Atlas of Nose and Paranasal Surgeries

ATLAS OF NOSE AND PARANASAL SURGERIES 21 Authors: D. Marchioni, M. Bettini, D. Soloperto Title: Anatomy of the Lacrimal Drainage System Book: Endoscopic Surgery of the Lacrimal Drainage System DOI: 10.1007/978-3-319-20633-2_1 © Springer International Publishing Switzerland 2016 Endoscopic Dacryocystorhinostomy The lacrimal sac fossa is situated anterior and lateral to the middle turbinate; the ostium achieved in an external dacryocystorhinostomy (DCR) is at the anterior tip of the middle turbinate while in endoscopic approach it is in a more inferior site Dacryocystorhinostomy is the procedure of choice for nasolacrimal duct obstruction and chronic dacryostenosis in the setting of patent canaliculi and a functional lacrimal pump. Two major approaches are utilized: external, via a transcutaneous incision, and endonasal endoscopically-guided. While endonasal DCR has been performed by both ophthalmic surgeons and otorhinolaryngologists (ENT) in the past, the advancement of nasal endoscope and functional endoscopic sinus surgery (FESS) has led to more ENT surgeons performing endoscopic DCR. The surgical procedure is developed under general anesthesia, with controlled hypotension to reduce intraoperative bleeding. Before surgery a local anesthesia with Xylocaine combined with 5 % naphazoline (if possible) is performed, to have a good mucosal decongestion and for a better identification of surgical landmarks. Endonasal view: Zps endonasal projection of the lacrimal sac, PU uncinate process, TM middle turbinate, Atm middle turbinate axilla (continued)... thal tendon • Body inferiorly, which extends approximately 10 mm below the fundus till the opening of the nasolacrimal canal. At this junction is located the valve of Krause (Fig. 1.12 ). oculi muscle; the superficial head of the muscle travels around the front of the sac to attach to the anterior lacrimal crest, and the deep head of the muscle travels behind the sac to attach to the pos- terior lacrimal crest. Between the lacrimal fascia and the lacrimal sac lies a venous plexus. All these structure avoi direct contact with bone at this level. The lacrimal sac is lined by pseudostratified epithelium with two apparent layers, the superfi- cial of which is columnar, the deeper flattened. The bases of the column cells pass throu h the deeper layer to reach the basement membrane. Beneath this, a layer of connective tissue with linfocites is present (Fig. 1.11 ). True lymph fol- licles are not present in the normal situation; however, they may form q ickly in response to infection or irritative phenomena. 1.4.3 Nasolacrimal Duct The nasolacrimal duct consists of a 12-mm- length superior intraosseous portion and a 5-mm- length inferior membranous portion (Fig. 1.8 ). Fig. 1.10 Endonasal view: Zps endonasal projection of the lacrimal sac, PU uncinate process, TM middle turbi- nate, Atm middle turbinate axilla