Original article 105

External endoscopic multiportal frontal sinus obliteration forlaterally pneumatized frontal sinus: a feasibility studySameh M. Amin

Department of Otorhinolaryngoogy, Fayum

University, Faiyum, Egypt

Correspondence to Sameh M. Amin, MD,

Department of Otorhinolaryngology Head and

Neck Surgery, Fayoum University, 128 Gisr El

Suis heliopolis, Faiyum, 11321, Egypt

Tel: +20 100 661 3574; e-mails:

abdelgalils@yahoo.com;

drsamehmohamed71@gmail.com

Received 28 November 2017

Accepted 14 December 2017

The Egyptian Journal of Otolaryngology2018, 34:105–110

© 2018 The Egyptian Journal of Otolaryngology | Publish

IntroductionOsteoplastic flap procedure is a standard method used for frontal sinus obliteration.Endoscopic external frontal sinus obliteration is a minimally invasive new techniqueconfined to small-sized and medium-sized pneumatized frontal sinuses.ObjectiveThe aim of this study was assess the feasibility and surgical application of thistechnique for far-lateral pneumatized frontal sinuses.Materials and methodsTen sides of adult dry skull were assessed for frontal sinus pneumatization andsupraorbital cells by computerized tomography. Three sides were selected withfrontal sinus pneumatization extending beyond midorbital line. Feasibility ofobliteration of frontal sinus was tested. Endoscopic external multiportal frontalsinus approach was done using angled endoscopy and standard instrumentation.Classic frontal sinus trephine port was performed initially to safely locate the frontalsinus. In-situ nondisplaced superiorly based miniosteoplastic flap reaching tomidorbital plane was performed providing another port. Additional lateraltrephine port beyond midorbital plane was performed. Angled endoscopy andstandard instrumentation were used reciprocally through different ports to reachdifferent areas of frontal sinus. Outcome parameters were ability to reach corners offrontal sinus, remove sinus septae and nasofrontal duct, and maintain integrity ofanterior wall of frontal sinus. Surgical application was done in two cases of frontalsinus mucocele and meningoencephalocele.ResultsIn three laterally pneumatized frontal sinuses of dry skulls, corners, septae, andnasofrontal ducts could be handled using external multiportal endoscopic approachwithout disruption of anterior frontal wall. Three ports allowed two-hand surgicaltechnique. Surgical application in two cases with follow-up over 6 months revealedno significant complication. Subcutaneous collection developed in one case after 2weeks and resolved with medical treatment.ConclusionExternal endoscopic multiportal obliteration is feasible for frontal sinuses withlateral pneumatization beyond midorbital line. This technique is minimallyinvasive with less morbidity. Long-term follow-up in a larger series is needed.

Keywords:endoscopic, frontal sinus obliteration, feasibility, laterally pneumatized

Egypt J Otolaryngol 34:105–110

© 2018 The Egyptian Journal of Otolaryngology

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IntroductionFrontal sinsus obliteration is indicated in chronicfrontal sinusitis with failed or infeasible endoscopicendonasal surgical treatment like Draf III procedure.According to Draf and colleagues, type III endoscopicendonasal frontal sinostomy is technically not possibleif anterior-posterior diameter of frontal sinus is lessthan 0.8 cm. This fact excludes from the beginning asignificant portion of frontal sinuses to be amenable tofull range of endoscopic frontal sinostomies. Otherindications of frontal obliteration include lateral-placed pathology like mucoceles, destruction ofposterior wall, marked destruction of anterior all,cerebrospinal fluid (CSF) leak, and tumors and riskfactors for failure of endonasal endoscopic sinostomy

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like sinonasal polyposis and recurrence. Frontal sinusobliteration is usually performed through bicoronal orunilateral frontal incision with osteoplastic elevationand fat or synthetic material sinus packing [1].

Complications of obliteration include injury of frontalbranch of facial nerve, disruption of osteoplastic flapwith necessary reconstruction, intracranial entry duringflap elevation, and long-term danger of mucoceleformation, esthetic defects, infection, and prolonged

know DOI: 10.4103/ejo.ejo_89_17

Figure 1

106 The Egyptian Journal of Otolaryngology, Vol. 34 No. 2, April-June 2018

hospital stay [2,3]. In an attempt to reduce thesemorbidities, Ung et al. [4] reported an endoscopicminimally invasive frontal sinus obliteration withequivalent short-term results to osteoplastic flap andobliteration. The procedure was performed through asmall supraorbital incision and frontal trephine portand therefore confined only to small-sized to medium-sized frontal sinus [4]. In the endoscopic era,obliteration is still needed particularly in far-lateralfrontal pathology. The aim of this study was to testthe feasibility of external endoscopic multiportalapproach for frontal sinus obliteration with far-lateral pneumatization.

Dry skull 5. Computerized tomography of paranasal sinuses coronalcuts bony windows showing bilateral frontal sinus pneumatizationbeyond midorbital plane (yellow star). Yellow arrow indicates inter-frontal cell.

Materials and methodsRadiological studyThe anatomical part was done on noncadaver dry skullmodels. A detailed consent was taken from patientssubjected to surgery. An ethical approval was obtainedfrom Committee of the Department of Otorhino-laryngology, Fayoum University. Computerizedtomography (CT) axial cuts bony windows ofparanasal sinus (PNS) less than 1mm were done forfive adult dry skulls as part of navigation-guided studyprotocol. Registration error proved to be less than0.025mm during trial indicating high accuracy inall dry skulls. Reconstructed coronal and sagittal cutswere obtained to determine degree of frontal sinuspeumatization, supraorbital cells, and other cells if any.Lateral pneumatization of frontal sinus was definedas presence of pneumatization beyond the midorbitalplane passing through superior rectus muscle. Lateralpneumatization was best assessed in cuts showinglateral orbital walls and frontal sinus (Fig. 1).

Dry skull feasibility studyThe dry skull was fixed in supine position with slightextension allowed in a holder similar to that used fortemporal bones. A classic frontal trephine was done0.5 cm from midline at level of orbital roof. Angled 45°endoscopy was done to explore sinus cavity anddimensions. A superior miniosteoplastic flap wasfashioned. Initially, a horizontal osteotomy withKerrison punch ronguer was done from first trephine tomidorbital plane 1 cm above orbital roof. Two verticalosteotomies were fashioned at both end of horizontalosteotomy. The second trephine port is performed alonglateral vertical osteotomy preferably bisecting it. Caremust be taken not to disrupt integrity of anteriorfrontal wall. The horizontal osteotomy serves as anadditional port for fine instruments like dissectors. Theminiosteoplastic flap is not elevated unless decisionis taken to abandon the endoscopic technique.

Performing multiple ports before fashioning of theminiosteoplastic flap make the later difficult to obtainin a stable manner. If more ports are needed or two-handtechnique is acquired an additional port is done laterallymidway betweenmidorbital plane and lateral orbital wall.All bony septae were removed and sinus corners handledwith different instrumentation. In case of supraorbitalcells, septations with frontal sinus should be removed andjunctionwithethmoidal complexoccluded(Fig.2aandb).

Surgical techniqueA medial supraorbital incision was done through theeyebrow. In the two cases, an approach was adoptedsimilar to that used in feasibility study. The mucosa andseptation were removed and or ablated with unipolardiathermy. The nasofrontal duct was occluded andmucosa was inverted inside. In case of CSF leak, themeningoencephalocele was reduced with bipolardiathermy and posterior wall reconstructed with fascialata. Similar occlusion of junction of supraorbital cellswith ethmoid complex can be done with pledgets offascia. The frontal sinus cavity was packed with fatimpregnated in betadine solution. Additional gel-foam packing can be used. The supraorbital incision isclosed in two layers with final subcuticular layer.

Case 1

A 22-year-old male presented with late (after 1 year)post-traumatic CSF leak after motor car accident.Patient had failed conservative therapy. CT andmagnetic resonance of PNSs (Fig. 3) revealedmeningoencephalocele of right sphenoid and leftfrontal sinus. The latter was situated far-lateral in thefrontal sinus with defect in posterior wall at junctionwith supraorbital cell. Endoscopic endonasal repair

Figure 3

CT paranasal sinus showing right sphenoidal (horizontal arrow) and left frontal (vertical arrow) meningoencephalocele. Left frontal posterior walldisrupted at septum with supraorbital cell.

Figure 2

(a) Dry skull model. Right frontal in situ mini osteoplastic flap (blue star) with horizontal limb (white arrow), three ports (green, black and yellowarrows). Left frontal sinus open showing septum a supraorbital cell (blue arrow). (b) Same dry skull model. Right frontal multiportal approach withtwo instruments (right curved suction tip and left 45 degrees angled Bleksely forceps).

External multiportal frontal sinus obliteration Amin 107

and obliteration of right sphenoid sinus were done.External endoscopic multiportal repair and obliterationwas performed. Follow-up after 6-month revealedsuccessful repair without complications (Fig. 4a and b).

Case 2

A17-year-oldmalepresentedwithnasal obstructionandleft inferolateral proptosis. CT and magnetic resonanceof PNSs (Fig. 5a and b) revealed extensive allergic fungalsinusitis with left orbital invasion and laterally placedfrontal mucocele with defect of orbital roof. Endoscopicendonasal eradication of fungal sinusitis was done withfrontal recess clearance. CT PNS revealed distortedanatomy of frontal recess, asymmetrical skull baselevel, and distorted middle turbinate. Frontal ostiumwas not localized endoscopically. Frontal fungal

sinusitis and laterally placed mucocele were clearedthrough external endoscopic multiportal approach andobliteration (Fig. 6a and b). The patient developedsubcutaneous collection 2 weeks postoperatively,which was cleared by antibiotic therapy. Otherwisefollow-up 6 months later revealed successfulobliteration with no complication (Fig. 7).

ResultsResults of computerized tomography for selection ofdry skull with lateral pneumatization of frontal sinusSkull 1

Left frontal pneumatization to midway betweenmidorbital plane and lateral nasal wall, right frontalpneumatization to midorbital plane, and bilateralsupraorbital cells were recorded.

Figure 4

(a) Axial soft tissue windows showing successful obliteration (yellow arrows). (b) Postoperative CT paranasal sinus bony windows.

Figure 5

(a) CT PNS showing left frontal posterior table disruption with left supra orbital cell. (b) MRI PNS showing extensive allergic fungal sinusitis withleft frontal far lateral mucocele.

108 The Egyptian Journal of Otolaryngology, Vol. 34 No. 2, April-June 2018

Skull 2

Bilateral frontal pneumatization reaching not extendingbeyond midorbital plane, with no supraorbital cells, wasrecorded.

Skull 3

Right frontal pneumatization reaching to midorbitalplane and left hypoplastic pneumatization reaching themedial orbital wall were recorded.

Skull 4

Bilateral hypoplastic frontal sinus just reaching mediaorbital walls was recorded.

Skull 5

Bilateral lateral pneumatization extending to midwaybetween midorbital line and lateral nasal wall,

no supraorbital cells, and large interfrontal andsupraorbital cells were recorded.

Consequently, only three sideswere included in the study.

Dry skull feasibility studyIn the three dry skull sides encountered in this study,frontal sinus corners, septae, and nasofrontal ductwere accessible by angled endoscopy and standardcurved instrumentations including curved suctiontips, 30° and 45° angled Bleksely forceps, andstraight hand pieces of drills. Two ports wereenough for endoscopy and one instrument, whereasthree ports allowed two-hand technique.

Surgical application resultsThe technique was used successfully in two casesremoving mucosa and septa and drilling the sinus

Figure 7

CT PNS coronal cut showing clearance of allergic fungal sinusitis, farlateral mucocele and successful obliteration (yellow arrow).

Figure 6

(a) Endoscopic view of left fronat asinus after removal of septum (S) and far lateral mucocele (M). (b) Endoscopic view of supraorbital incision(SOI) and in situ mini osteoplastic flap with multiportal approach.

External multiportal frontal sinus obliteration Amin 109

floor and narrow corners. The nasofrontal ductwas successfully occluded. No disruption of anteriorwall or esthetic complication has occurred. Incase 2, subcutaneous collection occurred 2 weekspostoperatively and subsided without recurrence withshort-term medical treatment. The same casedeveloped transient postoperative frontal numbness.

DiscussionIn the era of endoscopic endonasal sinus surgery,frontal sinus obliteration is still indicated in asignificant portion of patients particularly in far-lateral frontal pathologies. Limited reports suggestedthe use of flexible endoscopy to reduce the need of openapproaches [5]. This applies for visualization but notfor surgical procedures. Osteoplastic flap obliterationhas better results and less recurrence in comparisonwith endoscopic approaches. Osteoplastic frontal flapwith obliteration is still a highly efficient procedure for

long-term results, yet with considerable morbidity andrelative invasiveness. Undue cost effectiveness isattributed to possible need of navigation-guidedharvest of osteoplastic flap to avoid intracranial andorbital entrance, long hospital stay, and possibility ofmini plates or titanium mesh reconstruction [6].Furthermore, the learning curve of the procedureamong rhinologists is poor, amenable to few casesand predominance of endoscopic procedures.Although highly effective, the procedure does notexclude future development of mucocele. Therefore,candidate patients are asked to consent for suchcomplications and long-term follow-up [1].

Early attempts to reduce such morbidity were thesuggestion of performing miniosteoplastic flap. It,however, does not resolve the problem of reconstruction[2]. Further reports of Ung et al. [4] described anendoscopic frontal obliteration through trephine withequivalent short-term results to osteoplastic flapobliteration. Ung et al. [4] confined the procedure tosmall-sized and medium-sized frontal sinuses. Theyused a single port through classic trephine, whichlimited instrumentation to reach different areas offrontal sinus [4]. This study therefore tested thefeasibility of performing obliteration of laterallypneumatized frontal sinuses through minimally invasiveexternal endoscopic multiportal approach. Lateralpneumatization was defined as extension beyondmidorbital line with an incidence of 30% of dry skullsides in this study in CT. The use of multiportal accessto frontal sinus allowed better visualization, ease ofinstrumentation allowing surgery in large frontalsinuses, and probably improving essential steps forsuccessful obliteration. These steps include total removalof septae and mucosa, drilling of corners, and obliterationof nasofrontal duct.Our results show that extension lateralto midway between midorbital plane and lateral orbitalwall usually necessitates two ports for endoscopicmaneuverability. Extension beyond this level may

110 The Egyptian Journal of Otolaryngology, Vol. 34 No. 2, April-June 2018

indicate addition of third port in lateral part of frontalsinus. The first port of classic frontal trephine is essentialnot only for safe location of frontal sinus but also forcontrol and obliteration of nasofrontal duct. Incomparison, fashioning of osteoplastic flap needspreferably neuronavigation to avoid intracranial entry.The horizontal limb of in-situ miniosteoplastic flapallowed free instrumentation of frontal sinus while stillmaintaining anterior frontal wall integrity. At same time,the option of osteoplastic flap is maintained in case thesurgeon doubts proper removal of frontal sinus mucosa.

Radiological assessment of frontal sinus is essential toselect proper surgical treatment. Distance betweenanterior and posterior tables less than 8mm excludesthe trial of Draf III endoscopic sinostomy [1]. Far-lateral pneumatization beyond midorbital planemakes endonasal endoscopic surgery difficult even ifcombined with ‘from above’ approach. Volumetricclassification of frontal pneumatization is impracticalfor surgical decision between endoscopic or openapproaches [7]. Meticulous search for presence orabsence of supraorbital cell is mandatory. Afterremoval of septa between frontal sinus proper andsupraorbital cells, obliterating the opening of lateralin ethmoidal complex is important to avoid mucoceleformation. The presence of other frontal cells ininfundibulum or interfrontal cells must be studiedpreoperatively to avoid residual mucosa or missingthe nasofrontal duct.

The follow-up period in this study was 6 months, beingprimarily a feasibility study. This is in comparison witha study by Ung et al. [4] where follow-up period was2.5 years comparing similar technique with osteoplasticflap. Both studies showed successful obliteration withminimal complications [4].

One disadvantage of this study was the use of dry skullmodel. The model lacks sinus mucosa but allowedperfect testing of possible visualization of sinus

corners and instrument maneuverability. Anotherdisadvantage was the small sample size attributed tostrict selection criteria of lateral frontal pneumatizationbeyond midorbital plane. This led to exclusion of sevensides of dry skulls. The two cases used for surgicalapplication had same selection criteria.

ConclusionThe external endoscopic multiportal frontal sinusobliteration is feasible for far-lateral pneumatizedfrontal sinuses. The technique is minimally invasive,with minimal complications and achieved successfulfrontal sinus obliteration over short-term follow-up. Alarger sample is needed with long-term follow-up tocompare these results with conventional osteoplasticfrontal sinus obliteration.

Financial support and sponsorshipNil.

Conflicts of interestThere are no conflicts of interest.

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