PMC8416255_01
Preoperative sagittal (A) and transverse (B) T1-weighted contrast enhanced MRI of case 1 depicting an anteriorly located meningioma of the upper cervical spine with cranial extension into the foramen magnum. Postoperative sagittal (C) and transverse (D) T1-weighed contrast enhanced MRI showing complete resection of the WHO  II meningioma without the need of resecting any boney structures.
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F2
It showed homogeneous contrast enhancement and was located anterolateral to the spinal cord on the right side (Figures 2A,B). The dura mater was split and the inner sheath of the dura removed for complete resection of the tumor (Figures 2C,D).
PMC8416255_02
Preoperative sagittal (A) and transverse (B) images depicting an anteriorly located craniocervical meningioma (case 2) removed through the atlantooccipital space. After dura tuck-up sutures the microsurgical view shows a nicely exposed tumor surface (C) without any removal of boney structures. The vascular tumor base was bipolar coagulated and resected in total so that finally a Simpson  II resection was achieved (D).
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F3
The neuroradiological imaging (including MRI and CT) showed a homogeneously contrast-enhancing tumor with dural tailing in the CVJ, measuring 19 x 17 x 11 mm (diameter 17 mm) and reaching from the lower part of the clivus down to the first third of the odontoid (Figures 3A,B). After dural opening, the microsurgical view showed a well-exposed posterior tumor surface (Figure 3C). A Simpson  II resection was achieved (Figure 3D).
PMC8416255_03
Preoperative sagittal T2-weighted (A) MRI of case 3 depicting a foramen magnum and lower clivus meningioma with a cranial extension up to the vertebral junction. Axial 3D-CISS images (B) show a sufficiently wide craniocervical cerebrospinal fluid (CSF) space and a bilaterally well distinguishable vertebral artery. After preparation of the paravertebral muscles, an Adson retractor was placed exposing all boney structures from occiput down to C2 (C) showing a wide enough space for tumor resection.
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F4
Having its origin in the midline on the lower third of the clivus, the tumor dislocated the medulla oblongata posteriorly with a left-sided accentuation (Figures 4A,B). After preparation of the paravertebral muscles, a retractor was placed exposing all bony structures from the occiput down to the lamina of C2 (Figure 4C).
PMC8416255_04
Preoperative sagittal (A), coronary (B) and transverse (C) contrast-enhanced T1-weighted image of case 4 depicting a lateral craniocervical meningioma growing anterior and posterior from the denticulate ligament.
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F5
CVJ, compressing the medulla oblongata from the anterior right side by 50% and showed calcifications in CT scans (Figures 5A-C). Clinically, the patient suffered from a reduction of fine motor skills of both hands and mild gait ataxia.