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

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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.
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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).
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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.

Table 1:

Frequency and measurements of intracranial findings^{^a}

	CSF Leak (n = 76)	No CSF Leak (n = 98)	P Value
Smooth dural enhancement	54 (57.4%)	9 (12.5%)	P < .001^{^b}
Dural enhancement in IACs	34 (36.2%)	4 (5.6%)	P < .001^{^b}
Subdural fluid collections	9 (9.2%)	4 (5.3%)	P = .32
Superficial siderosis	3 (3.1%)	1 (1.3%)	P = .44
Pituitary engorgement	56 (57.1%)	17 (22.4%)	P < .001^{^b}
Non-Chiari cerebellar tonsillar descent of >5 mm	22 (22.4%)	8 (10.5%)	P = .04^{^b}
Dural venous sinus engorgement	Yes = 25 (25.8%) Indeterminate = 27 (27.8%)	Yes = 5 (6.6%) Indeterminate = 4 (5.3%)	P < .001^{^b}
Layered hyperostosis	8 (8.2%)	3 (3.9%)	P = .25
Cerebral aqueduct iter below incisural line	33 (33.7%)	15 (19.7%)	P = .04^{^b}
Average mamillopontine distance (mm)	5.5 (SD, 2.1) mm	5.9 (SD, 1.7) mm	P = .13
Average prepontine cistern size (mm)	4 (SD, 1.5) mm	4.2 (SD, 1.6) mm	P = .35
Average suprasellar cistern size (mm)	3.2 (SD, 2.1) mm	4.8 (SD, 2.7) mm	P < .001^{^b}

↵a Indeterminate dural sinus engorgement is counted as positive in this analysis.
↵b Statistically significant P values.

Table 2:

Scoring system based on 7 intracranial imaging findings

Finding	Points
Smooth dural enhancement	1
Dural enhancement in the IACs	1
Pituitary engorgement	1
Non-Chiari cerebellar descent of >5 mm	1
Dural venous sinus engorgement	1
Cerebral aqueduct iter below incisural line	1
Suprasellar cistern ≤2.5 mm	1