Surgical Anatomy and Efficient Modification of Procedures for Selective Extradural Anterior Clinoidectomy

Abstract

Objective: The surgical anatomy of structures surrounding the anterior clinoid process (ACP) was examined in 39 cadavers to enable safe performance of selective extradural anterior clinoidectomy.

Methods: The lateral portion of the optic canal (OC) at the end of the orbit was defined as point A, and the lateral margin of the dural insertion into the superior orbital fissure (SOF) as B. A vertical line from A to the lateral margin of the ACP was assumed to define a crossing, defined as C. Distances between A and B, C and B, and C and A were measured. The length and width of OC and the optic strut were also measured.

Results: The mean distances between A and B, C and B, and C and A were 11.8, 8.9 and 6.3 mm, respectively. The mean length and width of OC were 8.9 and 5.7 mm, and those of the optic strut 5.4 and 2.4 mm, respectively.

Conclusion: We propose a modified, efficient procedure for selective extradural anterior clinoidectomy, as follows. Drilling is started from the point approximately 9 mm posterior to the lateral margin of the dural insertion into the SOP, and pointed medially in the direction with a right angle to the lateral margin of the ACP. After drilling about 6 mm to reach the lateral border of the OC, unroofing of the OC is carried out to remove the ACP en bloc by fracturing of the optic strut. Using the present procedure, the distance of drilling of the lesser wing of the sphenoid bone is minimized.

Key words

Anatomy - anterior clinoidectomy - skull base surgery - surgical technique

References

• 1 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
• 2 Dolenc V V. A combined epi- and subdural direct approach to carotid ophthalmic artery aneurysms.  J Neurosurg. 1985;  62 667-672
• 3 Drake C O. The surgical treatment of aneurysms of the basilar artery.  J Neurosurg. 1968;  29 436-446
• 4 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 1018-1023
• 5 Guidetti B, La Torre E. Management of carotid-ophthalmic aneurysms.  J Neurosurg. 1975;  42 438-442
• 6 Hakuba A, Tanaka K, Suzuki T, Nishimura S. A combined orbito-zygomatic infratemporal epidural and subdural approach for lesions involving the entire cavernous sinus.  J Neurosurg. 1989;  71 699-704
• 7 Heros R C, Nelson P B, Ojeman R G, Crowell R M, DeBrum G. Large and giant paraclinoid aneurysms: Surgical techniques, complications, and results.  Neurosurgery. 1983;  12 153-163
• 8 Iwabuchi T, Suzuki S, Sobata E. Intracranial direct operation for carotid ophthalmic aneurysm by unroofing of the optic canal.  Acta Neurochir. 1978;  43 163-169
• 9 Knosp E, Muller G, Perneczky A. The paraclinoid carotid artery: Anatomical aspects of a microsurgical approach.  Neurosurgery. 1988;  22 896-901
• 10 Kobayashi S, Kyoshima K, Gibo H, Hegde S, Takemae T, Sugita K. Carotid cave aneurysms of the internal carotid artery.  J Neurosurg. 1989;  70 216-221
• 11 Nutic S. Carotid paraclinoid aneurysms with intradural origin and intracavernous location.  J Neurosurg. 1978;  48 526-533
• 12 Ohmoto T, Nagao S, Mino S, Ito T, Honma Y, Fujiwara T. Exposure of the intracavernous carotid artery in aneurysm surgery.  Neurosurgery. 1991;  28 317-323
• 13 Sengupta R P, Gryspeerdt G L, Hankinson J. Carotid-ophthalmic aneurysms.  J Neurol Neurosurg Psychiatry. 1976;  39 837-853
• 14 Sundt Jr T M, Piepgras D G. Surgical approach to giant intracranial aneurysms: Operative experience with 80 cases.  J Neurosurg. 1979;  51 731-742
• 15 Yasargil M G, Gasser J C, Hodosh R M, Rankin T V. Carotid-ophthalmic aneurysms: Direct microsurgical approach.  Surg Neurol. 1977;  8 155-165
• 16 Yonekawa Y, Ogata N, Imhof H G, Olivecrona M, Strommer K, Kwak T E, Roth P, Groscurth P. Selective extradural anterior clinoidectomy for supra- and parasellar processes: Technical note.  J Neurosurg. 1997;  87 636-642
• 17 Matthews L S, Hirsch C. Temperatures measured human cortical bone when drilling.  J Bone Joint Surg [Am]. 1978;  54 297-308
• 18 Toews A R, Bailey J V, Townsend H GG, Barber S M. Effect of feed rate and drill speed on temperatures in equine cortical bone.  Am J Vet Res. 1999;  60 942-944
• 19 Hadeishi H, Suzuki A, Yasui N, Satou Y. Anterior clinoidectomy and opening of the internal auditory canal using an ultrasonic bone curette.  Neurosurgery. 2003;  52 867-871