PMC9282784_01
Key features and imaging findings before the dural defect closure operation. (a) Brain CT: chronic thin left subdural hematoma. (b) Brain T2*-MRI: thick symmetrical deposition of hemosiderin on surface of cerebellum/brainstem. (c) Contrast Brain MRI: marked dural thickening/ enhancement, consistent with CSF hypovolemia. (d) Intraoperative view during aneurysmal clipping: diffuse hemosiderin deposition, and engorged pial vessels throughout the surface of the cerebrum (arrowheads). (e) Hematoxylin-eosin stain of arachnoid: hemosiderin-laden macrophages (arrowheads) is prominent on the surface (original magnification x200, black bar = 100 microm). (f) Sagittal reverse FIESTA-MRI: longitudinal ventral/dorsal fluid collection interdurally from C6 to Th4. (g and h) Axial reverse FIESTA-MRI: fluid collection (asterisk) adjacent to the dural sac, and dural defect at the left C6/7 level (arrowhead). Cross-sections as indicated by the lines in Figure 1f.
SNI-13-296-g001.jpg
PMC9282784_01_SNI-13-296-g001.jpg
F1
The brain CT on arrival demonstrated a left chronic subdural hematoma, and following evacuation, the headache was promptly resolved [Figure 1a]. In addition, the patient underwent neck clipping of a right middle cerebral artery aneurysm, because a latent subarachnoid hemorrhage from the aneurysm was suspected on brain MRI [Figures 1b and c]. The CSF was xanthochromic and engorged pial vessels were prominent throughout the surface of the cerebrum [Figure 1d]. The whole brain surface was yellowish, and we confirmed microscopically the hemosiderin-laden macrophages on the surface of the arachnoid [Figure 1e]. T2*WI after the evacuation surgery revealed hemosiderin deposition throughout both cerebral hemispheres and cerebellar hemispheres as well as spinal cord [Figure 1b], and the dura matter was thickened and remarkably enhanced by gadolinium consistent with intracranial hypovolemia [Figure 1c]. Reversed FIESTA-MRI (TR = 4.6 ms, TE = 1.9 ms, ST = 0.5 mm; Discovery MR750w 3.0Tesla, General Electric; Fairfield, CT) revealed an accumulation of CSF between two dural layers of C6-Th4, involving both the dorsal and ventral dural layers [Figures 1f-h].
(a) A 3D-reconstruction of the FIESTA-MRI: preoperatively estimated location of the dural defect left side at C6/7. (b) A dorsal view of 3D-FIESTA-MRI showing the characteristic surface structure. (c) After opening the outer layer of the dura, a blue-colored spinal cord is shown through the opening. (d) Intraoperative photograph showing the identical duplicated dural folds around C6/7 (broken line: incision in outer dura). (e) Another intraoperative photograph showing the inner dural defect. All red arrows/red dots indicate the same dural defect, with black arrowheads in (b) and (d) indicate the same characteristic folds of the outer dural layer.
SNI-13-296-g002.jpg
PMC9282784_01_SNI-13-296-g002.jpg
F2
A 3D reconstruction of FIESTA-MRI scan was used to visualize the range of duplicated dura matter and the characteristic shape of the outer layer [Figures 2a-c]. After completing a left C6-7 hemilaminectomy, no extradural fluid collection was identified, and a nearly identical dural structure to the preoperative 3D-FIESTA-MRI was confirmed [Figure 2d]. Once a 5-mm incision was made in the outer dural layer, CSF within the interdural space flowed out, and a fistula of inner dural layer was found exactly at the site of exposure which was closed completely with an adipose tissue and fibrin glue [Figure 2e].
(a) Postoperative sagittal reverse FIESTA-MRI: interdural fluid collection was slightly decreased. (b and c) Axial reverse FIESTA-MRI showing a slight decrease of CSF in the interdural space. Both pictures are cross-sections corresponding to lines in Figure 3a.
SNI-13-296-g003.jpg
PMC9282784_01_SNI-13-296-g003.jpg
F3
Postoperatively, the reverse FIESTA-MRI revealed slight decrease of CSF in the interdural space [Figures 3a-c].