Approach Considerations
Management of the meningioma largely is divided into observation, surgery, or radiation, alone or in combination. Small meningiomas in patients who otherwise are asymptomatic may be monitored with serial imaging to document growth. Tumors that demonstrate growth or cause symptoms may be considered for surgical removal and histopathologic evaluation. Adjuvant radiation may be considered for high-grade or recurrent tumors. Primary radiation may be considered for patients when surgical removal is not deemed possible. [94]
Surgical Care
Total microsurgical resection of sphenoid wing meningioma usually is curative. A recurrence risk approaching 30% has been reported when incomplete removal is attempted. [65, 95] Depending on the bony involvement and the soft tissue component of the tumor, the principles of resecting a sphenoid wing en plaque meningioma are complete removal of all the involved bone, including the sphenoid wing, orbital roof, and orbital lateral wall; decompression of optic nerve; and decompression of the superior orbital fissure, and maxillary branch of the trigeminal nerve posteriorly to foramen rotundum.
The skin incision is made 0.5-1 cm anterior to the tragus at the level of the zygomatic arch and extended behind the hairline toward the widow peak. It can be curved back across the midline toward the contralateral superior temporal line, if needed. Care must be taken not to injure the temporal branch to the frontalis muscle or the facial nerve that passes anterior to it. The temporalis muscle, along with the superficial and the deep fascial layers, are incised in similar fashion from the skin down to the bone. The musculocutaneous flap is reflected anteriorly using a periosteal elevator. Avoid cauterizing the blood supply and innervation to the temporalis muscle to prevent future muscle atrophy.
After elevation of the myocutaneous flap; note the underlying bone is infiltrated with tumor.
Once the muscle is elevated and reflected anteriorly, lateral sphenoid wing hyperostosis is usually apparent, and any tumor noticed during elevation of the temporal muscle is excised.
Multiple bur holes then are made around the invaded or hyperostotic bone to prevent excessive bleeding and dural tear. The drill is used to connect the bur holes and to remove the invaded bone.
A frontotemporal craniotomy is performed to elevate the affected bone. Underlying it, dura is seen. The dura is also infiltrated with the tumor.
This process continues until all hyperostotic tissue is removed from the sphenoid wing down to the meningo-orbital band. The meningo-orbital band is then coagulated and cut sharply, followed by dural stripping from the superior orbital fissure and the anterior part of the lateral wall of the cavernous sinus, exposing the middle fossa floor laterally to the foramen spinosum and posteriorly to the foramen rotundum.
The tumor debulking is performed using the micro-instruments and high-speed diamond drill bit.
Hyperostotic tissue then is removed in a similar manner from the orbital roof and lateral walls of the orbit. The superior orbital fissure is completely decompressed. The optic nerve in the canal is unroofed, and anterior clinoidectomy is performed.
Once the bone removal is complete, attention is focused on resecting the intradural portion of the tumor, and the dura is resected beyond the enhanced dural tail.
The dura is opened. Any intradural portion of the tumor is resected, if any. The involved dura is cut and discarded.
The intraorbital extension with involvement of the periorbita and extraocular muscles should also be removed.
Important neurovascular structures are decompressed including the orbit, orbital apex, superior orbital fissure. The tumor has also infiltrated the periorbita. Some periorbital fat can be seen.
After gross total resection of the tumor (star = orbit, circle = frontal lobe, triangle = temporal lobe).
Abdominal fat or temporalis fascia with or without pericranial flap can be used to repair the frontal, maxillary, and ethmoid sinuses if they have been opened to prevent postoperative development of a CSF leak and rhinorrhea. A duraplasty is performed using a dural substitute.
There is no clear consensus in the literature regarding whether to reconstruct the orbit. Orbital wall reconstruction has been recommended whenever the orbital floor or more than 1 wall has been resected or the periorbita was resected to prevent occurrence of pulsatile enophthalmos postoperatively. [96] However, studies have concluded that this complication is uncommon and that orbital reconstruction is unnecessary except in rare occasions when the orbital rim is resected. [9, 97, 98]
When orbital reconstruction is needed, the area can be reconstructed using mesh, dural substitute, or split bone if only the superior and lateral walls of the orbit have been removed. The cranial flap is placed back if it was not involved by the tumor, or a piece of Medpor can be used to cover the cranial defect, making sure to cover the keyhole area. The temporal muscle is reattached, and the skin is closed in 2 layers.
After closing the dura with a synthetic dural substitute, cranium is replaced and secured with titanium hardware. Medpore cranioplasty (white plates) are placed for further reconstruction and to restore cosmesis.
Medical Care
Anecdotal reports have described using antihormonal agents in the treatment of meningiomas. Medical treatment is reserved for atypical and malignant meningiomas as an adjunct to surgery.
Complications
The complexity of skull base approaches; proximity of the cranial nerves; poor accessibility; dural attachments; and involvement of extracranial compartment, especially the nasal sinuses for skull base meningiomas, makes the complication frequency for these lesions higher compared with other locations. [72]
Depending on the exact location of the meningioma, a different subset of neural structures may become involved.
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For medial sphenoid wing meningiomas, visual loss and abnormalities of cranial nerves III, IV, VI, V1, and V2 may occur because the meningioma may have some degree of encasement of these structures as they involve the cavernous sinus.
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Seizures, paresis, and sensory loss may result depending on potential damage to adjacent brain parenchyma for patients with lateral sphenoid wing meningiomas.
Long-Term Monitoring
Patients are typically monitored for a significant length of time. Patients with asymptomatic meningioma may be monitored with serial imaging, sometimes indefinitely. Postsurgical patients may be seen at 1-, 3-, and 6-month and 1- and 2-year intervals to observe growth (if subtotal resection) or recurrence. Immediate postoperative care usually involves pain control, incision care, and setting up oncologic appointment based on histopathology.
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Coronal T1-weighted MRI with gadolinium enhancement of a sphenoid wing meningioma with some degree of encasement of bilateral cavernous sinuses.
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T1-weighted MRI with gadolinium (coronal section) of same patient with sphenoid wing meningioma. A better visualization of en plaque growth of the meningioma along the convexity of the cerebral hemisphere on the left side is seen, in addition to better illustration of intracavernous carotid arteries bilaterally and en plaque growth of meningioma inferiorly and laterally around both temporal lobes.
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T1-weighted gadolinium enhanced (sagittal section) of same patient with meningioma of the sphenoid wing.
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CT scan brain bone window showing intraosseous meningioma involving left sphenoid wing, lateral orbital, superior orbital fissure, and the anterior part of the middle fossa floor.
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MRI brain T2W (left) and T1W Fat-Sat (right) sequences showing involvement of the left sphenoid wing associated with dural thickening and the periorbita. Notice proptosis of the left globe secondary to left orbital wall thickening.
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This is a typical appearance of a sphenoorbital meningioma on the MRI. The image depicts a contrasted MRI of the brain which shows an enhancing mass along the sphenoid ridge, orbital apex, and even the temporalis muscle. The orbital involvement of the tumor causes significant proptosis of the affected eye.
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After elevation of the myocutaneous flap; note the underlying bone is infiltrated with tumor.
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A frontotemporal craniotomy is performed to elevate the affected bone. Underlying it, dura is seen. The dura is also infiltrated with the tumor.
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The tumor debulking is performed using the micro-instruments and high-speed diamond drill bit.
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The dura is opened. Any intradural portion of the tumor is resected, if any. The involved dura is cut and discarded.
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Important neurovascular structures are decompressed including the orbit, orbital apex, superior orbital fissure. The tumor has also infiltrated the periorbita. Some periorbital fat can be seen.
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After gross total resection of the tumor (star = orbit, circle = frontal lobe, triangle = temporal lobe).
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After closing the dura with a synthetic dural substitute, cranium is replaced and secured with titanium hardware. Medpore cranioplasty (white plates) are placed for further reconstruction and to restore cosmesis.
