Keywords

Introduction

Spheno-orbital meningiomas (SOMs) are secondary tumors of the orbit arising from the sphenoid ridge. SOMs are the most frequent meningiomas of the skull base, accounting for up to 18 % of all intracranial meningiomas [3, 5, 14, 17, 19].

These tumors may expand from the sphenoid medially into the lateral wall of the cavernous sinus, anteriorly into the orbit, and laterally into the temporal bone. SOMs are often associated with hyperostosis of the sphenoid ridge and may have a really invasive characteristic, spreading to the dura of the frontal, temporal, orbital, and sphenoidal regions [2, 7, 8, 11, 15, 16, 18, 23–25].

The most common symptoms at presentation include slowly developing unilateral exophthalmos, vision or visual field impairment, and extraocular movement palsy, as well as cosmetic deformities, such as a bony prominence in the temporal region [4, 9, 10, 17, 18, 21, 22].

SOMs are very difficult to manage, with high surgical morbidity and mortality. Sphenoidal hyperostosis represents a limit for complete resection, and the rate of recurrence is very high when compared with meningiomas in other locations [3–5, 10, 18, 20–22, 24].

For years, traditional fronto-temporal, fronto-temporo-orbital, and supraorbital craniotomies were the only approaches to treat SOMs. In the past few years, endoscopic endonasal and transorbital approaches to remove these tumors have been successfully performed.

Material and Methods

All patients underwent preoperative and postoperative ophthalmological evaluation to assess visual acuity, visual field campimetry, and extraocular movement integrity.

Brain magnetic resonance imaging (MRI) with gadolinium and bone computed tomography (CT) were performed in all patients before and the day after surgery.

Different surgical approaches were employed to treat the SOMs. Transcranial fronto-temporal, fronto-temporo-orbital, and supraorbital approaches, as well as endoscopic endonasal and lateral transorbital approaches, were used in different cases, with some combined approaches also used.

Illustrative Case

A 43-year-old woman presented at our Department with a 6-month history of worsening left eye proptosis.

CT scan and MRI showed a spheno-orbital meningioma with large hyperostosis of the sphenoid lesser wing involving the lateral orbital wall and extracranial compartment (Fig. 1).

Fig. 1
figure 1figure 1

Illustrative case: preoperative (a) and postoperative (b) computed tomography (CT) scans; there were no extraocular movement deficits or cosmetic deformities after surgery (c)

Full size image

Ophthalmological evaluation was negative for oculomotor deficits or visual field impairment.

A lateral transorbital endoscopic approach was performed to remove the tumor completely (Fig. 2).

Fig. 2
figure 2figure 2

Illustrative case: drilling of the tumor with spatula protecting the periorbit (left); removing all the pathologic bone tissue up to the dura mater of the middle cranial fossa (right)

Full size image

No cranial nerve deficits or cosmetic deformities were observed after the surgery (Fig. 1).

The patient was discharged 3 days after the procedure.

Results

Thirty patients, 22 females (73 %) and 8 males (27 %), suffering from SOM were operated on between 2013 and 2014.

The mean age was 46 years (range, 8–82 years).

Proptosis was the most frequent sign at presentation, with 21 patients suffering from it, 13 in the right eye and 8 in the left eye. Twenty patients had visual impairment, with campimetric defects in 19 and amaurosis in 1. Oculomotor nerve deficits were found in 8 patients, with diplopia in 5. In particular, 4 patients had a deficit of the third cranial nerve; 3, a deficit of the fourth cranial nerve; and 1, a deficit of the sixth cranial nerve. One patient had trigeminal hypoesthesia in V1 and V2.

Traditional transcranial surgery was performed in 23 patients, using a fronto-temporal approach in 19, fronto-temporal orbital approach in 2, and supraorbital approach in 2.

Six patients underwent endoscopic surgery, in four cases by a lateral transorbital approach, in one case by an endonasal approach, and in one case by a combined transorbital and endonasal approach.

A combined transcranial-transorbital endoscopic approach was performed in one patient.

No approach-related mortality or morbidity, such as temporomandibular joint dysfunction or trismus, occurred after the surgery.

Four patients complained of new, but temporary, third cranial nerve paresis in the postoperative period. A new permanent fourth cranial nerve paresis occurred in one patient. No hyperpathic trigeminal sensation appeared after the procedure.

Visual function, as well as proptosis, improved in all patients, remaining stable at 2-year maximum follow-up.

Postoperative neuroradiological evaluation by MRI with gadolinium and bone CT scan on the day after surgery confirmed a gross-total resection in 24 (80 %) patients, with no recurrences after 2 years.

Six patients with residual tumor in the cavernous sinus were considered candidates for gamma-knife radiosurgery.

Discussion

Spheno-orbital meningiomas usually arise from the inner or outer parts of the sphenoid lesser wing, with intraosseous tumor growth, resulting in hyperostosis, and thin soft-tissue growth at the dura [2, 7, 8, 11, 15, 16, 18, 19, 23–25].

Bony tumor growth usually involves the lesser sphenoid wing, the orbital roof, the lateral orbital wall, the superior orbital fissure, the optic canal, and the anterior clinoid process. In cases of orbital extension the growth may occur through the natural canals, such as the optic canal and superior orbital fissure, or the lateral orbital wall [2, 7, 11, 14–16, 18, 23–25].

Soft-tissue growth can spread to extracranial compartments, including the orbital content and the infratemporal fossa with the temporalis muscle.

Dural growth is often widespread, including the basal sphenoid wing, cavernous sinus, and temporal convexity [24].

In most patients, minor symptoms, such as minimal painless proptosis and mild visual impairment, are complained of at presentation. However, cases of loss of vision, severe proptosis, and large cosmetic deformities can be observed [9, 18, 19, 23, 25].

Due to their anatomical, radiological, and morphological aspects, SOMs are considered complex tumors to remove. The involvement of bone, orbit, and neural structures makes the surgery difficult and the resection often incomplete [3–5, 8, 10, 18, 20–22, 24].

However, in cases of visual impairment, oculomotor dysfunction, and severe proptosis, tumor removal is required.

Conversely, a ‘wait and see’ strategy might be appropriate in patients with barely visible proptosis, incidental tumor finding, or little ocular pain.

For years, surgical removal by traditional fronto-temporal and fronto-temporal orbital craniotomy was the gold standard of treatment for SOMs.

Recently, new endoscopic approaches to these tumors have been proposed and have been performed successfully and safely.

The use of endoscopes in orbital surgery was first described in 1981, but their use was limited to the biopsy excision of orbital tumors and to the removal of foreign bodies from the orbit [12, 13].

Even though the endonasal route to approach intraorbital pathologies is increasing in surgical practice, transorbital non-endonasal endoscopic approaches are still little known and used.

In using the endonasal intraorbital approach, a standard spheno-ethmoidectomy has to be performed together with a medial maxillectomy, thus exposing the lamina papyracea. After the lamina papyracea opening, free access to the medial and inferomedial walls of the orbit and, afterwards, to the periorbita, can be obtained [1, 6].

The endoscopic transnasal approach is mainly effective in cases of orbital and optic canal decompression, repair of medial and inferomedial wall fractures, and in intraconal and extraconal lesions with inferomedial location. Accordingly, SOMs located on the medial orbital wall and the inferomedial part of the orbital floor can be removed in this way.

Surgical access to the orbit and periorbital structures through the eyelids and anterior orbital compartment can be achieved through different cutaneous and transconjunctival incisions.

A lateral transorbital approach is performed with an incision on the superior eyelid. The orbital rim is reached by dissection in a superolateral direction. Once the orbital rim is identified and exposed, a careful subperiosteal dissection has to be performed until the superior and inferior orbital fissures are reached [1, 6] (Fig. 3).

Fig. 3
figure 3figure 3

Endoscopic lateral transorbital approach: superior eyelid incision (a), sparing the levator palpebrae aponeurosis (b), identifying the orbital rim (c), and performing a subperiosteal dissection (d)

Full size image

In case of SOMs with extension to the middle cranial fossa, the greater wing of the sphenoid should be removed as far as the dura mater (Fig. 2). In this case, the superomedial boundary of the approach is defined by the superior orbital fissure, while the lateral boundary is delineated by the temporalis muscle. Superiorly, the approach can be partially extended to the lesser wing of the sphenoid towards the anterior clinoid process. If necessary, the frontal bone can be partially resected and the spheno-orbital sinus can be coagulated. When you need to go intracranial, the dura mater can be opened and the anterior part of the temporal lobe reached.

In all cases, even in patients with no visual impairment, the abnormal bone has to be removed as much as possible, including the opening of the optic canal, if required. On the other hand, in cases of periorbital infiltration by the tumor, complete resection is not mandatory, considering the high risk of damaging intraconal structures in a setting where the rate of recurrence is low.

SOMs with intraorbital extension and widespread dural growth involving the anterior or middle cranial fossa, as well as those infiltrating the cavernous sinus, can be properly treated by combined endoscopic-transcranial decompression and radiosurgery on the sinus infiltration.

Finally, when a large endoscopic decompression is carried out, a reconstruction of the bone defect is useful to avoid enophthalmos and other cosmetic defects [2]. An autologous fat graft can be used for this purpose.

The transorbital superior eyelid approach can be successfully performed in patients with superiorly and laterally located extra- and intraconal lesions, as well as for lesions located in the anterior and middle cranial fossa. Actually, if the endonasal approach is preferred for SOMs involving the medial orbital wall and the inferomedial part of the orbital floor, a lateral transorbital approach is mainly indicated in cases of tumors that extend to the superior and lateral orbital wall or to the lateral part of the orbital floor, a lateral transorbital approach is mainly indicated.

This transorbital access, in combination with the transnasal route, enables the performance of a ‘multiportal’ endoscopic approach to lesions located in the anterior and middle cranial fossa [6].

We performed endoscopic procedures in seven patients, with no mortality or morbidity during or after the surgery. The extent of removal was high and the rate of permanent deficits very low.

Summing up, SOMs with large hyperostosis and growth into the orbit can be successfully removed by endoscopic approaches. In selected cases, endoscopic approaches, compared with traditional craniotomies, are more effective in removing the tumor completely, reducing proptosis and cranial nerve compression.

Endoscopic surgery is safe and quite easy to perform, with a low complication rate and reduced hospital stay, as well as an optimal neurological outcome and cosmetic result for the patient.