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DOI: 10.1055/s-0032-1329626
Anatomic Variation of the Optic Strut: Classification Schema, Radiologic Evaluation, and Surgical Relevance
Publikationsverlauf
15. Mai 2012
08. Juni 2012
Publikationsdatum:
09. November 2012 (online)
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Abstract
Objective Anatomic variability of the optic strut in location, orientation, and dimensions is relevant in approaching ophthalmic artery aneurysms and tumors of the anterior cavernous sinus, medial sphenoid wing, and optic canal.
Methods In 84 dry human skulls, imaging studies were performed (64-slice computed tomography [CT] scanner, axial view, aligned with the zygomatic arch). Optic strut location related to the prechiasmatic sulcus was classified as presulcal, sulcal, postsulcal, and asymmetric. Morphometric analysis was performed.
Results The optic strut was presulcal in 11.9% specimens (posteromedial margin bilaterally anterior to limbus sphenoidale), sulcal in 44% (posteromedial part adjacent to the sulcus's anterior two thirds bilaterally), postsulcal in 29.8% (posteromedial margin posterior to the sulcus's anterior two thirds), and asymmetric (left/right) in 14.3%. Optic strut length, width, and thickness measured 6.54 ± 1.69 mm, 4.23 ± 0.69 mm, and 3.01 ± 0.79 mm, respectively. Optic canal diameter was 5.14 ± 0.47 mm anteriorly and 4.79 ± 0.64 mm posteriorly. Angulation was flat (>45 degrees) in 13% or acute (<45 degrees) in 87% specimens.
Conclusions Anatomical variations in the optic strut are significant in planning for anterior clinoidectomy and optic-canal decompression. Our optic strut classification considers these variations relative to the prechiasmatic sulcus on preoperative imaging.
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References
- 1 Parkinson D. A surgical approach to the cavernous portion of the carotid artery. Anatomical studies and case report. J Neurosurg 1965; 23: 474-483
- 2 Jefferson G. Radiography of the optic canals. Proc R Soc Med 1936; 29: 1169-1172
- 3 Lang J. The anterior and middle fossa including the cavernous sinus and orbit. In: Sekhar L, Janecka I, , eds. Surgery of Cranial Base Tumours. New York: Raven Press; 1993: 99-121
- 4 Kodama S. Developmental studies of the presphenoid of the human sphenoid bone. In: Bosma JF, , ed. Development of the Basicranium. Bethesda: US Department of Health, Education, and Welfare; 1976: 144-155
- 5 Kier EL. Embryology of the normal optic canal and its anomalies. An anatomic and roentgenographic study. Invest Radiol 1966; 1: 346-362
- 6 Cares HL, Bakay L. The clinical significance of the optic strut. J Neurosurg 1971; 34: 355-364
- 7 Engeset A, Torkildsen A. On changes of the optic canal in cases of intracranial tumor. Acta Radiol 1948; 29: 57-64
- 8 Holman CB. Roentgenologic manifestations of glioma of the optic nerve and chiasm. Am J Roentgenol Radium Ther Nucl Med 1959; 82: 462-471
- 9 Raitta C. Ophthalmic artery aneurysm causing optic atrophy and enlargement of the optic foramen. Br J Ophthalmol 1968; 52: 707-709
- 10 Shapiro R, Robinson F. Alterations of the sphenoidal fissure produced by local and systemic processes. Am J Roentgenol Radium Ther Nucl Med 1967; 101: 814-827
- 11 Kier EL. The infantile sella turcica. New roentgenologic and anatomic concepts based on a developmental study of the sphenoid bone. Am J Roentgenol Radium Ther Nucl Med 1968; 102: 747-767
- 12 Kier EL, Rothman LG. Radiologically significant anatomic variation of the developing sphenoid in humans. In: Bosma JF, , ed. Development of the Basicranium. Bethesda: US Department of Health, Education, and Welfare; 1976: 107-140
- 13 Parkinson D. Carotid cavernous fistula: direct repair with preservation of the carotid artery. Technical note. J Neurosurg 1973; 38: 99-106
- 14 Parkinson D. Optic strut: posterior root of sphenoid. Clin Anat 1989; 2: 87-92
- 15 Dolenc V. Direct microsurgical repair of intracavernous vascular lesions. J Neurosurg 1983; 58: 824-831
- 16 Dolenc VV. A combined epi- and subdural direct approach to carotid-ophthalmic artery aneurysms. J Neurosurg 1985; 62: 667-672
- 17 Inoue T, Rhoton Jr AL, Theele D, Barry ME. Surgical approaches to the cavernous sinus: a microsurgical study. Neurosurgery 1990; 26: 903-932
- 18 Keyes JEL. Observations on four thousand optic foramina in human skulls of known origin. Arch Ophthalmol 1935; 13: 538-568
- 19 Andaluz N, Beretta F, Bernucci C, Keller JT, Zuccarello M. Evidence for the improved exposure of the ophthalmic segment of the internal carotid artery after anterior clinoidectomy: morphometric analysis. Acta Neurochir (Wien) 2006; 148: 971-975 , discussion 975–976
- 20 Froelich SC, Aziz KM, Levine NB, Theodosopoulos PV, van Loveren HR, Keller JT. Refinement of the extradural anterior clinoidectomy: surgical anatomy of the orbitotemporal periosteal fold. Neurosurgery 2007; 61 (5) (Suppl. 02) 179-185 , discussion 185–186
- 21 Huynh-Le P, Natori Y, Sasaki T. Surgical anatomy of the anterior clinoid process. J Clin Neurosci 2004; 11: 283-287
- 22 Takahashi JA, Kawarazaki A, Hashimoto N. Intradural en-bloc removal of the anterior clinoid process. Acta Neurochir (Wien) 2004; 146: 505-509
- 23 Gonzalez LF, Walker MT, Zabramski JM, Partovi S, Wallace RC, Spetzler RF. Distinction between paraclinoid and cavernous sinus aneurysms with computed tomographic angiography. Neurosurgery 2003; 52: 1131-1137 , discussion 1138–1139
- 24 Beretta F, Sepahi AN, Zuccarello M, Tomsick TA, Keller JT. Radiographic imaging of the distal dural ring for determining the intradural or extradural location of aneurysms. Skull Base 2005; 15: 253-261 , discussion 261–262
- 25 Alfieri A, Jho HD. Endoscopic endonasal cavernous sinus surgery: an anatomic study. Neurosurgery 2001; 48: 827-836 , discussion 836–837