Surgical Management of Sphenoid Wing Meningiomas

Schmidek Chapter 36GERARDO GUINTO

Outline

• Anatomy• Classification• Clinical course• Diagnosis• Treatment• Complication and result

Anatomy

Classification

En-plaque meningiomas• Spheno-orbital meningiomas or hyperostotic

meningiomas of the sphenoid wing• Carpet-like dural growth tumor• It frequently extends posteriorly toward the cavernous

sinus and anteriorly toward the orbital apex, where it causes proptosis and oculomotor deficits growth tumor

Globoid meningiomas• Deep, inner, or clinoidal

– Most common– Subtype : tumors without extradural growth and tumors

with extradural growth into the cavernous sinus• Middle • Lateral, outer, or pterional

Clinical course• Most common : Protosis which usually is slowly

evolving, unilateral, nonpulsatile, and irreducible• Protosis Ddx

– Hyperostosis of the orbital walls– Periorbital tumor invasion– Intraorbital tumor– Venous stasis caused by compression of the

ophthalmic veins

Clinical course• Related symptoms : headache, orbital pain, visual

deficit, ptosis, diplopia, ectropion, conjunctivitis, corneal ulceration, and scleral hemorrhages

• Clinoidal meningioma– Visual field problems– When tumor invade cavernous sinus, the most common

symptoms are oculomotor deficit (especially on cranial nerve VI) and facial hypoesthesia

Clinical course• Middle or alar meningiomas

– Late symptoms– Headache and signs or symptoms suggesting increased

intracranial pressure, such as nausea, vomiting, and papilledema

• Not common– Memory impairment– Olfactory hallucinations– Personality changes – Seizures– Hemiparesis

Diagnosis• CT• MRI• Angiography

Computed tomography• The extent of bone invasion• The dural component of these tumors is typically found

as an isodense image with contrast enhancement• The most common locations of hyperostosis of en-

plaque meningiomas– the lesser wing of the sphenoid bone– the greater wing of the sphenoid– the roof of the orbit– the inferior orbital fissure– the infratemporal fossa– the orbital rim.

Computed tomography• Globoid tumors : well-defined isodense lesions that

present an intense and homogeneous contrast enhancement• Clinoidal meningiomas : hyperostosis of the anterior

clinoid process (ACP), causing narrowing of the optic canal and the superior orbital fissure

MRI• Globoid meningiomas show different appearances on

MRI– When their vascularity is not so marked, they usually

present as a homogeneous isointense lesion in both T1- and T2-weighted images

– When they are highly vascularized (angioblastic meningiomas), multiple hypointense images (“empty signals”) can be seen in the interior of the tumor

MRI• Gadolinium enhancement is usually intense and uniform• T2-weighted image is particularly useful in demonstrating

perilesional edema• Functional MRI• MRA

Angiography• Selective catheterization provides specific information

about the blood supply of the tumorand allows the possibility of preoperative embolization

Treatment• Indication

– all patients who are in good health and have a tumor size greater than 2.5 cm

– presence of signs or symptoms– changes in the adjacent cerebral(edema)

• Objective– radical excision of the tumor, which means resection of the

lesion, along with the dural implant (1-cm margin) and all hyperostotic bone

Treatment• Preparation : general anesthesia, antiepileptic drugs, broad-

spectrum antibiotics, neurophysiologic monitoring• Positioning and Incision• Preserve : superficial temporal artery, frontotemporal branch

of facial nerve •

Pterional• Pterional craniotomy• Hyperostosis is usually seen immediately in the

pterion once the temporal muscle is detached : craniotomy about 5 cms from lesion

• Resection of hyperostosis : 1 cm from margin• The meningeal portion of the tumor : 1 cm from margin• In some cases of predominantly osseous tumors :

craniectomy

Pterional

Alar or middle• Frontotemporal craniotomy• Extradural resection of the lesser wing of the sphenoid

bone• Bone removal is continued until complete exposure of the

superior orbital fissure and base of the ACP• Dura open in curvilinear frontotemporal incision• Splitting of the sylvian fissure is done• “En bloc” resection is only possible in small tumors• Debulking is preferred in the majority of these cases• Leaving deeper portions and dural implant for the end of the

procedure.

Clinoidal• Frontotemporal craniotomy• Bone resection of the sphenoid ridge from the pterion to

the base of the ACP• If there is an orbital component of the tumor, the

posterolateral wall of the orbit is also removed• Anterior clinoidectomy : holding the ACP with a rongeur

and applying a gentle “wiggle and jiggle” movement of the surgeon’s wrist

• The curvilinear dural incision is done• Splitting of the sylvian fissure is done

Clinoidal• Initially, the dural implants in the frontal and temporal

regions are coagulated, which reduces vascular supply of the tumor and facilitates its resection

• Dissection of the tumor• The optic nerve is next referred intradurally and released

from the tumor• Extirpation of the dural implant is done

En Plaque• Pterional craniotomy is combined with an OZ osteotomy

when the lesion extends into the inferior orbital fissure, infratemporal fossa or orbit

• It is easy to observe the totality of the hyperostosis from a lateral perspective and the drilling begins

• All infiltrated dura are resected, attempting to extend this resection beyond the area of dural enhancement seen on imaging studies.

En Plaque

Reconstruction and closure• Closure of the dura

– Local tissue : aponeurotic galea, pericranium, or temporal fascia

– Distant tissue : fascia lata or abdominal fascia

• Reconstruction of the pterional defect– Autologous materials : split calvarial bone graft or ribs – Synthetic materials : methylmethacrylate and titanium

Reconstruction and closure• The floor, the orbital rim or both are removed, all

authors agree that reconstruction is required due to the high risk of orbital ptosis, postoperative diplopia, or cosmetic defect

• Reconstruction of the orbital walls is controversial : the superior and lateral walls of the orbit

Complication• Postoperative hematoma, especially epidural, due to the

wide dural detachment done in some cases and the spaces created by resection of large bone formations

• CSF leakage due to wide resection of the dural implant• Seizure• Cosmetic• Infection : when prosthetic materials are used for

reconstruction or when frontal ethmoid or sphenoid sinuses are inadvertently opened

Result• The short and midterm follow-up results after SWM

resection are excellent• In the majority of cases,gross total resection is

accomplished with minimal morbidity• However, the critical point is in long-term follow-up

because of the high risk of recurrence, which is inversely proportional to the degree of tumor resection

• Factors : incomplete resection of these tumors are extent of bone invasion, underevaluation of the dural component, and invasion of adjacent neurovascular structures, anaplasia