¥Endonasal endoscopic (microscopic) dacryocystorhinostomy (EDCR)

3.2Endonasal Endoscopic (Microscopic) Dacryocystorhinostomy (EDCR)

Endonasal dacryocystorhinostomy allows the simultaneous surgical management of endonasal pathologies such as septal deviation, chronic sinusitis, ethmoid cells impinging medially on the lacrimal sac or an enlarged middle turbinate extending too far anteriorly. These anatomical corrections not only treat the pathologies but also facilitate follow-up treatment and should therefore provide better results in the end. Moreover, with the endonasal approach, there is no externally visible scar; division of the medial palpebral ligament and removal of the bony framework for the suspension of the horizontal lacrimal ducts are avoided. In addition, the operating time is shorter and post-opera- tive morbidity is lower than with the external procedure [16].

stage procedure with external incision and later operation is not necessary. It also reduces patient morbidity. Dacryoliths too are good indications for endonasal DCR (Fig. 3.1). Sometimes patients report that symptoms are less severe they lie down for sleeping because the dacryolith moves upwards.

Primary endonasal management of pre-saccal stenoses is also not a problem [28]. Either primary resection of the stenotic pre-saccal portion of the canaliculus is performed endonasally or the stenosis is stented and widened over a period of months by probing and bouginage and insertion of silicone tubing. Recurrences after treatment of intraand post-saccal stenosis can again be treated endonasally. Recurrences of a pre-sac- cal stenosis in which reconstruction of the lacrimal passages cannot reliably be achieved are an indication for conjunctivorhinostomy or for insertion of a HeermannJones tube [83].

3.2.1 Indication for EDCR

Indications include all forms of post-saccal and intrasaccal stenosis. In particular, dacryoliths can be removed in this way. Acute dacryocystitis is also an ideal indication for endonasal procedure as an operation in the acute stage can both evacuate the empyema and treat the underlying post-saccal stenosis [45, 47]. A two-

3.2.2Surgical Technique (See Video Enclosed, See Additionally Training CD-ROM [8, 35, 36, 84], Fig. 3.2a–i)

Surgery is usually performed under general anaesthesia. Procedures under local anaesthesia are feasible

Fig. 3.2 (a–i) Endonasal DCR on the right side (endoscopic view with a 45¡ endoscope). (a) Exposure of the bone over the lacrimal sac (processus frontalis maxillae). (b) Removal of the bone with a drill (microdebrider, 15¡ angle, 5 mm diameter, Karl Storz, Tuttlingen, Germany). (c) Stepwise further removal of bone with parts of the lacrimal sac visible. (d) The lacrimal sac

protrudes spontaneously into the nasal cavity. (e) Probing of the lacrimal sac via the inferior canaliculus. (f) Incision of the lacrimal with a sickleknife. (g) Removal of the mobilised medial wall of the lacrimal sac. (h) Probing demonstrates the position of the common canalis, which is completely free. (i) Irrigation of the lacrimal system proves an open and unobstructed pathway

when general anaesthesia is not recommended or the patient prefers it. In these cases, inÞltration of the supratrochlear and infraorbital nerves is added to the intranasal topical anaesthesia. However, topical anaesthesia of the lacrimal sac may be difÞcult when an acute infection is present. The nasal cavity is vasoconstricted using cottonoids soaked in topical anaesthesia with epinephrine (1:1,000). The agger nasi is inÞltrated with local anaesthesia and epinephrine (1:200,000).

According to the available literature, the manner of visualisation (microscope, endoscope, head lamp) has no inßuence on the outcome [94], but the author favours the endoscopic approach (45¡ or 0¡, 30¡), which is less invasive than the microscopic procedure.

Occasionally, the head of the middle turbinate may need to be trimmed to achieve a proper approach to the lacrimal sac. Septal deviations facing the Agger nasi should be corrected prior to the DCR. If this is the only

deviated septal area, a minimised septoplasty through an ÒLÓ-shaped mucosal incision is prefered, followed by circumscribed cartilage resection or correction and reposition of the mucosal ßap. Thus, providing a larger space between the septum and lacrimal sac makes it easier to carry out post-operative care.

Some authors recommend the creation of mucosal ßaps [8, 50, 75, 79]. The ßap measures about 1 cm in height and half a cm in width. At the end of the DCR, the mucosal ßap is repositioned to create an anastamosis between the lacrimal sac mucosa and nasal mucosa, partially covering the lateral wall.

In the case of Agger nasi, two vertical incisions are made through the mucosa down to the bone, slightly anteriorly and superiorly to the middle turbinate, using the Freer elevator, and the mucosa is removed.

The posterior edge of the ascending part of the maxilla is called the Òmaxillary lineÓ. It provides a clear anatomic landmark and the bone resection is performed from this edge anteriorly. The bone may be very strong. The true lacrimal bone, located more laterally and posteriorly, is quite thin and more fragile.

Dissection of the lacrimal sac can be achieved by different methods.

¥Bone removal with the help of hammer and chisel, the latter directed towards the orbit, implies a strong conÞdence in the person holding the hammer. Backbiting of the process with Kerrison rongeurs, postioned at the very edge of the Òmaxillary lineÓ is feasible as long as the bone is not too thick.

¥In these cases it is better to employ a diamond or cutting burr under irrigation with saline to drill the ascending process of the maxilla, until a circumscribed exposure of the lacrimal sac surface is achieved.

¥Alternatively microdebrider burrs with a 15¡ bent head are very helpful, particularly in endoscopic DCR.

If there is any doubt about the correct identiÞcation of the lacrimal sac, the surgeon can introduce a lacrimal probe through the inferior canaliculus or press against the sac from outside and then push gently. The lacrimal sac may be identiÞed by its bulge (Fig. 3.2). Then, a 90¡ Kerrison rongeur is used to remove additional bone anteriorly and a 45¡ Kerrison rongeur to remove the bone superiorly until the entire medial wall and most of the anterior wall of the lacrimal sac are exposed in its superior aspect, where the common canaliculus enters the sac.

8,8+/-0,2 mm

4,1+/-2,3 mm

Fig. 3.3 Topographic anatomy of the lacrimal sac using the middle turbinate as landmark (data from 76 CT [96])

A large part of the lacrimal sac lies above the attachment of the middle turbinate and above the oriÞce of the common canaliculus (Fig. 3.3). Endonasally, adequate exposure is shown by spontaneous tenting of the lacrimal sac into the nasal cavity.

While a helping hand exercises a Þrm pressure from outside (best: putting a Þnger on the inner edge of the eye) a vertical incision is then made in the anterior face of the lacrimal sac with the help of a number 11 or a sickle knife. The pressure from outside prevents the sack from the lateral displacement when trying to make the incision. The entire medial wall is removed using straight Blakesley forceps or true cutting forceps. In cases of severe inßammation or infection the medial wall is easily removed by sheer force with the instrument. At this point, pus or mucus usually ßows from the sac.

The likelihood of a successful outcome is very high if at the end of the operation practically the entire medial wall of the lacrimal sac has been removed and its lateral wall can heal with the adjacent nasal and paranasal sinus mucosa unhindered by neighbouring structures.

¥The bony window must be sufÞciently large to allow for shrinking, which is sometimes considerable. For this, the bone should be removed as far as the fornix, i.e. depending on the anatomy, beyond the medial palpebral ligament (in a rostral direction).

¥If there is any doubt, the opening of the anterior ethmoid cells or resection of the uncinate process should be performed generously so as to minimise any potential for obstruction dorsally.