PMC7468191_01
Preoperative brain magnetic resonance imaging showed severe brain sagging signs, in the axial plane (a) a distorted midbrain anatomy was observed at the level of the tentorial incisura in which an anteroposterior midbrain elongation (35 mm) and temporal lobe herniation were evident. Notice the anterior and posterior parahippocampal herniation (b). In the sagittal plane, there was sagging of the brainstem, cerebellar tonsillar descent, shortened pontomammillary distance (2.8 mm/abnormal <5.5 mm) (c), flattening of the pontomesencephalic angle (10.5 /abnormal <50 ) (d), narrow vein of Galen/straight sinus angle (50.7 ), aqueduct displacement (e), and cerebellar tonsillar descent using the McRae line (2.4 mm/abnormal >5 mm) (f). Notice the generalized pachymeningeal enhancement (g). In the coronal plane, the third ventricle was thin and elongated, the mammillothalamic tract was displaced downwardly, and bilateral uncal herniation was observed (h and i).[2]
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F1
The brain MRI showed severe brain sagging, minimal cerebellar tonsillar descent, bilateral temporal lobe herniation, and pachymeningeal enhancement [Figure 1].
Hyperdense paraspinal vein sign[6,18] was observed on computed tomography (CT) myelogram. A curvilinear high attenuation vascular structure was observed in connection with a T7 nerve root diverticulum (a and b). The contrast filling paraspinal vein and CSF leak was better observed on CT myelography in the prone and right lateral decubitus position. Notice the paraspinal vein (c) and the 3D reconstruction of the thoracic diverticula (d). CSF-venous leak was localized, and the thoracic roots were exposed (e). Multiples veins were coagulated (f) during the root dissection; vascular Sugita straight clips were placed at the origin of the root sleeves (g).
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A computed tomography (CT) myelogram performed in prone, supine, and lateral positions revealed a right T6 thoracic meningeal diverticulum associated to a CSF-venous leak and a T7 small meningeal diverticulum [Figure 2]. T6-T7 laminotomy was performed to address the CSF-venous leak (e.g., using fluoroscopic and neuronavigation). The T6 and T7 nerve roots were exposed, the diverticulum was isolated/dissected and ligated from the surrounding veins (e.g., ligated with vascular Sugita straight clips placed at the origin of the root sleeves) [Figure 2].
MRI showed axial, coronal, and sagittal planes (a-l). Notice the progressive hypotension resolution over the time. Anterior-posterior midbrain diameter was 35 mm preoperative versus 25 mm postoperative (1 year). Pontomammillary distance was 2.8 mm preoperative versus 8.1 mm postoperative (1 year). Pontomesencephalic angle was 10.5  preoperative versus 51  postoperative (1 year). Vein of Galen/straight sinus angle was 50.7  preoperative versus 68.1  postoperative. Sagging index (anterior-posterior midbrain diameter/pontomammillary distance) improved significantly 1 year after surgery (12.5 vs. 3.08). A sagging index higher than 10 suggests an atypical clinical presentation for craniospinal hypovolemia.[1]
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The postoperative MRI's (48 h, 1 month, and 12 months after surgery) showed progressive improvement of the sagging index/uncal herniation [Figure 3].