gms | German Medical Science

ESBS 2005: Skull Base Surgery: An Interdisciplinary Challenge
7th Congress of the European Skull Base Society held in association with
the 13th Congress of the German Society of Skull Base Surgery

18. - 21.05.2005, Fulda, Germany

Management of primary optic nerve sheath meningiomas: presentation of a new classification system

Meeting Contribution

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  • Uta Schick - Neurosurgery, Wedau Kliniken, Duisburg, Germany
  • Werner Hassler - Neurosurgery, Wedau Kliniken, Duisburg, Germany

ESBS 2005: Skull Base Surgery: An Interdisciplinary Challenge. 7th Congress of the European Skull Base Society held in association with the 13th Congress of the German Society of Skull Base Surgery. Fulda, 18.-21.05.2005. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc05esbs17

DOI: 10.3205/05esbs17, URN: urn:nbn:de:0183-05esbs172

Published: January 27, 2009

© 2009 Schick et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.


Outline

Text

Introduction

The management of optic nerve sheath meningiomas (ONSM) remains controversial, but includes surgery, radiotherapy and plain observation. A new classification system based on the tumor location and extent is provided to clarify the possible manifestations of ONSM. Treatment modalities are derived from the different types and subtypes.

Methods

A retrospective analysis was performed on 73 patients with optic nerve sheath meningiomas who underwent surgery between 1991 and 2002. The follow-up period ranged from between 6 to 144 months (mean 45.4 mo). Ten patients underwent postoperative radiotherapy. We introduced a new classification system for ONSM according to the tumor location (Figure 1 [Fig. 1]).

Classification

We differentiate between intraorbital (type I), intracanalicular or intrafissural (type II), and intraorbital and intracranial (type III) types of ONSM.

Type I is located purely intraorbital (n=8). Type Ia is restricted to a flat extension around the optic nerve (n=1). Type Ib is manifested as a large bulbiform mass (n=4), growing concentrically around the optic nerve with marked proptosis. Type Ic shows exophytic tumor growth upon the optic nerve (n=3).

Type II is located intraorbitally with extension through the optic canal or superior orbital fissure (n=36). Type IIa is manifested as intraorbital tumor with tumor growth through the optic canal (n=32). Type IIb involves the orbital apex (n=4) and the superior orbital fissure, and sometimes even infiltrates the cavernous sinus.

Type III is located intraorbitally with large intracranial tumor extension (more than 1 cm) (n=29). Type IIIa extends to the chiasm (n=21). Type IIIb involves the chiasm up to the contralateral optic nerve, and planum sphenoidale (n=8).

Recommendation of treatment

In 2002, several remarkable papers upon the radiotherapy of ONSM were published in relevant journals with good results. Thus, we were compelled to rethink our surgical treatment and to declare radiotherapy as the new standard of care except for those with a mass effect intracranially. We would like to recommend radiotherapy without biopsy as the treatment of choice in flat purely intraorbital ONSM (type Ia) (Figure 1 [Fig. 1]) once mild vision loss develops. Otherwise these tumors should only be observed. Purely intraorbital tumors manifesting as large mass (type Ib) around the optic nerve should only be operated on to treat painfully uncomfortable eyes without useful vision. Otherwise these tumors can be observed and radiated once visual decline begins to occur. Type Ic tumors with large exophytic parts should be operated on.

Tumors with involvement of the optic canal (type IIa) and questionable intracranial extension with visual decline should be explored with intradural bony decompression of the optic canal. Then, the intracranial tumor is removed with preservation of the feeding vessels. The intraorbital part, that still facilitates useful vision should not be removed. Radiation should be the next treatment option for these subtotally resected tumors.

Type IIb tumors of the apex should be biopsied to verify histology. An extradural decompression of the optic canal and superior orbital fissure is recommended. The intracavernous part should be radiated.

Specific indications for surgery [2] are the intracranial extension (type III), to prevent afflection of the contralateral optic nerve and resect the intracranial tumor mass. These patients should first undergo intracranial resection with decompression of the optic canal. IIIa subtype already extends to the chiasm and the tumor around the optic nerve is resected. IIIb subtype reaches the contralateral optic nerve and the tumor is removed from the planum sphenoidale, chiasm and optic nerves. The intraorbital part should be radiated once visual decline has occurred.

Conclusions

Our classification system differentiates between intraorbital, intracanalicular or intrafissural, and intraorbital and intracranial types of ONSMs.

Treatment options can be derived from the types including radiotherapy, surgery and observation. If visual function is good, observation alone can be employed in intraorbital ONSM until progression is noticed. The role of radiotherapy has to be reevaluated and offered to adults once mild vision loss develops in intraorbital ONSMs. Surgery with decompression of the optic canal and intracranial tumor resection is favored for tumors with intracanalicular and intracranial extension. In case of residual or recurrent tumor growth, surgery should be followed by radiotherapy.


References

1.
Andrews DW, Faroozan R, Yang BP, et al. Fractionated stereotactic radiotherapy for the treatment of optic nerve sheath meningiomas: preliminary observations of 33 optic nerves in 30 patients with historical comparison to observation with or without surgery. Neurosurgery. 2002;51:890-904.
2.
Pitz S, Becker G, Schiefer U, Wilhelm H, Jeremic B, Bamberg M, Zrenner E. Stereotactic fractionated irradiation of optic nerve sheath meningioma: a new treatment alternative. Br J Ophthalmol. 2002;86:1265-8.
3.
Schick U, Dott U, Hassler W. Surgical management of meningiomas involving the optic nerve sheath. J Neurosurg. 2004;101:951-9.
4.
Turbin RE, Thompson CR, Kenderell JS, Cockerham KP, Kupersmith MJ. A long-term visual outcome comparison in patients with optic nerve sheath meningioma managed with observation, surgery, radiotherapy, or surgery and radiotherapy. Ophthalmology. 2002;109:890-900.