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Sphenopalatine Foramen Computed Tomography Landmarks

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Objective: The aim of the study was to assess different radiologic bony landmarks for endoscopic localization of the sphenopalatine foramen (SPF). Methods: Paranasal computed tomography (CT) scans of adults without sinonasal pathology were included.
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  Copyright © 2019 Mutaz B. Habal MD. Unauthorized reproduction of this article is prohibited. Sphenopalatine Foramen ComputedTomography Landmarks  Mohammad Waheed El-Anwar, MD,   Alaa Omar Khazbak, MD,   Atef Hussein, MD,  Sameh Saber, MD, y  Ahmed Awad Bessar, MD, y and Diaa Bakry Eldib, MD z Objective:  The aim of the study was to assess different radiologic bony landmarks for endoscopic localization of the sphenopalatineforamen (SPF). Methods:  Paranasal computed tomography (CT) scans of adultswithout sinonasal pathology were included. On axial cuts, theanteroposterior distances from the SPF to maxillary line, anterior head of the middle turbinate, basal lamella of the middle turbinate,choanal arch, and posterior fontanel of the maxillary sinus ostiumwere measured. While on coronal cuts, the vertical distances fromthe SPF to the nasal floor was measured. The registered measurements were then studied and statistically analyzed. Results:  In 70 patients (140 sides, 840 measurements), the meandistances from the SPF to nasal floor, choanal arch, maxillaryline, anterior head of the middle turbinate, basal lamella,and posterior fontanel were 25.6  2.4, 8.5  1.38, 36.4  2.6,34.6  4.26, 8.1  1.27, and 13.7  1.7mm, respectively,without significant differences between right and left sides.Females showed significantly shorter mean distances betweenSPF and the nasal floor ( P ¼ 0.0011), choanal arch ( P ¼ 0.0459),and posterior fontanel ( P < 0.0001) than males. While nosignificant differences were detected between both sexes asregard distances from SPF to maxillary line ( P ¼ 0.5579),anterior head of middle turbinate ( P ¼ 0.8581), and basal lamella( P ¼ 0.0638). Conclusion:  Preoperative CT can provide multiple easilydetected, reliable, and simple bony landmarks that can helpSPF endoscopic localization. Thus the authors recommend adding these measurements to the preoperative CT checklist for  patients scheduled for sphenopalatine artery ligation and/or excision of vascular lesions. Key Words:  Computed tomography, endoscopic sinus surgery,endoscopic sinus surgery, sinus surgery, sphenopalatine artery,sphenopalatine foramen (  J Craniofac Surg   2019;00: 00–00) E  pistaxis is one of the commonest otorhinolaryngology emergen-ciesthatareseeninabout10%ofthepopulation. 1,2 Eventhough90% of epistaxis arises from Kiesselbach plexus anteriorly,lateral nasal wall represents the primary site of refractory posterior epistaxis. 1–4 Becausesphenopalatineartery(SPA)withitsbranches,providethe bloodsupplytothelateralnasalwallandpartofthenasalcavity,thusitis considered the most common source of posterior epistaxis. 1,3,4 Severe posterior epistaxis that is refractory to conservativemanagement usually demands surgical cauterization or ligationof the SPA. 3,5–7 Thedirect transnasalendoscopicSPA ligationorcauterization isnow considered the procedure of choice due to its eff ectiveness and  low morbidity 4,7 with no need for sinus dissection. 3–5 The sphe-nopalatine foramen (SPF) is identified after mucoperiosteal flapelevation and crista ethmoidalis identification from the posterior aspect of the middle meatus. Sometimes, when landmarks of SPFare not detected easily and rapidly, the maxillary sinus is opened toassist the surgeon to identify the SPF. 7 Failure of SPA ligation or cauterization may reach up to 10% 8 that was attributed to the wide anatomical variations of the SPF and SPAinthelateralnasalwall. 9 Inaddition,localizationoftheSPAasit exits SPF may be not easy and challenging due to the active bleeding that could obscure the operative field, due to the fr iabilityand edema of the nasal tissues by previous nasal packing, 7 or by previous surgery or trauma. Therefore, presence of reliable simplefixed surgical landmarks to identify the SPF would be more helpfulthan the traditional reliance on the crista ethmoidalis. Thus, preop-erative proper radiologic localization of SPA during endoscopicsinus surgery (ESS) will make the operation more safe and cariesless incidence of morbidity.Although the anatomical location of the SPF has been previouslyreported, there are few studies on the computed tomography (CT) bony landmarks 7,10 and the CT landmarks are still not popularized amongsurgeonsorradiologistsandnotinvestigatedindifferentraces.Therefore, the aim of this study was to evaluate differentradiologic landmarks for localization of the SPF. METHODS This study was conducted in otorhinolaryngology and radio-diag-nosis departments, Zagazig University Hospitals, betweenDecember 2016 and December 2018.The study was approved by Zagazig University IRB and writteninformedconsentwasobtainedfromtheparticipants.Thestudywasconducted according to the Declaration of Helsinki on BiomedicalResearch for Human.All participants were selected from patients referred to CTexamination of the headof different etiologies (parotid gland, brain, From the   Otorhinolaryngology-Head and Neck Surgery Department,Faculty of Medicine;  y Radio Diagnosis Department, Faculty of Medi-cine, Zagazig University, Zagazig; and   z Radio Diagnosis Department,Faculty of Medicine, Benha University, Benha, Egypt.Received March 16, 2019.Accepted for publication June 14, 2019.Address correspondence and reprint requests to Mohammad Waheed El-Anwar, MD, Otorhinolaryngology-Head and Neck Surgery Department,Faculty of Medicine, Zagazig University, Zagazig, Egypt;E-mail: mwenteg@yahoo.com The authors report no conflicts of interest.Supplementaldigitalcontentsareavailablefor thisarticle.DirectURLcitationsappearintheprintedtextandareprovidedintheHTMLandPDFversionsof this article on the journal’s Web site (www.jcraniofacialsurgery.com). Copyright  #  2019 by Mutaz B. Habal, MDISSN: 1049-2275 DOI: 10.1097/SCS.0000000000005857 C LINICAL  S TUDY The Journal of Craniofacial Surgery     Volume 00, Number 00, Month 2019  1  Copyright © 2019 Mutaz B. Habal MD. Unauthorized reproduction of this article is prohibited. the mandible, and temporomandibular joint). The multislice CT(MSCT) examination of the nasal cavity was done as a part of therequested examination.Included patients were asymptomatic adults (as regard nose andparanasal sinus). Proper history taking, clinical and endoscopicnasal examination, and then MSCT examination were done for allpatients and any patient with nasal or peripheral nervous systemlesion was excluded. Patients younger than 20 years, patients whounderwent previous sinonasal surgery, or patients with sinonasalpathology or trauma were excluded from the study.All CT examinations were performed with a 64-slice CT scan(Phillips Ingenuity core 128 TM (v3.5.7.25001; Philips HealthcareSystems, the Netherlands). We used the protocol of 64-slice multi-detector CT with a detector width of 0.625mm, a section width of 1.5mm, and an interval reconstruction of 0.5mm.We took axial cuts while the patient was in supine position and thebeam was parallel to the hard palate. The cuts began from the hardpalatetothetopoffrontalsinus(glabella),using130kVand150mA/swithscantime1.5seconds.Widewindow(Windowwidthsabout1300to 2000 and window levels about   80 to   200). Examinations weredonewithbonewindowsettingof2000HU,centeredat300HU.High-resolutionalgorithmwasusedforenhancementofthefinebonydetails.A dedicated postprocessing workstation (Extended BrillianceWorkspace; Philips Medical System-PHILIPS IntellSpace Portal)was used for multiplanar reconstructions and coronal plane we gotdelicate detail for all patients. Films were inspected in routinestandardized fashion to ensure that small details are not missed.On axial cuts, the anteroposterior distances from the SPF tomaxillary line, anterior head of the middle turbinate, basal lamellaof the middle turbinate, choanal arch, 7 and posterior fontanel of themaxillary sinus ostium 10 were measured (Figs. 1–2) and registeredfrom each side. While on coronal cuts, the vertical distances fromthe SPF to the nasal floor was measured and recorded 11 (Figs. 1A-2B).ThesesurgicallandmarkswereselectedfortheirconsistentandreliableidentificationduringnasalendoscopyandCTexamination. 7 The registered measurements were then studied and statisticallyanalyzed using the SPSS statistical software package (version 18;SPSS, Inc, Chicago, IL). A  P -value of   < 0.05 was consideredstatistically significant. RESULTS Seventy adult patients (140 SPFs, 840 measurements) wereincluded; 49 males (70%) and 21 females (30%), with a meanage of 31.8  7.29 years (range 21–51).The mean height of the SPF above the nasal floor was25.6  2.4mm (25.6  2.41 for the right side and 25.7  2.41 for the left side). The mean distance from SPF to the choanal arch was8.5  1.38mm (8.48  1.33 at right sides and 8.68  1.21 at the leftsides). The mean distance between SPF and maxillary line was36.4  2.6mm (36.40  2.61 at right sides and 36.37  2.61 at leftsides), while the mean distance between the SPF and the anterior head of the middle turbinate was 34.6  4.26mm (34.4  4.17 onright sides and 34.89  4.16 on the left sides). On the contrary,the mean distance between SPF and the basal lamella was8.1  1.27mm (7.98  1.2 at right sides and 8.25 for the left sides).The mean distance between SPF and the posterior fontanel of themaxillary sinus osteom was 13.7  1.7mm (14  1.29 at right sidesand 13.6  1.3 at left sides). For all measured distances, there wereno significant differences between right and left sides (Table S1,http://links.lww.com/SCS/A787).Females showed significantly shorter mean distances betweenSPF and the nasal floor ( P ¼ 0.0011), choanal arch ( P ¼ 0.0459),and posterior fontanel ( P < 0.0001) than males. While no signifi-cant differences were detected between both sexes as regard dis-tances from SPF to maxillary line ( P ¼ 0.5579), anterior head of middle turbinate ( P ¼ 0.8581) and basal lamella ( P ¼ 0.0638)(Table S2, http://links.lww.com/SCS/A787). DISCUSSION As the standard diagnostic tool, CT provides an essential guideduring ESS and external nasal, paranasal, skull base, and cranio-maxillofacial surgeries. 12–14 Thus, the radiologist and the endo-scopic sinus surgeons should be aware of CT sinonasal details to perform a safe and effective surgery. Sinonasal CT anatomy should  bereviewedasacriticalstepinthepreoperativeplanningforESS. 12 Endoscopic ligation or cauterization of the SPA is the currentlyfavored  and popular intervention to control intractable posterior epistaxis. 4 On the contrary, injury to the SPA during sinonasaloperations may delay the progress of surgery and excessive bleed-ingcouldincrease theriskoforbitalcomplicationsbydisturbing theoperating field. In addition, in some patients, bleeding may make ithard to continue the surgery. So, it is highly important to preciselylocalize the SPA preoperatively. Moreover, the k nowledge of SPAlocation is inevitable in transnasal neurosurgery. 15 Endoscopic SPF localization basically depends on identifyingthe ethmoidal crest of  the palatine bone, onto which the middleturbinate is attached. 10 However, the SPF may open purely in thesuperior meatus, above the middle turbinate and the ethmoidal crestof the palatine bone (class I), the SPF may span the ethmoidal crestto open at the transition ofthe superior and middle meatus (class II),or 2 d istinct SPFs open on either side of the ethmoidal crest (classIII). 16 Such anatomical variations of the SPF or its surroundings canresult in failure of operative SPF identification. In addition, SPFidentification becomes more difficult during active epistaxis, under medical anticoagulation therapy, with the mucosal friability after  FIGURE 1.  Computed tomography measurements for distances betweensphenopalatine foramen and nasal floor (A), choanal arch (B), maxillary line(C), anterior head of the middle turbinate (D), basal lamella (E), and posterior fontanel (F). FIGURE 2.  Diagram for sphenopalatine foramen (white circle) that exit fromptergopalatinefossa(PPF)thatliesbehindthemaxillarysinus(MS).(A)Axialcutshows measurement for distances (yellow lines) from sphenopalatine foramento(1)choanalarch,(2)anteriorheadofthemiddleturbinate(MT),(3)maxillaryline, and (4) posterior fontanel. (B) Coronal cut shows measurement for distances from sphenopalatine foramen to nasal floor (5).  El-Anwar et al   The Journal of Craniofacial Surgery     Volume 00, Number 00, Month 2019 2  #  2019 Mutaz B. Habal, MD  Copyright © 2019 Mutaz B. Habal MD. Unauthorized reproduction of this article is prohibited. repeated nasal packing or recent surgical interventions attempts 7 or with changes caused by different nasal pathology. Thus, SPFlocalization in relation to reliable fixed bony landmarks is essentialfor optimum and harmless endoscopic approaches.However, SPF identification via bony landmarks is poorlydocumented in the literature, with most available data relying on cadaveric dissection 15,17 with limited surgical application. 10 Theused cadavers in such studies can be subject to artifactual damageand it is hard er to detect the SPF in cadavers with artifactual tissue preservation. 10,17 On the contrary, even though endoscopic studiesare helpful in expecting the site of the SPF, such studies do not provide actual SPF localization for the operated patient himself ascan do the patient’s preoperative CT. Thus, depending on preoper-ative CT for SPF localization definitely provides accurate and realSPF relations to the endoscopically detectable fixed bony land-marks of same patients before and during the surgical intervention.So recently, authors have directed to CT studies searching for  dependable SPF landmarks. 7,10,11  Nalavenkata et al 10 suggests the posterior fontanel and inferior turbinate attachment as reliablesurgical landmarks forendoscopic approaches to the SPF. AlthoughinferiorturbinateattachmentiseasilydetectedonCT,itisnoteasilynor accurately localized during ESS because inferior turbinate haslarge nonbony part (mucosa and submocosal tissue) particularlymedially and the inferior turbinate is the most susceptible turbinateto enlargement. 18 So we could not consider the inferior turbinateattachment as a consistent endoscopic landmark. Later, Maxwelet al 7  proposed utilizing the CT expected distances from SPF to 5simple endoscopic bony landmarks as guides to the most likely siteof the SPA. 7 These landmarks were selected because of easyendoscopic localization and their expected presence, even after  previous trauma or operation. 7 In present study, we assessed these 5landmarks plus the posterior fontanel in our population as land-marks for the SPF.Because the maxillary sinus reaches its mature size approxi-mately at the age of 20 years after full development of the perma-nent teeth, 13,19 only patients older than 20 years were included in present study.Inourstudy,wefoundthattheSPFwas25.6  2.4mmabovethenasal floor, 8.5  1.38mm anterior to choanal arch, 36.4  2.6mm posterior to maxillary line, 34.6  4.26mm posterior to anterior head of middle turbinate, 8.1  1.27mm from basal lamella, and 13.7  1.7mm posterior to the posterior fontanel. Current measured distances are near to the distances reported before. 7,10 Distances between SPF and the nasal floor, choanal arch, posterior fontanel were significantly longer in males than females,in accordance with the larger dimensions of the nasal cavitytypically seen in males. 7,20 While no significant differences weredetected between both sexes as regard distances from SPF tomaxillary line, anterior head of middle turbinate and basal lamella.Theresultsofpresentstudy,inagreewithMaxweletal 7 reported that choanal arch and basal lamella are the most reliable landmarks,as evidenced by their small standard deviations, perhaps because of their close proximity to the SPF and the SPF is nearly situated in themidpoint between the choanal arch and basal lamella. Thus thequickest initial way to localize the SPF in initial ESS is to 1stidentify the basal lamella and choanal arch as was suggested byMaxwel et al 7 and this particularly beneficial during direct trans-nasal approach to SPF. We also found that posterior fontanel is alsoa reliable landmark for the same reasons and is especially valuablewhen maxillary antrostomy performed during SPF localization. Butwe think that even in the situation of maxillofacial abnormality, previous surgery or trauma with disturbed anatomy, choanal arch,maxillary line, and nasal floor will be the most untouched reliablelandmark for endoscopic approaches to the SPF. However, all theselandmarks need to be investigated in revision patients.The described radiographic measurements may be used to directthe mucosal flap assignment during SPA ligation so elevate asmaller flap directly toward the SPF or coagulate directly on topof it. 7 Distance between posterior fontanel and SPF is few millimeters(about 4mm) longer than distance measured before by El-Anwar et al 13 from maxillary sinus osteom to posterior maxillary wall(9.2  3.4mm). Thus we insure that widening the maxillary sinusosteom posteriorly should be cautiously done using cutting instru-ment to avoid traction on the SPA 13  particularly in females whoshowed significantly nearer SPF ( P < 0.0001).We believe that the suggested fixed bony landmarks that areeasily identified on CT of the paranasal sinuses will be useful and reliable landmarks for all rhinologist and will minimize the opera-tivetimeusedforintraoperativeidentificationofthesiteoftheSPA.The addition of the described simple and dependable surgicallandmarks to localize the SPF would be valuable beside thetraditional reliance on the crista ethmoidalis. So we recommend adding these measurements to the preoperative check list particu-larly for patients had severed epistaxis or vascular pathologyas angiofibroma. CONCLUSION Preoperative CT can provide multiple easily detected, reliable, and simple bony landmarks that can help SPF endoscopic localization.Thus we recommend adding these measurements to the preopera-tive CT checklist for patients scheduled for SPA ligation and/or excision of vascular lesions such as angiofibroma. REFERENCES 1. RudmikL,SmithTL.Managementofintractablespontaneousepistaxis.  Am J Rhinol Allergy  2012;26:55–602. Hadoura L, Douglas C, McGarry GW, et al. Mapping surgicalcoordinates of the sphenopalatine foramen: surgical navigation study.  J  Laryngol Otol  2009;123:742–7453. Douglas R, Wormald PJ. Update on epistaxis.  Curr Opin Otolaryngol Head Neck Surg  2007;15:180–1834. Elsheikh E, El-Anwar MW. Sepal perforation and bilateral partialmiddleturbinatenecrosis after bilateralsphenopalatineartery ligation.  J  Laryngol Otol  2013;127:1025–10275. Seno S, Arikata M, Sakurai H, et al. Endoscopic ligation of thesphenopalatine artery and the maxillary artery for the treatment of intractable posterior epistaxis.  Am J Rhinol Allergy  2009;23:197–1996. Schwartzbauer HR, Shete M, Tami TA. Endoscopic anatomy of thesphenopalatine and posterior nasal arteries: implications for theendoscopic management of epistaxis.  Am J Rhinol  2003;17:63–667. Maxwel AK, Barham HP, Getz AE, et al. Landmarks for rapidlocalization of the sphenopalatine foramen: a radiographicmorphometric analysis.  Allergy Rhinol (Providence)  2017;8:e63–e668. Kumar S, Shetty A, Nilssen E. Contemporary surgical treatment of epistaxis. What is the evidence for sphenopalatine artery ligation?  ClinOtolaryngol Allied Sci  2003;28:360–3639. Padua FGM, Voegels RL. Severe posterior epistaxis. Endoscopicsurgical anatomy.  Laryngoscope  2008;118:156–16110. Nalavenkata S, Meller C, Novakovic D, et al. Sphenopalatine foramen:endoscopic approach with bony landmarks.  J Laryngol Otol 2015;129:S47–S5211. Lund VJ, Stammberger H, Fokkens WJ, et al. European position paperon the anatomic terminology of the internal nose and paranasal sinuses.  Rhinol Suppl  2014;24:1–3412. El-Anwar MW, Khazbak AO, Eldib DB, et al. Lamina papyraceaposition in patients with nasal polypi: a computed tomography analysis.  Auris Nasus Larynx  2018;45:487–49113. El-Anwar MW, Raafat A, Almolla RM. Maxillary sinus ostiumassessment: a CT study.  Egypt J Radiol Nucl Med   2018;49:1009–101314. El-Anwar MW, Ali AH, Ghada A, et al. Radiological middle turbinatevariations and their relation to nasal septum deviation in asymptomaticadult.  Egypt J Radiol Nucl Med   [in press]. The Journal of Craniofacial Surgery     Volume 00, Number 00, Month 2019  Sphenopalatine Foramen Assessment  #  2019 Mutaz B. Habal, MD  3  Copyright © 2019 Mutaz B. Habal MD. Unauthorized reproduction of this article is prohibited. 15. Eordogh M, Grimm A, Gawish I, et al. Anatomy of the sphenopalatineartery and its implications for transnasal neurosurgery.  Rhinology 2018;56:82–8816. Wareing MJ, Padgham ND. Osteologic classification of thesphenopalatine foramen.  Laryngoscope  1998;108 (pt. 1):125–12717. Chiu T. A study of the maxillary and sphenopalatine arteries in thepterygopalatine fossa and at the sphenopalatine foramen.  Rhinology 2009;47:264–27018. El-Anwar MW, Hamed AA, Abdulmonaem G, et al. Computedtomography measurement of inferior turbinate in asymptomatic adult.  Int Arch Otorhinolaryngol  2017;21:366–37019. Jovanic S, Jelicic N, Kargovska-Klisarova A. Postnatal developmentand reports of the maxillary sinus.  Acta Anat   1984;118:122–12820. Samolin’ ski BK, Grzanka A, Gotlib T. Changes in nasal cavitydimensions in children and adults by gender and age.  Laryngoscope 2007;117:1429–1433  El-Anwar et al   The Journal of Craniofacial Surgery     Volume 00, Number 00, Month 2019 4  #  2019 Mutaz B. Habal, MD
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