Neurosurg Focus 10 (5):Article 5, 2001, Click here to return to Table of Contents Meningiomas of the orbit: contemporary considerations PAUL T. BOULOS, M.D., AARON S. DUMONT, M.D., JAMES W. MANDELL, M.D., PH.D., AND JOHN A. JANE, SR., M.D., PH.D. Departments of Neurological Surgery and Pathology, University of Virginia Health Sciences Center, Charlottesville, Virginia Meningiomas are the most frequently occurring benign intracranial neoplasms. Compared with other intracranial neoplasms they grow slowly, and they are potentially amenable to a complete surgical cure. They cause neurological compromise by direct compression of adjacent neural structures. Orbital meningiomas are interesting because of their location. They can compress the optic nerve, the intraorbital contents, the contents of the superior orbital fissure, the cavernous sinus, and frontal and temporal lobes. Because of its proximity to eloquent neurological structures, this lesion often poses a formidable operative challenge. Recent advances in techniques such as preoperative embolization and new modifications to surgical approaches allow surgeons to achieve their surgery-related goals and ultimately opti- mum patient outcome. Preoperative embolization may be effective in reducing intraoperative blood loss and in improv- ing intraoperative visualization of the tumor by reducing the amount of blood obscuring the field and allowing unhur- ried microdissection. Advances in surgical techniques allow the surgeon to gain unfettered exposure of the tumor while minimizing the manipulation of neural structures. Recent advances in technology—namely, frameless computer-assist- ed image guidance—assist the surgeon in the safe resection of these tumors. Image guidance is particularly useful when resecting the osseous portion of the tumor because the tissue does not shift with respect to the calibration frame. The authors discuss their experience and review the contemporary literature concerning meningiomas of the orbit and the care of patients harboring such lesions. KEY WORDS • meningioma • orbital tumor • surgical resection “There is nothing in the whole realm of surgery more assumed an important role in the evolution of the special- gratifying than the successful removal of a meningioma ty of neurological surgery. Some individuals have even with subsequent perfect functional recovery, especially asserted that meningiomas have had the most significant should a correct pathological diagnosis have been previ- impact in the development of our specialty.71,72 Mac- ously made. The difficulties are admittedly great, some- Carty71 wrote, “If we were to designate an intracranial times insurmountable, and though the disappointments neoplasm that has had the most effect on the development still are many, another generation of neurological sur- of neurologic surgery, very likely the intracranial menin- geons will unquestionably see them largely overcome.” – gioma would be prominently considered.” Harvey Cushing,26 1922. Meningiomas with orbital involvement have captured Meningiomas are the most common benign intracranial the interests of neurosurgeons, neurologists, and ophthal- lesions accounting for approximately 18% of all intracra- 98 mologists alike for over a century. Members from each of nial neoplasms. Meningiomas have kindled much inter- these specialties have contributed to the treatment of these est over the years because of their biological and clinical lesions. In the not-so-distant past, however, a collegial behavior and of the possibility of cure with appropriate 125 relationship did not always exist among practitioners. In therapy. Virchcow was the first to describe the classic 1938 Cushing reminisced, “[In] recent years, the ophthal- pathological feature of the meningioma—namely, the mic surgeon, the earliest surgical specialist, and the neu- psammoma body (“sandlike,” referring to the presence of rosurgeon, the latest, have from the opposite directions granules within the tumor). The nomenclature of these tu- mors evolved with time; numerous descriptions and con- come to meet at the barrier of the optic foramen—each somewhat hesitant to trespass on the other’s field of siderable ambiguity have been generated by scholars. To 27 eliminate such confusion Cushing26 in 1922 introduced work.” The successful treatment of these fascinating yet the simple yet all-encompassing term meningioma. Sub- often formidable lesions has required the harmonious sequently, meningiomas as a pathological entity have amalgamation of the expertise of ophthalmological and neurosurgical surgeons. Indeed, comprehensive and mul- tidisciplinary cranial base teams have been assembled at Abbreviations used in this paper: CT = computerized tomogra- many institutions to treat patients harboring orbital me- phy; MR = magnetic resonance. ningiomas and other lesions of the cranial base. Neurosurg. Focus / Volume 10 / May, 2001 1 Unauthenticated | Downloaded 09/26/21 05:15 PM UTC P. T. Boulos, et al. Meningiomas of the orbit can be thought of as primary ics meningioma.21,37 Suffice it to say that meningiomas are and secondary in origin. Primary orbital meningiomas overall uncommon in children (1.5 to 2.3% of all intracra- arise from the optic nerve sheath and may extend through nial tumors24); however, the relative incidence of orbital the optic canal intracranially, or they may infiltrate the involvement in childhood meningiomas has increased. sphenoid wing producing hyperostosis. Nearly two thirds Several groups have endeavored to determine the pre- of orbital tumors, however, originate from outside the disposing factors for orbital meningiomas. Neurofibroma- confines of the orbit.10,22,49,60,126 Secondary orbital menin- tosis appears to be one predisposing factor, particularly in giomas usually arise from the inner and outer aspects of pediatric meningiomas.47,58,67,83,88,106,108,120,126 Exposure to the sphenoid wing but not the middle sphenoid wing. radiation has clearly been associated with meningioma They may infiltrate medially into the orbit, often with formation (with a latency ranging from 12–27 years), intraorbital, intracranial, and intraosseous portions. They although there have been few cases in which orbital in- often compress the optic nerve by narrowing the optic volvement is described. The role of trauma and viral canal. They may infiltrate the contents of the supraorbital infection in the development of meningiomas is contro- fissure and cavernous sinus or compress the frontal and versial. temporal lobes. There may also be cases of primary in- traosseous meningiomas in which the tumor arises from within the bone. Tumors originating along the sphenoid CLINICAL PRESENTATION wing have a relatively high incidence of bone involve- ment.95 It is thought that nearly 30% of orbital menin- The clinical presentation of orbital meningiomas has not changed since it was described by Cushing and giomas may involve bone (thus producing so-called hy- 27 perostosis), and 12% may originate from within the orbital Eisenhardt in 1938. Unilateral visual loss and progres- 102 sive, usually painless exophthalmos are the most com- bones. 21,97,105,124,131 The primary purpose of the present discussion is to ad- mon presentations described in the literature. Visual acuity tends to be involved early and exophthalmos dress comprehensively the unique topic of meningiomas 131 of the orbit. Data from the authors’ experience will be manifests later. The apparent visual loss generally de- included and the contemporary literature will be reviewed. velops gradually, although acute visual loss may occur in 2 to 5% of intracanalicular and 8 to 12% of intracranial Additionally, a recent case, complete with radiographic 128,129 and pathological data and intraoperative video clips will meningiomas. Other relatively common clinical fea- be used to illustrate many of the salient points germane to tures include optic disc changes, diplopia, headaches, and meningiomas of this region. nausea and vomiting. Optic nerve changes may be due to intracranial hypertension, which causes papilledema, or direct compression on the optic nerve, resulting in papil- ledema or optic atrophy. Additionally, intracranial hyper- EPIDEMIOLOGY tension may produce papilledema in the contralateral eye. Meningiomas comprise approximately 18 to 20% of all Diplopia may be caused by cranial neuropathies or by intracranial tumors90 and are the most common benign in- direct disruption of the rectus muscles. Headache, as well tracranial neoplasm and the second most common intra- as nausea and vomiting, are typically associated with in- cranial tumor overall (second to only gliomas). Intracra- tracranial hypertension. Wright131 emphasized that visual nial meningiomas have been estimated to occur with an loss was the most common initial symptom, followed by incidence of 2.1/100,000 people.101 exophthalmos, diplopia, afferent papillary defect, and op- Meningiomas account for 3 to 9% of all orbital tu- tic nerve changes with shunt vessels present. So-called op- mors49,99 and are certainly not considered rare.81 Primary tociliary shunt vessels on the disc surface, representative orbital meningiomas represent between 0.4 to 2% of all of collateral circulation between the central retinal vein intracranial meningiomas.19,72,101 Secondary orbital menin- and the choroidal/ciliary venous drainage system,87 are giomas are considerably more common than their prima- strongly suggestive of meningiomas involving the anteri- ry counterparts. Sphenoid ridge meningiomas