Assessing Spinal Cerebrospinal Fluid Leaks in Spontaneous Intracranial Hypotension With a Scoring System Based on Brain Magnetic Resonance Imaging Findings

Abstract

Importance: Various signs may be observed on brain magnetic resonance imaging (MRI) in patients with spontaneous intracranial hypotension (SIH). However, the lack of a classification system integrating these findings limits decision making in clinical practice.

Objective: To develop a probability score based on the most relevant brain MRI findings to assess the likelihood of an underlying spinal cerebrospinal fluid (CSF) leak in patients with SIH.

Design, setting, and participants: This case-control study in consecutive patients investigated for SIH was conducted at a single hospital department from February 2013 to October 2017. Patients with missing brain MRI data were excluded. Three blinded readers retrospectively reviewed the brain MRI scans of patients with SIH and a spinal CSF leak, patients with orthostatic headache without a CSF leak, and healthy control participants, evaluating 9 quantitative and 7 qualitative signs. A predictive diagnostic score based on multivariable backward logistic regression analysis was then derived. Its performance was validated internally in a prospective cohort of patients who had clinical suspicion for SIH.

Main outcomes and measures: Likelihood of a spinal CSF leak based on the proposed diagnostic score.

Results: A total of 152 participants (101 female [66.4%]; mean [SD] age, 46.1 [14.3] years) were studied. These included 56 with SIH and a spinal CSF leak, 16 with orthostatic headache without a CSF leak, 60 control participants, and 20 patients in the validation cohort. Six imaging findings were included in the final scoring system. Three were weighted as major (2 points each): pachymeningeal enhancement, engorgement of venous sinus, and effacement of the suprasellar cistern of 4.0 mm or less. Three were considered minor (1 point each): subdural fluid collection, effacement of the prepontine cistern of 5.0 mm or less, and mamillopontine distance of 6.5 mm or less. Patients were classified into groups at low, intermediate, or high probability of having a spinal CSF leak, with total scores of 2 points or fewer, 3 to 4 points, and 5 points or more, respectively, on a scale of 9 points. The discriminatory ability of the proposed score could be demonstrated in the validation cohort.

Conclusions and relevance: This 3-tier predictive scoring system is based on the 6 most relevant brain MRI findings and allows assessment of the likelihood (low, intermediate, or high) of a positive spinal imaging result in patients with SIH. It may be useful in identifying patients with SIH who are leak positive and in whom further invasive myelographic examinations are warranted before considering targeted therapy.

Figure 1.. Illustration of Typical Findings on Brain Magnetic Resonance Imaging in Intracranial Hypotension

A, Coronal illustration of the brain demonstrating normal findings. B, Coronal illustration of the brain with typical findings in a patient with a spinal cerebrospinal fluid leak with venous engorgement of the superior sagittal sinus (arrowhead 1), pachymeningeal enhancement (arrowhead 2), superficial siderosis (arrowhead 3), enlarged pituitary gland (arrowhead 4), prominent intercavernous sinus (arrowhead 5), effaced suprasellar cistern (arrowhead 6), and subdural fluid collection (arrowhead 7). C, Sagittal illustration of the posterior fossa demonstrating normal findings. D, Sagittal illustration of the posterior fossa with typical findings in patients with a spinal cerebrospinal fluid leak with effaced suprasellar cistern (arrowhead 8; pathologic ≤4 mm), effacement of the prepontine cistern (arrowhead 9; pathologic ≤5 mm), decreased mamillopontine distance (arrowhead 10; pathologic ≤6.5 mm), and low-lying cerebellar tonsils (arrowhead 11).

Figure 2.. Imaging Findings Included in the Final Diagnostic Score

A, Coronal T2-weighted magnetic resonance imaging (MRI) with subdural effusion (white arrowhead 1). B, Coronal T1-weighted MRI after gadolinium injection of the same patient, with dural enhancement (white arrowhead 2) and venous engorgement (white arrowhead 3). C, Sagittal T2-weighted MRI with effaced suprasellar cistern (black arrowhead 4; pathologic ≤4 mm), decreased mamillopontine distance (black arrowhead 5; pathologic ≤6.5 mm), and effaced prepontine cistern (black arrowhead 6; pathologic ≤5 mm).

Figure 3.. Predictive Model Scores

A, Scores for individuals in the derivation cohort: patients with spontaneous intracranial hypotension (SIH) who are leak positive, healthy control participants, and patients with orthostatic headache without a cerebrospinal fluid leak. B, Scores for individuals in the internal validation cohort including patients with spontaneous intracranial hypotension and a myelographically confirmed leak and patients presenting with orthostatic headache without a cerebrospinal fluid leak.