case_images: PMC4163907_01
case_images: (a) Sagittal T1 MRI shows descended tonsils at C2 level and occupying posterior aspect of the foramen magnum. CSF flow is blocked at this point (arrow). (b) Sagittal T2 MRI shows a small syrinx at C3-C4 level (arrow). (c) Axial T2 MRI shows that the posterior aspect of the foramen mag-num is occupied by the descended tonsils (arrows)
case_images: SNI-5-278-g001.jpg
case_images: PMC4163907_01_SNI-5-278-g001.jpg
case_images: F1
case_images: A magnetic resonance imaging (MRI) showed mild basilar impression, cerebellar tonsils at C2 level, a small syrinx at C3-C4, and no hydrocephalus [Figure 1a and b].
case_images: (a) Postoperative routine CT scan (48 h postoperative) shows the absence of complications. (b) Urgent cranial CT scan on the fifth postoperative day shows a posterior fossa epidural hematoma (white arrow) causing compression of cerebellar hemispheres, vermis, and fourth ventricle (gray arrow)
case_images: SNI-5-278-g002.jpg
case_images: PMC4163907_01_SNI-5-278-g002.jpg
case_images: F2
case_images: The immediate postoperative course was uneventful with a routine computed tomography (CT) scan performed 48 h after surgery demonstrating the absence of complications [Figure 2a]. Emergent CT scan revealed a posterior fossa epidural hematoma compressing cerebellum, upper spinal cord, and the fourth ventricle [Figure 2b].
case_images: (a) One year after initial surgical procedure, sagittal T1 MRI shows the patent bone decom-pression of the posterior fossa and fibrous tissue (arrow). (b) Sagittal T2 MRI: shows a great syrinx cavity at C3-C4 levels (white arrow) and the absence of CSF signal around the cerebellar hemispheres (arrowhead). (c) Axial T2 MRI at the level coincident with obex: it shows the intense adherence of arachnoid tissue (arrow), which produces a blockage of CSF flow
case_images: SNI-5-278-g003.jpg
case_images: PMC4163907_01_SNI-5-278-g003.jpg
case_images: F3
case_images: A remarkable enlargement of the previous syrinx cavity was also demonstrated at C3-C4 level [Figure 3].
case_images: (a) The syrinx cavity has become smaller (white arrow) and CSF signal appears in the pos-terior aspect of cerebellum-medulla (arrowhead). (b) The dural graft has been detached from the parenchymal surface (arrow)
case_images: SNI-5-278-g004.jpg
case_images: PMC4163907_01_SNI-5-278-g004.jpg
case_images: F4
case_images: The postoperative MRI showed decreasing of the sirynx and patency of the subarachnoidal space [Figure 4].