans’ ratio of 0.35 ± 0.02. Following the tap test, 4 of 5 patients showed ≥10% improvement in either 3m TUG time or 10m gait velocity. More focal activation of motor cortex corresponding to the legs observed after post drainage rather than pre drainage of CSF in 7T fMRI. Activity of left ventral prefrontal cortex (PFC) increased, and activity of parietal lobe decreased after CSF drainage in 7T fMRI. Absolute stroke volume (ASV) which stands for the total amount of CSF through the aqueduct of Sylvius decreased after CSF drainage. However, ASV of pre and post CSF drainage in NPH patients is higher than ASV of healthy individuals. Cumulative net flow increase and direction of CSF circulation augmented to craniocaudal after CSF drainage.

Conclusion: CSF drainage changes the regional activation of cerebral cortices and increases the brain compliance for the hyper pulsatile flow of CSF. The evaluation of CSF dynamics could be a clue for understanding of the mechanism of NPH and clinical efficiency for managing NPH.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/changes-in-csf-dynamics-and-regional-brain-activation-following-csf-drainage-in-normal-pressure-hydrocephalus-a-combined-7t-fmri-and-3t-cine-mri-pilot-study/