CSF pressures in spontaneous intracranial hypotension due to CSF-venous fistula: A retrospective analysis

Objective

To report CSF pressure (P_csf) and its correlations in patients with SIH due to CSF-venous fistula (CVF).

Methods

Following IRB approval, consecutive SIH patients undergoing myelography between 2021 and 2025 at a single center were retrospectively analyzed. P_csf was defined as opening pressure (OP) during myelography, with patient in decubitus positioning with mild hip elevation. Low OP was defined as < 6 cm H₂O; elevated OP as > 20 cm H₂O.

Results

Of the 86 SIH patients analyzed, 35 (41 %) had a CVF [average age 59 ± 13; 12/35 (34 %) male; 23/35 (66 %) female]. Of the 35, OP was reported for 32 patients. The mean ± SD OP was 13.97 ± 3.91 cm H₂O (range: 6–25 cm H₂O). None (0 %) of the patients had low OP. 29/32 (91 %) had OP in normal range, 3/32 (9 %) had elevated OP. P_csf was positively correlated with BMI (p = 0.045); but not correlated with age, sex, prior epidural blood patching, symptom duration, or mean arterial pressure. High variability in P_csf values was not fully accounted for by predictors included in our model (pseudo-R² = 0.188).

Conclusions

An absence of low P_csf should not be used to rule out SIH, as all our patients with SIH due to CVF had normal or elevated P_csf. Such P_csf readings in patients with active CSF leaks suggest that the development of CVF and post-treatment rebound headaches may be due to pre-existing intracranial hypertension. While BMI is positively correlated with P_csf, limited explanatory power of our model suggests influence of other factors.