Anatomical landmarks for transnasal endoscopic skull base surgery

Abstract

Resection of midline skull base lesions involve approaches needing extensive neurovascular manipulation. Transnasal endoscopic approach (TEA) is minimally invasive and ideal for certain selected lesions of the anterior skull base. A thorough knowledge of endonasal endoscopic anatomy is essential to be well versed with its surgical applications and this is possible only by dedicated cadaveric dissections. The goal in this study was to understand endoscopic anatomy of the orbital apex, petrous apex and the pterygopalatine fossa. Six cadaveric heads (3 injected and 3 non injected) and 12 sides, were dissected using a TEA outlining systematically, the steps of surgical dissection and the landmarks encountered. Dissection done by the "2 nostril, 4 hands" technique, allows better transnasal instrumentation with two surgeons working in unison with each other. The main surgical landmarks for the orbital apex are the carotid artery protuberance in the lateral sphenoid wall, optic nerve canal, lateral optico-carotid recess, optic strut and the V2 nerve. Orbital apex includes structures passing through the superior and inferior orbital Wssure and the optic nerve canal. Vidian nerve canal and the V2 are important landmarks for the petrous apex. IdentiWcation of the sphenopalatine artery, V2 and foramen rotundum are important during dissection of the pterygopalatine fossa. In conclusion, the major potential advantage of TEA to the skull base is that it provides a direct anatomical route to the lesion without traversing any major neurovascular structures, as against the open transcranial approaches which involve more neurovascular manipulation and brain retraction. Obviously, these approaches require close cooperation and collaboration between otorhinolaryngologists and neurosurgeons.

Transnasal, Endoscopically Guided Skull‐Based Surgery by Pharyngotomy for Mass Removal from the Sphenopalatine Sinus in a Horse

“…Diseases of the sphenopalatine sinus and surrounding skull base, including pituitary tumors, may be accessible with these techniques in the future, perhaps even in the standing horse. Minimally invasive skull‐based endoscopic surgery is currently being investigated further in animal models and human surgery for the access and treatment of many problems . Although improvements to the technique are warranted, the direct access to the ventral aspect of the sphenopalatine sinus provided by this novel approach provides an alternative method of entry and may prove useful for the removal of mass lesions inaccessible through the rostral paranasal sinuses, and where close approximation to the brain or other vital structures may limit other treatment options.…”

“…In people, diseases of the skull base, including the sphenopalatine sinus, were previously treated with aggressive open transcranial procedures to allow lesion access and removal. 17,18 With the development and advancement of endoscopy technology and image guidance systems, these diseases are now treated using endoscopic techniques. Compared to previous open techniques, transnasal endoscopic skullbased surgery provides many advantages.…”

Danger points, complications and medico-legal aspects in endoscopic sinus surgery

“…In the scope of routine sinus surgery, the cavernous (interdural/ intracavernous) and clinoid (interdural/paracavernous) sections are particularly relevant, and in exceptional cases, the cisternal (intradural/intracisternal) section may also be significant [409], [410], [411]. There are important neighbouring anatomical structures, especially the optic n. The distance between the internal carotid a. and the optic nerve is 2–10 mm, bridging the lateral optico-carotid recess [412], [413]. …”

Effectiveness of Optic Decompression by Endoscopic Endonasal Approach on Patients with Traumatic Fracture of Optic Canal

“…Accordingly, when the dura mater needs to be cut, the best parts of incision are above the lateral wall of optic nerve sheath. This could avoid damaging the eye arteries [20].…”