Anatomical assessment of the endoscopic endonasal approach for the treatment of paraclinoid aneurysms

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Endoscopic endonasal approaches (EEAs) are increasingly being incorporated into the neurosurgeon’s armamentarium for treatment of various pathologies, including paraclinoid aneurysms. However, few anatomical assessments have been performed on the use of EEA for this purpose. The aim of the present study was to provide a comprehensive anatomical assessment of the EEA for the treatment of paraclinoid aneurysms.


Five cadaveric heads underwent an endonasal transplanum-transtuberculum approach to expose the paraclinoid area. The feasibility of obtaining proximal and distal internal carotid artery (ICA) control as well as the topographic location of the origin of the ophthalmic artery (OphA) relative to dural landmarks were assessed. Limitations of the EEA in exposing the supraclinoid ICA were also recorded to identify favorable paraclinoid ICA aneurysm projections for EEA.


The extracavernous paraclival and clinoidal ICAs were favorable segments for establishing proximal control. Clipping the extracavernous ICA risked injury to the trigeminal and abducens nerves, whereas clipping the clinoidal segment put the oculomotor nerve at risk. The OphA origin was found within 4 mm of the medial opticocarotid point on a line connecting the midtubercular recess point to the medial vertex of the lateral opticocarotid recess. An average 7.2-mm length of the supraclinoid ICA could be safely clipped for distal control. Assessments showed that small superiorly or medially projecting aneurysms were favorable candidates for clipping via EEA.


When used for paraclinoid aneurysms, the EEA carries certain risks to adjacent neurovascular structures during proximal control, dural opening, and distal control. While some authors have promoted this approach as feasible, this work demonstrates that it has significant limitations and may only be appropriate in highly selected cases that are not amenable to coiling or clipping. Further clinical experience with this approach helps to delineate its risks and benefits.

ABBREVIATIONS DDR = distal dural ring; EEA = endoscopic endonasal approach; ICA = internal carotid artery; LOCR = lateral opticocarotid recess; OphA = ophthalmic artery; PDR = proximal dural ring; SHA = superior hypophyseal artery.

Article Information

Correspondence Mark C. Preul: Barrow Neurological Institute, St. Joseph’s Hospital and Medical Center, Phoenix, AZ.;

INCLUDE WHEN CITING Published online December 21, 2018; DOI: 10.3171/2018.6.JNS18800.

Disclosures Dr. Little: ownership in SPIWay and Kogent.

© AANS, except where prohibited by US copyright law.



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    Stepwise depiction of the EEA for exposure of the paraclinoid region. A: Exposure of the left paraclival ICA using the vidian nerve (n.) and the pterygoclival ligament (PCL) as anatomical landmarks. The pterygoclival ligament is a thick, fibrous tissue running between the body of the sphenoid bone and medial pterygoid process to reach the medial aspect of the lacerum segment of the ICA. The ICA is prepared for proximal clipping by drilling bone on its lateral, anterior, and medial aspects. On the lateral aspect of the ICA, there is a quadrangular space (i.e., the lingular recess), drilling of which leads to Meckel’s cave (MC). In order to protect the abducens nerve running on the superior aspect of this space, drilling should be limited superiorly to the level of the maxillary division (V2) of the trigeminal nerve. B: Dural exposure extending from the planum sphenoidale to the anterior sellar region in the sagittal plane and extending laterally to the optic canals and parasellar carotid arteries. Dashed lines designate the approximate course of the paraclival (including the extracavernous [ex.] and intracavernous [in.] parts), parasellar (PS), and paraclinoid (PC) segments of the ICA separated by solid white lines. The lateral tubercular recess (TR) is a triangle-shaped area on the lateral end of the tubercular recess reaching medial to the optic nerve and ICA (shown on the right side). The corner of this triangular area faces medially; the upper arm (white arrow) reaches the medial opticocarotid point (point 2), and the lower arm (double black arrow) reaches the caroticosellar point (point 3). C: Dural reference points: 1 = midtubercular recess point; 2 = medial opticocarotid point; 3 = caroticosellar point; 4 = medial vertex of the LOCR. The white dashed line shows the approximate level of the DDR, and the yellow dashed double-arrowed line shows the approximate level of the PDR. D: Proximal control obtained on the extracavernous paraclival ICA. E: Exposure of the clinoidal ICA using 3 consecutive dural cuts (black arrows) starting from the caroticosellar point reaching the medial opticocarotid point, and then continuing inferior to the DDR to reach the medial vertex of the lateral opticocarotid recess, and finally descending on the lateral aspect of the clinoidal ICA. F: Proximal control on the clinoidal ICA. G: Dural incision to expose the supraclinoid ICA. The dural incision could be started either on the lateral tubercular recess or in the midline (dashed arrows—both crossing the superior intercavernous sinus [red arrowhead]) to reach the tubercular recess. Next, the dural incision is continued in the midline to reach planum sphenoidale and then turns laterally to reach the region of the optic canal. Small black arrows show the interfalciform ligament (interfalc. lig.). H: The supraclinoid ICA is exposed by reflecting the dural flap. All views were obtained using a 0° endoscope. cav. sin. = cavernous sinus; CP = carotid protuberance; CR = clival recess; ON = optic nerve. Copyright Mark Preul. Published with permission. Figure is available in color online only.

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    A and B: Enhancing exposure of the supraclinoid ICA by cutting the superior intercavernous sinus (small black arrow) and the diaphragma sellae (red dashed line). This cut (red dashed lines in B) could reach the posterior clinoid process (PCP) posteriorly to allow medial mobilization of the pituitary. C and D: Distal control of the supraclinoid ICA after incising the diaphragma sellae. Note the superior retraction of the optic nerve (ON) necessary to apply the clip. The white arrow (D) indicates the origin of the OphA. All views were obtained using a 30° endoscope. Copyright Mark Preul. Published with permission. Figure is available in color online only.

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    Opticotubercular line shown on the right parasellar area. Left: The opticotubercular line runs from the midtubercular recess point (point 1) to the medial vertex of the LOCR (point 2). The OphA origin was found on this line (or close to it) within 4 mm of the medial opticocarotid point (point 3; yellow shaded area). Right: The dura is opened and the origin of the OphA (white arrow) is found. The opticotubercular line is drawn, and the OphA origin is shown to be very close to this line near the medial opticocarotid point (white dot). All views were taken with a 30° endoscope. Copyright Mark Preul. Published with permission. Figure is available in color online only.

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    Close relationship between the oculomotor nerve and the clinoidal ICA. Left: Endoscopic endonasal view of the left parasellar area (30° endoscope) shows that violation of the PDR is easily possible; hence clipping the clinoidal ICA may pose risk to the adjacent oculomotor nerve running immediately inferior to the PDR. Right: Cavernous sinus dissection on the right side showing the close relationship between the PDR (black arrowheads) and the underlying oculomotor nerve. The dashed line shows the DDR. The yellow star designates the clinoidal ICA. Note that the anterior clinoid process has been removed. CN = cranial nerve; GG = Gasserian ganglion; OS = optic strut; PCA = posterior cerebral artery. Copyright Mark Preul. Published with permission. Figure is available in color online only.



Abhinav KAcosta YWang WHBonilla LRKoutourousiou MWang E: Endoscopic endonasal approach to the optic canal: anatomic considerations and surgical relevance. Neurosurgery 11 (Suppl 3):4314462015


Bhatki AMCarrau RLSnyderman CHPrevedello DMGardner PAKassam AB: Endonasal surgery of the ventral skull base—endoscopic transcranial surgery. Oral Maxillofac Surg Clin North Am 22:1571682010


Colli BOCarlotti CG JrAssirati JA JrAbud DGAmato MCDezena RA: Results of microsurgical treatment of paraclinoid carotid aneurysms. Neurosurg Rev 36:991152013


Day AL: Aneurysms of the ophthalmic segment. A clinical and anatomical analysis. J Neurosurg 72:6776911990


Di Somma Ade Notaris MStagno VSerra LEnseñat JAlobid I: Extended endoscopic endonasal approaches for cerebral aneurysms: anatomical, virtual reality and morphometric study. BioMed Res Int 2014:7037922014


Dumont ASCrowley RWMonteith SJIlodigwe DKassell NFMayer S: Endovascular treatment or neurosurgical clipping of ruptured intracranial aneurysms: effect on angiographic vasospasm, delayed ischemic neurological deficit, cerebral infarction, and clinical outcome. Stroke 41:251925242010


D’Urso PIKaradeli HHKallmes DFCloft HJLanzino G: Coiling for paraclinoid aneurysms: time to make way for flow diverters? AJNR Am J Neuroradiol 33:147014742012


Durst CRStarke RMGaughen JNguyen QPatrie JJensen ME: Vision outcomes and major complications after endovascular coil embolization of ophthalmic segment aneurysms. AJNR Am J Neuroradiol 35:214021452014


Eddleman CSBatjer HH: Comment on “Germanwala AV, Zanation AM: Endoscopic endonasal approach for clipping of ruptured and unruptured paraclinoid cerebral aneurysms: case report.” Neurosurgery 68 (Suppl):onsE2402011


Fernandez-Miranda JCTormenti MLatorre FGardner PSnyderman C: Endoscopic endonasal middle clinoidectomy: anatomic, radiological, and technical note. Neurosurgery 71 (2 Suppl Operative):ons233ons2392012


Forbes JAD’ Herbemont SLehner KRPineda Martinez DNavarro-Chávez IPMendez Rosito D: Feasibility of endoscopic endonasal approach for clip application of cerebral aneurysms: a systematic review. J Neurosurg Sci [epub ahead of print] 2018


Gardner PAVaz-Guimaraes FJankowitz BKoutourousiou MFernandez-Miranda JCWang EW: Endoscopic endonasal clipping of intracranial aneurysms: surgical technique and results. World Neurosurg 84:138013932015


Germanwala AVZanation AM: Endoscopic endonasal approach for clipping of ruptured and unruptured paraclinoid cerebral aneurysms: case report. Neurosurgery 68 (1 Suppl Operative):2342402011


Heiferman DMSomasundaram AAlvarado AJZanation AMPittman ALGermanwala AV: The endonasal approach for treatment of cerebral aneurysms: a critical review of the literature. Clin Neurol Neurosurg 134:91972015


Jacquesson TAbouaf LBerhouma MJouanneau E: How I do it: the endoscopic endonasal optic nerve and orbital apex decompression. Acta Neurochir (Wien) 156:189118962014


Joo WFunaki TYoshioka FRhoton AL Jr: Microsurgical anatomy of the carotid cave. Neurosurgery 70 (2 Suppl Operative):3003122012


Kallmes DFHanel RLopes DBoccardi EBonafé ACekirge S: International retrospective study of the pipeline embolization device: a multicenter aneurysm treatment study. AJNR Am J Neuroradiol 36:1081152015


Kamide TTabani HSafaee MMBurkhardt JKLawton MT: Microsurgical clipping of ophthalmic artery aneurysms: surgical results and visual outcomes with 208 aneurysms. J Neurosurg [epub ahead of print January 26 2018; DOI: 10.3171/2017.7.JNS17673]


Kassam ASnyderman CHCarrau RLGardner PMintz A: Endoneurosurgical hemostasis techniques: lessons learned from 400 cases. Neurosurg Focus 19(1):E72005


Kassam ABGardner PAMintz ASnyderman CHCarrau RLHorowitz M: Endoscopic endonasal clipping of an unsecured superior hypophyseal artery aneurysm. Technical note. J Neurosurg 107:104710522007


Kassam ABPrevedello DMCarrau RLSnyderman CHGardner POsawa S: The front door to Meckel’s cave: an anteromedial corridor via expanded endoscopic endonasal approach—technical considerations and clinical series. Neurosurgery 64 (3 Suppl):ons71ons832009


Kassam ABThomas ACarrau RLSnyderman CHVescan APrevedello D: Endoscopic reconstruction of the cranial base using a pedicled nasoseptal flap. Neurosurgery 63 (1 Suppl 1):ONS44ONS532008


Kassam ABVescan ADCarrau RLPrevedello DMGardner PMintz AH: Expanded endonasal approach: vidian canal as a landmark to the petrous internal carotid artery. J Neurosurg 108:1771832008


Kulwin CSchwartz THCohen-Gadol AA: Endoscopic extended transsphenoidal resection of tuberculum sellae meningiomas: nuances of neurosurgical technique. Neurosurg Focus 35(6):E62013


Labib MDehdashti AR: Extended endoscopic endonasal transclival clipping of posterior circulation aneurysms—an alternative to the transcranial approach. Acta Neurochir (Wien) 157:208720882015


Labib MAPrevedello DMCarrau RKerr EENaudy CAbou Al-Shaar H: A road map to the internal carotid artery in expanded endoscopic endonasal approaches to the ventral cranial base. Neurosurgery 10 (Suppl 3):4484712014


Labib MAPrevedello DMFernandez-Miranda JCSivakanthan SBenet AMorera V: The medial opticocarotid recess: an anatomic study of an endoscopic “key landmark” for the ventral cranial base. Neurosurgery 72 (1 Suppl Operative):66762013


Lai LTMorgan MKSnidvongs KChin DCSacks RHarvey RJ: Endoscopic endonasal transplanum approach to the paraclinoid internal carotid artery. J Neurol Surg B Skull Base 74:3863922013


Lin NBrouillard AMKeigher KMLopes DKBinning MJLiebman KM: Utilization of Pipeline embolization device for treatment of ruptured intracranial aneurysms: US multicenter experience. J Neurointerv Surg 7:8088152015


Liu JKSchmidt RFChoudhry OJShukla PAEloy JA: Surgical nuances for nasoseptal flap reconstruction of cranial base defects with high-flow cerebrospinal fluid leaks after endoscopic skull base surgery. Neurosurg Focus 32(6):E72012


Pasqualin AMeneghelli PCozzi FChioffi F: Outcome after surgical treatment of paraclinoid carotid aneurysms. Acta Neurochir Suppl 123:33392016


Peris-Celda MKucukyuruk BMonroy-Sosa AFunaki TValentine RRhoton AL Jr: The recesses of the sellar wall of the sphenoid sinus and their intracranial relationships. Neurosurgery 73 (2 Suppl Operative):ons117ons1312013


Pribitkin EAMcJunkin JKung BCarrasco JRBilyk JRSavino PJ: Technique selection for orbital decompression: combined endoscopic and transconjunctival versus combined endoscopic and transantral approach. Ear Nose Throat J 88:E122009


Rhoton AL Jr: The cavernous sinus, the cavernous venous plexus, and the carotid collar. Neurosurgery 51 (4 Suppl):S375S4102002


Shimizu KImamura HMineharu YAdachi HSakai CSakai N: Endovascular treatment of unruptured paraclinoid aneurysms: single-center experience with 400 cases and literature review. AJNR Am J Neuroradiol 37:6796852016


Silva MASee APDasenbrock HHPatel NJAziz-Sultan MA: Vision outcomes in patients with paraclinoid aneurysms treated with clipping, coiling, or flow diversion: a systematic review and meta-analysis. Neurosurg Focus 42(6):E152017


Srinivasan VMKan PGermanwala AVPelargos PBohnen AChoy W: Key perspectives on Woven EndoBridge device for wide-necked bifurcation aneurysms, endoscopic endonasal clipping of intracranial aneurysms, retrosigmoid versus translabyrinthine approaches for acoustic neuromas, and impact of local intraoperative steroid administration on postoperative dysphagia following anterior cervical discectomy and fusion. Surg Neurol Int 7 (Suppl 27):S720S7242016


Stieg P: Comment on “Germanwala AV, Zanation AM. Endoscopic endonasal approach for clipping of ruptured and unruptured paraclinoid cerebral aneurysms: case report.” Neurosurgery 68 (Suppl 1):onsE2402011


Szentirmai OHong YMascarenhas LSalek AAStieg PEAnand VK: Endoscopic endonasal clip ligation of cerebral aneurysms: an anatomical feasibility study and future directions. J Neurosurg 124:4634682016


Tayebi Meybodi ALittle ASVigo VBenet AKakaizada SLawton MT: The pterygoclival ligament: a novel landmark for localization of the internal carotid artery during the endoscopic endonasal approach. J Neurosurg [epub ahead of print May 18 2018; DOI: 10.3171/2017.12.JNS172435]


Valentine RWormald PJ: A vascular catastrophe during endonasal surgery: an endoscopic sheep model. Skull Base 21:1091142011


Vaz-Guimaraes FGardner PAFernandez-Miranda JCWang ESnyderman CH: Endoscopic endonasal skull base surgery for vascular lesions: a systematic review of the literature. J Neurosurg Sci 60:5035132016


Wang YLi YJiang CJiang FMeng HSiddiqui AH: Endovascular treatment of paraclinoid aneurysms: 142 aneurysms in one centre. J Neurointerv Surg 5:5525562013


Yadla SCampbell PGGrobelny BJallo JGonzalez LFRosenwasser RH: Open and endovascular treatment of unruptured carotid-ophthalmic aneurysms: clinical and radiographic outcomes. Neurosurgery 68:143414432011


Yilmazlar SSaraydaroglu OKorfali E: Anatomical aspects in the transsphenoidal-transethmoidal approach to the optic canal: an anatomic-cadaveric study. J Craniomaxillofac Surg 40:e198e2052012




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