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An insight into endoscopic transethmoidal resection of intraorbital tumors.

Yi Wang1, Lihua Xiao1*, Robert A. Goldberg2

1Institute of Orbital Diseases, the General Hospital of Armed Police, Beijing, PR China2Jules Stein Eye Institute, University of California Los Angeles (UCLA), Los Angeles, CA, USA

Abstract

This study aims to evaluate indications, complications and surgical technique in the endonasalendoscopic approach to orbital tumor resection. In this retrospective review, 11 patients who admittedand underwent endoscopic orbital surgery were reviewed. Demographics, preoperative andpostoperative eye examination, and size and imaging characteristics of the tumours were tabulated. Theendonasal approach was selected for tumors located nasal to optic nerve and in medial-inferior orbit toorbital apex. Under general anaesthesia, ethmoidotomy was performed with the aid of endonasalendoscope. The lamina papyracea was then fenestrated and through that opening, the intraorbitaltumor was isolated and removed. If necessary, an auxiliary transcaruncular incision was made tofacilitate the exposure. An en bloc removal of tumors was achieved in all cases. Pathological examinationhas confirmed that 9 patients had cavernous haemangioma, 1 patient had schwannoma and 1 haddermoid cyst. The dimension of tumors ranged from 15 × 12 × 10 mm3 to 24 × 23 × 16 mm3. Fourtumours were located nasal to the muscular cone and 5 tumors were in the muscle cone, 1 tumor in themedial rectus. After operation, the best-corrected visual acuity improved in 3 patients, with a fullrecovery of visual field defects. Two patients had impaired visual acuity. Three patients had transientlimitation of ocular movements. Abduction and adduction remain restricted in 1 case, respectively.Combination of endonasal endoscopy and orbital surgery technique can improve safety and efficacy inthe transethmoidal resection of medial or inferior orbital tumours or orbital apex tumours.

Keywords: Endoscopy, Intraorbital tumors, Surgery.Accepted on July 31, 2017

IntroductionEndoscopic endonasal approach has been developed in thefield of sinus surgery during the last 20 y with the advantage ofless invasiveness and better visibility. With the advancement ofimaging, nasal endoscopic anatomy and surgicalinstrumentation, this approach has been applied in the skullbase surgery, e.g. skull base tumor excision and optic canaldecompression [1-4]. But the use of endoscopic techniques tomanage lesions in the orbit is still restricted. This is becauseorbits are solid organs with highly dense structures likeeyeballs, optic nerve, etc., making it difficult to operateendoscope locally, given the fact that orbital fat and extraocularmuscles obstruct view. However, in recent years, there hasbeen increasing interest in the use of the endoscope to repairorbital wall fractures and intraorbital tumors [5-10]. Theendoscopic transethmoidal approach can be a candidate if atumor is located in the muscle cone, with its centre located inthe medial-inferior quadrant of the orbit on the axial slice andnasal and inferior to the optic nerve on the coronal slice [11].Traditionally a medial orbital lesion can be approached via acombined medial and lateral orbitotomy, which could makeobvious operation injury and spend more operation time. The

visual surgical space is very narrow, so postoperative loss ofvision in cases with medial tumours is more common thanthose with lateral ones. The skin scar of lateral canthus can’t beavoided. The endoscopic transethmoidal approach hasadvantages on these issues. This is because the tumor is easilyaccessed between medial and inferior rectus through theskeletonized lamina papyracea. A tumor will become moreapproachable when its medial surface is close to medial orbitalwall without any fat intervening. The easiest cases arecharacterized by tumors resting on the lamina papyracea,sometimes with bulging of the lamina into the sinus cavity as aresult of chronic compression.

The aim of this study is to summarize author’s experience tocarry out endoscopic transethmoidal resection of intraorbitaltumors, and discuss indications and relevant surgicaltechniques.

Materials and Methods

PatientsThis study was approved from hospital ethics committee of theGeneral Hospital of Armed Police. We retrospectively

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reviewed 11 patients who underwent endonasal transethmoidalresection of intraorbital tumors between May 2014 andNovember 2014. Eye function variables were assessedincluding of corrected vision, exophthalmos, ocular motility,upper eyelid movement, etc. Patients with a reduced correctedvision received fundus, pupils and vision field examination(Humphrey automated perimeter 750, Zeiss, Germany). Thenature, shape and location of tumors were demonstrated byComputed Tomography (CT) or Magnetic Resonance Imagingscans (MRI), with a detailed record of maximal anterior-posterior diameter in the axial view and maximal transversediameter and vertical diameter in the coronal view. This studywas conducted in accordance with the declaration of Helsinki.This study was conducted with approval from the EthicsCommittee of the General Hospital of Armed Police. Writteninformed consent was obtained from all participants.

Based on imaging analysis (CT and MRI scan, Figure 1), theinclusion criteria includes: (1) On the axial view, anterior poleof the tumor is situated behind the posterior pole of eyeball,and may reach up to the orbital apex; (2) On the coronal view,the center of tumor is situated nasal to the optic nerve in themuscle cone. In some cases, a large tumor may present with itsborder extended superior to the optic nerve and to the temporalquadrant; (3) The tumor is situated nasal to the muscle cone,and the top of the tumor can reach the nasal side of superioroblique muscle and the bottom can reach below to the inferiorrectus muscle; (4) No sinus inflammation or severe nasalseptum deviation; (5) Preoperative imaging diagnosissuggestive of cavernous haemangioma, schwannoma ordermoid cyst. The features of cavernous haemangioma areround or oval lesion with clear margin. It shows middle signalin T1WI and T2WI MR with multifocal enhancement. Thefeatures of schwannoma are also round, oval or dumb-bellshaped lesion with clear margin. It shows middle signal inT1WI and high signal in T2WI MR with extensiveenhancement. Dermoid cyst shows low density in CT scan. It’sMR features are both high signal in T1WI and T2WI with noenhancement.

Surgical procedureStandardized endonasal ethmoidectomy was performed using a0 degree endoscope (HD380, De Long Cooperation, andBeijing, China). The whole process was monitored andrecorded. Under the general anaesthesia, vasoconstriction wasachieved with ribbon gauze soaked with 1% adrenaline packedaround nasal cavity and middle meatus, which shrinks mucosa,making it thinner and thereby reducing bleeding. Next,ethmoidotomy was performed. Briefly, the lower third of theuncinate process was excised, and then ethmoidal bulla wasexposed with backbiting forceps. Subsequently, the basallamella of middle turbinate was removed, followed by a furtherdissection of posterior ethmoid cells. An adequate exposureresults in the middle turbinate as the medial border of operationfield, the roof of ethmoidal sinus as the top border, andaperture of sphenoidal sinus as the deep border. Sometimes,middle turbinate may be excised entirely to facilitate surgeon’s

view. The lamina papyracea was then gently fenestrated andorbital periosteum was incised.

Figure 1. Patients’ imaging appearances. (A) Patient 1 T2-weightedMRI images in the coronal view shows a right orbital tumor locatedextracone inferior to the roof of ethmoid sinus; (B) Patient 2 T2-weighted MRI images in the coronal view shows a left orbital bigtumor located in the muscle cone nasal to the optic nerve, spreadssuperiorly to the superior nasal quadrant and laterally to inferiortemporal quadrant; (C) Patient 3 T2-weighted MRI image in theaxial view shows a right orbital tumor located nasal to the musclecone, deep into the anterior edge of optic canal; (D) Patient 5 T1-weighted MRI enhanced image shows a left dumb-bell shape tumor inthe orbital apex, which located inferior and nasal to the muscle cone;(E) Patient 6 CT image in the axial view shows a right round tumoroccupied in the orbital apex, inferior to the optic nerve.

If necessary, an adjunctive transcaruncular incision was madeto prevent orbital fat herniation into the operation field andbetter expose the tumor. After a gentle separation along medialorbital wall to the depth of tumor location, two malleableribbon retractors were used to retract the surrounding fat,allowing the tumor to herniate into the ethmoid cavity.Sometimes, it was necessary to retract the medial and inferiorrectus muscle in order to characterise the relationship of thetumor and rectus muscle. Next, tissue forceps were used todeliver the tumor into the sinus cavity. In case of adhesions tosurrounding tissues, suction or blunt dissection was used todefine and dissect the tumor, taking advantage of the accessfrom both nasal sinus and orbital entries. Careful dissectionand optimal visualization may minimize possible injuries toextraocular muscles, optic nerve and other delicate orbitalstructures. Finally, the tumor was clamped out with tissueforceps (Figure 2). In cases of schwannoma, a curette was usedinstead to scrape the tumor out as a whole or in blocks, so as toavoid clamping (Figure 3). In cases of cysts, the contents wereemptied first and then the remaining capsule was then carefullydissected and clamped out. No special treatment is required fora mild intraorbital bleeding, because small ooze willpresumably drain out into sinus through the fenestrated laminapapyracea. For major bleeding, careful haemostasis wasperformed with bipolar cauterization or packed absorbablehaemostatic materials into the nasal cavity. Postoperatively, theeye was placed under a pressure bandage for 1 to 3 d.Antibiotics and haemostatics were routinely administered. Allthe patients were reviewed at 1, 2, and 3 months to assessocular functions and sinus healing. Imaging studies wererepeated at 3 months after surgery.

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Figure 2. Endoscopic endonasal resection of a left orbital big cavernous haemangioma in the muscle cone nasal to optic nerve in the patient 2(M: Medial Rectus, I: Inferior Rectus, T: Tumor. The arrow shows brain spatula). (A) A tumor that is located inferior and nasal to the optic nerveexposed through the fenestrated lamina papyracea, and brain spatulas used to block out the surrounding fats; (B) The tumor will be clamped outwith a tissue forceps; (C) The tumor is moved out via the ethmoid sinus.

Figure 3. Endoscopic endonasal resection of a left orbital smallschwannoma inferior to the optic nerve in the patient 5 (T indicatesthe tumor. The arrow shows a strabismus hook is placed deep into theorbit via transcarunclar incision and points towards the ethmoidsinus cavity. The double arrow indicates optic nerve). (A) The blackdotted line marks the border of the tumor, which is covered byperiosteum; (B) Hoar tumor parenchyma is visualized after openingthe periosteum; (C) A curette is used to scrape the tumor out; (D) Theblack dotted line marks the tumor bed after removal, no residues. Theoptic nerve is under the direct view.

ResultsAn en bloc removal of tumors was achieved in all the cases.Pathological examination has confirmed that 9 patients hadcavernous haemangioma, 1 patient had schwannoma and onehad dermoid cyst. The dimension of tumors ranged from 15 ×12 × 10 mm3 to 24 × 23 × 16 mm3. Four tumors were locatednasal to the muscular cone and 5 tumors were in the musclecone. Additionally, one tumor was in the medial rectus, onewas simultaneously in the intraconal and extraconal spaces. In8 cases, the tumors were located in the orbital apex and in theother 3 cases; The tumors were in the medial-inferior orbit.After operation, the best-corrected visual acuity improved in 3patients, with a full recovery of visual field defects. Twopatients had impaired visual acuity. Three patients hadtransient limitation of ocular movements, which disappeared in1 month at follow-up (Patient ID 2, 6 and 8). Abduction andadversion remain restricted in 1 case after 3 months,respectively (Patient ID 4 and 9). All complications arerecorded in the cases with intraconal tumors. Details areshowed in Table 1.

Table 1 illustrates patients’ demographics, preoperative andpostoperative ophthalmic features, nature, size and location ofthe tumors. The follow-up period ranged from 3 to 7 months,with a median of 4.5 months. Pathological examination wasdone in all of the 11 cases. Postoperative imaging studiesshowed no tumor recurrence.

Table 1. Demographics, presentations, tumour characteristics and complications.

Patient

ID

Gender

Age

Affectedeye

Preoperativepresentation

Postoperativepresentation

Tumour location Pathology Size (mm ×mm × mm)

Complications

Axial view Coronal view

1 F 67 Right Proptosis 2 mm No proptosis orenophthalmos

Anterior tooptic canaland medial tomedial rectus

Below theethmoid roofand medial tomedial rectus

Cavernoushaemangioma

16 × 16 × 8 None

An insight into endoscopic transethmoidal resection of intraorbital tumors


2 F 44 Left Proptosis 3 mm Enophthalmos 2mm

Medial to opticnerve andspread tooptic apex

Full of superiormedial toinferiortemporalquadrant in themuscle cone


24 × 23 × 16 Transientlimitation ofocularmovement

3 F 47 Right Progressive visualloss for 6 months,visual acuity 6/150,RAPD+, pale opticdisc, significant lossof visual field,proptosis 1 mm

Enophthalmos 1mm, visual acuity6/60, RAPD-,Reddish opticdisc, normalvisual field

Anterior tooptic canaland medial tomedial rectus

Medial tomedial rectus


20 × 13 × 10 None

4 M 56 Left Proptosis 3 mm Enophthalmos 1mm

Inferior tooptic nerve,and spread tomedial-inferiororbit

The centre oftumour locatedInferior to opticnerve, nasalside close toorbital wall andtemporal sidedown to inferiortemporalquadrant


23×20×19 Mild limitedabduction

5 F 39 Left Progressive visualloss for 17 months,visual acuity 6/30,pale optic disc,significant loss ofvisual field

Visual acuity 6/15,reddish optic disc,normal visual field

Medial andinferior tooptic nerve

Inferior to opticnerve andmedial toinferior rectusat orbital apex

Schwannoma 15 × 16 × 9 None

6 M 35 Right Progressive visualloss for 6 months,visual acuity 6/150,pale optic discRAPD+, significantloss of visual field,proptosis 3 mm

Visual acuity 6/18

RAPD-, reddishoptic disc, normalvisual field

Inferior tooptic nerve,full of orbitalapex

Inferior andmedial to theoptic nerve inorbital apex


17 × 10 × 14 Transientlimitation ofocularmovement

7 F 54 Left RAPD+, partial lossof visual field,proptosis 1 mm

RAPD-normalvisual field

Medial tomedial rectus

Medial andinferior tomedial rectus atthe orbital apex


15 × 12 × 10 None

8 F 51 Right Visual acuity 6/15,proptosis 3 mm

Visual acuity 6/60

Enophthalmos 1mm

Medial to opticnerve andspread toorbital apex

Medial to opticnerve andspread toorbital apex


21 × 19 × 17 Transientlimitation ofocularmovement,impaired vision

9 M 15 Left Proptosis 1 mm Enophthalmos 1mm

Swellingmedial rectuswith a fluidlevel

Swelling medialrectus

Dermoid cyst 17 × 14 × 13 Mild limitedadversion

10 F 45 Right Proptosis 3mm Enophthalmos 1mm

Medial to opticnerve

Medial andinferior to opticnerve


20 × 15 × 7 None

11 M 43 Left proptosis 2mm

visual acuity 6/6

Visual acuity 6/30

enophthalmos 1mm

Inferior tooptic nerveand full oforbital apex

Inferior to opticnerve and fullof orbital apex


18 × 15 × 13 Impaired vision

Note: RAPD is relative afferent pupil defect; Visual acuity is best-corrected visual acuity.

DiscussionEndoscopic transnasal orbital surgery is gradually considered agood alternative to external approaches for cavernoushaemangioma and others tumors located in the medial andinferior quadrant of the orbit, with the advantages of minimallyinvasive surgery. Dubal reviewed all studies on purelyendoscopic endonasal orbital tumor resections by the

MEDLINE database in 2014 [12]. In all 71 cases, the mostcommon tumor was cavernous haemangioma (45%), followedby osteoma, schwannoma and solitary fibrous tumor. In ourstudy, there is one case with dermoid cyst, which hasn’t beenreported in present literatures. Lenzi made a literature reviewof endoscopic transnasal surgery of orbital cavernoushaemangioma in 2014 using PubMed and Scopus and 12papers with 17 cases were identified [13]. His conclusions

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showed intraconal cavernous haemangioma located inferiorlyand/or medially to the optic nerve were amenable to transnasalendoscopic resection. One of the key skills of this surgery wasthe management of the medial rectus muscle to obtain access tothe intraconal space. With these literatures and ourexperiences, endoscopic endonasal approach for intraorbitaltumors has the following advantages: (a) Intrinsic drawbacksare associated with anterior, lateral or combined orbitotomy,e.g. inadequate illumination when exploring the area medial tothe optic nerve, limited space for surgical manipulation,especially in the orbital apex. Furthermore, to reach andseparate tumors, temporal muscle, extraocular muscles, orbitalfat are inextricably displaced. It may even cause compressionto the optic nerve and eyeballs when brain spatula is used toprovide additional space for operation. In contrast, endonasalapproach is able to bypass the biggest obstacle to orbitalsurgeries-eyeballs and orbital margin, and get easy access tointraorbital lesions through sinus cavity. The illumination andmagnification functions of endoscopes greatly improve thevisualization, making the exposure process of a tumor easierand at the same time, only a minor damage to ethmoid cell andlamina papyracea being expected; (b) A tumor in the medialorbit that is approached via the transethmoidal approach can bedelivered into ethmoidal sinus with tissue forceps. By doingthis, adequate surgical space is obtained between the lateralaspect of a tumor and the optic nerve, thereby allowing for anideal separation of the tumor from surrounding tissues andprotection of visual function, especially when optic nerve inthe apex is heavily adhered; (c) Benefit from the use of amonitoring that is able to amplify and achieve directobservation of de-adhesion process, especially that at theposterior pole of a tumor, the application of endoscopictransethmoidal approach prevents optic injury from accidentalinjury caused by using aspirator or probe. This has figured outthe challenge of an inability to separate the posterior pole of atumor under direct vision when taking traditional externalapproach, as the tumor itself can block the view; (d) Thetransethmoidal surgical approach can be regarded as drainagefor intraorbital bleeding into sinuses through the fenestratedlamina papyracea, although the risk of enophthalmos mayexist.

Although endoscopic transethmoidal orbital surgery has beenadopted as an effective alternative to external approaches,some limitations must be noted. Firstly, in terms of the locationof a tumor, it is not appropriate for tumors in the anterior orbit,which should be accessed through an anterior orbitotomy. Themedial endoscopic approach is certainly contraindicated if themass extends superolaterally to the optic nerve. Our experienceshows that endoscopic transethmoidal approach is a reliableoption for a mass situated nasal to the optic nerve with adiameter>2 cm, no matter whether it extends superior to theoptic nerve or in the inferior temporal quadrant. However, it isless feasible if the main body of a mass is in the superior nasalquadrant to the optic nerve and its diameter is <1.5 cm,because the dissection in the quadrant between the inferior andmedial rectus and then between medial rectus and optic nervemay cause a crush injury to the optic nerve laterally. Lenzi’s

review showed mean maximum diameter of cavernoushaemangioma resected by endoscopic transnasal skill was only16.0 ± 6.8 mm [13]. Our results are obvious out of this range.So, the location of lesion is more important factor than thediameter.

Secondly, the nature of a tumor should be considered, either.Given the fact that there is a limited space in the orbit to placeinstruments, making it difficult to perform complicated actionssuch as haemostasis, suturing, etc. Endoscopic transethmoidalapproach is applicable is suitable for the removal of cavernoushaemangioma, schwannoma and dermoid cyst. Cavernoushaemangioma is readily clamped out with tissue forcepswithout the concern that the capsule would be broken. Chhabraet al. found the ophthalmologic Cryoprobe® (MIRA Inc.,Waltham, MA) to be useful to freeze and excise these tumors[7]. The rapid freezing and thawing of the Cryoprobe tipallows for instant grasping and release of the tumor. In case ofschwannoma, after opening the capsule, a curette was used toscrape the tumor out as a whole or in blocks. Usually withtypical imaging findings, dermoid cyst tends to occur at thelateral orbit, especially near the frontozygomatic suture. It iscrucial to remove the remaining coat thoroughly. We have onlyone patient diagnosed of dermoid cyst in this study, whichoriginated from medial rectus. A careful dissection wasrequired to separate it from the muscle fibres. Anothercommon feature of these tumors is generally not secondary tosevere bleeding. Other solid tumors such as lymphoma,meningioma, and osseous tumors may be biopsied or resectedwith this approach, either [8,14,15].

The orbit is not a hollow organ, which is occupied by intensestructures. Based on our experiences, the following tips help tooperate in the orbit with endoscope: (a) For tumors in themuscular cone, 1 to 2 brain spatulas were placed via nasalcavity or transcaruncular incision and used to block out thesurrounding fats and extraocular muscles, making the tumorreadily to herniate out through the fenestrated laminapapyracea; (b) Sometimes, it is difficult to identify smalltumors in the orbital apex, which may be closely attached toextraocular muscles. To avoid possible injury to muscles, atechnique of rectus muscle retraction was developed wherebythe medial and inferior rectus muscles are isolated [9].Furthermore, by doing this, a mass is readily differentiatedfrom muscles and herniated out due to an alteration ofmuscular tone. Alternatively, Wu et al. proposed to detach andrelax the medial rectus so as to get access to the superior nasalquadrant of the optic nerve [10]; (c) During the process ofposterior pole de-adhesion of a tumor, it is more flexible toapproach a probe transcaruncularly rather than transnasally,and therefore improve the angle of access; (d) If imaging testsshow a large space occupying lesion in the orbital apex with adisplacement of optic nerve and no identified fat, which isindicative of a serious adhesion, a separation process shouldinitiate from nasal cavity or transcaruncular incision [16]. Ifstill difficult, a transconjunctival or lateral orbitotomy shouldbe undertaken to make more room between lateral aspect of atumor and optic nerve [17,18]; (e) Cavernous haemangioma isdistressing for its fragility and bleeding tendency when being



clamped. Bleeding can make the operation field less clear. Thetumor also becomes smaller in volume and is easily shelteredby fat tissues. Therefore, adequate exposure is necessary beforeit being clamped out gently. If necessary, brain spatulas areused to block out surrounding fats. In summary, depending onthe endoscopic experience and familiarity with the orbitalanatomy, one can develop his own surgical skills.

It has been frequently reported that the application ofendoscope in the treatment of nasal sinus diseases is associatedwith serious orbital complications, e.g. the injuries of opticnerve or medial rectus [19,20]. This occurs because laminapapyracea may be mistakenly treated as ethmoid cells,consequently entry into the orbit. An easy approach to identifythe lamina papyracea and the lesion is to place a strabismushook deep into the orbit via the transcaruncular incision andpoint it towards the ethmoid sinus cavity. This procedure helpsto determine the site to fenestrate the lamina papyracea.Intraoperative navigation maybe is the best solution forlocating the tumor, but the expensive equipment limits it’susing [21].

There were no serious complications in the cases reported inthis study. Two patients had impaired visual acuity that wasprobably due to optic nerve injury in the orbital apex related todissection of adhesions between the tumor and optic nerve.Five patients had limited ocular movements, 3 of whichresulted from operation-induced oculomotor nerve palsy orextraocular muscle injury and resolved in one month. Mildreduced abduction was recorded in one patient, and has notresolved. Based on imaging results, the reason may be adisplacement of medial rectus into the ethmoid sinus, withmuscle function restricted by surrounding scar tissue. Anotherpatient with dermoid cyst had mild adduction limitation,possibly caused by the injury to the medial rectus or itsdominant nerve following cyst excision.

In our study the complications are more frequently associatedwith a tumor inside the muscle cone than extraconal tumors,which are confirmed by Bleier et al. Dubal’ s review supportedthis opinion too, the complication rate of which was higher forintraconal tumors (48.0%) than for extraconal tumors (26.7%),but without statistical significance [12,22]. The majordeterminants of the incidence of complications are the extent towhich the tumor adheres to the optic nerve, oculomotor nerveor extraocular muscles, the relationship between the tumor andits feeding artery, and bleeding tendency after tumor excision.Future innovations in orbital surgery should focus ontechniques to optimize the dissection of the tumor from thedelicate nerves, vessels and muscles of the orbit, and to furtherreduce complications. A multidisciplinary team, includingorbital and rhinologic surgeons, is an essential component forthe surgical planning and management [23].

Competing InterestsThere are no competing interests to report for this submission.

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*Correspondence toLihua Xiao

Institute of Orbital Diseases

The General Hospital of Armed Police

Beijing

PR China

