Foramen Magnum Meningioma

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Foramen Magnum Meningioma

• General Overview by
• Dr. Haitham H. Shareef
• www.haithamhandhel.jeeran.com

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Anatomy

• 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.

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Classification

• According to origin
• 1. Primary originated from within the confines
  of the foramen magnum.
• 2. Secondary invaded the region but originating
  elsewhere.
• According to location
• 1. Most lesions 68- 98 arise anterolat.
• 2. Posterolat. origin is the 2nd most frequent.
• 3. Post. lesions
• 4. Ant. lesions

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Classification

• 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 downward.
• 2. Spinocranial those arising post or
  posterolat. are at the level of the spinal cord
  and extends sup.

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Clinical Features

• 1. Occipital headaches
• 2. Neck pain
• 3. Cold or burning dysesthesias
• 4. Lhermittes phenomena
• 5. Weakness, atrophy of the intrinsic hand
  muscles, spastic quadriparesis
• 6. Cranial nerves disturbances especially 11th
  nerve
• 7. Horners syndrome
• 8. Late respiratory distress
• 9. Sphincteric disturbances
• 1o Piano playing fingers and astereognosis

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Radiological Diagnosis

• 1. CT Scans of the area are unsatisfactory
  because of bony artifacts.
• 2. Plain MRI may not reveal a small meningioma.
• 3. GADO enhanced MRI is the mainstay of
  radiological diagnosis.
• 4. Angiography should be considered in all cases
  of suspected meningioma to determine the
  vascularity and vascular supply of the tumor.

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Left Sagittal T2-weighted MR image obtained in a
48- year-old man, demonstrating an anteriorly
situated foramen magnum 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
contribution. The large tumor occupies slightly
more than half of the transverse diameter of the
foramen magnum and affords an adequate surgical
corridor of approximately 1 cm. The rostral
spinal cord (arrow) is compressed and displaced
posteriorly.
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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 removal 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 structures.
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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.
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Surgical Approaches

• 1. A post. op. approach is commonly selected for
  intradural lesions.
• 2. An ant. op. approach is frequently selected
  for extradural lesions situated ant. to the FM.

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Ant. Op. Approaches

• Indications
• 1. To reach tumors of the atlas, axis clivus.
• 2. For the resection fixation of the odontoid
  process.
• 3. For decompressing bony malformations of the
  C.V.J.
• 4. For approaching aneurysms of the V.A. B.A.
• Advantage direct route to the lesion.
• Disadvantage CSF leak, pseudomeningocele
  meningitis.

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Surgical Approaches
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Post. Op. Approaches

• The post. op. approaches are preferred for most
  intradural lesions.
• 1. Suboccipital craniectomy
• Vertical midline suboccipital incision
• Hockey stick suboccipital incision
• 2. Extreme lat.
• Horse shoe incision

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Thank You