INTRODUCTION

The first successful removal of a tuberculum sellae meningioma was performed by Cushing in 1916. Later, in 1929, Cushing and Eisenhardt classified the meningiomas of the tuberculum sellae in four stages, according to their size.^1,2 Although Cushing emphasized that the early diagnosis, which determines the surgical results, is based on the attendance and accuracy of ophthalmologists, even in the magnetic resonance imaging (MRI) era the history of the symptoms remains too long. However, surgical treatment of these meningiomas evolved significantly over the following decades and in recent series complete removal has been achieved with an acceptable morbidity rate and the mortality is approaching 0%.^3–8

The precise definition of SM remains controversial, however. Tumors arising from different locations and extending either primarily or secondarily in the suprasellar area are regarded as such by some authors.^3,9–11 Alternatively, taking into account some clinical and therapeutical differences, they are regarded as separate entities according to their exact location, for example, diaphragm sellae, planum sphenoidale, or anterior clinoid meningiomas.^5–7,12

SM originate from tuberculum sellae, chiasmatic sulcus, limbus sphenoidale, and partly from diaphragma sellae and extend sub- or retrochiasmatic.^6,7 Preoperative differentiation between tuberculum and diaphragma sellae meningiomas might be impossible sometimes and only when tumor attachment to the basal dura is visualized intraoperatively is the exact diagnosis made. Although frontobasal, olfactory tract, planum sphenoidale, anterior clinoid, and medial sphenoid wing meningiomas might extend into the area, they are located prechiasmatically and are not discussed in the current chapter.

CLINICAL PRESENTATION

SM represent approximately 5% to 10% of intracranial meningiomas.3–5,^8,13,14 They have a typical female preponderance with a female/male ratio of 4 to 4.9:1, and a mean patient age of 50 to 58 years.

Patients typically present with a history of slowly progressive uni- or bilateral visual decline. At presentation, 90% to 96% of the patients have a chiasmal syndrome that is usually asymmetrical. Up to 25% of the patients have an onset of headaches. Hemispheric deficits, seizures, or mental changes are relatively rare and are observed in the case of very large tumors. Similarly, clinical signs and symptoms of endocrine disturbances are late consequences of tumor growth.

NEUROIMAGING

In all patients computed tomography (CT) and MRI, both native and with intravenous administration of a contrast agent, should be made. High-resolution CT scans best reveal the generally hyperostotic bony changes in the region of interest.^5,10,12 Meningiomas are usually isointense to brain on T1-weighted MR sequences and hypointense on T2-weighted sequences. They are normally located above the diaphragma sellae, where pituitary gland and stalk can be identified. After administration of intravenous contrast, they enhance homogeneously. In contrast, pituitary macroadenomas tend to demonstrate a higher T2-weighted signal and patchy contrast enhancement. The presence of intrasellar calcifications on CT or of a hyperostosis may suggest meningioma; however, pituitary adenoma or craniopharyngioma sometimes cannot be ruled out. Another important difference is the size of the sella turcica: in the case of SM it is generally not expanded or only slightly enlarged.¹⁵

Carotid artery angiography might be performed in patients harboring large tumors and typically shows elevation of one or both A1 segments of the anterior cerebral artery. In a recent study, tumor blush was noted in 70% of the cases and narrowing or lateral displacement of the internal carotid artery was seen in 9.1%.⁵ Magnetic resonance angiography (MRA) is used to analyze the location of the carotid artery and anterior cerebral artery complex. If the meningioma extends superiorly toward the floor of the third ventricle behind the anterior cerebral artery complex, complete tumor removal might be more difficult.¹⁶

ENDOCRINE TESTING AND OPHTHALMOLOGIC EXAMINATION

Endocrinologic tests for assessment of anterior pituitary function—of the hypothalamopituitary–adrenal, –thyroidal, and –gonadal axes—should be performed before the surgery, then 1 week and 3 months postoperatively. Posterior pituitary function is monitored for at least 1 week postoperatively by measuring fluid intake and urine output, as well as of the specific gravity of the urine. Endocrine deficits, in contrast to pituitary adenomas, are exceptional, but may arise postoperatively, especially if the pituitary has been irritated. In the hands of experience surgeons, these, however, tend to be transient.⁵

The standard examination should include at least testing the visual acuity for both eyes, Goldmann perimetry, funduscopy, and measuring intraocular pressure.⁵

SURGICAL TREATMENT

Historically, several approaches to the suprasellar area have been developed and controversy still exists as to the most effective one. Some authors state that the approach should be individually selected according to tumor size and attachment in this area, while others prefer more confined and safe approaches and consider the approach-related morbidity of paramount importance. The approaches that are commonly utilized are the bifrontal,^10,12,17 the unifrontal,^3,6,11,13 the pterional,^5,7,12,13,18 and the frontolateral.^3,7,9 In the past few years the extended endoscopic transsphenoidal approach has gained acceptance.

The craniotomy is done generally on the right side unless the tumor has a significantly eccentric extension toward the optic nerve and carotid artery on the left side.^5,7,13,19,20 Some surgeons prefer to approach the tumor on the side of worse vision.⁶ Whatever side is chosen, however, it should be remembered that it is more difficult to remove the tumor portion from underneath the ipsilateral optic nerve. Further, the optic nerve on that side is more prone to surgical lesion.