CHAPTER 55 Endoscopic Dacryocystorhinostomy

• Chronic epiphora should be investigated with a dacryocystogram and possibly a scintillogram prior to surgery to localize the site of obstruction to ensure that it is amenable to dacryocystorhinostomy.

• Although anatomic obstructions of the lacrimal system are associated with excellent surgical outcomes, functional obstructions have less impressive responses to surgery. It is important to differentiate between these two types of obstruction to determine a patient’s prognosis.

• The superior edge of the lacrimal sac is located well above the insertion of the middle turbinate. Surgical outcomes are improved when the entire sac is marsupialized.

• The primary surgical goal is to lay the marsupialized lacrimal sac flat without tension in direct contact with surrounding mucosa for primary intention healing. This concept allows outcomes of endonasal dacryocystorhinostomy to equal those of the external procedure.

• Advantages of endonasal over external dacryocystorhinostomy include the lack of an incision and no disruption of the lacrimal pump mechanism.

E. Weitzel has no financial interest/arrangement or affiliation with one or more organizations that could be perceived as a real or apparent conflict of interest in the subject of this paper. P-J. Wormald has a financial interest/arrangement with Medtronic Xomed for royalties received from design of surgical instruments.

Endoscopic dacryocystorhinostomy (DCR) was first described in the otolaryngology literature by McDonogh ¹ in 1989. Over the ensuing years, there has been a steady improvement in outcomes owing to advances in surgical technique, instrumentation, and comprehension of the anatomy. Specifically, once the superior extent of the lacrimal sac was recognized to extend significantly above the middle turbinate, surgical outcomes improved.² Today’s endoscopic DCR is a reliable and effective technique that is comparable to external DCR in outcome measures.³^–⁶ In 2007, endoscopic DCR was reported to be economically superior to the external technique.⁷

Pathophysiology

Obstructions of the lacrimal apparatus can occur anywhere along its course. DCR surgically bypasses the most distal portion of the lacrimal apparatus, creating a new outflow in the lateral wall of the nasal cavity instead of below the inferior turbinate. Thus, DCR is specifically designed to manage obstructions of the lacrimal sac and duct. It is important to note that DCR is not capable of reliably managing obstructions within the lacrimal apparatus proximal to and including the common canaliculus (Fig. 55-1). In selected cases, a stenosis of the common canaliculus immediately proximal to its entry into the lacrimal sac can be managed by temporary stenting with O’Donoghue tubes.

Figure 55-1. A, Anatomy of the left lacrimal apparatus: 1, superior punctum; 2, superior canaliculus; 3, inferior punctum; 4, inferior canaliculus; 5, medial canthal ligament; 6, common canaliculus; 7, lacrimal sac; 8, lacrimal duct; 9, middle turbinate; 10, lacrimal bone; 11, inferior turbinate; 12, Hasner’s valve. B, Position of lacrimal sac as seen during endonasal visualization. The lacrimal sac is located under mucosa and the frontal process of the maxilla.

There are two principal categories of lacrimal obstruction, anatomic and functional. Anatomic obstructions are more common than functional obstructions, the approximate rates being 70% and 30% respectively.⁵ Anatomic obstructions are complete blockages most commonly noted between the lacrimal sac and nasal cavity. Functional obstructions are caused by either critical narrowings within the lacrimal system that delay normal lacrimal flow or a failure of the proximal pumping mechanism. Both anatomic and functional obstructions may be managed with endoscopic DCR; however, surgery of anatomic obstructions is noted to have superior outcome.

Evaluation

The clinical evaluation of the patient presenting for DCR excludes other causes of epiphora, including entropion, ectropion, lid malposition, punctal abnormalities, and blepharitis. The discovery of reflux of purulent material from the lacrimal puncta during medial canthal palpation indicates obstruction of the nasolacrimal system that is amenable to DCR. Probing of the lacrimal system with a Bowman’s lacrimal probe adds a more detailed clinical picture to the level of blockage. A “hard stop” implies that the probe has impacted against the lacrimal bone, suggesting a patent lacrimal system up to the lacrimal sac. A “soft stop” implies that distal progress of the probe is impeded by soft tissue, suggesting either stenosis of the common canaliculus or a tight common canaliculus-sac junction. Further information is gleaned by syringing of the lacrimal apparatus. A 25-gauge blunt lacrimal needle is inserted into the inferior puncta, and saline is gently flushed. The taste of saline confirms a patent system, although the test is not diagnostic because the pressures developed during the test are much higher than normal and thus cannot identify functional constrictions within the system. An anatomically blocked system causes reflux through the superior punctum during irrigation. More proximal canalicular obstructions can cause reflux out of the punctum being injected.

Radiologic evaluation of lacrimal obstructions begins with the dacryocystogram (DCG). Because it, like saline irrigation, causes elevated pressures within the lacrimal system, this study is capable of diagnosing only anatomic obstructions (Fig. 55-2). Failure of DCG to identify a blockage in a symptomatic patient necessitates lacrimal scintilligraphy. Unlike DCG, scintilligraphy is a physiologic test of the lacrimal system; thus functional obstructions cause delays in the flow of radioisotopes from the conjunctiva into the nasal cavity over the 30-minute duration of the test. If isotope delay is detected in the lacrimal sac during the test, a narrowed segment is more likely than a failure of the lacrimal pump mechanism (Fig. 55-3). However, if the isotope does not penetrate the lacrimal system, a pump failure is then more likely. Studies have shown that outcome of DCR performed for anatomic obstructions is superior to that of DCR done for functional obstructions.⁵ The ability to confirm an obstruction with scintilligraphy and to differentiate anatomic from functional obstruction with DCG allows the surgeon to better prepare the patient for the prognosis of the procedure.