29 Endoscopic Dacryocystorhinostomy
Endoscopic dacryocystorhinostomy (DCR) is becoming ever more popular as patients seek minimally invasive options for surgical procedures. As instrumentation and surgical techniques have advanced, the success rates of endoscopic DCR performed by experienced surgeons is at least equivalent to that of traditional external DCR surgery. Many oculoplastic surgeons, in transitioning from external to endoscopic technique, may employ the use of a “light pipe” to transilluminate the lacrimal sac fossa endonasally. This can be helpful, but can also potentially misdirect the surgeon to make the osteotomy more inferiorly and posteriorly than is ideal if one does not fully understand the relevant anatomy. This chapter serves to outline some of these considerations, as well as to describe the author’s surgical technique, to aid the surgeon engaging in endoscopic DCR surgery.
Dacryocystorhinostomy (DCR) is the standard surgical correction for nasolacrimal duct obstruction in the setting of patent canaliculi to resolve problematic epiphora. The basic surgical concept dates back over one-hundred years, 1 and has been modified over time. The majority of DCR surgery over the past few decades has been performed externally (extDCR) via a skin incision placed near the tear trough/lower medial canthal region with generally great success. As patients and surgeons alike have aimed for more minimally invasive approaches, endoscopic DCR (enDCR) has become more popular. There was a period when enDCR was considered a second-rate “trade-off” procedure in which the patient was exchanging lack of a skin incision scar for a lower surgical success rate; however, with modern instrumentation and technique, this is no longer the case, as success rates for extDCR and mechanical enDCR are equivalent. 2 Today, both external and endoscopic DCR are excellent procedures and both are within the standard of care to be offered to patients based upon patient preference and surgeon comfort and personal outcome measures.
Note that the present report concerns mechanical enDCR only, not laser-assisted DCR.
The most oft-cited advantage of enDCR over extDCR is lack of a “scar”; however, it must be acknowledged that the extDCR incision generally heals quite well with high patient satisfaction. 3 The author considers the main advantages of enDCR to be lack of external facial incision (and thus lack of external bruising, edema, or potential wound infection); lack of disruption of orbicularis oculi muscle and potential tear-pump dysfunction 4 ; wide-view, magnified, high-definition visualization of the surgical site; potential to address other intranasal factors relevant to surgical success such as nasal septal deviation, concha bullosa of middle turbinate, etc..
As in all surgical procedures, it is important to set patient expectations ahead of time. While modern enDCR performed by an experienced surgeon with the right equipment has very high success, this is not true if performed by a novice surgeon transitioning from extDCR. The success rates quoted in the literature do not apply to that individual; thus, an individual surgeon should have a sense for his or her personal success rate. The goal should be to reliably achieve success at least comparable to the reported literature, and to do so may require training courses, practice, mentorship, etc.
If one assumes a 90% success rate, it still means that one out of ten patients will “fail” the surgery, meaning they will continue to experience problematic tearing. This can be in the setting of a scarred DCR ostium, or in the setting of a patent DCR ostium (in which case the tearing is multifactorial, and particularly difficult to remedy). This should be discussed with patients preoperatively. The author will often use the example that the DCR surgery involves creating a hole in the blocked tear drain—the body views this hole as a wound and tries to “heal” it closed, and when it does close the surgery fails. This is one of the reasons stents and absorbable packing materials, etc. may be placed within the ostium—that is, to prevent the body from “healing” the ostium (fistula) closed.
Patients should also be warned about the possibility of early stent prolapse or loss, epistaxis, nasal congestion, sinusitis, cerebrospinal fluid leak, the possibility of air reflux from a lacrimal punctum when blowing the nose, and possible need for additional surgery, whenever preoperative counseling is performed.
29.4 Key Principles
The main principle of DCR, whether external or endoscopic, is to establish a patent and permanent internal fistula between the lacrimal sac and the nasal cavity for effective tear drainage.
enDCR is appropriate for any and all patients with nasolacrimal duct obstruction whether congenital, primary acquired, or secondary. The author no longer performs extDCR.
DCR, whether external or endoscopic, should be delayed when there is a recent history of cancer excision surgery in the medial canthal/lacrimal sac area in adherence to the oncologic principle of not violating bone and periosteum between a cavity involved with malignancy and cavity uninvolved, with the concern being that the DCR osteotomy could open a pathway for a cancer recurrence to enter the nasal cavity. The exact timeframe for which to wait between cancer treatment and lacrimal surgery ranges from 1 year to never, depending on the authority queried. The author addresses this situation on a case-by-case basis, and this analysis involves serial imaging (CT and MR), sometimes a surveillance biopsy, etc., with the earliest intervention occurring 1 year after cancer treatment.
In the setting of acute dacryocystitis, the author prefers to administer systemic antibiotics and treat the active fulminant infection and allow the inflammation to settle prior to undertaking surgery. Incision and drainage is performed if there is a pointing abscess or if the infection has failed empiric treatment.
29.7 Preoperative Preparation
A history of dacryocystitis connotes nasolacrimal duct obstruction, and thus the author does not routinely perform nasolacrimal irrigation on these patients.
The evaluation of the tearing patient otherwise includes the assessment of the tearing history (does it occur at all times? Intermittently? Every day? Is there discharge? Do the eyes itch or burn? Is there a history of trauma or prior surgery?) A history of radioactive iodine therapy, particularly high-dose radioactive iodine therapy as used for treatment of thyroid cancer, is highly associated with secondary nasolacrimal duct obstruction. 5 Eyelids are assessed for laxity, which if severe may be addressed at the time of DCR surgery. A history of chronic rhinosinusitis is ascertained; if present, a CT scan may be obtained, and if significant sinus disease is noted, enDCR may be performed in collaboration with an otolaryngologist for simultaneous functional endoscopic sinus surgery. Otherwise the author does not routinely obtain CT scan on all patients unless the patient has an unusual circumstance (young age; history of trauma or prior surgery; bloody tears; mass; etc.)
Nasal endoscopy is performed on all patients preoperatively. This is important for many reasons. First, the overall surgical anatomy may be assessed, in particular the status of the nasal septum (whether there is deviation blocking access to the nasal sidewall and maxillary line that would limit the ability to perform surgery and also raise the risk of postoperative scarring and surgical failure; whether there is a concha bullosa of the middle turbinate that blocks the maxillary line and would interfere with the DCR ostium). In addition, the general health of the nasal cavity can be assessed, looking for the status of the mucosa, evidence of polyps, mucopus, adhesions, ulceration, melanosis, bleeding, tumor, etc. It is important that any abnormality should be investigated by referral to an otolaryngologist. One can learn diagnostic nasal endoscopy technique by working with an otolaryngologist mentor and studying a rhinology atlas. Compact self-contained video-endoscopy units are available for the office setting that work quite well.
29.8 Operative Technique
The patient is supine on the operating table and placed under general endotracheal anesthesia. A time-out is observed. The bilateral nasal cavities are packed with neurosurgical cottonoids soaked in oxymetazoline. The patient is draped in the usual sterile fashion. If the patient has a prosthetic heart valve or joint, a systemic antibiotic is administered intravenously.
A zero-degree rigid video endoscope system is used throughout the procedure, occasionally augmented with a 30-degree endoscope for better lateral visualization.
The eyes are treated with a topical anesthetic such as proparacaine eye drops, and corneoscleral protecting shields are placed. The upper and lower puncta of the operative side are dilated.
A light pipe (such as a 23-gauge vitrectomy endoilluminator) may be used to aid with endonasal confirmation of the lacrimal sac anatomy, although care must be taken with this step as will be described later. The light pipe is connected to a headlight light source and the light pipe can be advanced through the lower canaliculus to a hard stop with the pipe maintained in a horizontal position. The tip of the light pipe should be maintained against the hard stop and not allowed to rest within the soft tissues as thermal injury to the canaliculi could result. The light source should be kept on a relatively lower power setting such as 25% to further reduce the risk of thermal injury to lacrimal soft tissues.
The nasal packing is removed and the endoscope is introduced into the nasal cavity. A bilateral intranasal examination may be performed. The transillumination may be visualized at this time, and reducing the endoscope illumination may be necessary temporarily to adequately see this. It is not uncommon to see all of the transillumination sharply posterior to the maxillary line, completely within the middle meatus under the middle turbinate (Fig. 29‑1). This is because the posterior lacrimal sac fossa (lacrimal bone) is quite thin and readily transmits the light, while the anterior lacrimal sac fossa (frontal process of the maxilla) is thicker and blocks light. Further, the light pipe will often have a posterior angulation due to the ergonomics of passing it over the ocular surface, brow, or cheekbone, which directs the illumination posteriorly. Thus, it is important to note that the visualized light gives an accurate latitude or cranio-caudal position of the lacrimal sac, but the sagittal center of the lacrimal sac is not the visualized light but actually more closely the maxillary line (Fig. 29‑2). 6
The nasal septum, nasal sidewall at the maxillary line and root of the inferior turbinate, and middle turbinate are injected with 1% lidocaine with epinephrine 1:100,000 via a long 25-gauge needle. It is beneficial to wait 5 minutes to effect maximal hemostasis. Often the oxymetazoline cottonoids can be replaced at this time, and equipment, such as the drill, may be set up during this waiting period. The light pipe can be turned off during this time.
Once the cottonoids are removed, surgery commences using a #15 blade to create bilobed interlacing posteriorly based rectangular flaps over the fundus of the lacrimal sac (extending from just anterior to the maxillary line posteriorly to the axilla of the middle turbinate) and then a vertical incision proceeding inferiorly along the maxillary line from the middle of the above flap down to just above the root of the inferior turbinate. 7 Alternatively, a singular posteriorly based flap can be created (Fig. 29‑3). A periosteal elevator is used to develop the flaps, and the superior flap is reflected posteriorly; the inferior flap is reflected anteriorly and inferiorly (if a single flap is employed, it is reflected posteriorly and may be “tucked” under the middle turbinate during surgery). This exposes a wide section of maxillary bone. The maxillary line is now well-visualized directly, and the light source may be turned on again, usually showing posterior to the maxillary line. The author begins drilling away the thick bone of the anterior lacrimal sac maxillary bone with a diamond coated high-speed drill, working toward the lacrimal bone and light source posteriorly, thus staying out of the middle meatus directly. As the anterior lacrimal sac bone is thinned with the drill, light will begin to transmit through it. The light source may be turned off at this point.
As the bone is further thinned it can be subsequently further removed with Kerrison rongeurs or Takahashi forceps.
Once the ostium is adequately sized (approximately 1 cm diameter) the lacrimal sac is tented into the nasal cavity either with the light pipe or the stylet of the bicanalicular stenting system or a Bowman probe. A sickle knife is used to carefully open the lacrimal sac in a vertical sagittal incision, pulling in toward the nasal cavity to avoid directing cutting forces toward the orbit. Mucopus may be encountered at this stage and can be suctioned clear. If a dacryocystitis has been present, a culture may be obtained.
Bellucci micro scissors or a comparable instrument may be used to perform horizontal cuts superiorly and inferiorly on either side of the vertical lacrimal sac incision to create anterior and posterior flaps of the lacrimal sac. A Kerrison rongeur can be used to remove a small segment of the lacrimal sac mucosa to be sent as a specimen to pathology.
Bicanalicular silicone stenting is passed and retrieved endonasally and tied as a square knot approximately 1.5 cm from the DCR ostium.
The surgical area is checked for hemostasis; generally hemostasis is not a problem as long as blood pressure is controlled and the patient is in a recumbent supine position. If cautery is necessary, suction monopolar cautery can be carefully administered, taking care to not cauterize directly over the area of the internal common punctum if this has been exposed (generally this would require a quite high/cranial exposure).
The mucosal flaps are then redraped into their normal anatomical positions, which minimize any exposed bone and areas needed to heal by secondary intention. If double flaps are employed, the surgeon should take care that the flaps do not occlude the ostium. With the single posterior flap, a central portion of mucosa is excised with through-biting forceps to correspond to the underlying marsupialized lacrimal sac (Fig. 29‑4).
The author prefers to place MeroGel nasal packing (Medtronic, Minneapolis, MN, USA) soaked in triamcinolone 40 mg, as small pieces placed within the DCR ostium, within the middle meatus, and between the middle meatus and nasal septum, as an added measure to combat adhesion formation.
Shells are removed, the eyes are treated with an ophthalmic lubricant ointment, the patient is extubated from anesthesia, and taken to the recovery room.
Note that if a septoplasty is required it is performed as follows: Both sides of the nasal septum have been decongested with neurosurgical cottonoids soaked in oxymetazoline. A 0-degree endoscope is used to identify the site of septal deflection to allow for planning of placement of the cartilaginous incision. Next a Killian incision is made contralateral to the DCR side with a #15 blade from posterior to anterior along the root of the septum, taking care not to score the underlying cartilage. A Cottle elevator is used to develop a submucoperichondrial plane ipsilateral to the Killian incision. The endoscope is placed under the mucosal flap and the flap is continued to be elevated posteriorly just beyond the osteocartilaginous junction of the septum. At this point the endoscope is again used to verify the site of septal deflection and an angled beaver blade is used to score the cartilage approximately 5 mm anterior to the site of deflection, ensuring that a caudal strut of at least 1 cm is kept intact to prevent a saddle nose deformity. A Cottle elevator is then used to create a full-thickness cartilaginous incision, taking care to prevent perforation of the contralateral mucosal flap. A straight-through cutting forceps is used to create a cartilaginous window to allow for the introduction of the endoscope into the contralateral submucoperichondrial flap. The contralateral flap is then raised posteriorly beyond the level of the deflection. A swivel-blade is then used to create a controlled superior incision in the cartilage to prevent torsion on the superior aspect of the septum at the site of its insertion at the skull base. The remainder of the inferior aspect of the region of deflection is then removed using a combination of straight-through cutting forceps, Takahashi forceps, and Jansen Middleton rongeurs. Once the deflection is fully removed, the mucoperichondrial flaps are redraped over the remaining cartilage and inspected to ensure that there are no regions of opposing perforations or areas of active bleeding. The mucosal flaps may be allowed to co-apt naturally or may be secured with a 4–0 plain gut suture on a Keith needle as a quilting stitch. If the septum has a tendency to bow in one direction, silicone Doyle splints may be placed and secured anteriorly with a 4–0 polypropylene suture through the columella.