Purpose: To determine whether technology is available to secure a larger-diameter Crawford tube swedged onto the metal Crawford introducer and to use the system in a closed intubation to treat a failed dacryocystorhinostomy.
Methods: A metal ferrule has been developed to swedge a larger-diameter Crawford tube onto the standard Crawford probe. Seven patients with failed dacryocystorhinostomy procedures were treated with probing and intubation with the use of this larger-tube Crawford system.
Results: Six of the 7 patients had patent lacrimal systems after the tubes were removed, a result comparable to open revision after a failed dacryocystorhinostomy. In each case, on insertion, the tube remained firmly attached to the Crawford probe and did not dislodge.
Conclusions: The technology of using a metal ferrule at the junction of the standard Crawford probe and a larger silicone tube was successful in creating a Crawford system with greater dilation capability than the standard Crawford system. The technique of probing and intubation with this larger Crawford system may be a simple alternative to open revision of a failed dacryocystorhinostomy procedure.
Stenting of the nasolacrimal drainage system has been routinely performed at the time of repeat probing of congenital obstruction, 1 after repair of lacerated canaliculi, 2,3 or in conjunction with some dacryocystorhinsotomy (DCR) operations. The material of choice for stenting a lacrimal system is silicone, first used in 1967. 4 Silicone tubes are generally inert within the system but occasionally may cause inflammatory granulation 5 or slitting of the canaliculi. 6
Over the years, many techniques of stent placement have been described. Attachment of the tube to an olive-tipped metal introducer was first described by Crawford, 7 and Crawford tubes have been widely used throughout the world. The original Crawford tube has an outer diameter of 0.64 mm and an inner diameter of 0.3 mm. A modified ear-hook (Crawford hook) facilitates engaging the olive tip, so the metal connector can be atraumatically withdrawn from the nose. Despite many described techniques of tube fixation within the nose, prolapse of the canthal loop is a common complication. 8
The purpose of a stent within the nasolacrimal system is to temporarily prevent adherence of the mucosal lining of the channels during healing, to maintain long-term patency after removal. It would seem that the larger the diameter of the stent, the further the walls of the channel would be separated. This concept would apply to probed obstructions at the valve of Hasner, to repaired lacerated canaliculi, and to reconstructed DCR channels. It would seem that the larger the tube diameter, the better, as long as the puncta and canaliculi can accommodate it.
The punctal opening is 0.2 to 0.3 mm in diameter; the ampulla at the junction of the vertical and horizontal limbs is 2.0 mm in diameter; and the horizontal segment is 0.5 to 1.0 mm in diameter. 9 A punctum can be enlarged significantly and still maintain its function, as demonstrated by a snip procedure (punctoplasty). 10 Therefore, it appears that a larger-diameter tube could be tolerated within the canalicular and nasolacrimal system.
When we insert tubes at the time of a DCR, we prefer to use larger-diameter tubing (outer diameter of 0.94 mm) in the bicanalicular intubation. The tubing is easily inserted through the DCR by introducing a No. 0.1 probe through a small cut made in the tube 4 mm from its end. The ends can be easily retrieved under direct vision in the DCR opening and then passed down in the nose. We put an outer sleeve around the tube to prevent migration of the loop and to keep the anterior and posterior flaps of the DCR as far apart as possible. The sleeve has an outer diameter of 2.41 mm. 11 This system has been used quite effectively over the years. However, if the system has not been opened as in a DCR, these larger tubes cannot be passed in this fashion.
With renewed interest in the endonasal DCR, 12 there may be advantages to stenting the new opening as widely as possible, given the limited ability to construct flaps using this technique. This would also apply to failed DCR through any route.
The broader application of larger-diameter stents has been limited by technical problems in swedging a larger tube onto a probe that will not be separated in its passage. Other attempts to pass a larger tube utilizing techniques with rigid sutures in the middle have been unsuccessful.
This report discusses a technique of swedging the larger-diameter tube onto the Crawford probe, which can then be successfully passed through the system.