The Microscopic Transcanal Approach in Stapes Surgery Revisited

This article describes the microscopic transcanal technique for stapes surgery, providing step-by-step surgical instructions for familiarizing surgeons with this approach.

Transcript

The transcanal surgical approach is challenging and needs special training for otologic surgeons. This protocol aims to give step-by-step instructions. The main advantage of this protocol is its minimally invasive approach.

No retroauricular or endaural incision is required. There is less postoperative pain and circular bandaging is not needed. For positioning the patient place the operating table at the lowest position tilted in a reverse Trendelenburg position"with the angle of the headrest at its maximal reclination.

Then rotate the patient's head towards the contralateral side. Use bent instruments to keep the working field open. Hold the instruments correctly with fingers to prevent any blocked fission.

Clean the ear canal thoroughly to avoid any intraoperative infection and disinfect the canal with diluted povidone-iodine solution. After anesthetizing the ear canal perform a tympanomeatal flap using a U-shape incision with a sickle or a round knife, starting at the six o'clock position. Detach the ear canal skin with a rosen knife until the inferior annulus rim is reached.

Next, install the speculum holder and insert the largest possible ear speculum ensuring that the orientation is correct. Complete the tympanomeatal U-shaped flap by cutting the superior posterior part with the bellucci scissor. Then, detach the ear canal skin until the superior annulus rim is reached.

Use an absorbable gelatin sponge soaked with adrenaline to stop the bleeding. Then, detach the whole flap until the edge of the annulus. Before entering the middle ear, ensure that the facial nerve monitoring is working.

Then, enter the middle ear at the posterior superior part of the annulus, since it is easier to detach at this position. Dissect and visualize the anatomical middle of your structures. Visualize the chorda tympani, promontory and incudostapedial joint, stapedial tendon, and facial nerve.

If any of these structures are not sufficiently exposed, place an absorbable gelatin sponge in the middle ear and widen the posterior superior part of the ear canal, first, using a two-millimeter rough, diamond drill and then a bone curette. The facial nerves should be visible at this point. For stapes suprastructure removal, disconnect the incudostapedial joint with a small 0.3 to 0.6 millimeter hook or a sickle knife and make an anterior movement to prevent breaking of the footplate.

Test the mobility of all three ossicles by touching each ossicles with a needle to confirm isolated ankylosis of the stapes. After wearing protection glasses, test the strength of the laser and dissect the stapedial tendon, using the laser. Then, dissect the posterior crus of stapes near the attachments of the footplate or at the anterior crus, if the footplate is too mobile.

Then, remove the stapes suprastructure. If the anterior crus are still intact break the stapes away from the facial nerve towards to promontory, keeping the footplate intact. Using the FOX Laser"carbonize or weaken the footplate by making a rosette pattern.

Then, use a perforator micro drill to perforate the last shell of the footplate in the posterior third section. For stapes prosthesis insertion, measure the distance between the long process of the incus and the footplate using a measurement instrument with a four-millimeter measuring mark. Use a 0.25 millimeter longer prosthesis, than measured.

Prior to insertion, hold the prosthesis hook with small alligator ear forceps using a predefined angle of orientation. Insert the prosthesis. Then, crimp the stapes piston hook on the long process of the incus.

Check the movement of the prosthesis by moving the malleus handle. Avoid touching the prosthesis to the promontory or the facial nerve. Consider using otologic cement if there is an interplay between the prosthesis and incus process.

Avoid over-crimping, since there is risk for incus necrosis in the long-term. Seal the perforated footplate with a small water-soaked, absorbable, gelatin sponge. For wound closure, reposition the tympanomeatal flap adapt with silk dressing and pack with absorbable gelatin sponge soaked with a solution containing hydrocortisone, neomycin, and polymyxin b sulfates.

Finally, pack the ear canal using a 10 centimeter ribbon gauze soaked in the same solution. Shown here is a retrospective cross-sectional analysis of 66 patients, with 37 males and 29 females aged between 9 to 68 years who underwent 48 standard and 18 revisions stapes surgeries. Out of the 66 patients, a retroauricular incision was required, only in one patient.

While a posterior canaloplasty was necessary for 37 patients. 58 patients received a Richards piston prosthesis"One patient, a Matrix Slim Line KURZ prosthesis"and five patients, a Malleo-vestibulo-pexy prosthesis"The mean size of the prosthesis was 4.4 and the mean diameter was 0.46 millimeters. The prosthesis was additionally fixed with otologic cement in 33 patients and the chorda tympani was preserved in 55 out of 65 cases.

Correct preparation and positioning of the patient's head is important. Since exposure of the anatomy is limited. Also, the use and the correct handling of suitable, bended instruments is important for a successful surgery.

The transcanal approach can be used, not only for a large variety of otologic procedures such as, tympanoplasty, and ossiculoplasty but also for cholesteatomas with limited extension.

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Journal (Medicine)

The Microscopic Transcanal Approach in Stapes Surgery Revisited

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