Tuberculum sellae (TS) meningiomas represent a distinct subgroup of anterior cranial fossa meningiomas with distinctive features. Early visual deterioration with optic canal infiltration occurs because of the site of dural origin. The expanded endonasal transsphenoidal approach and the eyebrow supraorbital craniotomy have been advocated as minimally invasive techniques for TS meningiomas. The authors review the current literature on minimally invasive techniques for TS meningiomas to define visual outcomes, extent of resection, and operative morbidity associated with each approach and highlight pertinent features of individual tumors, which favor either a cranial or an endonasal approach to achieve optimal outcomes.
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Supraorbital craniotomy and expanded endonasal transsphenoidal approach both provide a minimally invasive solution to tuberculum meningiomas.
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Deciding on an approach must take into account specific imaging features in each case.
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Recommendations are based on class C evidence only.
| EBM Question | Level of Evidence | Grade of Recommendation |
|---|---|---|
| Are visual outcomes better with expanded endonasal transsphenoidal approach than open approaches? | 4 | C |
Anatomy and pathophysiology
Tuberculum sellae (TS) meningiomas arise from the dura of the TS, chiasmatic sulcus, limbus sphenoidale, and diaphragma sellae. As the TS meningiomas grow in the subchiasmal area compressing the optic nerves, they produce quite distinctive clinical, imaging, and microsurgical features. TS meningiomas are often grouped with other suprasellar and anterior cranial fossa meningiomas, but, because of the distinct dural attachment, TS meningiomas elevate the optic nerves and chiasm, and early optic canal involvement is common. Optic canal involvement is reported in 10% to 90% of TS meningiomas and is often appreciated on preoperative imaging in only a small number of patients.
When the tumor is small, the area of dural attachment remains on the TS anterior to the pituitary fossa but may extend to the planum sphenoidale or posteriorly to the diaphragma and infundibulum, with tumor filling the pituitary fossa. In the early stages of growth, the arachnoidal plane is well preserved and the tumor compresses the chiasmatic cistern; however, with further growth, vascular and optic nerve encasement can occur.
Clinical presentation
TS meningiomas commonly present with visual deterioration, even at a small tumor size. The chiasmal syndrome was described by Cushing and Eisenhardt in 1929. This syndrome, as originally described, includes a primary optic atrophy with asymmetric bitemporal field defects in adult patients showing a normal sella on plain skull radiograph and has been the classic characteristic presentation of TS meningiomas. Although the most common pattern of visual disturbance is gradual vision loss in one eye, followed by gradual visual disturbance in the contralateral eye, visual symptoms may sometimes be acute or fluctuating. Other symptoms include headache, anosmia, seizures, and, rarely, pituitary dysfunction.
Clinical presentation
TS meningiomas commonly present with visual deterioration, even at a small tumor size. The chiasmal syndrome was described by Cushing and Eisenhardt in 1929. This syndrome, as originally described, includes a primary optic atrophy with asymmetric bitemporal field defects in adult patients showing a normal sella on plain skull radiograph and has been the classic characteristic presentation of TS meningiomas. Although the most common pattern of visual disturbance is gradual vision loss in one eye, followed by gradual visual disturbance in the contralateral eye, visual symptoms may sometimes be acute or fluctuating. Other symptoms include headache, anosmia, seizures, and, rarely, pituitary dysfunction.
Management
The primary goal of surgery is maximal tumor resection to improve or at least stabilize visual function. Traditional surgical approaches, such as pterional, subfrontal, and interhemispheric, are familiar to most neurosurgeons, but, in the past decade, minimally invasive techniques have evolved. Both the endonasal endoscopic transsphenoidal approach and the eyebrow keyhole craniotomy have been advocated for TS meningioma, both potentially achieving the goals of a minimally invasive technique: minimal access but maximal resection with minimal collateral soft tissue destruction. The definitive choice of a high or low approach for TS meningiomas has been widely debated. In all patients, the approach should be tailored to the individual case and the specific imaging characteristics, particularly the presence of neurovascular encasement and the lateral extent of the tumor.
Expanded endonasal transsphenoidal approach
The expanded endonasal transsphenoidal approach (EETA) has been described extensively. In brief, the authors perform the procedure entirely under endoscopic vision. The head is placed in Mayfield pin fixation, and image guidance is used throughout (BrainLAB, Westchester, IL, USA). The nasal cavity is packed with lintin strips soaked in 1:2000 adrenaline before draping the field, and, subsequently, the middle turbinate and septal mucosa are infiltrated with 1% bupivacaine with 1:100,000 adrenaline; under endoscopic vision, the middle and superior turbinates are resected. A nasoseptal flap pedicled on the posterior septal branch of the sphenopalatine artery (Hadad-Bassagasteguy flap) is harvested and stored in the nasopharynx for the duration of the procedure. A wide sphenoidotomy is performed after a posterior septectomy. The sella face is then removed, and the bony opening continued through the TS to the planum sphenoidale. The position of the carotids is localized by direct visualization; by frameless stereotaxy; or, when there is bony dehiscence, using a micro-Doppler probe. After bony opening, the dura above and below the diaphragma is coagulated and opened, with control of bleeding from the superior circular sinus with Gelfoam (Pfizer Inc, New York, NY, USA), Floseal (Baxter International Inc, Deerfield, IL, USA), and a bipolar cautery. Further dural coagulation reduces the tumor blood supply and allows internal debulking with minimal obscuration of vision. After tumor volume reduction, the tumor capsule is dissected sharply away from arachnoid attachments and delivered. Both 0° and 30° endoscopes are used during the procedure. After tumor removal, the anterior fossa floor is reconstructed with Duragen (Integra Life Sciences, Boston, MA, USA) and the nasoseptal flap rotated into position. Mucosal to bone flap adherence is maintained with Tisseel (Baxter International Inc, Deerfield, IL, USA) and Gelfoam packing to fill the sphenoid sinus. The Gelfoam is supported with a 14 F Foley catheter left in situ for 48 hours postoperatively. No lumbar drains are used.
TS meningiomas particularly suited to an EETA approach are those that are truly midline with little eccentric lateral growth, those in patients with a large sphenoid sinus, and tumors situated entirely inferior and medial to the optic nerves. Encasement of the optic nerves, carotids, or anterior cerebral artery complex should be sought and excluded on preoperative imaging. In particular, the presence of a cortical cuff separating the tumor capsule from the anterior cerebral arteries is an excellent marker that vascular encasement is unlikely to be encountered ( Fig. 1 ). The advantages and disadvantages of the EETA are listed in Box 1 .
Advantages
No incisions
Faster recovery
Early devascularization of tumor
No brain retraction
Minimal manipulation of optic apparatus
Disadvantages
Risk of cerebrospinal fluid leak
Potential loss of olfaction
Difficult to remove tumor in optic canal when superolateral to optic nerve
Difficult to dissect adherent/encased small vessels at posterior margin
Eyebrow supraorbital keyhole craniotomy
This technique has been well described. In brief, following the induction of general anesthesia, the head is placed in the Mayfield pin fixation with the head turned 30° to the contralateral side and the head extended to bring the malar uppermost. The side of the approach is determined by the lateral projection of the tumor. The skin incision is placed in the upper border of the eyebrow, medial to the supraorbital nerve ( Fig. 2 A). After skin and muscle dissections, which are retracted superiorly using fishhooks, a pericranial flap is reflected inferiorly and the keyhole exposed. A single burr hole is made at the keyhole, and a free supraorbital bone flap is made approximately 20 mm in height (or the equivalent of the width of an open bipolar shaft). The inner table of the supraorbital rim is then drilled down along with the bony protuberances of the anterior fossa floor to gain additional exposure (see Fig. 2 B). The dura is opened in a C-shaped manner and reflected inferiorly. Under microscopic vision, the arachnoid of the carotid cistern is identified and opened to allow cerebrospinal fluid (CSF) release. No fixed brain retraction is used. Standard microsurgical techniques of tumor removal are used and the optic canals opened when required for complete tumor removal and decompression of the optic nerves. After tumor removal, the dura is closed watertight and the bone flap replaced using 2 Craniofix clamps (Aesculap Inc, Center Valley, PA, USA). The bone flap is approximated flush to the upper border of the craniotomy and the resulting inferior margin bone defect filled with Surgicel (Ethicon Inc, Johnson and Johnson, Piscataway, NJ, USA), to reduce depressions in the forehead. The pericranial flap is carefully reapproximated, and the galea and skin are closed without tension. A subcuticular nylon running suture provides the best cosmetic outcome for skin closure.
TS meningiomas for which an eyebrow approach would be most suitable are those with the tumor extending lateral to the carotid artery or superior and lateral to the optic nerves. Patients with normal pituitary function may also be considered preferentially for the eyebrow approach. In addition, better microsurgical control of adherent or encased vessels can be achieved. The advantages and disadvantages of the eyebrow approach are listed in Box 2 .
Advantages
Rapid access
Low risk of CSF leak
Good access to optic canals
Standard microsurgical dissection technique
Disadvantages
Breach of frontal sinus if large
Brain retraction
Difficult to remove tumor if it extends anterior to planum
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