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

Abstract

OBJECTIVEEndoscopic 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.METHODSFive 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.RESULTSThe 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.CONCLUSIONSWhen 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.

Combined endoscopic endonasal and transcranial approach for internal carotid artery aneurysms: usefulness and safety of endonasal proximal control

“…Additionaly, aneurysmal clipping with endonasal approach is considered highly risky because it is more di cult to manipulate than the transcranial approach, and it di cult to control the intraoperative rupture and bleeding from the aneurysm. Similarly, endoscopic endonasal approaches have been reported for clipping surgery of vertebrobasilar artery aneurysms, using only an endoscopic approach is considered highly risky [13,14]. However, endonasal approach of our method is performed without intradural manipulation, only exposes the epidural ICA for proximl control.…”

Microsurgical anatomy of the dorsal clinoidal space: implications for endoscopic endonasal parasellar surgery

“…Exposure of the DCS, while limited from the transcranial route, is necessary to individualize the neck of the aneurysm, obtain proximal control of the ICA, and properly place the clip blades. 19,20 The carotid cave, first called as such by Kobayashi et al 21 in 1989, is a small pouch that extends below the level of the distal dural ring on the medial side of the paraclinoi- dal ICA, which serves as a potential subarachnoid space extension for paraclinoidal aneurysms. The results of our study showed that the carotid cave sits superolaterally to the DCS and can potentially be reached via the endoscopic endonasal approach.…”

Endoscopic endonasal approach for simultaneously treating a pituitary adenoma coexisting with a paraclinoid aneurysm: illustrative case

“…Endoscopic endonasal clipping of intercranial aneurysms, which has been shown to be feasible in many anatomical studies and clinical applications, 5–14 is not the principal strategy of the aneurysm-clipping surgery. Meanwhile, among the reports of planned endoscopic endonasal clipping surgery, paraclinoid aneurysm accounted for most.…”

“…The branches of the trigeminal nerve, gasserian ganglion, abducens nerve, and ICA were not in danger if the dura posterior to lingual process and petroclival fissure were kept intact, as cautioned in anatomical study. 5 In the case of pituitary adenomas invading the cavernous sinus, the extradural paraclival ICA exposure cannot be omitted because using the cavernous segment of ICA as the site of proximal occlusion may result in cranial nerve injury, and this site can only be exposed after resection of most of the tumor, which is not a good option for preventing aneurysm rupture during surgery.…”