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7/31/2019 Journal Fess

1/1170 Oman Medical Journal 2009, Volume 24, Issue 2, April 2009

Functional Endoscopic Sinus Surgery: Indications andComplications in Ophthalmic Field

Abdullah Al-Mujaini,1 Upender Wali,1 Mazin Al-Khabori2

Introduction

Historical Perspective

Endoscopic sinus surgery or the treatment o acute andchronic sinusitis was well established by the rst third o this

century.1

It was based on the commendable anatomical studies oZuckerkandl, 2 Onodi 3 and Grnwald. ransnasal endoscopic

sinus surgery was introduced in the mid 1980s. Te term FESS

was coined by Kennedy.4 Endoscopic orbital decompression was

rst described by Kennedy5 and Michel6 in the early 1990s. Over

the years, enhanced visualization o key anatomic landmarks

such as the region o the orbital apex, which is a critical area o

decompression in optic neuropathy, has made endoscopic surgery

a versatile tool.

Functional Endoscopic Sinus Surgery (FESS) and InstrumentationTe concept o FESS is the removal o tissue obstructing the

Osteo Metal Complex (OMC) and the acilitation o drainage

while conserving the normal non-obstructing anatomy and

mucous membrane. Te rigid beroptic nasal telescope provides

superb intra-operative visualization o the OMC, allowing the

surgery to be ocused precisely on the key areas. Te image can

be projected onto a television monitor through a small camera

attached to the eyepiece o the endoscope. Microdebriders remove

the pathologic tissue while preserving normal mucosa.7 Over the

past 20 years, endoscopic sinus surgery has been widely used as a

sae and eective treatment or Para Nasal Sinus (PNS) disorders.

Powered instrumentation and stereotactic image-guided surgery

have improved efciency and saety o this procedure. Endoscopic

approaches to benign tumors o the nose, sinuses, anterior

cranial ossa and the orbit are now becoming widely established.Te combination o suction with powered dissection has

revolutionized endoscopic sinus surgery.7 However, the potential

or complications 8 has shadowed the procedure. Endoscopic sinus

surgery presented a series o complications in the late 1980s and

early 1990s.9 However, new technology o instrumentation has

produced undisputable advances. Te powered cutting instrument

is thought to be sae around the skull base and lamina papyracea

because it cannot grasp the intact bone, however, this sense o

saety is undermined by the act that the instrument can grasp and

cut ree edges o the bone.10

Te eld o FESS was not only limited to the domain o

Otolaryngology. Its indications in ophthalmology, orbit endoscopy

in particular, became clearer but oten at a great risk. Te

ophthalmic indications or FESS include orbital decompression

o thyroid orbitopathy,5 lacrimal obstruction,11 Optic Nerve (ON)

decompression, traumatic loss o vision, and pituitary tumor

surgery. 12

Te relationship between ophthalmology and otolaryngology

has been exploited in conditions such as silent sinus syndrome,

lacrimal duct problems, optic nerve decompression, and orbital

decompression, drainage o subperiosteal abscess, orbital trauma,

tumor surgery, and complications o endoscopic sinus surgery.

Review Article

Abstract

Functional Endoscopic Sinus Surgery (FESS) is a highlysophisticated type o surgery, which has revolutionized the surgical

management o chronic sinus diseases. In the ophthalmic eld,

FESS plays a crucial role in the management o a ew conditions,

but not without risks. Ophthalmic complications associated

with FESS are well documented. Tey mainly occur due to the

shared common anatomic areas between ophthalmology and

otolaryngology. Ophthalmic complications can vary in severity

rom very trivial cases such as localized hematoma collection,

which is not very problematic to very devastating cases, such as

optic nerve damage, which can lead to complete blindness. In

order to minimize such complications, saety measures need to be

considered prio to the surgery, these include; precise knowledgeo detailed anatomy, the operating surgeons ability to interpret

precisely the para nasal sinus C scan and experienced procedural

surgical skills.

From the 1Department of Opthalmology, College of Medicine and Health Sciences,Sulatn Qaboos University Hospital, Muscat, Oman 2Department of Otolaryngologyand Head and Neck Surgery, Al-Nahda Hospital, Muscat, Oman.

Received: 08 Jan 2009Accepted: 12 Mar 2009

Address correspondence and reprint request to: Dr. Abdullah Al-Mujaini, Departmentof Opthalmology, College of Medicine and Health Sciences, Sultan Qaboos University

Hospital, Musact, Oman.E-mail: [email protected]

Al-Mujaini A, et al. OMJ. 24, 70-80 (2009); doi:10.5001/omj.2009.18


2/1171Oman Medical Journal 2009, Volume 24, Issue 2, April 2009

Clinical Anatomy

TeSinonasal tract and orbit are contiguous structures. As rightly

mentioned by Chastain and Sindwani,13

practical limits betweenthe elds o otolaryngology and ophthalmology have produced an

area o no mans land in which otolaryngologists eel as uneasy in

the orbit as ophthalmologists do in the nose.

Developmentally, until the age o our years, the maxillary

sinus expands laterally to the inraorbital canal. Yet, at the age o

eight years, pneumatization extendes laterally to the inraorbital

canal. It is extremely important or all FESS surgeons and

ophthalmologists to remember the ollowing important relations

o the orbit to the cranium:

1. Te orbital apex and the lateral orbit are related to the middle

cranial ossa.2. Superiorly, the orbit is related to anterior cranial ossa.

3. Inerior orbital ssure communicates with the middle cranial

ossa.

During anterior to posterior dissection in FESS, the ollowing

ocular clinical anatomy should be considered to avoid iatrogenic

complications:

1. Laterally, the optic nerve may lie in intimate contact with the

posterior ethmoid cells (cells o Onodi) and sphenoid sinus.9

2. In cases where it is necessary to open the sphenoid sinus, entry

should be as ar medially and ineriorly as possible, to decrease

the risk o injury to the optic nerve and internal carotid

artery.

Surgical Aspects

Endoscopic sinus surgery under local and topical anesthesia has

presented some saety concerns in the sense that any periorbital

injury would evoke a painul response rom the patient and any

injury o the orbital hematoma would result in visual loss to the

patient. Tus No such advantages are possible under general

anesthesia.

Te extent to which the surgeon enlarges the ostium o ineriorturbinate is important. Excessive anterior extension risks damage

to the nasolacrimal duct and should be avoided. Te patients

should be instructed not to blow their nose during rst 48 hours

ater surgery because there is a risk o surgical emphysema o the

orbit and sometimes ace and cranial cavity.

In the presence o ethmoiditis with orbital edema or

subperiosteal abscess located lateral to the lamina papyracea, it is

better to use the endonasal approach in FESS.

During FESS an intact muco-periosteum lined cavity should

be preserved in the areas o the medial orbital wall, skull base and

the rontal recess to avoid orbital complications. Use o powered

instruments during FESS requires great care and a wide knowledge

o the anatomy related to the orbit. It has been shown that these

instruments can cause suction and or lead to the exposure o the

periorbital at.14

In acute orbital conditions (< 3 weeks), the orbital at is dirty

due to diuse edema and / or hemorrhage, while in chronic stages

it is dirty due to scarring.

Radiology in FESS

Te PNS and orbit are areas o high contrasting densities with air,

at and sot tissue, which increase the accuracy o the examination.

Axial views are better or delineation o medial rectus muscle

and the orbital abscess, while coronal cuts are useul or orbital

and sinus anatomy. Anatomical variations o the orbit and PNS

can occur not only among individuals but also within the sameindividual between two sides. In the context o FESS and its

associated neuro-ophthalmic complications, all FESS surgeons

should be well versed with the ollowing variations in clinical

anatomy:

1. Dehiscence o the Lamina Papyracea (LP) or developmental

anomalies o the medial orbital wall.15

2. Te ON may be direct ly exposed within the sphenoid sinus.16

3. Presence o Onodi cells (pneumatized posterior ethmoidal cells).

Radiological studies o the orbital and PNS structures prior to

surgery can ully appreciate such anatomical variations.17 C scans

perectly display any orbital and intracranial complications. It has

been ound to correlate with surgical ndings in only 84% o the

orbital complications o sinus involvement.18 Magnetic Resonance

Imaging (MRI) is better or ungal inections o the PNS and

orbit. Careul review o coronal and axial C scans beore surgery

acilitates the approach to the sphenoid sinus.

Ophthalmic Indications for FESS

Giving ull details o the surgical steps is beyond the scope o this

article; however, important surgical steps corroborating with theclinical anatomy, complications and prevention have been briey

touched.

Advances in beroptic technology, endoscopic techniques and

instrumentation have expanded applications o endoscopic surgery

rom inammatory, inectious and neoplastic diseases o the PNS

to include disorders o the orbit and cranium.19 Te risks o injuries

to the ocular structures associated with FESS depend on:

1. Surgeons experience

2. Extent and severity o sinonasal disease

3. History o previous sinus surgery

4. Intraoperative view o the anatomical structures o the PNS

and orbit20

Functional Endoscopic Sinus Surgery... Al-Mujaini et al.



1. Orbital Apex Lesions

Such lesions oten present a diagnostic challenge. Besides C, 21

MRI and clinical ndings, tissue histological diagnosis is otennecessary.22 Several approaches to the orbital apex have been

described.23 C-guided ne needle aspiration biopsy,21 has several

pitalls or example; the exact cytological diagnosis cannot be

obtained, the posterior apex lesions are oten difcult to aspirate

and there is always a risk o injury to the optic nerve and contents

o the superior orbital ssure. With endoscopes, it is possible

to approach the orbital apex transnasally or tissue biopsy or

decompression o the orbit or optic nerve.

2. Orbital Decompression in Dysthyroid Orbitopathy

Proptosis is usually associated with thyrotoxicosis, diuse toxicgoiter, and rarely Hashimotos thyroiditis. However, it can also

maniest in hypothyroid and euthyroid patients ater radioactive

iodine therapy. Endomysial broblasts produce mucopolysachrides

which contribute to the inammatory process, ultimately

leading to degeneration o extraocular muscles ollowed by at

replacement.24 Surgery is the mainstay o therapy or treatment

o acute sight-threatening Graves disease. It is the most direct

and eective way to treat orbital apex syndrome. Ocular recession

rom endoscopic decompression alone ranges rom 2mm to 12 mm

(average 3.5mm). Additional concurrent lateral decompression to

endoscopic procedure provides extra 2mm o globe recession.25

Te goals o the orbital surgery are:

1. o expand the orbital connements, thereby, reducing intra-

orbital pressure, and relieving the optic nerve compression.

2. Eliminate corneal exposure.

3. ake care o cosmetic disgurement 26

General guidelines or endoscopic orbital decompression in Graves

orbitopathy:

1. Only that portion o the oor should be removed that lies

medial to the inraorbital nerve.2. Postoperative diplopia can be avoided or reduced i a 10mm-

wide sling o ascia overlying the medial rectus muscle is

preserved during orbital decompression.

3. Do not remove bone in the region o rontal recess, or the

herniated at may obstruct drainage o the rontal sinus.

Several external approaches or decompression o the orbital

walls have been described in the literature.27-28 Decompression

o the medial orbital wall and the oor using an external

ethmoidectomy incision is most commonly used in spite o the

act that this approach provides limited access to the orbital apex.

Endoscopic surgical technique allows excellent visualization o

the landmarks and ull decompression o the medial orbital wall

which may be extended as ar as the optic canal.5 Te thicker

sphenoidal bone overlying the optic nerve may also be removed

more saely using a drill. Te inerior wall can be decompressed upto the inra-orbital nerve via a wide middle meatal antrostomy. Te

endoscopic approach avoids scarring and carries a much smaller

risk or the nasolacrimal system and inra-orbital nerve. In Gravess

orbitopathy, it is preerred to perorm orbital decompression

during a chronic phase. Te incidence o improvement ollowing

endoscopic orbital decompression or Graves orbitopathy ranges

rom 22% to 89%.1 Postoperative deterioration o visual acuity

occurs in less than 5% o patients. 25

3. Orbital Abscess

Sinusitis continues to be the most common cause o orbitalinammation and inection, especially in children. Te causes o

vision loss in orbital inections include optic neuritis, traction on

the optic nerve or retinal artery thrombosis. Residual visual sequel

tend to occur more in patients who had a visual acuity o 20/60 or

less at the time o start ing treatment or those who did not undergo,

or had delayed surgery.29 Subperiosteal abscesses are usually on

the medial wall o the orbit between the periosteum and the LP.

Lateral displacement o MR muscle by at least 2mm is diagnostic

o a r im- enhancing subperiosteal abscess. 30

Surgical indications include:

1. Deterioration in visual acuity.

2. Relative Aerent Pupillary Deect (RAPD).

3. Continuing ever ater 36 hours o medical treatment.

4. Clinical deterioration ater 48 hours.

5. No improvement ater 72 hours o medical treatment.31

An intraorbital abscess with a high intraorbital pressure should

undergo a wide orbital wall decompression, in addition to periorbital

incision and drainage o the abscess. Posterior ethmoidectomy

is done i there is extension o the abscess towards orbital apex.

Tis also acilitates a wide exposure and decompression o the

medial orbital wall, especially i orbital pressure remains elevated.

Tis step is more indicated or intra-orbital abscesses, and rarely

or subperiosteal abscesses. One should be careul not to violate

periorbita in the case o subperiosteal abscess.

Extra-conal intraorbital abscesses are better dealt with using

a 30-degree telescope ater incision o the periorbita. Intraconal

abscesses need a combined approach, as well as an active

participation o an ophthalmologist.

Computer Aided Surgery (CAS) has gained momentum during

the past two decades. Tough there is paucity o literature on its

application in the aspect o the management o orbital abscesses,32

the objective is to nd a signicant technique in dealing with

tumors and mucoceles o the sinonasal cavities involving the orbit.




Te endonasal endoscopic approach or subperiosteal abscesses

involves intranasal ethmoidectomy and removing portions o the

LP,33

allowing the pus to drain into the middle meatus and thenasal cavity. A combined external transcaruncular and transnasal

approach has also been used.

Advantages of endoscopic surgey in orbital abscesses are:

1. Unsurpassed and magnied view o the medial orbital wall.

2. Lateral and round the corners view with angled telescopes.

3. Simultaneous dealing o sinonasal cavities.

4. No acial incisions.

Te endoscopic technique has a similar success rate as

traditional open approaches, but with a shorter hospital stay and

less postoperative edema.34

4. Orbital Fractures

Amongst many injuries o head and neck, orbital oor Blow Out

Fractures (OBFs) are technically easiest to treat endoscopically

because the maxillary sinus provides an optical cavity to work

in. Visualization o the middle and posterior third o the orbital

racture is challenging with conventional approaches because o

postero-superior angulation o the orbital oor, relative to antero-

inerior orbital rim. Endoscopy guided orbital racture repair has

become popular in terms o better visualization, illumination

and reduction o herniation o orbital sot tissues. Due to a wide

variation in orbital wall anatomy based on gender and ethnicity,

there may be no sae area o dissection to guarantee no damage

to the posterior structures o the orbit.33 Deterrence in exploring

the posterior dissection may lead to residual entrapped tissue

or improper implant positioning, leading to enophthalmos. Te

endoscope is a vital tool to overcome such limitations.

4.1 Indications for endoscopic repair of OBFs:

Tese indications remain same as or traditional repair, namely:1. Isolated orbital oor injuries with EOM entrapment.

2. Enophthamos.

3. More than 50% disruption o the orbital oor.

rapdoor and medial OBFs are the best candidates or

endoscopic surgery. Large dissections lateral to the inraorbital

nerve may lead to postoperative paresthesia. Complex (two-walled)

ractures should not be managed endoscopically.

For small orbital oor ractures the use o endoscope via

gingivo-buccal incision and a maxillary sinus approach allow

visualization o suspected trapdoor ractures o inerior orbital

oor with entrapped inerior rectus or inerior oblique muscles.

Tis approach is ideal or cases not requiring implants.35Alternative

endoscopic approaches to the oor or larger ractures include:

1. ransantral approach described by Persons and Wong.36

2. Sublabial (Caldwell-Luc) incision by Strong.37

3. Combination o endoscopic orbital oor racture repair and

balloon catheter technique by Ikeda and colleagues.38

Endoscopy guided surgery is very helpul in cases o delayed

racture repair or secondary repair with tissue scarring. Isolated

medial orbital wall ractures are more common, more severe and

more requently the cause o enophthalmos than inerior orbital

oor ractures.39 Te endonasal endoscopic approach in these cases

has shown promising results with less incidence and less severity o

enophthalmos, and improved or resolved diplopia.40 Conventional

current transconjunctival and subciliary hidden incisions provide

a wide exposure or visualization and implant placement; however,orbital at proplapse makes it difcult to see posterior orbital shel.

Besides, postoperative lower eyelid malposition is known to occur

in 1.2% to 4.2% o patients.41 Hence the endoscopic transmaxillary

approach eliminates the potential or such limitations and

complications.

4.2 Advantages related to orbital blow out fractures and endoscopy

1. Conrmation o implant placements.

2. Conservative mucosal dissection.

3. Ensuring almost no le t over o orbital oor bone ragments.

4. Intraoperative assessment o orbital oor disruption and

zygomatico-maxillary complex racture.

4.3 Complications related to orbital blow out fractures and endoscopy

Te complications related to orbital blow out ractures and

endoscopy are the same as or open repair except the eyelid injury;

these include diplopia, enophthalmos and blindness. Te incidence

o enophthalmos is less with endoscopic surgery because o its

ability to visualize the posterior bony shel and conrmed implant

position. Te incidence and severity o iatrogenic V2

paresthesia is

much less with endoscopic approach compared to open one.

5. Endoscopic Dacryocystorhinostomy (EDCR)

Te concept o intranasal DCR is not new. Te approach was

introduced by Caldwell,42 almost one hundred years ago but ailed

due to difculties in visualization. In 1974 Jokinen and Karza43

revived the endonasal approach or the lacrimal system. New

operating microscopes and endoscopic telescopes,44 provided better

illumination and magnication or transnasal lacrimal surgery.

EDCR allows drainage o an obstructed lacrimal sac without the

need or a skin incision. Te beroptic light is passed through the

canaliculi to identiy the lacrimal sac. Te medial wall o the canal

is removed by a drill, curette or laser.45 Te use o drills rather than




laser is recommended because drills can create a wide exposure

o both sac and the duct without heating the surrounding bone

at the edge o the opening.46

Built in suction at the resection siteincreases visibility and maneuverability while irrigation minimizes

bone heating. Anterior and posterior aps o the sac mucosa can be

rotated over the bony edges and screwed in place with a small bipolar

weld. Te past decade has seen a tremendous increase in the use

o endoscopic surgery or the correction o primary and recurrent

lacrimal obstructions.47 Key points or localization o the lacrimal

sac include the point o insertion o root o the middle turbinate

on the lateral nasal wall, and the maxillary line. Te lacrimal

sac is located lateral to the maxillary line at its superior aspect.

It may be handy to introduce a 20-gauge vitreoretinal beroptic

endoilluminator into the superior or inerior canaliculus aterpunctal dilatation. Tis aci litates visualization and identication

o the anatomical structures like lacrimal sac by transillumination.

Te endoilluminator is advanced gently until a hard stop that

signies the lacrimal bone medial to the lacrimal sac.

In revision cases o EDCR, it is important to create a

generous bony rhinostomy extending rom above the middle

turbinate attachment to the level o midpoint o the maxillary

line. In revision procedures many anatomic structures like nasal

mucosa, medial wall o the lacrimal sac, the lateral portion o the

lacrimal sac containing internal punctum, and orbital sot tissue,

are incorporated into a zone o cicatrial tissue that occludes the

ostium. Any vigorous avulsion o this cicatrix can injure the

common canaliculus and medial canthal tendon. It is thereore,

recommended that the surgeon closely observe the medial

commissure while gentle traction is placed on the tissue at the

rhinostomy site. Reports have conrmed the value o transnasal

DCR as a highly successul alternative to external DCR in children

with persistent distal nasolacrimal system obstruction.48-49 Earlier

removal o silicone tubing (3-6 weeks) is recommended in children

to decrease the incidence o DCR ailure due to granuloma

ormation at the nasolacrimal stula site.50

5.1 Advantages of EDCR over external DCR

1. Absence o acial incision.

2. Preservation o integrity o orbicularis oculi muscle and medial

palpebral ligament which orm the unctional lacrimal pump

mechanism.

3. Simultaneous correction o any intranasal pathologic

conditions which may contribute to EDCR ailure.

5.2 Indications for primary EDCR

1. earing and inection associated with primary acquired NLD

obstruction.

2. NLD obstruction secondary to inammatory and inltrative

disorders.

3. Lacrimal duct injuries associated with sinus surgery and acialtrauma.

4. Atypical dacryostenosis.

5.3 Contraindications for EDCR

1. Suspected neoplasm involving lacrimal outow system.

2. Relative contraindications include large diverticulum lateral to

lacrimal sac, common canalicular stenosis and large lacrimal

system stones.

5.4 Complications of EDCR

1. Formation o synechiae between lateral nasal wall and middleturbinate or nasal septum.

2. Lacrimal sump syndrome (accumulation o lacrimal debri

in inerior portion o the lacrimal sac due to gravity, and its

inadequate removal.

3. Bleeding.

5.5 Predicaments of successful EDCR

1. Adequate rhinostomy at a proper place.

2. Sufcient bone removal inerior to the level o sac-duct

junction.

3. Due respect to the nasal-mucosal structures.

6. Endoscopically Assisted Conjunctivodacryocystorhinostomy

(ECDCR)

In CDCR, a stula is created rom medial commissural conjunctiva

into the nasal cavity. Pyrex glass tube (Jones tube) is placed in the

stula in most cases. Leaving the posterior hal o the caruncle in

place protects the medial bulbar conjunctiva rom inammation

due to contact with Jones tube orice. Te success rate o ECDCR

is 60% to 99%, compared to 80% to 90% in external CDCR.51

6.1 Indications of ECDCR1. Canalicular agenesis.

2. Canalicular obstruction.

3. Common Canalicular obstruction.

4. Lacrimal pump dysunction e.g. acial nerve palsy

6.2 Advantages of ECDCR over external CDCR

1. Less operative time.

2. Less blood loss.

3. Higher primary success rate due to better visualization o

intranasal landmarks.

4. Successul conrmation o the tube placement by endoscopy.51



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approach oers an excellent solution without any need or globe

retraction. Also conventional non-endoscopic surgeries are oten

delayed increasing the chances o permanent damage to the EOMdue to strangulation.

Te most commonly lost EOM rom any cause is the Medial

Rectus (MR).57 Other muscles reported to be injured during

FESS are inerior rectus and superior oblique.60-61 Te injury to

the superior oblique occurs due to direct drawing o the orbital

periosteum in the area o the muscle, into the suction port o the

drill, producing traction on the trochlea. Strabismus surgery should

be preceded by orbital exploration and release o entrapped tissues,

i possible. Surgical retrieval o the lost MR muscle may be quite

difcult because the muscle has no ascial attachments to oblique

muscles. When MR muscle is lost, it tends to recoil into the orbit,posterior to where the recti muscles penetrate the enons capsule.

MR lies close to the LP. Te injury may damage the muscle itsel,

its nerve and vascular supply or combination. Te injury to the MR

muscle presents clinically as a gross divergent squint and almost

absent adduction. Delayed recovery o the adduction explains the

nerve injury and the time taken to regenerate.

Plager and Parks59 have reported retrieving only one o ten

lost MR muscles. Tey advise against trying to retrieve a lost MR

muscle as the search may result in at adherence syndrome.

Te transnasal endoscopic approach to retrieve a lost MR

muscle involves inracturing o middle turbinate, removing the

uncinate process, ethmoidectomy, removing LP to the level

o anterior and posterior ethmoidal arteries and incising the

periosteum ater exposing the periorbita.

Te medial orbitotomy route or external approach involves a

modied Lynch incision along the inerior margin o the eyebrow

extending down halway between the inner canthus and the

anterior aspect o the nasal bone. Te anterior ethmoidal artery

should be coagulated and divided. Te periorbita is incised and

dissection carried into the at until MR is identied and grasped

with orceps through the Lynch incision. Te muscle is held withthe Alligator tooth orceps through the sub-tenon incision and

reattached to the globe with 6-0 polyglactin.62Absence o MR

muscle may require medial transposition o vertical recti but not

without a risk o anterior segment ischemia. Any muscle when

injured by the powered dissection is seldom surgically repairable.

Te rotating cutting jaws churn a portion o the muscle, raying the

remaining ends, which are not possible to approximate with perect

anatomical landmarks. In such cases a used vision in primary

gaze may be accepted as a surgical success. Te new powered

endoscopic sinus devices reduce the risk o hemorrhage but have

a greater potential or damaging EOMs i used by inexperienced

surgeons or misdirected.63

I on imaging there is lack o evidence o structural damage to

the orbital contents and EOMs but clinically there is an obvious

ocular motility dysunction, it may be an indication o a vascularor nerve injury to the muscle. For management o multiple muscle

injuries, multipositionl MRI can be used to demonstrate muscle

contractility in various gazes and determine i the transected

muscle is unctioning, and suitable or primary repair. C imaging

is not indicated here due to radiation exposure hazard. Also C

may not detect edema o the muscle in acute or subacute stages.

Iris angiography is useul to avoid anterior segment ischemia.

Guidelines or treating muscle injuries during FESS.60

1. In cases where the involved muscle is intact, but paretic due

to contusion injury or the injury is to its nerve, no immediatesurgical intervention is recommended. Te antagonistic rectus

muscle should be injected with botulinum toxin while awaiting

recovery o the paretic muscle to avoid its contracture.

2. In cases with transection injury, i the remaining posterior

segment o the MR muscle is longer than 20mm and is

unctional, muscle recovery via an anterior orbital approach

should be attempted.

3. In cases o muscle destruction, muscle transposition procedures

may be helpul and the potentially hazardous posterior orbital

explorations avoided.

Complications of FESS

Te orbit is at risk o complications during FESS because o the

ollowing important clinical anatomical relations with the PNS

and skull base:

1. Orbit is the lateral margin o the ethmoid area.

2. LP is a thin bone and can be ractured easily resulting in at

herniation, intra-orbital bleeding and EOM damage.

3. Posteriorly, ON is at risk as it lies in a more medial plane, and

closer to the lateral wall o the posterior ethmoid cells (Onodi

cells) and sphenoid sinus.4. Superiorly the ethmoid artery is at risk o transaction.

5. Lacrimal duct is susceptible to damage because it lies just

anterior to the uncinate process.

Orbital involvement in endoscopic sinus surgery occurs in

0.5% 64 to 3% o all procedures, and represents 16% to 50% o all

complications. Most common risks encountered in endoscopic

sinus surgery include bleeding, inection, injury to the eye and

its adnexa, cerebrospinal uid leak, anosmia etc. Most orbital

complications occur when the suction cutting tip o this incredible

powered instrument is inadvertently misdirected into the orbit or

intracranially. Many minor orbital injuries which would have been

trivia l with conventional instruments turn into major complications




when powered dissection or suction is used. Any injury or

dehiscence o the LP and consequent exposure o periorbital or

orbital at starts the sequence o events or orbital complications.I surgery is not stopped at this stage, the suction orces at the tip

o the instrument can draw in exposed tissue, and then severed

by the cutting, rotational jaws. Tis can include the medial rectus

muscle and the ON as well. Te presence o at or periorbita in the

surgical eld can be conrmed by gentle ballotment o the eye and

endoscopic observation at the site o the injury.65

Te stages o surgery during which the orbit may be at the

greatest risk o breach include ethmoidectomy or any ethmoid

sinus surgery,66 and uncinectomy or the medial orbital wall, and

maxillary antrostomy plus sinusotomy or the inerior orbit. Tis

is so because the LP, especially at the extremes o age, is very thin,and may be incomplete in some patients. Te LP is especially at risk

when approached rom the nasal space through a diseased sinus.

Anatomical variations o the sinus,15 and lack o tactile eedback

rom mechanized systems add to the risk o orbital complications.

Overall the orbital complications o FESS can be divided into

minor and major complications. Minor complications include;

periorbital ecchymosis, orbital emphysema, transient diplopia,

edema and ormation o l ipogranuloma.67

Major complications include; Extra-ocular muscle injury,

persistent diplopia, nasolacrimal duct injury, orbital hemorrhage

or hematoma, orbital oreign body, optic nerve injury, blindness,

subperiosteal abscess, abscess o the orbital tissue, orbital

cellulitis, cavernous sinus thrombosis, enophthalmos, injuries to

the vascular and nervous structures o the orbit,68-69 andorbital

emphysema leading to blindness.70 Open globe injury to the eye

during endoscopic surgery, probably secondary to peroration

o the LP, and entrance into the orbit and the globe by the

electrocautery tip has been reported by Castellarin et al. 71 Te

injury resolved spontaneously without any surgical intervention.

Te clinical sequel o orbital injuries can range rom pain, diplopia

to blindness.

1. Orbital Hematoma

Orbital hematoma is an ophthalmic emergency, because an

intraorbital bleed can rapidly produce an orbital compartment

syndrome (visual loss, external ophthalmoplegia, tense orbit,

central retinal artery occlusion) with permanent injury to the optic

nerve i ischemia persists more than 90 minutes. Te source o

bleeding may be injured lamina papyracea, periorbita, extraocular

muscles, or traction on the orbital at resulting in avulsion o an

orbital vessel. Orbital hemorrhage may be rapid rom arterial

bleeding (most likely source is the anterior ethmoidal artery,

which can be easily encountered posterior to the rontal recess) or

slow due to venous ooze.72 ypically this artery is located within

the skull base; however, it can project rom the skull base. When

injured, the artery retracts into the orbit causing rapid hemorrhageinto a conned space, resulting in orbital hematoma. Tis

complication is less likely to occur with the posterior ethmoidal

artery because o its location near anterior roo o the sphenoid,

and its less accessibility to the instruments. I bleeding arteries

cannot be approached endoscopically, external incisions may be

necessary to ligate them manually. Following FESS, C orbits is

indicated to assess the status o the globe.

Early signs o an orbital hematoma include preseptal edema,

ecchymosis, orbital proptosis and raised IOP. Bleeding in the eld

o surgery makes it very difcult to distinguish between important

anatomical landmarks like mucosa, periorbita and orbital at.Orbital hemorrhage is usually intraorbital, but subperiosteal

orbital hematoma has been reported.73

Fundus examination is an important part o FESS when

assessment o the blood ow to the optic nerve head is indicated.

In normal blood ow, digital pressure on the globe raises orbital

pressure above the diastolic pressure so that retinal arteries pulsate.

Orbital hemorrhage may raise the orbital pressure to this level so

that vessels ash spontaneously. I the orbital pressure rises above

systolic pressure, as can happen in severe intraorbital hemorrhage

rom anterior ethmoidal artery bleeding, the arteries will close so

that no pulsations can be seen. I this episode lasts over two hours,

two phenomena can occur:

1. Boxcarring (stagnant ow creating intra-arteria l clots) o the

retinal blood vessels.

2. Cherry red spot, which i persists or 90 to 120 minutes, can

lead to irreversible retinal ischemia.

Management

Not all patients with orbital hemorrhage require surgical

intervention; however, the role o an ophthalmologist in such cases

is undisputable. I the IOP is



19mmHg. Although requently advocated, lateral canthotomy and

cantholysis may be insufcient to treat a major orbital hemorrhage.

In such cases subciliary incision, transorbital decompression withenestration o the periorbita ensuring at prolapse and evacuation

o hematoma may be required. ranscaruncular orbitotomy can

identiy ethmoid arterial bleed and pave way or medial wall

decompression.77 Additional decompression o the orbital oor

and lateral orbital wall is also possible. As a matter o act, it is

rare that an ophthalmologist will be immediately available in

operation theatre (unless everything is planned), and i ortunate

to have one, he or she must be experienced in orbital surgery.

Also not all otolaryngologists are likely to be amiliar with newer

transcaruncular approaches or orbital decompression. Under

these circumstances it is desired that the operating otolaryngologist

should be amiliar with primary treatment or orbital hemorrhage

like canthotomy and catholysis.

2. Diplopia

15% to 63% o postoperative FESS patients report new onset

diplopia or worsening o pre-existing symptoms o diplopia.25,6

Diplopia is due to change in the vector o pull o EOMs.

Decompressive surgery rarely alleviates pre-existing diplopia, and

those who develop diplopia ater decompression surgery oten

need strabismus surgery.Guidelines to decrease or avoid diploia ater FESS:

1. Strut preservation o ineromedial bone between decompressed

oor and medial wall.78

2. Maintenance o the acial sling in the region o MR muscle.79

3. Balanced decompression (concurrent medial and lateral

wall).54

However, techniques designed to limit diplopia also limit

the extent o decompression, and postoperative diplopia is oten

accepted as a concession to improve visual acuity and other more

serious complications.

3. Epiphora

Te incidence o this complication ater FESS ranges rom 0.3%

to 1.7%. 80 It is more likely to occur i maxillary antrostomy is

extended too ar anterior with transection o the nasolacrimal duct,

hence EDCR is the remedy. Surgery on rontal sinus may damage

lacrimal sac, whereas uncinectomy or middle meatal antrotomy

may injure the nasolacrimal duct within the lacrimal canal.

4. Complications Related to Optic Nerve Sheath Decompression

Tese may include damage to the optic nerve bers, ophthalmic

artery, CSF leakage, meningitis etc. clear risks and absence o the

data to suggest benets o sheath decompression do not recommend

this procedure in general.

5. Neuro-opthalmic Complications

Anisocoria and accomodation palsy have been reported ater

endoscopic surgery.81 Tese probably occur due to perineural

edema caused by intra-maxillary manipulation around LP and / or

damage to the parasympathetic bers within the oculomotor nerve

or ciliary ganglion.20 Spread o local anesthetic agent can also cause

anisocoria lasting or ew hours. 82 Tere is a avorable response

to oral corticosteroids. Image aided neuro-ophthalmic procedures

have made the procedure saer and improved the prognosis. A

detailed review o the intraoperative use o computer aided surgery

can be ound rom the American academy o otolaryngology at thegiven website.83

Following are the general guidelines or intraoperative

prevention o complications:

1. Tickness, contour and presence o inraorbital or supraorbital

structures should be identied.

2. Anterior ethmoidal artery is a critical structure to identiy in

order to avoid intra-operative bleeding. Coronal C images

show a bony nipple at the junction o the medial rectus and

superior oblique muscles to identiy a useul landmark or the

location o this artery.

3. Identication o sphenoethmoidal cells (Onodi), which occurin 8% to 14% o the general population beore FESS is critical.

Mistaking Onodi cells or the sphenoid sinus can lead to

incomplete dissection and place the optic nerve and the orbit

at risk.

4. Both optic nerve and carotid artery orm an indentation in

the lateral wall o the sphenoid sinus. Tis can be unilateral

or bilateral. 5%-7% o these have dehiscent bone which

exposes these two vital structures to the intraoperative injury.

Preoperative imaging in the axial plane reveals excellent detail

o the sphenoid sinus and its relationship with these two

structures, thus avoiding iatrogenic complications.

5. IV anesthesia, relative hypotension and relative bradycardia

minimize intraoperative blood loss.

6. opical decongestants, prothrombotic agents and bipolar

cautery should be available.

7. Inspection o periorbita and periorbital at i LP is violated.

I periorbita is not injured and there are no signs o orbital

injury, surgery can proceed. I periorbita is cut, and orbital

at is exposed, intraocular pressure measurement and orced

duction test should be perormed.

8. Blind cautery o the periorbital at should be avoided to prevent

injury to the EOMs and the ON. Bipolar electrocautery works

well where bleeding does not involve the orbit itsel.




9. It is wise to keep the eyes uncovered during endoscopic surgery

so that surgery can be stopped immediately i there is any

indication o orbital swelling, aerent pupillary deect or eyelidbruising.

10. Do not use nasal packing over the exposed orbital apex to avoid

pressure on the ON.

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