Neurosurg Focus 14 (6):Article 6, 2003, Click here to return to Table of Contents Tuberculum sellae meningiomas JOHN H. CHI, M.D. M.P.H., AND MICHAEL W. MCDERMOTT, M.D. F.R.C.S.(C) Department of Neurological Surgery, University of California, San Francisco, California Tuberculum sellae meningiomas are a classic tumor of the anterior fossa that present in patients with gradual visu- al deterioration secondary to optic apparatus compression. If untreated, complete blindness can occur. Treatment involves tumor removal and decompression of the optic chiasm via several operative approaches. Gross-total resection (Simpson Grade I or II) is the goal of treatment and can usually be accomplished safely. Special excision-related con- siderations include appreciation of arachnoid planes separating the tumor from neural tissue, adequate drilling of osseous elements for optimal exposure, and intraoperative preservation of the vascular supply to the optic apparatus. The authors reviewed their experience at the University of California, San Francisco, in cases of tuberculum sellae meningiomas treated between 1992 and 2002. In most patients, improvement of vision can be achieved with minimal postoperative complications and morbidity. KEY WORDS • tuberculum sellae • meningioma • anterior skull base • operative technique Meningiomas of the tuberculum sellae arise from the REVIEW OF SURGICAL TREATMENT limbus sphenoidale, chiasmatic sulcus, and tuberculum.14,22 They comprise approximately 3 to 10% of all intracrani- Clinical Presentation and Demographic Features al meningiomas.19,22 Correct diagnosis and management require an appreciation of the unique clinical, neuroim- Visual deterioration is the most common problem in aging, and surgery-related features that distinguish these patients harboring tuberculum sellae meningiomas. Pa- meningiomas from others of the anterior skull base. Tu- tients typically present with a history of uni- or bilateral berculum sellae meningiomas characteristically lie in a visual decline progressing over months to years. Visual suprasellar subchiasmal midline position, displacing the deterioration seems to be present early and often begins optic chiasm posteriorly and slightly superiorly, and the unilaterally. Because growth is slow and insidious in most optic nerves laterally.14 In cases involving large tumors ex- cases, evaluation and diagnosis are typically delayed, and tending toward the planum sphenoidale, sellae, and cav- significant vision loss of one or both eyes occurs. As such, ernous sinus, it can be difficult to differentiate tuberculum pre- and postoperative ophthalmological evaluation for sellae meningiomas from others originating from the pla- both visual acuity and visual fields is mandatory. Hum- num sphenoidale, olfactory groove, clinoid process, sell- phrey visual fields are standard in the pre- and postopera- ae, and medial sphenoid wing. Slowly progressing visual tive evaluation of these patients. If evaluation is delayed deterioration is the most common initial complaint, and tumors can grow and cause optic chiasm compression, prompt treatment is directed at preserving and improving which is less common today because of earlier diagnosis. vision. Management ideally consists of gross-total resec- On examination, greater than 95% of patients suffer visu- al acuity and/or field deficits and approximately 75 to tion without injury to neighboring vital structures. To limit 1–3,6,19 morbidity and mortality rates, knowledge of the ana- 90% have optic atrophy. The pattern of vision loss can vary, and although a bitemporal hemianopsia has been tomical relations of tuberculum sellae meningiomas is 1 necessary. described as the most frequent field cut observed, this has not been corroborated in recent series. Quadrantanopsia and unilateral temporal field defects are commonly report- Abbreviations used in this paper: ACA = anterior cerebral artery; ed in patients who have undergone formal ophthalmolog- CT = computerized tomography; EBL = estimated blood loss; ical visual field testing.3,8 MR = magnetic resonance. Headache is the second most common associated symp- Neurosurg. Focus / Volume 14 / June, 2003 1 Unauthenticated | Downloaded 10/06/21 11:30 AM UTC J. H. Chi and M. W. McDermott tom occurring in approximately 35 to 45% of patients, and tapered dural tail are both suggestive of meningioma ra- it may occasionally be the only presenting symptom.4,10 ther than pituitary adenoma.21 Other lesions in the differ- Facial numbness, altered mental status, seizures, endo- ential diagnosis include optic glioma, sarcoidosis, aneu- crinopathies, and anosmia have all been reported in asso- rysm, craniopharyngioma, and metastasis. ciation with tuberculum sellae meningiomas but are ex- Angiographic embolization of tuberculum sellae me- ceedingly rare. ningiomas is not routinely performed. The vascular supply Evidence of endocrinopathies at presentation is present tends to derive from small perforating branches from the in only a small number of patients. Reduced libido, alter- posterior ethmoidal, ophthalmic, superior hypophysial, and ation in menses, and elevated prolactinemia are found in A1/A2 artery segments. Preoperative angiography can help 5 to 10% of patients, but clear evidence of endocrino- demonstrate distorted vascular anatomy secondary to tu- pathies should suggest a diagnosis of pituitary adenoma mor mass effect, which usually reveals posterior displace- 2 rather than meningioma. Diabetes insipidus, however, is ment of the A1 and A2 segments of the ACA in 80% of 6,22 encountered in cases involving meningiomas originating patients and encasement of the A1 segment in 24%. from the diaphragma sellae, and serum sodium and pitu- itary function tests should be performed in all patients.2,9 Surgical Options Preoperative differentiation between tuberculum and di- Although controversy exists as to the best surgical ap- aphragma sellae meningiomas may be difficult to make proach, in truth several approaches may be suitable for based on clinical features or neuroimaging findings, and a variety of tumor sizes and attachments in this area. diagnosis is made intraoperatively when dural attachment The pterional, unilateral subfrontal, and orbitofrontal ap- to the diaphragma is visualized. Unilateral weakness has proaches may be used alone or in combination for small- also been reported, usually in the presence of significant to medium-sized tumors, whereas a bifrontal approach frontal lobe edema, and bilateral frontal lobe involvement may be performed for larger tumors. We have come to ap- can manifest with disinhibition and behavioral changes. preciate the flexibility and limited morbidity rate associat- Tuberculum sellae meningiomas are more common in ed with the bifrontal extended frontal craniotomy to reach women than men, and diagnosis is typically made in the tumors of this region. The bifrontal subfrontal exposure fifth to sixth decade of life. provides excellent views of the entire tuberculum sellae and proximal medial portion of the optic canal; it also al- Diagnostic Imaging lows the option of swinging laterally to open the proximal Although tuberculum sellae meningiomas follow the sylvian fissure to identify the optic nerves displaced by typical CT and MR imaging characteristics of meningi- tumor. The supraorbital osteotomy greatly reduces the ex- omas in general, in this region they can easily be confused tent of frontal retraction, limiting postoperative neuropsy- for pituitary adenoma. Meningiomas appear isodense to chological sequelae. brain on CT scans and generally isointense to brain on T1- Surgical Approach: Surgeon’s Perspective weighted and hypointense on T2-weighted on MR images, whereas pituitary adenomas tend to demonstrate a higher Prior to surgery, Humphrey visual fields should be doc- T -weighted signal. After administration of intravenous 2 umented to allow for postoperative comparisons. Con- contrast, meningiomas produce a homogeneous contrast frontation eye fields provide an inadequate assessment. enhancement (Fig. 1), whereas adenomas demonstrate Axial and coronal fat-suppressed MR images should be patchy enhancement. Although hyperostosis and intrasel- reviewed to determine the extent of optic canal involve- lar calcifications on CT may suggest meningioma, pitu- ment and whether there is hyperostosis and osseous infil- itary adenoma or craniopharyngioma can not be ruled out. tration of the tuberculum sellae. Midsagittal images will The sellae turcica is usually not expanded or only slightly always demonstrate a component of the tumor extending enlarged in tuberculum sellae meningiomas, in contrast to down over the tuberculum sellae to the superior aspect of pituitary adenomas, which usually expand the sellae. Ad- the pituitary gland. Typically, this component cannot be ditionally, a suprasellar base, optic canal extension, and a adequately resected unless the tuberculum sellae is drilled off, and blind scraping with pituitary curettes is potential- ly injurious to the pituitary stalk and/or medial portions of the optic nerves. At surgery a lumbar subarachnoid drain is inserted for cerebrospinal fluid drainage. The patient is positioned su- pine on the operating room table, with the neck flexed on the chest and the head extended on the neck. Draping for a bicoronal incision is performed with care not to place draping towels above the eyebrows because this will cre- ate too much pressure for the skin when the scalp flap is turned forward. A small quadrant of the abdomen is pre- pared