Likelihood of Discovering a CSF Leak Based on Intracranial MRI Findings in Patients without a Spinal Longitudinal Extradural Collection: A New Probabilistic Scoring System

Abstract

Background and purpose: The likelihood of discovering a CSF leak can be determined by assessing intracranial abnormalities. However, the Dobrocky scoring system, which is used to determine this likelihood, did not incorporate patients with CSF-venous fistulas. This study sought to create a new probabilistic scoring system applicable to patients without a spinal longitudinal extradural collection.

Materials and methods: A retrospective review was completed of patients with suspected spontaneous intracranial hypotension who underwent brain MR imaging followed by digital subtraction myelography with same-day CT myelography. Patients with and without leaks found on digital subtraction myelography were included. MRIs were assessed for numerous reported stigmata of spontaneous intracranial hypotension and were compared between cohorts.

Results: One hundred seventy-four patients were included; 113 (64.9%) were women (average age, 52.0 [SD, 14.3] years). A CSF leak was found in 98 (56.3%) patients, nearly all of which (93.9%) were CSF-venous fistulas. Diffuse dural enhancement, internal auditory canals dural enhancement, non-Chiari cerebellar descent, pituitary engorgement, brain sag, dural venous sinus engorgement, and decreased suprasellar cistern size were associated with a CSF leak. A probabilistic scoring system was made in which a single point value was assigned to each of those findings: 0-2 considered low probability and ≥3 considered intermediate-to-high probability of a CSF leak.

Conclusions: This study offers a new probabilistic scoring system for evaluating the likelihood of discovering a CSF leak on the basis of intracranial MR imaging findings, though the new system is not superior to that of the Dobrocky method for predicting the presence of CSF leaks.

FIG 1.

An example of a distal nerve root sleeve tear (type 4 leak) diagnosed using a combination of DSM and delayed CTM findings. Left lateral decubitus unsubtracted image from a DSM (A) demonstrates contained contrast within a left T12 meningeal diverticulum (A, arrow). On a 30-minute delayed left decubitus CTM (B), there is a subtle contrast leak posterior to the diverticulum (B, arrow). The combined findings from a DSM and delayed CTM are often necessary to confidently diagnose type 4 leaks.

FIG 2.

An example of multiple intracranial sequelae of SIH in a 69-year-old woman. Axial (A) and sagittal (B) postcontrast images demonstrate diffuse smooth dural enhancement, with involvement of the IACs (arrows, A). The right transverse sinus is engorged (dashed circle, B).

FIG 3.

Schematics of intracranial findings used for the probabilistic scoring system developed in this study. Pertinent findings included diffuse dural enhancement and dural enhancement involving the walls of the IACs (pink lines, A), engorgement of the transverse sinus and non-Chiari cerebellar descent (B), and pituitary engorgement, effacement of the suprasellar cistern, and descent of the aqueduct iter below the incisural line (dotted line, C). Used with permission of Mayo Foundation for Medical Education and Research, all rights reserved.