Anatomic Variation of the Optic Strut: Classification Schema, Radiologic Evaluation, and Surgical Relevance

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.

Change in the Location of the Optic Strut Relative to the Anterior Clinoid Process Pneumatization

“…Compared with adults, the attachment site of OS in fetuses is located more posteriorly. 19 Considering that the location of OS might affect surgical approach selection, patient positioning, and intraoperative surgical orientation, 18 further pediatric examinations related to the attachment site of OS relative to ACP are needed to understand the change its location after birth up to adulthood.…”

Anterior Clinoid Process and Optic Strut- A Morphometric Study

“…Statistical analysis was done to find out the values like mean and standard deviation and the results were tabulated. ( Table 1 and 2) ( Figure No 2). The data presented is the mean ± standard deviation of the actual value.…”

“…Its size and angle have been studied by Parkinson in 1989. (2),(3),(4), (5) Optic strut connects the body of sphenoid to the inferomedial aspect of base of anterior clinoid process and is removed during anterior clinoidectomy and optic canal decompression. (5) This is done for surgeries on tumours and aneurysms in the parasellar and suprasellar region to provide a better approach to the operating field primarily to the ICA, ON and to minimise the need for brain retraction.…”

Rhino-Neurochirurgie

“…Über den Recessus kann im Individualfall der weiter cranial gelegene Proc. clinoideus anterior mehr oder minder vollständig pneumatisiert werden [191,[194][195][196][197][198][199]. Unterhalb der Fissura orbitalis superior findet sich ein weiterer, etwa 4 mm starker Knochenpfeiler ("maxillary strut"), der seinerseite die Fissura orbitalis superior (cranial) vom Foramen rotundum (caudal) trennt [200][201][202].…”