Patterns of cerebrospinal fluid (CSF) distribution in patients with spontaneous intracranial hypotension: Assessed with magnetic resonance myelography

Background: Diagnosis of spontaneous intracranial hypotension (SIH) relies on the ability of medical staff to recognize cerebrospinal fluid (CSF) leakage at the spine. However, difficulties with interobserver discrepancy sometimes occurred while reading magnetic resonance myelography (MRM) because clear image definition was lacking. In this study, we tried to determine which pattern of CSF distribution is more reliable for diagnosis of CSF leakage by using MRM.

Methods: From January 2012 to August 2014, 19 SIH patients and 27 healthy controls (HC) were recruited into our study; 10 of the 19 patients were recovered (SIH-R) after treatment. Whole spine MRM was performed using the 3D-SPACE (three-dimensional sampling perfection with application-optimized contrasts using different flip-angle evolutions) sequence, and interpreted by two experienced neuroradiologists. Two 4-point classification systems of CSF distribution were used to evaluate the three-dimensional maximum intensity projection (3D MIP) and the thin-slice axial multiplanar reconstruction (MPR) images, respectively.

Results: The interobserver agreement between the two readers interpreting the 3D MIP and thin-slice axial MPR MRM were moderate to good (κ=0.60-0.78). Grade 3 of 3D MIP and Type D of axial MPR MRM were only noticed in the SIH. Overall, Grade 3 of MIP and Type D of MPR showed significant difference (p<0.008) between the SIH and the HC in the whole spine. Type C at the T-spine was more frequently noted in the SIH than in the HC (p<0.038). By using "Grade 3", "Type D", "Type D and Type C at T-spine" as the diagnostic criteria of CSF leakage, the sensitivity, specificity, positive predict value (PPV), and negative predict value (NPV) were all > 70%.

Conclusion: Grade 3 on 3D MIP and Type D on axial MPR MRM were definite criteria of MRM for localizing CSF leakage, and Type C in the T-spine was a probable leakage sign with high sensitivity and NPV.