Diagnostic relevance of β2-transferrin for the detection of cerebrospinal fluid fistulas

Objective: The beta(2)-transferrin assay is a specific method to identify cerebrospinal fluid (CSF). Hitherto, this test has not been widely used for the routine screening of patients with suspected CSF leakage. The purpose of this study was to investigate the clinical relevance of the identification of beta(2)-transferrin by comparing the test results with other diagnostic measures and intraoperative findings. Design: Case series. Patients: Retrospective analysis of 182 patients tested once or multiple times for beta(2)-transferrin. Main Outcome Measures: Information was obtained regarding different diagnostic procedures applied to diagnose CSF leakage. The effectiveness of those diagnostic measures was compared. Results: The main indication to test for beta(2)-transferrin was,posttraumatic rhinorrhea (25%), followed by spontaneous (22%) and postsurgical (22%) rhinorrhea. In 35 of 205 cases, beta(2)-transferrin was detected in the tested specimens. Thirteen of these required surgical intervention for treatment of the CSF fistula, and the leakage site was identified in all of them. Taking all results into consideration, the highest correlation was observed be-tween the beta(2)-transferrin assay, intrathecal fluorescein application, and surgical exploration. Conclusions: The beta(2)-transferrin assay is a reliable method for confirming suspected CSF and should be used as a primary screening method in all patients with suspected CSF leakage. Although less invasive, the beta(2)-transferrin assay almost matches the high sensitivity achieved by exploratory surgery and intrathecal application of fluorescein. However, the possibility of bias should be carefully considered, and in particular, negative results should be critically compared with clinical symptoms and with results from other diagnostic procedures.