Objectives: With respect to its characteristic pattern of growth from the orbit into the intracranial spacetoward the chiasm, patients with optic nerve sheath meningiomas (ONSM) are threatened to loose func-tion of both optic nerves. Fortunately, in less than 5% both optic nerves are involved initially. Hence,prevention of vision of the contralateral eye is the foremost aim of any therapy. Performing pre-chiasmatictransection might offer a further treatment option to avoid further tumor growth toward the chiasm.Patients and methods: In this retrospective study 12 patients with ONSM and blindness of the affected eyewere included. The surgical approach was performed either from pterional intradural or as a combinedapproach from pterional extra- and intradural.Results: Without any exceptions, vision of the contralateral eye could be preserved and did not show any
isionumor control
deterioration after surgery or during the follow-up time of 50.6 months. Furthermore in 58.3% of patientsgross total tumor resection could be achieved. During follow up observation in 67% of patients no furthertumor progress or recurrences could be observed. 4 patients, however, showed delayed tumor progressor recurrences that were treated by radiotherapy.Conclusion: Pre-chiasmatic transection of the optic nerve might offer a surgical treatment option to controltumor growth and to preserve vision of the contralateral eye.
. Introduction
Gliomas and meningiomas are the most frequent tumors relatedo the optic nerve [1,2]. Optic nerve sheath meningiomas (ONSM)re a rare tumor entity originating in the orbit and growing throughhe optic canal toward intracranial and are progressively affect-ng the function of the pertained optic nerve [3]. Fortunately, innly few patients, both optic nerves are involved initially, e.g. 5%n ONSM [2]. With respect to its characteristic pattern of growthlong the affected optic nerve, however, ONSM reach the chiasmhreatening the vision of the contralateral eye, and, in the case ofon-sufficient treatment finally leading to total blindness of theatient. According to the extent and the location of these tumors,nd the remaining function of vision of the affected eye, treatmentncompasses observation, radiotherapy or surgery [3–5]. Especially
n patients who already lost the vision of the ipsilateral affected eye,revention of the vision of the contralateral eye is the foremost
mportant aim of any treatment. In these patients pre-chiasmatic
∗ Corresponding author at: Department of Neurosurgery, University Hospital Hei-elberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany.el.: +49 6221 56 36314.
transection of the affected optic nerve, hence, might display anopportunity to avoid further tumor growth toward the chiasmand, thus, could offer the chance to forestall total blindness of thepatient. In contrast to a retro-bulbar transection that is usually beperformed during enucleations, pre-chiasmatic transection mightadditionally offer the chance of radical tumor resection and likelya better chance for tumor control.
In this paper, we accordingly describe our series of pre-chiasmatic transection of the optic nerve emphasizing technicalaspects, assessment of tumor control, and outcome of vision of thecontralateral eye.
2. Material and methods
This retrospective study includes 12 consecutively enrolledpatients with progressive ONSM treated at our university hospi-tal between 2006 and 2010. All information on clinical history,symptoms, surgical approaches, adjuvant treatment, outcome, andfollow-up were obtained by reviewing the patients’ charts and
radiological images.
The mean age of patients was 43 ± 17.5 years (range 28–75years). In this group gender distribution showed a female predom-inance of 3:1.
K. Zweckberger et al. / Clinical Neurology and Neurosurgery 115 (2013) 2426– 2431 2427
Table 1Overview of patients data and symptoms.
Case No. Sex Age Tumor type(ONSM)
Duration of symptoms(months)
Vision ipsilateral(dpt.)
Vision contralateral(dpt.)
Proptosis priorsurgery
1 F 55 II 5 0.1 0.7 Yes2 F 31 IIIa 72 0.05 1.0 No3 F 39 IIIa 72 0.1 1.0 No4 M 75 II 24 0 1.0 Yes5 F 28 II 102 0 1.0 No6 F 23 II 9 0 1.0 Yes7 M 30 II 54 0 1.0 Yes8 F 45 IIIa 40 0 1.0 No9 M 48 IIIa 96 0 1.0 No
10 F 36 IIIa 60 0 1.0 No0 1.0 No0 1.0 Yes
vt0eadciApac5stpd
iwtt
gwcpartnttsgsnetshwitctrwp
Fig. 1. Microscopical view into the intracranial space after opening the dura and
11 F 52 IIIa 40
12 F 44 II 120
Without any exceptions, all patients showed progressive loss ofision of the affected optic nerve that virtual resulted in blindness ofhe involved eye. In any case, the objectified vision ranged between
and 0.1 diopter. On the other hand, vision of the contralateralye was without any impairment in 92% of patients (1.0 diopter)t the time of first admission. In only 1 patient vision has alreadyeteriorated to 0.7 diopter, most likely because tumor masses wereompressing the chiasm, although, with respect to the MRI imag-ng prior surgery the chiasm itself was not tumor-infiltrated, yet.dditionally, since the intra-orbital mass effect of the tumor, in 5atients (41.6%) proptosis of the ipsilateral eye with thereby cre-ted complaints, encompassing irritation, pain, and watering eyesould be observed pre-operatively. In average symptoms lasted for7.8 ± 36.4 months (range 5–120 months) prior surgery, withouthowing any correlation between the duration of symptoms andhe occurrence of total blindness, limited by the small number ofatients (p = 0.714). Furthermore, no neurological deficits were evi-ent (Table 1).
All patients underwent evaluation by magnet resonance imag-ng (MRI) or additional computer tomography (CT). T1 and T2
eighted MR imaging were performed in three planes to analyzeumor configuration. All examinations were complemented by con-rast medium enhancement.
In accordance to the available literature, the indication for sur-ical or conservative treatment, including radiotherapy, in patientsith ONSM still remains controversial. In order to validate the indi-
ation for surgery, in this current study we have referred to theublished attempt that was made by the senior author to char-cterize different types of ONSM and thereof derive treatmentecommendations for each subtype, conceding that this charac-erization has been made from a surgical point of view and haso guideline character [3,4]. Briefly, according to their localizationumors have been assorted into three groups: type I intra-orbital,ype II tumor growth into the optic canal, and type III with exten-ion into the intracranial space. With respect to the pattern ofrowth and possible infiltration of adjacent structures further sub-pecification was suggested: type Ia: flat tumors sheathing the opticerve, type Ib: widespread and bulbiform tumor masses, type Ic:xophytic tumors on the optic nerve; type IIa: with tumor extensionhrough the optic canal and (type IIb) infiltration of the cavernousinus or the superior orbital fissure. Tumors regarded as type IIIaave been characterized by a primarily intra-orbital location, butith progressive tumor growth through the optic canal into the
ntracranial space and further intracranial tumor extension alonghe optic nerve, but without infiltration of the chiasm itself or theontralateral optic nerve. The last-mentioned one would represent
ype IIIb. In the majority and with only view exceptions radiothe-apy appears as the first choice of treatment, especially in patientsith intra-orbital tumor location and preserved vision (Ia or Ib). Inatients suffering from tumor-mass effects or with predominately
gentle retraction of the frontal lobe. The displayed menigioma is growing throughthe optic canal along the infiltrated and dislocated optic nerve toward the chiasm(II optic nerve; ACI internal carotid).
intracranial tumor extension and impaired or even lost vision, how-ever, surgery is still recommendable [3–5]. In this study we haveincluded only a highly selected cohort of patients with ONSM whoalready had lost their vision of the affected eye and showed tumorgrowth from the orbit into the optic canal (type II) and furthertumor extension into the intracranial space affecting the ipsilat-eral optic nerve, but not having infiltrated the chiasm, yet (typeIIIa) (Fig. 1).
One patient has received radiotherapy prior surgery as the firsttreatment option, unfortunately not leading to sufficient tumorcontrol and therefore resulting in the indication for surgery andwas, fulfilling the prerequisites, included in the study.
According to the location of these tumors, the surgical approachwas performed either from pterional intradural or, as a combinedapproach, from pterional intra- and extradural with the opportu-nity to resect the infiltrated optic nerve directly behind the globe. Inorder to perform a combined intra- and extradural approach, fol-lowing a pterional craniotomy, firstly the superior orbital fissurewas prepared extra-durally and a partial anterior clinoidectomywas done. As the next step the optic canal and the orbit wereopened by drilling carefully lateral of both sides of the optic canalas well as the roof and the lateral wall of the orbit itself, finallyallowing to explore the optic nerve and the peri-orbit (Fig. 2).Especially with respect to the cosmetic outcome, special atten-tion was paid to leave the supra-orbital rim intact. By a midline
incision the peri-orbit was opened and the intra-orbital part ofthe tumor-infiltrated optic nerve could be displayed and finallyresected. In order to achieve vast tumor resection, the optic nervewas transected directly behind the bulb. After removing the tumor
2428 K. Zweckberger et al. / Clinical Neurology and Neurosurgery 115 (2013) 2426– 2431
Fig. 2. Microscopical view into the extradual space, gently retracting the frontalloo
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5
tmw(noas
Fgst
obe from outside of the dura. The dorsal and lateral wall of the orbit, as well as theptic canal, were unroofed following careful drilling exposing the peri-orbit and theptic nerve (II optic nerve).
nfiltrated optic nerve out of the orbit, the apex and the unroofedptic canal, the dura was opened to reach the intradural part of theumor. In patients on whom exclusively an intradural approach waserformed, preparation started at this point. After opening the durand gentle retraction of the frontal lobe, the tumor-infiltrated nerveould be exposed and tumor masses were removed by preservingll adjacent vascular and nervous structures (Fig. 3). Finally, by per-orming pre-chiasmatic transection of the optic nerve, a completeemoval of the tumor-infiltrated nerve could be achieved and thus,ontinuous growth of the tumor toward the chiasm threatening theision of the still intact, contralateral eye could be avoided (Fig. 4).n order to prevent a CSF leak the optic canal was finally closed byat and fibrin glue.
On average, the follow-up time after surgery ranged over0.6 ± 25.7 months, but at least over 13 months for the shortest.
For statistical analysis a standard software package (SPSS Statis-ics, IBM, version 21) was used. All averaged data are reported as
ean ± standard deviation of the mean (SD) if not indicated other-ise. Absolute data are given as numbers (n) or as the percentage
%) of the total number. For comparison of two groups with non-ormal distributed data, one-way Anova was used. For estimationf potential correlations between non-parametric data the bivari-
nt Spearman-Rho correlation was calculated. A threshold value forignificance (p-value) of less than 0.05 was applied.
ig. 3. Microscopical view into the intracranial space after opening the dura andently retraction of the frontal lobe. The tumor has grown out of the optic canal,heathing and compressing the ipsilateral optic nerve. The chiasm and the con-ralateral optic nerve are still tumor-free.
Fig. 4. Microscopical view into the intracranial space after resecting the tumor andperforming a pre-chiasmatic transection of the tumor infiltrated optic nerve.
3. Results
Preoperative MRI and CT images showed the characteristic fea-tures of ONSM. In native T1 weighted images the affected opticnerve appeared hypointense, diffusely raised, and tend to growthrough the apex toward intracranial. After administration ofcontrast medium (CM) the tumor enhanced homogeneously andintensively (Fig. 5). In 8 cases an additional dilatation of the opticcanal could be depicted in CT scans. In contrast to gliomas of theoptic nerve, the dilatation of the optic canal in patients with ONSMis associated with a destruction or wedge out of the lamina com-pacta, especially at the edges toward the clinoid process.
In 9 patients (75%) a combined intra- and extradural, and inonly 3 patients (25%) an exclusively intradural approach wereperformed. In the latter ones the tumor was located overridinglyintradural with only small parts growing into the optic canal thatcould be reached from intradural by drilling and opening the canal.
In summary, in 58.3% of patients gross total tumor resectioncould be achieved, however, in 41.6% the resection remainedincomplete. Histopathological assessment of the excised tissueconfirmed the assumed diagnosis of ONSM (WHO I) (Table 2).
Following surgery, no patient showed any deterioration of thecontralateral vision, more specifically, neither any quadrant anopiaof the contralateral eye could be detected. One patient, however,was suffering from a partial paresis of the occulomotor nerve asso-ciated with transient ptosis. Apart from this, there were no furthercomplications.
Furthermore, all 5 patients suffering from pre-operative prop-tosis showed a significant improvement and a reduction of thereofcauses symptoms three months following surgery (8.54 ± 1.9 mmvs. 4.44 ± 1.8 mm post surgery; p < 0.05). In a reduced extend, how-ever, in two patients, proptosis was still apparent.
According to the histology and to the current recommendationsin the literature, none of the patients was subjected to any adju-vant treatment following surgery. During follow up observations,in 67% of all patients no recurrences or tumor progress could bedetected and no patient showed any impairment of the vision ofthe contralateral, intact eye. 4 patients, however, were affected ofrecurrent tumor growth after 13, 45, 60, and 63 months not lead-ing to deterioration of the contralateral vision. This happenstancecould only been put down to the fact that the recurrent tumors
have grown exclusively intra-orbital or in the supraorbital fissureof the ipsilateral side. In the two patients (50%) who pertained to theearly occurrence of recurrences (13 and 45 months), only a partial
K. Zweckberger et al. / Clinical Neurology and Neurosurgery 115 (2013) 2426– 2431 2429
Fig. 5. T1 weighted MRI scan (T1) showing a homogenously contrast media (CM) enhancing ONSM (right) growing from the orbit through the optic canal toward the chiasm.T , showi from t
rtp
4
cta[nlo
TO
he chiasm itself is still tumor-free. (a) Horizontal projection, (b) sagittal projectionnto the intracranial space, and (c, d) coronar projections displaying tumor growth
esection could be achieved during the previous surgery. In ordero gain tumor control in these patients, hence, radiotherapy waserformed in the further course.
. Discussion
Among the group of meningiomas primary ONSM assume a spe-ial position, both in treatment and outcome. The involvement ofhe optic nerve and tumor growth into the optic canal, however,re common in a wide variety of anterior skull base meningiomas
6], e.g. 77% in tuberculum sellae meningiomas [7,8] or 36% in cli-oidal meningiomas, but remain insufficiently canvassed in the
iterature. In these tumors surgical resection and decompressionf the optic nerve display the first choice of treatment by using
able 2verview of patients data, surgical approach and outcome.
Case No. Tumor type(ONSM)
Surgical approach (pterional) Gross totalremoval
Com
1 II Intra- and extradural No No2 IIIa Intradural No No3 II Intra- and extradural Yes No4 II Intradural Yes No5 II Intra- and extradural No No6 II Intra- and extradural Yes No7 IIIa Intra- and extradural Yes No8 IIIa Intra- and extradural Yes No9 IIIa Intra- and extradural No No
10 IIIa Intra- and extradural Yes No11 II Intra- and extradural Yes Par
occ12 II Intra- and extradural No No
ing vast intraconal tumor spread, as well as tumor growth through the optic canalhe orbit into the intracranial space partially infiltrating the cavernous sinus.
different surgical techniques according to the location of the indi-vidual meningioma [9–12]. In two comprehensive series publishedby the group of Stolke et al. and Al Mefty et al., an improvement ofvision could be achieved in 53% and 57%, respectively [6,13].
The management of ONSM, however, remains a peculiar con-troversial topic in the literature. Especially since the high amountof patients showing visual deterioration following surgery, radio-therapy, so far, seems to be accepted representing the primarytreatment for these lesions [14–22]. With respect to the avail-able literature fractionated radiotherapy seems to be in advance
in comparison to radiosurgery or gamma-knife, although differ-ent attempts have been described to fractionize dosage in orderto avoid toxic effects impairing the optic nerve [23]. Further-more, several authors have reported about long-term tumor control
nd preservation or improvement of vision following fractionatedadiotherapy with a cumulated dose of 50 Gy. Bloch et al. and Soldat al. have described long-term tumor control rates that reach to00% within 5 years and an improvement or stabilization of theision in 32% and 58%, respectively [24,25]. In a larger series of09 patients with primary and secondary ONSM, Paulsen et al.ave described tumor control in 100% within 3 years and of 98%ithin 5 years following stereotactic radiotherapy [19]. While they
ould achieve improvement of visual acuity in 13% of patients, 11%,owever, showed deterioration and 75% remained unchanged [19].ide effects like radiation-induced neuropathy occurred in only fewases and, compared to surgical results, appear acceptable. Never-heless, in the above-mentioned literature, pattern and extensionf tumor growth are neglected. Especially in patients with largentracranial tumor masses, and who already showed deteriorationf vision, surgery, however, is still legitimized and recommendable3–5]. In the long-term course, in patients with ONSM deteriora-ion or finally loss of vision appears as being only a question ofime [4,26,27]. Especially in consideration of this fact and the slowrowth of these tumors, it is questionable to claim “100% long-erm tumor control” over 3 or 5 years without, furthermore, givingny attention of possible infiltration of adjacent structures and thehereon based fact of high recurrence rates that are well knownn skull base tumors. Particularly in patients, who already lost theision of one eye, sufficient tumor control and prevention of theision of the contralateral eye is the foremost important aim of anyherapy. Fortunately, in less than 5% both optic nerves are involvednitially [2].
In this current study we could convincingly show for the firstime that pre-chiasmatic transection of the optic nerve could pre-erve the vision of the threatened contralateral eye in all patientsnd thus, offers a promising treatment option. Moreover, in 58% aomplete tumor resection could be achieved and, furthermore, dur-ng the follow up of 50.6 months in 67% of the patients no furtherumor progression or recurrences could be observed, concedinghat the time of follow up appears too short to conclude a final state-
ent, especially in slow growing tumor entities like meningiomas.t furthermore appears unsatisfying that these patients have notet medical attendance in an earlier stage of their disease, havingad the potential chance to avoid blindness of the affected eye.
Unlike to the common decompression of the optic canal orerforming a retro-bulbar transection, pre-chiasmatic transectionffers the chance of gross total tumor resection and preventionf the contralateral vision. This technique can be considered as aafe procedure convincingly proven by our own results showingo functional impairment of the contralateral vision in any patient.he existence of the so called “Wilbrand’s knee” can most probablye estimated as a myth. In 1904, Wilbrand described the anatomyf the human optic chiasm and observed crossing fibers taking aetour of 1–2 mm backwards into the atrophic contralateral opticerve before entering the optic tract. The interval in his subjectsetween loss of vision and death was not specified, but it mustave been considerable, judging from the severe optic nerve atro-hy visible in his illustrations [28]. In retrospective analysis of 153atients with chiasmal lesions cumulated in the Tuebinger Peri-etric Database no conclusive evidence for its existence could be
rovided [29]. Additionally, Lee et al. could not observe any junc-ional scotoma in visual perimetry after the transection of the opticerve directly at the chiasm in 3 patients with meningiomas [30].urthermore, Horton describes the optic pathway in Rhesus andquirrel monkeys under pathological and non-pathological condi-ions and concluded, that the “Wilbrand’s knee” does not exist in
ealthy primatic optic chiasm. It gradually forms over a period ofears following monocular enucleation, presumably from shrink-ge of the optic chiasm caused by atrophy of fibers from thenucleated eye [31]. Hence, shrinking processes of the optic nerve
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Neurosurgery 115 (2013) 2426– 2431
fibers might have created a “Wilbrand’s knee” most likely as anartifact.
The technique of pre-chiasmatic transection with the aim toachieve a gross total tumor resection offers furthermore someoptions, but is also associated with limitations. Different tumorentities, like meningiomas, metastases of carcinomas, and gliomasof the optic nerve might also infiltrate the optic nerve leadingto blindness of the affected eye [32–34] and, therefore, patientsmight benefit from a surgical removal of the tumor-infiltrated opticnerve. With respect to the radical resection of the impaired opticnerve out of the orbit, the apex, the optic canal, and the intracra-nial space there might be an increased chance to control tumorprogress. Additionally, a wide corridor is created that facilitatesthe resection of widespread skull base tumors preserving adjacentvascular and nervous structures easier. On the other hand, if thetumor has already infiltrated the superior orbital fissure or the cav-ernous sinus, the resection has to remain incomplete in order tosave the function of the corresponding cranial nerves. A furthermajor limitation is certainly constituted by the infiltration of thechiasm itself.
In summary, pre-chiasmatic transection of the optic nerve dis-plays a surgical treatment option both to achieve radical resectionand thus, better tumor control, and most notable to preserve visionof the contralateral eye in a selective cohort of patients with pro-gressive ONSM extending into the intracranial space and in patientswho have already lost the vision of the affected eye. Beside theopportunity to transfer this technique further to other tumor enti-ties, nevertheless, it has also its limitations, especially if the tumorhas already infiltrated the chiasm or the contralateral optic nerve.Since the small number of patients, however, final conclusions canonly be drawn with certain reserves.
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