射频技术新版.doc

Disclaimer: The information contained within the Grand Rounds Archive is intended for use by doctors and other health care professionals. These documents were prepared by resident physicians for presentation and discussion at a conference held at Baylor College of Medicine in Houston, Texas. No guarantees are made with respect to accuracy or timeliness of this material. This material should not be used as a basis for treatment decisions, and is not a substitute for professional consultation and/or peer-reviewed medical literature.
Endoscopic Dacryocystorhinostomy
June 1, 2023
Allen Lue, M.D

Endoscopic dacryocystorhinostomy or DCR has traditionally been performed for nasolacrimal duct obstruction via an external approach, although the procedure is actually uniquely suited for an endoscopic approach.

The first reported dacryocystectomy was performed by Celsus in 50 AD. This was probably done for a tumor. Galenas of Pergamos was reportedly the next person to perform a surgery on the lacrimal sac. He performed a medial canthal incision and cauterized with molten lead. Anel in the 1700s was the first to irrigate the lacrimal duct for this symptom of obstruction. Bowman in the 1800s later reported the technique of actually putting a probe through the duct to relieve obstruction of the nasolacrimal system. Toti, an Italian in 1904, was really the first person to perform external dacryocystorhinostomy for obstruction. He made an incision through the skin and created a new ostium between the nasolacrimal sack and the nose. By removing this bone, drainage to the nose was allowed through bypassing any obstruction distally. His technique is still being used today and is generally thought of as the gold standard for surgery of nasolacrimal duct obstruction. In 1895, Caldwell reported his experience with the endonasal approach but showed mediocre results and so the external procedure was used for quite some time. However, Rice in 1990 reported his experience using endoscopic instruments to create this neo-ostium and since then there has been quite a bit of literature on the subject.

The lacrimal system consists of superior and inferior puncta, which turn into the superior and inferior canaliculi, which then join into the common canaliculus. This region is known as the upper lacrimal system. The common canaliculus turns into the nasolacrimal sac, which is about 12-15-mm long, which eventually narrows into the nasolacrimal duct, which is about 18-mm long, and that eventually empties into the inferior meatus. The sac and the duct comprise the lower lacrimal system.

Tears move from the eye into the nose through a mechanism called the lacrimal pump. Lid movement causes the puncta to close against each other, pushing tears into the lacrimal sac, which contains the lacrimal lake. When the eyes open a negative pressure is created in the lacrimal lake, pushing it down further into the nose.

The nasal anatomy of the lacrimal system is pretty straightforward and very familiar to any endoscopic sinus surgeon. The lacrimal fossa overlies the lacrimal sac. A very good landmark is the anterior portion of the middle turbinate. The lacrimal fossa is bounded by the anterior lacrimal crest, which consists of the frontal process of the maxillary bone. The posterior lacrimal crest is made up of the lacrimal bone itself.

How do you evaluate epiphora, which is really the main indication for a DCR? First we should define our terms. Epiphora is excess tearing due to insufficient drainage.. One every important concept to note about a DCR is that drainage will only relieve obstruction distally. If the obstruction is in the puncta or the canaliculus, dacryocystorhinostomy will not help. We should also distinguish epiphora from pseudo-epiphora, which is essentially reflux tearing: the main gland over compensates secretion because of lack of secretion from minor glands of along the lid margin.

There are multiple causes of the nasolacrimal duct obstruction, the most common of which is recurrent dacryocystitis. In a series of 109 patients from Finland, approximately 70% of those patients with nasolacrimal duct obstruction had recurrent bouts of dacryocystitis. Contributing factors include nasal allergy, septal deviation and sinusitis. Lacrimal stones also cause obstruction. There is a controversy in the literature as to whether or not the stones precede the dacryocystitis and cause it due to the obstruction of the stone or are the result of actual infections. Tumors can also cause nasolacrimal duct obstruction, in particular from external compression. These tumors are usually malignant epithelial neoplasms. In tumors the mass often extends superior to the medial canthus, while in inflammation or infection, the mass usually stays inferior to this line. Lacrimal sac cysts can also cause obstruction in the pediatric population. Other things, such as surgical trauma or external trauma may also cause obstruction of the duct. Radiation therapy will also sclerose the duct and cause obstruction

In the patient's history it is important to note whether or not the epiphora is unilateral or bilateral, and whether the tearing is constant or intermittent. Unilateral constant tearing will usually direct you towards an obstructive phenomenon. The nature of the discharge is also important: clear or purulent.

Environmental factors, such as allergies should be elicited. Medication histories are important as well as previous history of trauma or surgery. On physical examination, palpate the region of the nasolacrimal sac to see if you can elicit any reflex from the puncta.

When examining the eyelid, note if there is any laxity, and look at the punctum to see if there is any obstruction that can be seen, or inflammation. Evaluate the canaliculi through probing. Place a Bowman probe through the puncta, and then swing the probe horizontally to cannulate the superior inferior canaliculus. There is a difference between a hard versus a soft stop. A hard stop would be a stop created by bones, such as the lacrimal bone. A soft stop can be felt as an obstruction in the soft tissue. Evaluate the nasolacrimal duct further through irrigation of the duct with a syringe. A nasal examination is certainly also very important to note any obstructive lesions on the nose.

The Jones test is a test of the patency of the nasolacrimal system. The test is performed by placing fluorescein in the conjunctival sac and seeing whether or not this fluorescein can be visualized in the nose. If after a period of five minutes there is impaired outflow, it is likely that there is an obstruction somewhere in the duct or somewhere in the system. If you do not see any dye in the nose after five minutes, then you can perform a secondary test, by irrigating the duct. If after irrigating the duct no dye is found in the nose, the dye has never really reached the lacrimal sac to begin with. The obstruction is likely proximal. If you do see dye in your irrigate, then dye did reach the nasolacrimal sac, and it is likely that your obstruction is distal.

You can image the nasolacrimal system using a dacryocystogram. You can also use a dacryoscintigraphy with radio labeled materials, and certainly you would not proceed with an endoscopic case without performing computed tomography. A CT can be very useful to find extrinsic tumors, lacrimal sac mucoceles, show the state of the sinuses and find dacryoliths for you. In a series performed in Australia, a 10% incidence of conditions that actually changed management of nasolacrimal duct obstruction was found when they got a CT scan.

If the obstruction is beyond or at the sac in the lower lacrimal duct system, a DCR may be performed. The external DCR is certainly still thought of as the gold standard with a success rate of approximately 91%. Revision procedures have a success rate of approximately 81%, although it should be noted that dissection through the previous scar can be somewhat laborious. The external incision is made just inferior to the medial canthus, taking care to avoid the angular artery. The lacrimal sac is exposed, and you drill through the lacrimal fossa through the frontal process of the maxillary bone until you enter the nasal cavity. You can also create mucosal flaps, which will keep the ostium open. A Crawford tube is placed through each puncta through each canaliculus and then out the neo-ostium into the nose. This is usually kept in place anywhere from six weeks to six months to maintain the patency of this neo-ostium.

Even though the success rate is high, there are certain complications to an external DCR. There is an external scar which is avoided with the endoscopic procedure. There is also danger of injury to the medial canthal structures, and CSF leak has been recorded. There is a 9% chance of recurrence of symptoms. One cause of recurrence of symptoms is if the obstruction is in the common canaliculus proximal to where the drainage procedure is done. There is also the possibility of closure of a small malpositioned ostium, entry into the ethmoid sinus, and causes of intranasal obstruction.

The endoscopic DCR was first described by McDonogh in 1989. He actually thought about the procedure when he exposed the duct by accident during one of his sinus procedures. For an endoscopic DCR, the anterior portion of the middle turbinate is used as a landmark. A mucosal flap is elevated, exposing the lacrimal fossa. This bone is drilled out, that is the frontal process of the maxillary bone and some of the lacrimal bone, exposing the nasal lacrimal sac. Place a probe tenting the sac, and incise this sac to create a neo-ostium so that tears can drain from the canaliculus directly into the nose through the middle turbinate and bypass any obstruction in the nasolacrimal duct. This ostium is kept open with a Crawford tube stent with a silicone tube placed through the puncta into the sac and out the nose. The tubes are kept in place for anywhere from six weeks to six months.

There are certain advantages of the endoscopic DCR. There is no external scar. It preserves the lacrimal pump system. Any intranasal pathology that might have caused failure of the first procedure can be addressed, including adhesions, enlarged middle turbinate and septal deviation. More of the lacrimal sac is preserved with the endoscopic procedure. There is actually only a 1 in 40 instance of air regurgitation during nose blowing noted after endoscopic procedures, while the incidence is higher with the external procedure. There is also diminished risk of a CSF leak with the endoscopic DCR.

There are also some disadvantages. The main disadvantage is that DCR is a fairly new procedure and so long-term results are unknown. No mucosal flaps are created. Mucosal flaps have been found to decrease recurrence rates in the external procedures. A smaller rhinostomy is performed in DCR than in the external procedure. It is interesting to note that in a study by Linberg there was no correlation between the original size of the bony opening and the size of the healed ostium at some later point. In fact, the average size was 1.8-mm.

In reviewing the success rates, the first was Rice who reported four patients with a 100% success rate. In 1943, Whittet reported on 40 patients with an 83% success rate. Weidenbocher from Germany had an 86% success rate. Sprekelsen from Spain had a very large series of 152 patients and had a 96% success rate. Most of these authors define success as maintenance of patency after a period of anywhere from three months to a year.

There has only been one prospective study comparing endoscopic to external DCR, which was performed by Hartikainen of Finland. He looked at 64 patients and followed up at one year. He found a patency rate of 75% in the endoscopic cases versus 91% externally. This did not, however, reach a statistically significant difference. It should be noted that after revision procedures, there was a 97% success rate in both groups.

What is not up for argument is that the endoscopic approach is actually ideal for revision cases, particularly because you do not have to drill out any new bone that had been done previously by an external approach. In 1991 Metson reported on 15 patients who were status post failed external DCR and reported a 75% success rate. Again, the main advantage is that it is unnecessary to remove any bone. There is also the added advantage of being able to perform secondary nasal procedures. Metson, in the 1991 study, performed the following secondary endoscopic nasal procedures: middle turbinate resections, septoplasty, and ethmoidectomies and antrostomies.

There are certain complications to an endoscopic DCR. Some are unique to the endoscopic approach and some are shared by the external approach. In particular, closure of the ostium, and intranasal adhesions from the endoscopic procedure can occur. Canalicular laceration, pyogenic granuloma, and CSF leak have been reported. Orbital hemorrhage can certainly occur from the interior ethmoid artery during the endoscopic procedure.

Recently, there has been literature on the use of the laser to perform endoscopic DCR. Massaro was the first to report in 1990. He used an Argon laser and had mediocre results. However, recently the Holmium-Yag laser has found a lot of use. Its advantages are fiberoptic delivery, effective bone ablation, soft tissue coagulation and shallow depth of penetration, which makes it safer. A light pipe is placed through the puncta. The pipe goes through the canaliculus, into the nasolacrimal sac and can localize the lacrimal fossa. Endoscopically, you can place the scope and the laser, at which point you can obliterate the soft tissue and the bone overlying the region of the lacrimal fossa.

The literature which reports retrospectively on the laser DCR includes Metson, who was one of the first to report: 40 patients with an 85% success rate. Sadiq had a 70% success rate and Szubin showed a 97% success rate. All of these studies used the Holmium-Yag laser.

Again, there has only been one prospective randomized study comparing laser and external DCR. This was actually done by the same group (Hartikainen) possibly using the same control group for the external approach. They studied 64 patients, and had a 95% success rate with the external approach at one year and 63% success rate with the laser. This was a significant difference. One notable thing is that the duration of the surgery was 23 minutes for the laser procedure versus 78 minutes for the external approach, so the laser approach did have the advantage of saving time.

In considering the future for endoscopic DCR, we should look at the use of anti-metabolites such as Mitomycin-C. This alkylating agent has found other use in ophthalmologic procedures including glaucoma and pterygium removal. Camara in 2023 increased his success rate for endoscopic DCRs