PMC9990808_01
Example of the last cases seen by the authors. Sagittal view of head magnetic resonance imaging showing a meningioma arising below the foramen magnum, the Spinocranial type (a). A craniospinal type 2 foramen magnum meningioma, reaching above the pontomedullary sulcus on sagittal and coronal views (b and c).
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F1
Magnetic resonance imaging (MRI) showed a mass-occupying lesion originating from the anterior aspect of the foramen magnum that caused significant displacement of the brainstem and extends from the pontomedullary sulcus to the cervical spinal cord [Figures 1 and 2]. Operative position and images can be seen in Figure 5 and at Video 1.
Head magnetic resonance imaging evidence large anterolateral foramen magnum mass with homogeneous enhancement of contrast in (a) sagittal, (b) axial, and (c) coronal views. (d) Note the important posterolateral displacement of brainstem (red traced lines).
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F2
Magnetic resonance imaging (MRI) showed a mass-occupying lesion originating from the anterior aspect of the foramen magnum that caused significant displacement of the brainstem and extends from the pontomedullary sulcus to the cervical spinal cord [Figures 1 and 2].
Neuronavigation in magnetic resonance imaging showing the direction to the mass allowed for the suboccipital midline approach. Note that the tumor was at the level of the pontomedullary sulcus (yellow arrow), and almost completely anterior to the tonsil. Red and green line represents the operative trajectory, shown with neuronavigation.
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F3
A midline suboccipital-subtonsilar approach was deemed appropriate for the case due to the significant posterolateral displacement of the brainstem [Figure 3].
Courtesy of the Rhoton Collection, American Association of Neurological Surgeons/Neurosurgical Research, and Education Foundation. The complex craniocervical junction anatomy from a posterior view from foramen magnum opening. The blue arrow indicates the surgery approach view in our case. P.I.C.A = posterior inferior cerebellar artery, VA = vertebral artery, CN XI = cranial nerve XI (accesory nerve), AO joint = atlanto-occipital joint, Dent. lig. = dentate ligament, Dors. ramus = Dorsal ramus, Trans. proc. = transverse process, Post. condylar V. = posterior condylar vein.
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F4
The anatomy of this approach it's seen in Figure 4.
Steps from the suboccipital midline approach. Programmed skin incision (a); Intraoperative view, tumor exposition and beginning of debulking (b); dissection and exposure of right vertebral artery (VA), arterial branches for the mass (c); complete resection and view of IX, X, XI complex (white arrows) and XII cranial nerve (yellow arrow) and VA intact (d).
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F5
Operative position and images can be seen in Figure 5 and at Video 1.
Postoperative magnetic resonance imaging showing complete removal of the tumor and the brainstem getting back to the normal position. T2 axial reconstruction (a); T1 + Gadolinium contrast sagittal and coronal reconstruction without contrast enhancement (b and c).
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F6
Post operative images [Figure 6] showed complete ressection of the lesion.