Enhanced Exposure of Carotico-Oculomotor Triangle Following Extradural Anterior Clinoidectomy: A Comparative Anatomical Study

ABSTRACT

Objective: To quantify and compare the carotico-oculomotor triangle (COT) area before and after extradural anterior clinoidectomy (AC). Methods: Ten cadaveric heads were dissected bilaterally. Before and after an extradural AC, the following points were measured: (1) the internal carotid artery (ICA) bifurcation to the tip of the anterior clinoid process (ACP) (A) and to the distal dural ring (A′), (2) the ICA bifurcation to the point where the oculomotor nerve becomes obscured by the tentorial fold (B) and to the porus oculomotoris after incision of the tentorial fold (B′), and (3) the tip of the ACP to the point where the oculomotor nerve becomes obscured by the tentorial incisura (C) and from the distal dural ring to the porus oculomotoris (C′). The area of the COT was calculated before and after AC (ΔABC and ΔA′B′C′, respectively). Results: The mean values were as follows: A: 9.15 ± 0.93 mm, A′: 13.45 ± 0.82 mm; B: 7.80 ± 1.24 mm, B′: 9.90 ± 1.21 mm; C: 7.15 ± 0.99 mm, C′: 9.3 ± 1.26 mm; ΔABC: 26.26 ± 6.05 mm², ΔA′B′C′: 45.06 ± 8.92 mm². Conclusions: Extradural AC enhances the exposure of the COT almost twofold. This increased exposure can be of significant help during resection of lesions of the parasellar and basilar apex regions.

KEYWORDS

Anterior clinoid - carotico-oculomotor triangle - clinoidectomy - extradural

REFERENCES

• 1 Hauser M J, Gass H. Optic nerve pressure by aneurysm relieved by decompression of optic nerve: report of a case.  AMA Arch Ophthalmol. 1952;  48 627-631
• 2 Drake C G. The surgical treatment of aneurysms of the basilar artery.  J Neurosurg. 1968;  29 436-446
• 3 Yasargil M G, Gasser J C, Hodosh R M, Rankin T V. Carotid-ophthalmic aneurysms: direct microsurgical approach.  Surg Neurol. 1977;  8 155-165
• 4 Dolenc V V. A combined epi- and subdural direct approach to carotid-ophthalmic artery aneurysms.  J Neurosurg. 1985;  62 667-672
• 5 Dolenc V V, Skrap M, Sustersic J, Skrbec M, Morina A. A transcavernous-transsellar approach to the basilar tip aneurysms.  Br J Neurosurg. 1987;  1 251-259
• 6 Dolenc V. Direct microsurgical repair of intracavernous vascular lesions.  J Neurosurg. 1983;  58 824-831
• 7 Sato S, Sato M, Oizumi T et al.. Removal of anterior clinoid process for basilar tip aneurysm: clinical and cadaveric analysis.  Neurol Res. 2001;  23 298-303
• 8 Youssef A S, Aziz KMA, Kim E Y, Keller J T, Zuccarello M, van Loveren H R. The carotid-oculomotor window in exposure of upper basilar artery aneurysms: a cadaveric morphometric study.  Neurosurgery. 2004;  54 1181-1187 discussion 1187-1189
• 9 Al-Mefty O. Clinoidal meningiomas.  J Neurosurg. 1990;  73 840-849
• 10 el-Kalliny M, van Loveren H, Keller J T, Tew Jr J M. Tumors of the lateral wall of the cavernous sinus.  J Neurosurg. 1992;  77 508-514
• 11 Lee J H, Jeun S S, Evans J, Kosmorsky G. Surgical management of clinoidal meningiomas.  Neurosurgery. 2001;  48 1012-1019 discussion 1019-1021
• 12 Yonekawa Y, Ogata N, Imhof H G et al.. Selective extradural anterior clinoidectomy for supra- and parasellar processes. Technical note.  J Neurosurg. 1997;  87 636-642
• 13 Inoue T, Rhoton Jr A L, Theele D, Barry M E. Surgical approaches to the cavernous sinus: a microsurgical study.  Neurosurgery. 1990;  26 903-932
• 14 Day A L. Aneurysms of the ophthalmic segment. A clinical and anatomical analysis.  J Neurosurg. 1990;  72 677-691
• 15 Day J D, Giannotta S L, Fukushima T. Extradural temporopolar approach to lesions of the upper basilar artery and infrachiasmatic region.  J Neurosurg. 1994;  81 230-235
• 16 Coscarella E, Baskaya M K, Morcos J J. An alternative extradural exposure to the anterior clinoid process: the superior orbital fissure as a surgical corridor.  Neurosurgery. 2003;  53 162-166 discussion 166-167
• 17 Hakuba A, Tanaka K, Suzuki T, Nishimura S. A combined orbitozygomatic infratemporal epidural and subdural approach for lesions involving the entire cavernous sinus.  J Neurosurg. 1989;  71 699-704
• 18 Sundt Jr T M, Piepgras D G. Surgical approach to giant intracranial aneurysms. Operative experience with 80 cases.  J Neurosurg. 1979;  51 731-742
• 19 Evans J J, Hwang Y S, Lee J H. Pre- versus post-anterior clinoidectomy measurements of the optic nerve, internal carotid artery, and opticocarotid triangle: a cadaveric morphometric study.  Neurosurgery. 2000;  46 1018-1021 discussion 1021-1023
• 20 Day J D, Tsachabitscher M. Microsurgical Dissection of the Cranial Base. New York, NY; Churchill Livingstone 1996: 39-42
• 21 Kim J M, Romano A, Sanan A, van Loveren H R, Keller J T. Microsurgical anatomic features and nomenclature of the paraclinoid region.  Neurosurgery. 2000;  46 670-680 discussion 680-682
• 22 Huynh-Le P, Natori Y, Sasaki T. Surgical anatomy of the anterior clinoid process.  J Clin Neurosci. 2004;  11 283-287
• 23 Seoane E, Rhoton Jr A L, de Oliveira E. Microsurgical anatomy of the dural collar (carotid collar) and rings around the clinoid segment of the internal carotid artery.  Neurosurgery. 1998;  42 869-884 discussion 884-886