This protocol describes different minimally invasive techniques for complete endoscopic cholesteatoma dissection and bone removal for epitympanectomy. The main advantage of endoscopic epitympanic cholesteatoma removal is the transcanal minimally invasive technique with superior visualization sparing external incisions and excessive temporal bone drilling. Since transcanal endoscopic cholesteatoma removal is mainly a one-handed technique, the specific procedures and technical refinements need to be practiced prior in a temporal bone model.
Before starting the operation, verify that all instruments are present at the operating table. With the patient in an anti-Trendelenburg position, perform local anesthesia and introduce the zero degree endoscope in the external auditory canal. Then, clean the canal by removing ear wax and cutting the hairs in the external auditory canal.
After cleaning the external auditory canal, inspect the tympanic membrane and the attic region with the zero degree endoscope. Then, mark the circumference of the tympanomeatal flap with the monopolar cautery, and elevate a tympanomeatal flap tailored to disease extension using an angled round knife and Plester knife. Provide hemostasis with epinephrine-soaked cottonoids.
Next, expose the annulus, and if possible, the chorda tympani. Then, open the middle ear cavity and evaluate in detail the cholesteatoma extension. Carefully separate the cholesteatoma matrix from the eardrum and the chorda tympani.
In case of an intact ossicular chain, dissect the cholesteatoma involving the middle ear and ossicular chain. To evaluate the extent of cholesteatoma infiltration, perform step-wise removal of the lateral portion of the attic by limited atticotomy. Remove smaller parts of bone with a chisel and hammer, and especially the scutum with a bone curette using rotary movements.
For attico-and antrotomy with bone drilling, remove larger parts of the bone either in an underwater technique, followed by cutting burrs at low speed, or cutting or coarse diamond burrs at slow speed with only a little irrigation. For attico-and antrotomy with ultrasonic devices, remove larger parts of the bone with the curved tip in an underwater technique to prevent heat damage to bone and soft tissues. If the cholesteatoma infiltrates deep into the anterior epitympanum, or erodes the incus, remove the incus, and if required, the malleus head to entirely remove the cholesteatoma.
To completely extricate the cholesteatoma, perform stepwise attico-and antrotomy with different devices, using angled dissectors if appropriate. After completion of cholesteatoma resection, perform an entire middle ear exploration with an emphasis on residual cholesteatoma and functional considerations with the greatest sparing of healthy mucosa, first using a zero degree and then a 45 degree angled lens. Check the anterior epitympanic space, tegmen tympani, posterior epitympanum, and antrum until the posterior limit of the lateral semi-circular canal.
Then inspect the retrotympanum, including posterior sinus, sinus tympani, subtympanic sinus, and hypotympanum. Finally, check the Eustachian tube, protympanum, supratubal recess, tensor fold, and isthmus. Restore the ventilation route in case of tensor fold obstruction.
To reconstruct the ossicular chain and scutum, make an incision five millimeter posterior to the tragus edge and cut through the cartilage. Then, harvest a large piece of cartilage with perichondrium on both sides. Trim the piece of cartilage and perichondrium and perform scutum reconstruction for defect closure.
If the stapes is intact, and incus or head of the malleus are not usable for possible malleolus head or incus interposition ossiculoplasty, use double block cartilage, or as demonstrated in this case, partial ossicular replacement prosthesis. Next, use resorbable gelatinous sponges to secure the reconstruction. In case of partial or total ossicular replacement prosthesis, reinforce the reconstruction using cartilage, as in this case, using a pressed perichondrium layer or cartilage.
Then, perform an underlay tympanoplasty using a trimmed piece of cartilage with overlapping perichondrium in island graft technique, or using perichondrium or temporalis fascia for defect closure of the tympanic membrane. If using cartilage, add perichondrium for supporting the construction as shown in this case. For wound closure, reposition the tympanomeatal flap and adapt it to the external auditory canal curvature.
Splint the tympanic membrane with silk strips or according to your institutional practices of adequate size for defect coverage. Finally, pack the external auditory canal with resorbable gelatinous sponges and the outer part with an antibiotic and hydrocortisone soaked gauze. A total of 43 consecutive cases of exclusive endoscopic cholesteatoma surgery were analyzed for this study.
The mean age at the time of surgery was 37.4 years. There were 36 cases of first cholesteatoma removal and seven revision surgeries. The left side was operated in 26 cases and the right in 17 cases.
Cartilage was used as grafting material in 38 cases and fascia in five cases. The graft intake rate was 90.7%with three cases of postoperative perforations. The mean follow up was 17.4 months, with 40 cases having no recurrent cholesteatoma at the last follow up.
The mean air bone gap improved significantly from 23.8 decibels before surgery to 18.2 decibels after surgery. While performing this procedure utmost care has to be applied in the transcanal access to prevent damage to the inner ear and facial nerve by using powered instruments like bone drilling and ultrasonic devices. This minimally invasive endoscopic approach together with powered instruments allows the surgeon to gain a more tailored transcanal access to further lateral skull-based pathologies.
