AnatomyTransethmoidal approach to the optic canal: Surgical and radiological microanatomy
Section snippets
Materials and methods
Twelve orbits of adult cadaver fixed in formalin were dissected, and anatomic measurements were made on the orbits in 25 adult human skulls. An assessment has been made on the orbits in 25 living human heads to find out the relation among optic canal, ethmoidal and sphenoid sinus. The relations among optic canal, ethmoidal, and sphenoid sinus were investigated with computed tomography (CT) scan in 25 living human heads. Surgical and radiologic anatomic images were obtained in cadaver studies
Anatomic results
Orbital walls have seven bones. Orbital opening is somewhat quadrangular; its supraorbital margin formed entirely by the frontal bone. The lateral margin is largely the frontal process of the zygomatic bone; infraorbital margin is zygomatic bone laterally and maxilla medially. The medial margin is formed above by the frontal bone, below by the lacrimal crest of the maxillary frontal process [15].
Frontal, maxilla, and lacrimal bones are combined with fronto-maxillo-lacrimal suture on medial
Discussion
Issues like compression of the optic nerve, precise pathogenesis and the best treatment remain controversial [20]. Various mechanisms of an injury may play a role in damage to the optic nerve. Direct fractures of the optic canal may be seen with bony fragment injury or transecting the optic nerve [7]. Other mechanisms of injury include intraneural edema, hematoma, and shearing injury to the microvasculature, altered cerebrospinal fluid circulation, and interruption of direct axoplasmic
Conclusion
A comprehensive knowledge of microanatomy and radiologic anatomy will contribute to the effective use of transethmoidal approach. Preoperative orbit CT scans performed with thin slices are very important in revealing the relation between optic canal, optic nerve, ethmoidal and sphenoidal sinuses structures, the existence of Onodi cell, and the location and grade of the compression. The assessment of relation between significant vascular and neural structures and morphologic measurements of bone
Acknowledgements
We are grateful to Isıl Özkoçak, M.D. for editing the draft. We are also grateful to Haluk Erdem, M.D., and artist Erdem Yücel for the excellent artwork.
References (20)
- et al.
Decompression of the optic canal by the transethmoid route
Am J Ophthalmol
(1961) Transnasal approach to optic nerve decompression
Oper Tech Otolaryngol Head Neck Surg
(1991)Respiratory system
Decompression of the optic nerve in the optic canal
Ophthalmic Plast Reconst Surg
(1986)Optic nerve sheath decompression
Eur J Implant Ref Surg
(1993)Results in 400 cases of surgical decompression of the optic nerve
Mod Probl Ophthalmol
(1975)- et al.
Combined transconjunctival/intranasal endoscopic approach to the optic canal in traumatic optic neuropathy
Laryngoscope
(1997) Anatomy of the optic nerve decompression
- et al.
Endoscopic optic nerve decompressionthe Graz experience
Laryngoscope
(1998) - et al.
Computerized tomographic scan findings in facial fractures associated with blindness
Plast Reconstr Surg
(1981)
Cited by (45)
An unusual arrangement of the neurovascular structures in one ethmoidal foramen of the human orbit
2020, Translational Research in AnatomyCitation Excerpt :These surgeries include management of the medial wall fractures, orbital decompression, anterior skull base reconstruction, tumor resection, trans-ethmoidal sphenoidotomy and sphenoidal hypophysectomy [4]. An understanding of the medial orbital wall, including the number, morphology, location and absence of the ethmoid foramina (taking into account the variability of these foramina as well as the fact that the medial orbital wall is very thin and prone to injury), is important in order to reduce intra-operative risks [4,7]. This knowledge is also important for proper identification of all anatomical structures during sinus surgery.
Endoscopic Transnasal Resection of Solitary Fibrous Tumor in the Optic Canal
2018, World NeurosurgeryThe role of Onodi cells in sphenoiditis: results of multiplanar reconstruction of computed tomography scanning
2017, Brazilian Journal of OtorhinolaryngologyCitation Excerpt :The HRCT scan can clearly show the relationship between the OC and the sphenoid sinus. The multiplanar reconstruction technique has recently been developed as a new imaging technique in the field of CT.17 The reported studies regarding the prevalence of OCs vary greatly, and computed tomography (CT) scans suggest that prevalence is between 7% and 65%.1,3,7–9,18 In cadaver studies, this prevalence was found to be 60% by Tanaviratananich et al.19 and 15% by Tan and Ong.20
Morphometric and morphological evaluation of the optic canal in three different parts in MDCT images
2023, International Ophthalmology