Diffuse pachymeningeal hyperintensity and subdural effusion/hematoma detected by fluid-attenuated inversion recovery MR imaging in patients with spontaneous intracranial hypotension

Abstract

Background and purpose: Fluid-attenuated inversion recovery (FLAIR) MR imaging has advantages to detect meningeal lesions. FLAIR MR imaging was used to detect pachymeningeal thickening and thin bilateral subdural effusion/hematomas in patients with spontaneous intracranial hypotension (SIH).

Materials and methods: Eight patients were treated under clinical diagnoses of SIH. Chronologic MR imaging studies, including the FLAIR sequence, were retrospectively reviewed.

Results: Initial MR imaging showed diffuse pachymeningeal thickening as isointense in 6 cases, hypoisointense in 1 case, and isohyperintense in 1 case on the T1-weighted MR images, and hyperintense in all cases on both T2-weighted and FLAIR MR images. Dural (pachymeningeal) hyperintensity on FLAIR MR imaging had the highest contrast to CSF, and was observed as linear in all patients, usually located in the supratentorial convexity and also parallel to the falx, the dura of the posterior fossa convexity, and the tentorium, and improved after treatment. These characteristics of diffuse pachymeningeal hyperintensity on FLAIR MR imaging were similar to diffuse pachymeningeal enhancement (DPME) on T1-weighted imaging with gadolinium. Initial FLAIR imaging clearly showed subdural effusion/hematomas in 6 of 8 patients. The thickness of subdural effusion/hematomas sometimes increased transiently after successful treatment and resolution of clinical symptoms.

Conclusion: Diffuse pachymeningeal hyperintensity on FLAIR MR imaging is a similar sign to DPME for the diagnosis of SIH but does not require injection of contrast medium. FLAIR is useful sequence for the detection of subdural effusion/hematomas in patients with SIH.

Fig 1.

Patient 5. Initial axial, half cut, and magnified MR images of a 39-year-old man with spontaneous intracranial hypotension who presented with a 1-month history of orthostatic headache, nausea, vomiting, and diplopia. Supportive treatment resolved the symptoms. A, T1-weighted image showing diffusely thickened dura mater as isointense. Subdural lesions are unclear. B, T2-weighted image showing that bilateral subdural effusion/hematomas could not be discriminated from CSF. C, T1-weighted image with gadolinium clearly showing diffuse pachymeningeal enhancement. D, FLAIR image showing diffuse pachymeningeal hyperintensity (arrowheads) and very thin bilateral subdural effusion/hematomas in the frontal region (arrow).

Fig 2.

Patient 4. Chronologic FLAIR and T1-weighted MR images of a 37-year-old woman with spontaneous intracranial hypotension. She had a 1-month history of orthostatic headache. Cervical epidural blood patch resolved the symptoms. A, Initial FLAIR image showing diffuse pachymeningeal hyperintensity at the falx, tentorium, and dura of the posterior fossa (arrowheads) and bilateral thick subdural effusion/hematomas (arrows). B, Second FLAIR image performed 1 month after effective blood patch showing disappearance of the diffuse pachymeningeal hyperintensity but thickening of the subdural effusion/hematomas (arrows). C, Follow-up FLAIR image showing remnant subdural effusion/hematomas (arrows). D, Initial T1-weighted image with gadolinium showing DPME at the falx, tentorium, and dura of the posterior fossa (arrowheads) and bilateral thick subdural effusion/hematomas (arrows). E, Second T1-weighted image taken 1 month after completely effective blood patch showing slight remnant of DPME and thickening of the subdural effusion/hematomas (arrows). F, Follow-up T1-weighted image showing remnant subdural effusion/hematomas (arrows).

Fig 3.

Patient 8. Chronologic FLAIR and T1-weighted MR images of a 47-year-old woman with spontaneous intracranial hypotension. She had a 1-week history of orthostatic headache. Lumbar epidural blood patch resolved the symptoms. A, Initial FLAIR image showing diffuse pachymeningeal hyperintensity (arrowheads). B, Second FLAIR image taken 1 week after completely effective blood patch showing thickened diffuse pachymeningeal hyperintensity (arrowheads) and partial subdural effusion/hematomas (arrows). C, Follow-up FLAIR image showing disappearance of the diffuse pachymeningeal hyperintensity and subdural effusion/hematomas. D, Initial T1-weighted image with gadolinium showing DPME (arrowheads). E, Second T1-weighted image taken 1 week after effective blood patch showing disappearance of DPME (arrowheads) and partial subdural effusion/hematomas (arrows). F, Follow-up T1-weighted image showing disappearance of the DPME and subdural effusion/hematomas.