β-Trace Protein as a Potential Biomarker for CSF-Venous Fistulas.

Background And Purpose: Accurately identifying patients with CSF-venous fistulas (CVF) causing spontaneous intracranial hypotension, is a diagnostic dilemma. This conundrum underscores the need for a CVF biomarker to help select who should undergo an invasive myelogram for further diagnostic work-up. β-trace protein (BTP) is the most abundant CNS-derived protein in the CSF and, therefore, is a potential venous biomarker for CVF detection. The purpose of our study was to measure venous BTP levels as a potential CVF biomarker.

Materials And Methods: We prospectively enrolled 14 patients with CVFs and measured the BTP in venous blood samples from the paraspinal veins near the CVF and compared those levels with those in the peripheral blood. Myelograms used initially to identify the CVF were evaluated for technique, CVF laterality, CVF level, and the venous drainage pattern. Patient sex and age and symptom duration were also collected. Brain MR images were reviewed for Bern scores. We also measured the peripheral blood BTP levels in 20 healthy controls.

Results: In patients with CVF, the mean BTP level near the CVF was 54.5% higher (0.760 [SD, 0.673] mg/L versus 0.492 [SD, 0.095] mg/L; = .069) compared with peripheral blood. Nine (64.3%) patients with CVFs had a higher paraspinal BTP level than peripheral BTP level. The 20 control patients had a higher mean peripheral BTP level of 0.720 (SD, 0.191) mg/L compared with patients with CVF ( < .001).

Conclusions: We found that venous blood at the site of the CVF had higher BTP values compared with peripheral blood in most but not all patients with CVF. This finding may reflect the intermittent leaking nature of CVF. Additionally, we found that patients with CVF had a lower peripheral blood BTP level compared with healthy controls. BTP requires further evaluation as a potential CVF biomarker.