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Background and ObjectivesSpontaneous intracranial hypotension (SIH) is characterized by loss of CSF volume. We hypothesize that in this situation of low volume, a larger CSF flow and spinal cord motion at the upper spine can be measured by noninvasive phase contrast MRI.MethodsA prospective, age-, sex-, and body mass index (BMI)-matched controlled cohort study on patients with SIH presenting with spinal longitudinal extradural fluid collection (SLEC) was conducted from October 2021 to February 2022. Cardiac-gated 2D phase contrast MRI sequences were acquired at segment C2/C3, and C5/C6 for CSF flow, and spinal cord motion analysis. Data processing was fully automated. CSF flow and spinal cord motion were analyzed by peak-to-peak amplitude and total displacement per segment and heartbeat, respectively. Clinical data included age, height, BMI, duration of symptoms, Bern score according to Dobrocky et al., and type of the spinal CSF leak according to Schievink et al. Groups were compared via the Mann-WhitneyUtest; multiple linear regression analysis was performed to address possible relations.ResultsTwenty patients with SIH and 40 healthy controls were analyzed; each group consisted of 70% women. Eleven patients with SIH presented with type 1 leak, 8 with type 2, and 1 was indeterminate. CSF flow per heartbeat was increased at C2/C3 (peak-to-peak amplitude 65.68 ± 18.3 vs 42.50 ± 9.8 mm/s, total displacement 14.32 ± 3.5 vs 9.75 ± 2.7 mm,p< 0.001, respectively). Craniocaudal spinal cord motion per heartbeat was larger at segment C2/C3 (peak-to-peak amplitude 7.30 ± 2.4 vs 5.82 ± 2.0 mm/s, total displacement 1.01 ± 0.4 vs 0.74 ± 0.4 mm,p= 0.006, respectively) and at segment C5/C6 (total displacement 1.41 ± 0.7 vs 0.97 ± 0.4 mm,p= 0.021).DiscussionSLEC-positive patients with SIH show higher CSF flow and higher spinal cord motion at the upper cervical spine. This increased craniocaudal motion of the spinal cord per heartbeat might produce increased mechanical strain on neural tissue and adherent structures, which may be a mechanism leading to cranial nerve dysfunction, neck pain, and stiffness in SIH. Noninvasive phase contrast MRI of CSF flow and spinal cord motion is a promising diagnostic tool in SIH.Trial Registration InformationGerman Clinical Trials Register, identification number: DRKS00017351.Classification of EvidenceThis study provides Class III evidence that noninvasive phase contrast MRI of the upper spine identifies differences in CSF flow and spinal cord motion in patients with SIH compared with healthy controls.