Spine MRI Diverticular Patterns Predict CSF-Venous Fistula Location: A 100-Patient Study.

Abstract

Background and purpose: CSF-venous fistulas (CVFs) are an increasingly recognized cause of spontaneous intracranial hypotension and require invasive myelography for localization. Whether spine MRI can noninvasively predict CVF origin remains unclear. The purpose of our study was to determine if spine MRI features, particularly the size and location of spinal meningeal diverticula, are predictive of the CVF location identified on myelography.

Materials and methods: Retrospective review of 100 patients with a CVF confirmed on decubitus CT myelography who underwent preprocedural spine MRI. The primary outcome was whether the CVF arose at or adjacent to the largest diverticulum. Secondary outcomes included distribution patterns of largest adjacent-level diverticula and their spatial relationship to the CVF (cranial, caudal, ipsilateral, contralateral). Chi-square tests, one-sided binomial tests, and t-tests were used to assess statistical significance.

Results: CVFs originated at or adjacent to the largest diverticulum in 77% of patients, significantly more than expected by chance (P < .001). 71.7% of CVFs were within one level of the adjacent largest diverticulum on spine MRI. Among adjacent-level cases of the largest diverticula, there was a significant directional preference for the adjacent largest diverticulum to occur caudal to the CVF compared to a uniform distribution (P = .001). There were three specific diverticular patterns that were statistically significant: caudal and ipsilateral 1 level below the CVF (P < .001), contralateral same level (P < .001), and caudal and contralateral 1 level (P= 0.002). There was no significant correlation between the laterality of the largest diverticulum size nor the laterality of the majority of the diverticula compared to the laterality of the CVF.

Conclusions: Spinal CVFs most commonly arise at or adjacent to the largest meningeal diverticulum. The adjacent largest diverticulum was commonly within one level to the CVF and most commonly caudal one level to the CVF or at the same level contralateral side to the CVF. These MRI-based predictors may help guide myelography.

Abbreviations: CVF ＝ CSF-venous fistula; CTM ＝ CT myelogram.