Brain distortion and cerebrospinal fluid shifts in spontaneous intracranial hypotension.

BACKGROUND: Spinal cerebrospinal fluid (CSF) leaks in spontaneous intracranial hypotension (SIH) are assumed to cause intracranial CSF volume changes and brain sagging. The spatial pattern of CSF and brain volume changes, or shifts, remains incompletely characterized. We aimed to quantify CSF and brain shifts before and after surgical closure of spinal CSF leaks. METHODS: We retrospectively analyzed 96 patients with SIH before and after surgical closure of their spinal CSF leaks. Artificial intelligence (AI)-assisted automated diffeomorphic registration and brain region segmentation of pre- and postoperative MRI imaging were used to extract a perioperative displacement map of the brain and the mean 3D displacement vector for each anatomical region. Regions were tested for significant changes using Hotelling's T2 and compared against a healthy control cohort (n = 61) processed identically. RESULTS: When comparing pre- and postoperative scans, brain structures demonstrated a consistent, predominantly upward-outward shift. Most major brain regions exhibited small, but statistically significant movement, with the highest magnitude seen in the parietal lobes and the left lateral ventricle (> 0.7 mm, p < 0.0001). Functionally connected regions, such as those within the fronto-limbic and visual networks, exhibited shifts in various directions, resulting in regional deformation. Displacement exceeded that of healthy controls roughly threefold (0.51 versus 0.16 mm across regions). CONCLUSION: Surgical CSF-leak closure in SIH leads to postoperative brain shift and tectonic-like deformation quantifiable on MRI. AI-assisted measurements reveal subtle brain movements and distortions, which could contribute to understanding of spinal leak pathophysiology and complement clinical assessment during follow-up.