Spheno-orbital meningiomas are benign tumors arising intracranially from the sphenoid ridge arachnoid villi cap cells with various configurations of intra-orbital extension.
The most common orbital component arises from tumor growth through the superior orbital fissure but optic canal extension is occasionally seen.
The classic spheno-orbital case involves an intracranial component in the anterior and/or middle cranial fossa and an intraorbital soft tissue component with associated hyperostosis and/or intraosseous tumor involvement of the greater wing of the sphenoid bone.
Meningiomas represent up to 95% of benign intracranial tumors (Heufelder, OPRS 2009). Around 20% will involve the sphenoid wing.
They are twice as common in females and present with increasing frequency as patients approach middle age.
Common history is that if a slow onset, unilateral, painless, progressive proptosis in a middle-aged woman (Saeed, BJO 2011).
Pain of a diffuse nature, headache or focally is found in about 30%.
Vision loss is noted in 20%–60% (Oya, J Neurosurg 2011; Marinello, Clin Neuro Neurosurg).
With a significant intracranial component, seizures can occur.
Proptosis is the hallmark and presents near uniformly (Marinello, Clin Neuro Neurosurg 2013).
- About 44% will have < 4 mm proptosis and 35% > 4 mm proptosis (Oya, J Neurosurg 2011).
Optic canal involvement and associated decreased vision is found in 20–25% (Oya, J Neurosurg 2011).
Less common presentations from the orbital involvement include inferior globe dystopia, temporal fossa mass, eyelid edema, chemosis, trigeminal hypoesthesia, or diplopia.
Elevated intracranial pressure with associated optic nerve swelling is rare. Optic nerve swelling or pallor can also occur from intracanal compression.
Brain and orbit imaging by both CT and MRI
CT demonstrates reactive hyperostosis and calcifications within the lesion.
MRI delineates the intraorbital tumor and dural extension.
Tumors enhance homogenously with gadolinium, and the presence of dural enhancement ("dural tail") helps distinguish meningioma from fibrous dysplasia.
Testing for staging, fundamental impairment
The tumor can be classified by various subtyping schema based on morphology.
- Intracranial meningiomas were defined by Cushing to have either mass-like or plaque-like growth patterns (Scarone J Neurosurg 2009).
- Guiot originally described "external" and "internal" sphenoid wing menigiomas, which is echoed by other authors (Scarone J Neurosurg 2009).
- External variety largely involves profound hyperostosis with sheet-like dural and intraorbital involvement (Figure 1).
- Internal varieties have more well-defined intradural and intraorbital mass lesions (Figure 2).
Other authors have classified the lesion by orbital involvement based on location at the apex or elsewhere in the orbit (Marinello, Clin Neuro Neurosurg 2013).
Because the lesions often involve the superior orbital fissure, orbital apex, cavernous sinus, inferior orbital fissure, and optic canal, a comprehensive orbital and neuro-ophthalmic examination is important to determine the level of impairment and surgical goals.
- Color testing, automated perimetry, and optic nerve exam for swelling or pallor
- Retinal nerve fiber layer OCT can also play a role in predicting potential recovery in patients with severe compressive neuropathy.
- Pupil exam for an APD, mydriasis and reactivity
- Exophthalmometry with a Hertel or perhaps preferably with a Naugle exophthalmometer as correction might involve a surgery that moves that lateral wall.
- Extraocular motility exam
- Trigeminal nerve exam including corneal sensation, V1 and V2 hyposthesia
- Levator function and MRD1
- Facial nerve function with particular attention to the frontalis muscle as the frontal branch is often temporarily weakened after stretch injury during a frontotemporal craniotomy.
- Periocular exam for signs of extraorbital extension
Figure 1. Patient with a "plaque-like" spheno-orbital meningioma with extensive hyperostosis around the superior orbital fissure extending throughout the skull base seen in coronal (A) and axial (B) CT images and on T1 MRI before (C) and also immediately after modified orbitozygomatic approach resection (D).
Figure 2. Patient with a "mass-like" spheno-orbital meningioma with hyperostosis and a well-defined posterior orbital mass causing rectus muscle distortion and a dural mass with temporal lobe distortion seen in axial (A) and coronal (B) CT imaging and on T1 fat-suppression MRI with gadolinium contrast (C). The patient underwent orbitozygomatic approach resection and immediate imaging was obtained postoperatively (D and E).