General Overview by
Dr. Haitham H. Shareef
FMM arise from arachnoid at the craniospinal
junction. The borders of this zone :
1. Ant. from the lower 1/3 of the clivus to upper
margin of the body of C2.
2. Lat. from the jugular tubercle to the upper margin
of the C2 laminae.
3. Post. from the ant. edge of the squamous occipital
bone to the C2 spinous process.
According to origin:
1. Primary: originated from within the confines of the
2. Secondary: invaded the region but originating
According to location:
1. Most lesions 68- 98% arise anterolat.
2. Posterolat. origin is the 2nd
3. Post. lesions
4. Ant. lesions
According to size :
1. Small, less than 1/3 of the transverse dimension of
the foramen magnum.
2. Medium, 1/3- ½ of its dimension.
3. Large, more than ½.
According to extension:
1. Craniospinal : tumors involving the ant. lip usually
arise from the lower 1/3 of the clivus and extend
2. Spinocranial: those arising post or posterolat. are at
the level of the spinal cord and extends sup.
1. Occipital headaches
2. Neck pain
3. Cold or burning dysesthesias
4. Lhermitte`s phenomena
5. Weakness, atrophy of the intrinsic hand muscles,
6. Cranial nerves disturbances especially 11th
7. Horner`s syndrome
8. Late respiratory distress
9. Sphincteric disturbances
1o Piano playing fingers and astereognosis
1. CT Scans of the area are unsatisfactory because of
2. Plain MRI may not reveal a small meningioma.
3. GADO enhanced MRI is the mainstay of
4. Angiography should be considered in all cases of
suspected meningioma to determine the vascularity
and vascular supply of the tumor.
Left: Sagittal T2-weighted MR image obtained in a 48-
year-old man, demonstrating an anteriorly situated foramen
meningioma (long arrow) causing compression and displacement
of the rostral spinal cord (short arrow). Right: Axial
T1-weighted Gd-enhanced MR image obtained at the level of the
foramen magnum. The homogeneously enhancing tumor arises
predominantly in an anterior location with some left lateral
The large tumor occupies slightly more than half of the
transverse diameter of the foramen magnum and affords an
surgical corridor of approximately 1 cm. The rostral spinal
cord (arrow) is compressed and displaced posteriorly.
Pre- and postoperative imaging studies. Upper: Preoperative contrast-enhanced MR
images (left: axial; center: sagittal; right: coronal views) revealing a slightly hyperintense
tumor (*) encasing the VA (arrows). Lower: Postoperative contrast-enhanced MR images
(left: axial; center: sagittal; right: coronal views) demonstrating a near-total tumor
with a few-millimeter-thick residual cuff of the cauterized tumor left around the VA
(arrows) because the arachnoidal plane could not be established between the two
Foramen magnum meningioma. This 49-year-old woman noted increasing difficulty
using her right upper extremity and weakness of her right lower extremity. An angiogram
showed mild compression of the vertebral artery. Total removal was followed by full
recovery. (A and B) MRI axial images, showing the tumor arising from the right anterior
lateral dura with displacement of the brainstem posteriorly and to the left. (C) MRI
sagittal image, showing the posterior compression of the cervical medullary junction and
the longitudinal extent of the tumor.
1. A post. op. approach is commonly selected for
2. An ant. op. approach is frequently selected for
extradural lesions situated ant. to the FM.
Ant. Op. Approaches
1. To reach tumors of the atlas, axis & clivus.
2. For the resection & fixation of the odontoid
3. For decompressing bony malformations of the
4. For approaching aneurysms of the V.A. & B.A.
Advantage: direct route to the lesion.
Disadvantage: CSF leak, pseudomeningocele &