MGH / MEEI Cranial Base Center Sphenoid Meningioma
Medial Sphenoid Wing Meningioma
by Robert G. Ojemann, M.D.
Stephen B. Tatter,M.D., Ph.D. ,
1: Medial Sphenoid Wing Meningioma
last issue of this Newsletter, I discussed tuberculum sellae meningiomas
which arise in the midline of the skull base from the region of
the tuberculum sellae and planum sphenoidale In this issue we move
laterally to discuss medial sphenoid wing meningiomas.
meningiomas involve the region of the anterior clinoid, adjacent
medial sphenoid wing, superior orbital fissure, and cavernous sinus
(Fig 1). They may grow into the orbit. As the tumor becomes larger,
it may encase the internal carotid and proximal middle and anterior
cerebral arteries. The optic nerve may be compressed or be surrounded
by tumor. Large tumors put pressure on the frontal and temporal
lobes and provoke edema in the adjacent brain tissue resulting in
neurologic deficits or seizures.
resonance imaging (MRI) outlines the extent of the tumor and shows
the relationship to the arterial structures (Fig 2). It is often
hard to define the optic nerves and chiasm. Angiography may be needed
to determine the extent of encasement of the internal carotid artery
and its branches and determines the blood supply to the tumor. Embollization
of external carotid artery branches is occasionally indicated prior
decisions are often difficult because symptoms may be mild, the
natural history is variable with some tumors having a very indolent
course, the long-term results of microsurgical radical resections
that have been proposed and the newer radiation therapy modalities
(single dose radiosurgery or fractionated radiotherapy programs)
| Figure 2: MRI Medial
Sphenoid Wing Meningioma
This 57 year old man presented with worsening vision in the
right eye and increasing dificulty with recent memory and judgement.
On the T1 coronal image (left) with gadolinium enhancement
the internal carotid and proxinial middle and anterior cerebral
arteries are encased. The T2 axial image (right) shows marked
edema in the surrounding brain. An extensive subtotal removal
of the tumor was done and he made a good recovery except for
residual visual loss in tha right eye.
However, some general guidelines for
the treatmeni of these tumors can be outlined. For those with mild
or non-progressive symptoms, it may be appropriate to follow the
patient with periodic MRI and examination to determine if the lesion
is growing and to see whether the symptoms are significantly interfering
with the pafient's life. The indications for surgery in younger
patients are worsening symptoms and/or growth seen on follow-up
scans, and in older patients a large tumor with worsening symptoms.
Radiotherapy is used in older patients with small and medium size
tumors with worsening symptoms and for regrowth after subtotal or
radical subtotal removal.
For most patients, a lateral subfrontal
and anterior temporal exposure is used. Internal decompression of
the tumor is done staying away from the region of the internal carotid
and middle cerebral arteries. Some soft tumors can be more easily
removed than very firm, hard tumors. The distal branches of the
middle cerebral artery are identified and followed to the tumor
capsule to determine if it is feasible to dissect them. In some
situations arachnoid planes help in separating the tumor from and
around the encased arteries. At some point, the relationship of
the optic nerve and chiasm to the tumor is determined.
In my series of 16 patients treated
over a 15 year period, there were 12 females and four males ranging
in age from 28-79 years with two over 70 years of age. In no patient
could I be absolutely sure of a total removal of the tumor because
of involvement of important arteries and/or cranial nerves or the
extension of the tumor into the cavernous sinus or orbit. However,
15 patients have had a good result. One patient had a postoperative
intracerebral hemorrhage two weeks after surgery and has a permanent
dysphasia and hemiparesis.
In 10 patients no radiation therapy
has been given and on follow-up scan there is no change in their
tumor over a period of 2 to 14 years (mean 7.2 yr) after operation.
Six patients were given radianon therapy, two immediately after
operation and four when there was evidence of recurrence. Two of
the patients with recurrence had reoperation and then radiation
therapy to the small residual tumor Following radiation therapy,
five patients are stable and one has shown slight growth over a
follow-up of 2-13 years (mean, 5-6 yr).
- Ojemann RG. Management of cranial
and spinal meningiomas. Clin Neurosurg 1993; 40: 321-383.
- Ojemann RG. Surgical management
of olfactory groove, suprasellar and medial sphenoid wing meningiomas.
In: Schmidek HH, ed. Meningiomas and Their Surgical Management,
Philadelphia: WB Saunders Co 1991:242-259.
- Ojemann RG. Meningiomas: Clinical
features and surgical management. In: Wilkins RH, Rengachary SS,
eds. Neurosurgery, New York: McGraw-Hill 1985:635-654.