DCR and Nasolacrimal System (Cadaver)

Abstract

Nasolacrimal duct obstruction (NDO) is the most common disorder of the lacrimal system that affects patients of every age and results in excessive tearing (epiphora) and if untreated, painful infection (dacryocystitis). When NDO symptoms progress and can no longer be managed with conservative measures, endoscopic dacryocystorhinostomy (DCR) is indicated. In this case, DCR exploration of the nasolacrimal anatomy is performed on a cadaver. The typical presentation of NDO is epiphora but the presence of painful swelling of the medial canthus and mucoid or purulent discharge may indicate the presence of dacryocystitis. The approach presented here is similar to the technique described by Tsirbas and Wormald in 2003 and involves the creation of a mucosal flap and subsequent use of the DCR drill to expose the nasolacrimal duct anatomy. Stenting and subsequent marsupialization of the flap is not shown in the cadaveric dissection. Postoperatively, patients are typically advised to use nasal irrigation twice daily with saline for six weeks and complete a 1-week course of PO antibiotics and 5-day course of antimicrobial eye drops.

Case Overview

Background

Nasolacrimal duct obstruction (NDO) is the most common disorder of the lacrimal system that affects patients of every age and results in excessive tearing (epiphora) and if untreated, can lead to painful swelling of the medial canthus and mucoid or purulent discharge infection (dacryocystitis).¹ NDO may be due to an idiopathic inflammatory stenosis called primary acquired nasolacrimal duct obstruction (PANDO), which can result in either partial stenosis or complete obliteration of the duct lumen and occurs primarily in middle age and elderly women.¹ NDO may also occur secondary to a variety of infectious, inflammatory, neoplastic, traumatic, and mechanical insults. In these cases, the disease is referred to as secondary acquired nasolacrimal duct obstruction (SANDO).² When a patient’s chief complaint and initial history are concerning for NDO, follow-up questioning focused on prior ocular, systemic, or traumatic disease should be done to discern between PANDO and SANDO. An appropriate physical exam includes an external exam of the eyelids, slit lamp exam, medial canthus exam, and a thorough endoscopic nasal exam to rule out inflammatory, structural, or neoplastic abnormalities in the nasal passage. Initial therapy for SANDO will depend on the specific etiology with antibiotics for infections, corticosteroids or immunomodulatory therapy for inflammatory causes, and chemotherapy/radiation for neoplasms. Most patients will require surgery.

Dacryocystorhinostomy (DCR) surgery is the primary surgery for NDO and involves surgically bypassing the nasolacrimal duct.³ A passage is created from the lacrimal sac to the lateral nasal wall and in some cases, silicon stents are temporarily placed to maintain patency and allow tear drainage.

Herein, Dr. Ellison leads the residents at Duke University in performing a DCR while identifying the relevant nasolacrimal anatomy. Use of picture-in-picture offers our viewers insight into how the lower canaliculus probe is managed with endoscopic assistance.

Focused History of a Typical Patient

A 55-year-old female presents to the otolaryngology clinic with a chief complaint of right eye tearing and conjunctival discharge for several weeks that progressively worsened over the past week. An external exam of the eye, eyelids and medial canthus reveal a distended, slightly tender lacrimal sac with conjunctival injection. Nasal endoscopy did not reveal any abnormalities of the nasal mucosa. Diagnostic probing and syringing of the lacrimal pathway demonstrated reflux through the opposite punctum, suggestive of stenosis of the common canaliculus or the lower lacrimal pathway.³ Subsequent CT scan of the lacrimal sac, orbit, and paranasal sinuses confirmed NDO of the lower lacrimal pathway. Surgery was scheduled.  

Options and Rationale for the Treatment

DCR surgery is indicated for patients with NDO who have epiphora. History and physical examination are typically sufficient to indicate a patient for surgery after initial conservative management is attempted. Additional functional radiologic studies such as dacryocystography, which involves localization of a complete obstruction with contrast, or dacryoscintigraphy, which involves localization of an incomplete obstruction with radionuclide tracers, are both less frequently used due to the sensitivity and prevalence of CT.³ 

Surgical Technique

Surgical Positioning

The patient is positioned supine with the head slightly extended and the head of the bed raised 20–30°. The procedure is generally performed under general anesthesia (GA). Oxymetazoline-soaked pledgets are placed in the middle meatus and along the lateral nasal wall to promote decongestion. The lateral nasal wall, axilla of the middle turbinate, and uncinate are infiltrated with 1% lidocaine with 1:100,000 epinephrine for hemostasis.⁴

Anatomic Landmarking

A combination of 0° and 30° rigid endoscope can be used to localize the lacrimal sac. Key landmarks include: the axilla of the middle turbinate (the roof of the lacrimal sac is situated above the axilla and extends 1–2 mm below this landmark) and the uncinate process. The superior and inferior turbinates should be identified as well along with an evaluation of the nasal septum.  

Incision

After ensuring adequate vasoconstriction of the mucosa, a horizontal incision is made above the insertion of the middle turbinate and anterior to the axilla. This incision is extended vertically down the frontal process of the maxilla and should be right above the bone. In this case, a sickle knife is used but intraoperatively a scalpel, beaver blade, or cautery may be used. The lower horizontal incision is made somewhere just above the inferior turbinate.

Mucosal Flap Elevation

The mucosal flap is elevated using either a Freer or Cottle elevator to obtain good exposure of the junction of the nasolacrimal duct to the underlying maxilla (lacrimal crest of the maxilla).⁵

Nasolacrimal Sac Exposure

After elevating the mucosal flap, a Kerrison bone punch is used to remove bone from the inferior aspect of the frontal process of the maxilla up to the level of the axilla of the middle turbinate. This process is done carefully, ensuring only bone is taken to prevent tearing of the nasolacrimal duct. The bone at the level of the axilla of the middle turbinate is too thick to punch. At this point, a 20°, guarded DCR drill is used to remove bone up to 8 mm above the axilla of the middle turbinate to expose the nasolacrimal sac. The guard on the drill protects the mucosal flap and the middle turbinate. Again, this process is done carefully to ensure adequate bone skeletonization with minimal damage to the lacrimal sac itself. 

Lacrimal Duct Probe & Incision

Once adequate visualization of the nasolacrimal sac is felt to have been achieved, a probe is inserted into the lower canaliculus via the lacrimal duct to confirm the location of the common canaliculus which ultimately empties into the lateral wall of the lacrimal sac. If the probe tip can be visualized on nasal endoscopy, this suggests that sufficient bone over the common canalicular opening has been removed and an incision into the lacrimal sac can be made. The main goal is to create a large bony ostium that allows communication between the lacrimal sac and the nasal mucosa. Some studies support the use of silicon tubes to stent open the canaliculi and prevent scarring of the rhinostomy site.⁶ Randomized trials provided by Xie C et al. have shown that silicone intubation after endoscopic lacrimal surgery does not change the outcome.²⁷

Cover of Exposed Bone with Mucosal Flap

Following exposure of the bone and any necessary stenting, the mucosal flaps can be folded back towards the uncinate process to facilitate marsupialization.⁵

Discussion

DCR for the treatment of NDO has been performed since the early 20th century with the original, external DCR technique first described by the Italian otolaryngologist, Addeo Toti.⁷ While external DCR was long considered the gold standard in NDO management, advances in endoscopic technology have afforded surgeons the ability to perform endoscopic DCR (endo-DCR), which has recently grown in popularity.⁸ While the advantages of external DCR include the ability to directly visualize the lacrimal sac and form and suture flaps between the lacrimal sac and nasal mucosa, the major disadvantage is the medial canthal scar and increased post-op morbidity from the skin incision.³ Endo-DCR does not involve an external incision or scar and allows the surgeon to treat concomitant endonasal pathology but makes the process of forming and suturing sac-nasal mucosal flaps more technically challenging.^5,9 Despite key differences in technique, a 2017 Cochrane review revealed there is uncertainty in which method is most effective due to lack of well-designed randomized control trials.¹⁰ While the majority of DCR surgeries in the United States are still performed externally, an increasing number are completed endoscopically with reports of equal safety and effectiveness.¹¹

Postoperative care has a major influence on successful DCR.¹² Patients are typically advised to use nasal irrigation twice daily with saline for six weeks and complete a 1-week course of PO antibiotics and 5-day course of antimicrobial eye drops.⁴ The assessment of a successful DCR is based on symptom relief as well as the absence of any objective signs of NDO (epiphora, dacryocystitis).¹³ In fact, detailed patient satisfaction surveys (Lacrimal Symptom Questionnaire¹⁴ and NLDO symptom score¹⁵) that assess symptom relief and improvement in quality of life are considered validated indicators of surgical success.

The overall complication rate after DCRs is reported to be around 6%.¹⁶ The most frequently reported postoperative complications localize primarily to the nasolacrimal duct and include hemorrhage, silicone tubing prolapse, and persistent canalicular obstruction which may require revision DCR.¹⁶ Postoperative ophthalmologic complications are uncommon and range from temporary ophthalmoplegia to orbital fat herniation which may be managed conservatively to orbital and subcutaneous emphysema, conjunctival fistula formation, and retrobulbar hematoma, all of which require urgent ophthalmologic consultation.¹⁶ 
Red flag symptoms following DCR include fever, severe headache, neck stiffness, light sensitivity, and rhinorrhea, which may indicate rare but severe complications such as CSF leak or meningitis.^17,18 If the presentation is concerning for a CSF leak, evaluation of rhinorrhea or otorrhea for beta-2 transferrin is necessary, and if positive, a high-resolution CT of the paranasal sinuses and temporal bone should be obtained to prepare for surgical management.¹⁹ If the presentation is concerning for meningitis, a prompt assessment of intracranial pressure is necessary. If the intracranial pressure is not elevated, a lumbar puncture is necessary and if it is consider a head CT prior to further management.²⁰

While outcomes after endo-DCR are typically positive with success rates between 84–94%,¹⁶ success rates are highest in patients without a history of dacryocystitis, sinusitis or chronic inflammation.³ Given the technical challenge of endo-DCR when compared to external DCR, surgeon experience plays an important role in surgical success as well.²¹ With respect to differences in specific endo-DCR techniques, a 2020 systematic review by Vinciguerra et al found that there were no differences in outcomes between mechanical and powered approaches in endo-DCR and that mucosal flap preservation was not necessary to achieve a better outcome.²²

When compared to primary procedures, revision procedures generally have lower success rates (76.5%).²³ The formation of granulation tissue over the rhinostomy site is the most likely contributor to lower success rates in revision procedures,^24,25 and evidence suggests that an antiproliferative agent such as mitomycin C can be applied postoperatively to improve outcomes in revision endo-DCR cases.^15,26

Future prospective, randomized trials with larger sample sizes are necessary to evaluate the efficacy of endo-DCR vs external DCR as well as intraoperative antiproliferative agents on the rate of healing and surgical outcomes.

Duke University Cadaver Lab Series

Check out the rest of the series below:

1. Functional Endoscopic Sinus Surgery: Maxillary, Ethmoid, Sphenoid (Cadaver)
2. Ethmoid Artery Anatomy (Cadaver)
3. Frontal Sinus Dissection (Cadaver)
4. DCR and Nasolacrimal System (Cadaver)
5. Parotid Dissection (Cadaver)
6. Thyroidectomy (Cadaver)