Not applicable.

The protocol followed the guidelines of the local institution&#39;s human research ethics committee and was approved by the local institutional review board (KEK-BE 2019-00555). All operations were performed in general anesthesia under controlled hypotension in anti-Trendelenburg positioning with standard otological instruments.
1. Preparation of the surgical site
<ol>
	<li>Manually adjust the endoscope screens (see Table of Materials) according to the surgeon&#39;s preferred position (sitting or standing).</li>
	<li>Monitor the facial nerve by checking impedances with a nerve monitoring system (see Table of Materials) and perform a tap test13.</li>
	<li>Disinfect the auricle and the retroauricular region with swabs soaked with commercially available povidone-iodine solution (see Table of Materials).</li>
	<li>Drape the periauricular region with sterile blankets.</li>
	<li>Clean and rinse the external auditory canal (EAC) with a blunt syringe and Ringer solution (see Table of Materials).</li>
	<li>Perform white balancing of the camera with white gauze and apply drops of anti-fog solution to the endoscope lens.</li>
</ol>
2. Exclusive transcanal endoscopic approach
<ol>
	<li>Introduce the 0&#176;, 3mm diameter, and 15cm length endoscope in the EAC (see Table of Materials) and clean the EAC by removing earwax and cutting the hairs in the EAC.</li>
	<li>Perform local anesthesia with 0.5 mL of diluted epinephrine (1:200.000) injection (see Table of Materials), each using four injection sites in all quadrants of the EAC under endoscopic control. Additionally, inject 0.5 mL of diluted epinephrine (1:200.000) to the vascular strip in the posterior-superior quadrant of the EAC.</li>
	<li>Inspect the tympanic membrane and the attic region with the 0&#176; endoscope.</li>
	<li>Elevate a tympanomeatal flap tailored to disease extension using an angled round knife and provide hemostasis with epinephrine (1:1000) soaked cottonoids. 
	NOTE: Additional hemostasis may be applied by electrocoagulation using mono- or bipolar cautery; alternatively, radio-frequency-cautery can be used (see Table of Materials). Be careful to use monopolar at the lowest intensities to minimize risks of spread of electricity to the facial nerve.</li>
	<li>Expose the annulus and, if possible, the chorda tympani; open the middle ear cavity, and evaluate in detail the cholesteatoma extension.</li>
	<li>Carefully separate the cholesteatoma matrix from the eardrum and from the chorda tympani.</li>
	<li>Carefully dissect the cholesteatoma involving the middle ear and the incudostapedial area in case of an intact ossicular chain.</li>
	<li>Perform limited atticotomy using unpowered instruments, bone drilling, or ultrasonic devices (see Table of Materials) by stepwise removal of the lateral portion of the attic and evaluate the extent of cholesteatoma infiltration by following the steps below.
	<ol>
		<li>For atticotomy with unpowered instruments: remove small parts of bone, especially the scutum, by a bone curette using rotatory movements or chisel and hammer.</li>
		<li>For attico- and antrotomy with bone drilling: remove larger parts of bone either in an underwater technique14, followed by cutting burrs at low speed (2000-8000 rpm) or cutting or coarse diamond burrs at slow speed with only a little irrigation. 
		NOTE: For the underwater technique, the EAC is filled with 0.9% of NaCl solution, and the endoscope lens is inserted into the EAC with the burrs. Subsequently, drilling for attico- and antrotomy is performed directly under visual inspection. Occasional suction is required due to bone dust and reduced visibility. Utmost care has to be applied to prevent damage to surrounding structures by direct or heat damage. The delicate lens and shaft of the endoscope have to be kept away from the rotatory instruments to prevent its damage.</li>
		<li>For attico- and antrotomy with ultrasonic devices: remove the larger parts of bone with the curved tip in an underwater technique to prevent heat damage to bone and soft tissues. 
		CAUTION: Do not touch the ossicular chain and the cochlea due to possible inner ear hair cell damage due to transmission of micro-vibrations.</li>
	</ol>
	</li>
	<li>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.</li>
	<li>Perform stepwise attico- and antrotomy with different devices (see Table of Materials) to follow and completely extirpate the cholesteatoma. Use angled dissectors if appropriate.</li>
</ol>
3. Middle ear exploration
<ol>
	<li>After completion of cholesteatoma resection, an entire middle ear exploration with an emphasis on residual cholesteatoma and functional considerations with the greatest sparing of healthy mucosa is performed. Use first 0&#176; then a 45&#176; angled lens. 
	NOTE: If appropriate, a 70&#176; endoscope may also be used.</li>
	<li>Check anterior epitympanic space, tegmen tympani, posterior epitympanum, antrum until the posterior limit of the lateral semicircular canal.</li>
	<li>Carefully inspect the retrotympanum, including posterior sinus, sinus tympani, subtympanic sinus, and hypotympanum.</li>
	<li>Check Eustachian tube, protympanum, supratubar recess, tensor fold, and isthmus; restore the ventilation route by tissue removal in case of obstruction.</li>
</ol>
4. Reconstruction of the ossicular chain and scutum
<ol>
	<li>Perform an incision 5 mm posterior to the tragus edge and cut through to the cartilage, then harvest a large piece of cartilage with perichondrium on both sides.</li>
	<li>Reconstruct the scutum with a trimmed piece of cartilage and perichondrium for defect closure after attico- and antrotomy.</li>
	<li>Perform underlay tympanoplasty using a trimmed piece of cartilage with overlapping perichondrium in island-graft technique or temporalis fascia for defect closure of the tympanic membrane. Add perichondrium in case of cartilage use for supporting the construction if necessary.</li>
	<li>If the stapes is intact, inspect the incus or head of the malleolus for possible malleolar head or incus interposition ossiculoplasty; otherwise, use double-block cartilage (Malafronte technique15) or PORP (partial ossicular replacement prosthesis).</li>
	<li>Use a TORP (total ossicular replacement prosthesis) if the stapes supra-structure is also affected by cholesteatoma and needs to be removed.</li>
	<li>Use resorbable gelatinous sponges to secure the reconstruction, reinforce the reconstruction using a pressed perichondrium layer or cartilage in case of PORP/TORP.</li>
</ol>
5. Wound closure
<ol>
	<li>Reposition the tympanomeatal flap and adapt it to the EAC curvature without sutures.</li>
	<li>Splint the tympanic membrane with silicone or silk strips of adequate size for defect coverage.</li>
	<li>Pack the EAC with a resorbable gelatinous sponge and the outer part with an antibiotic (polymyxin, neomycin) and hydrocortisone soaked gauze (see Table of Materials).</li>
</ol>

<ol><li>Thomassin, J. M., Korchia, D., Duchon Doris, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Endoscopic-guided+otosurgery+in+the+prevention+of+residual+cholesteatomas%5BTitle%5D)+AND+%22The+Laryngoscope%22%5BJournal%5D)">Endoscopic-guided otosurgery in the prevention of residual cholesteatomas.</a> The Laryngoscope. 103 (8), 939-943 (1993).</li>
<li>Tarabichi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Endoscopic+management+of+acquired+cholesteatoma%5BTitle%5D)+AND+%22The+American+Journal+of+Otology%22%5BJournal%5D)">Endoscopic management of acquired cholesteatoma.</a> The American Journal of Otology. 18 (5), 544-549 (1997).</li>
<li>Emre, I. E., Cingi, C., Bayar Muluk, N., Nogueira, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Endoscopic+ear+surgery%5BTitle%5D)+AND+%22Journal+of+Otology%22%5BJournal%5D)">Endoscopic ear surgery.</a> Journal of Otology. 15 (1), 27-32 (2020).</li>
<li>Anschuetz, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Management+of+bleeding+in+exclusive+endoscopic+ear+surgery%3A+Pilot+Clinical+Experience%5BTitle%5D)+AND+%22Otolaryngology-Head+and+Neck+Surgery%22%5BJournal%5D)">Management of bleeding in exclusive endoscopic ear surgery: Pilot Clinical Experience.</a> Otolaryngology-Head and Neck Surgery. 157 (4), 700-706 (2017).</li>
<li>Alicandri-Ciufelli, M., Molinari, G., Beckmann, S., Caversaccio, M., Presutti, L., Anschuetz, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Epinephrine+use+in+endoscopic+ear+surgery%3A+Quantitative+safety+assessment%5BTitle%5D)+AND+%22Journal+for+Oto-Rhino-Laryngology%22%5BJournal%5D)">Epinephrine use in endoscopic ear surgery: Quantitative safety assessment.</a> Journal for Oto-Rhino-Laryngology. 82 (1), 1-7 (2020).</li>
<li>Hulka, G. F., McElveen, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+randomized%2C+blinded+study+of+canal+wall+up+versus+canal+wall+down+mastoidectomy+determining+the+differences+in+viewing+middle+ear+anatomy+and+pathology%5BTitle%5D)+AND+%22The+American+Journal+of+Otology%22%5BJournal%5D)">A randomized, blinded study of canal wall up versus canal wall down mastoidectomy determining the differences in viewing middle ear anatomy and pathology.</a> The American Journal of Otology. 19 (5), 574-578 (1998).</li>
<li>Kerckhoffs, K. G. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+disease+recurrence+rate+after+the+canal+wall+up+or+canal+wall+down+technique+in+adults%5BTitle%5D)+AND+%22The+Laryngoscope%22%5BJournal%5D)">The disease recurrence rate after the canal wall up or canal wall down technique in adults.</a> The Laryngoscope. 126 (4), 980-987 (2016).</li>
<li>Ayache, S., Tramier, B., Strunski, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Otoendoscopy+in+cholesteatoma+surgery+of+the+middle+ear%3A+What+benefits+can+be+expected%5BTitle%5D)+AND+%22Otology+and+Neurotology%22%5BJournal%5D)">Otoendoscopy in cholesteatoma surgery of the middle ear: What benefits can be expected.</a> Otology and Neurotology. 29 (8), 1085-1090 (2008).</li>
<li>Tarabichi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Endoscopic+management+of+limited+attic+cholesteatoma%5BTitle%5D)+AND+%22The+Laryngoscope%22%5BJournal%5D)">Endoscopic management of limited attic cholesteatoma.</a> The Laryngoscope. 114 (7), 1157-1162 (2004).</li>
<li>Migirov, L., Shapira, Y., Horowitz, Z., Wolf, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Exclusive+endoscopic+ear+surgery+for+acquired+cholesteatoma%3A+Preliminary+results%5BTitle%5D)+AND+%22Otology+and+Neurotology%22%5BJournal%5D)">Exclusive endoscopic ear surgery for acquired cholesteatoma: Preliminary results.</a> Otology and Neurotology. 32 (3), 433-436 (2011).</li>
<li>Marchioni, D., Villari, D., Mattioli, F., Alicandri-Ciufelli, M., Piccinini, A., Presutti, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Endoscopic+management+of+attic+cholesteatoma.+A+single-institution+experience%5BTitle%5D)+AND+%22Otolaryngologic+Clinics+of+North+America%22%5BJournal%5D)">Endoscopic management of attic cholesteatoma. A single-institution experience.</a> Otolaryngologic Clinics of North America. 46 (2), 201-209 (2013).</li>
<li>Kozin, E. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Systematic+review+of+outcomes+following+observational+and+operative+endoscopic+middle+ear+surgery%5BTitle%5D)+AND+%22The+Laryngoscope%22%5BJournal%5D)">Systematic review of outcomes following observational and operative endoscopic middle ear surgery.</a> The Laryngoscope. 125 (5), 1205-1214 (2015).</li>
<li>Kartush, J. M., Rice, K. S., Minahan, R. E., Balzer, G. K., Yingling, C. D., Seubert, C. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Best+practices+in+facial+nerve+monitoring%5BTitle%5D)+AND+%22The+Laryngoscope%22%5BJournal%5D)">Best practices in facial nerve monitoring.</a> The Laryngoscope. 131 (4), 1-42 (2021).</li>
<li>Chen, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+treatment+of+cholesteatomas+involving+the+antrum+and+mastoid+using+transcanal+underwater+endoscopic+ear+surgery%5BTitle%5D)+AND+%22Otology+and+Neurotology%22%5BJournal%5D)">The treatment of cholesteatomas involving the antrum and mastoid using transcanal underwater endoscopic ear surgery.</a> Otology and Neurotology. 41 (10), 1379-1386 (2020).</li>
<li>Malafronte, G., Filosa, B., Mercone, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+new+double-cartilage+block+ossiculoplasty%3A+Long-term+results%5BTitle%5D)+AND+%22Otology+and+Neurotology%22%5BJournal%5D)">A new double-cartilage block ossiculoplasty: Long-term results.</a> Otology and Neurotology. 29 (4), 531-533 (2008).</li>
<li>Barakate, M., Bottrill, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Combined+approach+tympanoplasty+for+cholesteatoma%3A+Impact+of+middle-ear+endoscopy%5BTitle%5D)+AND+%22Journal+of+Laryngology+and+Otology%22%5BJournal%5D)">Combined approach tympanoplasty for cholesteatoma: Impact of middle-ear endoscopy.</a> Journal of Laryngology and Otology. 122 (2), 120-124 (2008).</li>
<li>Verma, B., Dabholkar, Y. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Role+of+endoscopy+in+surgical+management+of+cholesteatoma%3A+A+systematic+review%5BTitle%5D)+AND+%22Journal+of+Otology%22%5BJournal%5D)">Role of endoscopy in surgical management of cholesteatoma: A systematic review.</a> Journal of Otology. 15 (4), 166-170 (2020).</li>
<li>Magliulo, G., Iannella, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Endoscopic+versus+microscopic+approach+in+attic+cholesteatoma+surgery%5BTitle%5D)+AND+%22American+Journal+of+Otolaryngology+-+Head+and+Neck+Medicine+and+Surgery%22%5BJournal%5D)">Endoscopic versus microscopic approach in attic cholesteatoma surgery.</a> American Journal of Otolaryngology - Head and Neck Medicine and Surgery. 39 (1), 25-30 (2018).</li>
<li>Das, A., Mitra, S., Ghosh, D., Sengupta, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Endoscopic+versus+microscopic+management+of+attic+cholesteatoma%3A+A+randomized+controlled+trial%5BTitle%5D)+AND+%22The+Laryngoscope%22%5BJournal%5D)">Endoscopic versus microscopic management of attic cholesteatoma: A randomized controlled trial.</a> The Laryngoscope. 130 (10), 2461-2466 (2020).</li>
<li>Anschuetz, L., Alicandri-Ciufelli, M., Bonali, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Novel+surgical+and+radiologic+classification+of+the+subtympanic+sinus%3A+Implications+for+endoscopic+ear+surgery%5BTitle%5D)+AND+%22Otolaryngology+-+Head+and+Neck+Surgery%22%5BJournal%5D)">Novel surgical and radiologic classification of the subtympanic sinus: Implications for endoscopic ear surgery.</a> Otolaryngology - Head and Neck Surgery. 159 (6), 1037-1042 (2018).</li>
<li>Salami, A., Mora, R., Dellepiane, M., Crippa, B., Santomauro, V., Guastini, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Piezosurgery%C2%AE+versus+microdrill+in+intact+canal+wall+mastoidectomy%5BTitle%5D)+AND+%22European+Archives+of+Oto-Rhino-Laryngology%22%5BJournal%5D)">Piezosurgery® versus microdrill in intact canal wall mastoidectomy.</a> European Archives of Oto-Rhino-Laryngology. 267 (11), 1705-1711 (2010).</li>
<li>Kakehata, S., Watanabe, T., Ito, T., Kubota, T., Furukawa, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Extension+of+indications+for+transcanal+endoscopic+ear+surgery+using+an+ultrasonic+bone+curette+for+cholesteatomas%5BTitle%5D)+AND+%22Otology+and+Neurotology%22%5BJournal%5D)">Extension of indications for transcanal endoscopic ear surgery using an ultrasonic bone curette for cholesteatomas.</a> Otology and Neurotology. 35 (1), 101-107 (2014).</li>
<li>Mehta, R., Mankekar, G., Mayland, E., Melder, K., Arriaga, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Endoscopic+inside-out+mastoidectomy+with+the+ultrasonic+bone+aspirator%5BTitle%5D)+AND+%22OTO+Open%22%5BJournal%5D)">Endoscopic inside-out mastoidectomy with the ultrasonic bone aspirator.</a> OTO Open. 3 (1), 1-4 (2019).</li>
<li>Vincenti, V., Magnan, J., Saccardi, M. S., Zini, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Chemically+assisted+dissection+by+means+of+mesna+in+cholesteatoma+surgery%5BTitle%5D)+AND+%22Otology+and+Neurotology%22%5BJournal%5D)">Chemically assisted dissection by means of mesna in cholesteatoma surgery.</a> Otology and Neurotology. 35 (10), 1819-1824 (2014).</li>
<li>de la Torre, C., Villamor, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Chemically+assisted+dissection+with+sodium+2+mercaptoethanesulfonate+%28MESNA%29+in+the+surgical+management+of+pediatric+cholesteatoma%5BTitle%5D)+AND+%22Otology+and+Neurotology%22%5BJournal%5D)">Chemically assisted dissection with sodium 2 mercaptoethanesulfonate (MESNA) in the surgical management of pediatric cholesteatoma.</a> Otology and Neurotology. 40 (5), 645-650 (2019).</li>
<li>Lee, C. H., Kim, M. K., Kim, H. M., Won, C., Shin, T. H., Kim, S. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Endaural+laser-assisted+single-stage+inside-out+cholesteatoma+surgery+%28LASIC%29+to+treat+advanced+congenital+cholesteatoma%5BTitle%5D)+AND+%22Otology+and+Neurotology%22%5BJournal%5D)">Endaural laser-assisted single-stage inside-out cholesteatoma surgery (LASIC) to treat advanced congenital cholesteatoma.</a> Otology and Neurotology. 40 (7), 927-935 (2019).</li>
<li>Lucidi, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Use+of+IMAGE1+S+technology+for+detection+of+cholesteatoma+in+endoscopic+ear+surgery%3A+a+retrospective+case+series+on+45+patients%5BTitle%5D)+AND+%22European+Archives+of+Oto-Rhino-Laryngology%22%5BJournal%5D)">Use of IMAGE1 S technology for detection of cholesteatoma in endoscopic ear surgery: a retrospective case series on 45 patients.</a> European Archives of Oto-Rhino-Laryngology. 278 (5), 1373-1380 (2021).</li>
</ol>

LA is a consultant for Stryker ENT. All other authors declare no conflict of interest.

This article describes a step-by-step guide as a surgical manual for endoscopic removal of limited attic cholesteatoma. Different techniques for cholesteatoma dissection and bone removal techniques for atticotomy as curettage, bone drills, and ultrasonic devices (piezoelectric devices, ultrasonic bone curettes) are presented. However, single-handed surgery requires habituation, and particular care has to be taken to avoid damage to surrounding structures directly or indirectly during attico- and antrotomy with powered instruments.
Since the first description of exclusive endoscopic cholesteatoma surgery for limited cholesteatoma by Tarabichi in 19972, several studies have been published reporting its successful application in cases of limited attic cholesteatoma. Tarabichi presented in 2004 a cohort of 73 procedures in 69 patients, who all received transcanal exclusive endoscopic cholesteatoma removal, showing 5 cases of recurrence in a mean follow-up period of 43 months9. In 2008, Barakate and Botrill presented 68 procedures of endoscopic cholesteatoma surgery in 66 cases, all of them receiving a second look procedure within a mean of 16 months16. In the second look procedure, 10 ears revealed residual disease, and 4 ears presented a recurrence. Migirov et al. demonstrated no residual disease in 18 patients after exclusive endoscopic cholesteatoma eradication after more than 1 year10. In 2013 Marchioni et al. reported on 146 patients with attic cholesteatoma and 120 patients undergoing an exclusive endoscopic approach; 26 patients underwent an endoscopic procedure combined with mastoidectomy11. Thereof, 7 patients presented with residual cholesteatoma, with no case having limited attic cholesteatoma in the beginning. Thus, the residual and recurrent cholesteatoma rate of 6.4% after endoscopic assisted or exclusive endoscopic removal seems to be comparable to the rate after most CWD procedures with 0%-13.2%, while using a minimally invasive approach7,17. In addition, direct comparison of endoscopic with microscopic techniques revealed significantly better middle ear structural visibility, reduced pain scores, and faster wound healing as further advantages of an endoscopic minimally-invasive approach8,18. Thus, the endoscopic approach seems to be particularly suitable for limited attic cholesteatoma.
Nevertheless, the inaccessibility of cholesteatoma extending deep into the mastoid remains one of the limiting factors in the success of the transcanal exclusive endoscopic approach. Despite the use of angled optics, complete endoscopic explorability is not always feasible, especially in the case of more excavated retrotympanal regions20.
Extended atticotomy was mainly performed by curettes or bone drilling until recently. To avoid the rough and time-consuming bone removal with curettes and possible facial nerve or tympanomeatal flap injury caused by drills, ultrasonic devices may provide a safe and precise alternative in cholesteatoma surgery21. With the transcanal endoscopic retrograde mastoidectomy technique, even removing cholesteatoma extensions into the antrum in a sclerotic mastoid can be achieved by an exclusive endoscopic transcanal approach22,23. However, extensive cholesteatoma formation inside the mastoid or severe hemorrhage might require switching to a microscopic retroauricular approach.
Additionally, there are also recent developments described in the literature to reduce the residual rate of cholesteatoma with chemically or physically assisted dissections. Mesna (sodium 2-mercaptoethanesulfonate) is reported as a possible chemical agent to reduce the residual rate of cholesteatoma by breaking disulfide bridges between different tissues24,25. For physically assisted dissection, different types of lasers known from stapes mobilization procedures have also been used in cholesteatoma surgery, resulting in a low recurrence rate around the ossicular chain26. In addition to white light endoscopy, other image processing technologies based on spectral separation may further improve cholesteatoma removal by recognizing residual cholesteatoma in the final overview27.
Therefore, applying endoscopic cholesteatoma surgery with improved technical devices and chemically or physically assisted dissection is promising to further evolve the minimally invasive approach and reduce the residual disease rate.

The introduction and successive spread of endoscopic ear surgery led to considerable changes in the treatment of cholesteatoma in the past two decades. The first intraoperative use of endoscopes to prevent residual cholesteatoma was already described in 1993 by Thomassin et al.1, followed by the first description of exclusive endoscopic cholesteatoma surgery in 1997 for cases of limited cholesteatoma2. Compared to the excellent but straight-line view with limited illumination in the microscopic approach, the endoscopic approach provides a panoramic view combined with high resolution, high magnification, and the ability to use angled lenses. The technique experiences increasing interest, despite the loss of binocular vision and two-handed working possibility3. As a consequence of the one-handed technique, safe and sufficient hemostasis is required to reap the benefits of superior visualization of the endoscopic technique4,5.
Traditional microscopic approaches might require a canal wall down (CWD) technique with excessive temporal bone drilling for improved visualization and complete removal of the cholesteatoma6. A less invasive alternative for limited cholesteatoma is the canal wall up (CWU) technique, although the limited visualization is often associated with a higher rate of residual cholesteatoma7. Endoscopes were therefore incorporated as an adjunct in canal wall up surgery to reduce the residual rate of cholesteatoma after CWU surgery1,8. Proceeding from this, the transcanal exclusive endoscopic approach has emerged as a possible alternative approach in cholesteatoma surgery as a minimally invasive approach. This resulted in excellent results in limited cholesteatoma with a comparable rate of residual cholesteatoma compared to the traditional CWD technique9,10,11. Nowadays, the exclusive use of endoscopes in cholesteatoma surgery is increasingly documented in the literature, and indications for exclusive endoscopic approaches are continuously expanding12. This work presents an insight into the different technical refinements and latest technological developments for exclusive endoscopic cholesteatoma surgery.

<table><tbody><tr><td>Antifog Solution</td><td>Karl Storz</td><td>N/A</td><td></td></tr><tr><td>Epinephrine 1 mg/mL</td><td>Dr. Bichsel AG</td><td>N/A</td><td></td></tr><tr><td>Gelatinous sponge (Gelfoam)</td><td>Pfizer</td><td>N/A</td><td></td></tr><tr><td>HOPKINS Optic 0&amp;deg;</td><td>Karl Storz</td><td>7220AA</td><td></td></tr><tr><td>HOPKINS Optic 30&amp;deg;</td><td>Karl Storz</td><td>7220BA</td><td></td></tr><tr><td>HOPKINS Optic 45&amp;deg;</td><td>Karl Storz</td><td>7220FA</td><td></td></tr><tr><td>HOPKINS Optic 70&amp;deg;</td><td>Karl Storz</td><td>7220CA</td><td></td></tr><tr><td>Image 1S 4K</td><td>Karl Storz</td><td>TH120</td><td></td></tr><tr><td>ME 102</td><td>KLS Martin</td><td>N/A</td><td></td></tr><tr><td>Monitor 32&quot; 4K/3D</td><td>Karl Storz</td><td>TM350</td><td></td></tr><tr><td>NIM-Neuro 3.0</td><td>Medtronic</td><td>N/A</td><td></td></tr><tr><td>OsseoDuo</td><td>Bien Air</td><td>N/A</td><td></td></tr><tr><td>Otosporin (polymyxin, neomycin, hydrocortison)</td><td>GlaxoSmithKline</td><td>N/A</td><td></td></tr><tr><td>Piezosurgery device</td><td>Mectron</td><td>N/A</td><td></td></tr><tr><td>PM2 Line Drill</td><td>Bien Air</td><td>N/A</td><td></td></tr><tr><td>Povidone-iodine (Betadine)</td><td>Mundi-Pharma</td><td>N/A</td><td></td></tr><tr><td>Ringer Solution</td><td>B. Braun</td><td>N/A</td><td></td></tr><tr><td>Standard otological instruments</td><td>Karl Storz</td><td>N/A</td><td></td></tr><tr><td>Steel and diamand burrs</td><td>Bien Air</td><td>N/A</td><td></td></tr><tr><td>Syringe Injekt Solo 10 mL</td><td>B. Braun</td><td>N/A</td><td></td></tr></tbody></table>

endoscopic cholesteatoma surgery

Implementation of endoscopes in cholesteatoma surgery resulted in considerable changes in the management of cholesteatoma in the last two decades. Compared to the microscopic approach with an excellent but straight-line view and limited illumination, the introduction of endoscopes provides a wide-angled panoramic view. Moreover, angled lenses allow the surgeon to visualize the middle ear and its hidden recesses through a transcanal, minimally-invasive approach. The endoscope enables the surgeon to remove limited cholesteatoma of the middle ear and its recesses using an exclusive endoscopic technique by taking advantage of these benefits. This reduces the rate of residual disease and sparing external incisions and excessive temporal bone drilling as in a transmastoid approach. Since transcanal endoscopic access is mainly a one-handed technique, it implies the need for specific procedures and technical refinements. This article describes a step-by-step guide as a surgical manual for endoscopic removal of epitympanic cholesteatoma. Different techniques for cholesteatoma dissection and bone removal for epitympanectomy, including curettage and powered instruments such as drills and ultrasonic devices with their outcomes, are discussed. This may offer ear surgeons insight into technical refinements and the latest technological developments and open the horizon for different techniques.

A total of 43 consecutive cases of exclusive endoscopic cholesteatoma surgery were analyzed for this study. One surgeon performed all operations; cases needing conversion to a microscopic or combined approach were excluded. Preoperative computed tomography suspected an epitympanal cholesteatoma extension in every case. The mean age (&#177;standard deviation) at the surgery date was 37.36 years (&#177;15.64 years). Seven cases (16.3%) were revision surgeries, thirty-six cases (83.7%) were patients undergoing first cholesteatoma removal. The left side was operated in 26 cases (60.5%), the right side in 17 cases (39.5%).
Surgical Results 
All operations were completed without significant complications like facial nerve palsy or postoperative sensorineural hearing loss, as illustrated in Figure 1. Cartilage was used as grafting material in 38 cases (88.4%) and fascia in 5 cases (11.6%). The graft intake rate (GIR) was 90.7% showing 3 cases of postoperative perforations (7.3%). The mean follow-up was 17.4 months (&#177;10 months), with 40 cases (93%) having no recurrent cholesteatoma at the last follow-up.
Audiological Results 
Each patient underwent standard audiological testing before and after surgery. One patient was already deaf before surgery; thus, no hearing improvement was expected. Two more patients had no postoperative audiogram. Preoperative air bone gap (ABG) of 23.8 dB &#177; 12.6 dB improved significantly (paired t-test with p = 0.0005) to a postoperative ABG of 18.2 dB &#177; 10 dB after surgery. The detailed surgical results are presented in Table 1.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/63315/63315fig01.jpg" /> 
Figure 1: Overview of the essential surgical steps. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/63315/63315fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Age</td>
			<td>37.4 years (14-80 years)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Side</td>
			<td>26 left side</td>
			<td>17 right side</td>
			<td></td>
		</tr>
		<tr>
			<td>Revision surgery</td>
			<td>36 primary surgery</td>
			<td>7 revision surgery</td>
			<td></td>
		</tr>
		<tr>
			<td>Grafting sucess</td>
			<td>39 successful</td>
			<td>3 perforations</td>
			<td>1 missing follow up</td>
		</tr>
		<tr>
			<td>Grafting material</td>
			<td>38 cartilage</td>
			<td>5 fascia</td>
			<td></td>
		</tr>
		<tr>
			<td>Recidive</td>
			<td>40 without recidive</td>
			<td>3 with recidive</td>
			<td></td>
		</tr>
		<tr>
			<td>Mean ABG</td>
			<td>23.8 &#177; 12.6 dB preoperative</td>
			<td>18.2 &#177; 10 dB postoperative</td>
			<td></td>
		</tr>
	</tbody>
</table>
Table 1: Detailed surgical results.

Watch this Scientific Journal Video about Endoscopic Cholesteatoma Surgery at JoVE.com

Endoscopic Cholesteatoma Surgery

The present protocol describes a step-by-step guide for the complete endoscopic removal of epitympanic cholesteatoma with different techniques for cholesteatoma dissection and bone removal for epitympanectomy.

Implementation of endoscopes in cholesteatoma surgery resulted in considerable changes in the management of cholesteatoma in the last two decades. ...

Universidad San Sebastian

Research

JoVE Journal

Medicine

9.9K Views.  Inselspital, Bern University Hospital, University of Bern. The present protocol describes a step-by-step guide for the complete endoscopic removal of epitympanic cholesteatoma with different techniques for cholesteatoma dissection and bone removal for epitympanectomy.

Video: Endoscopic Cholesteatoma Surgery

Murine Flexor Tendon Injury and Repair Surgery

Tendon connects skeletal muscle and bone, facilitating movement of nearly the entire body. In the hand, flexor tendons (FTs) enable flexion of the fingers and general hand function. Injuries to the FTs are common, and satisfactory healing is often impaired due to excess scar tissue and adhesions between the tendon and surrounding tissue. However, little is known about the molecular and cellular components of FT repair. To that end, a murine model of FT repair that recapitulates many aspects of healing in humans, including impaired range of motion and decreased mechanical properties, has been developed and previously described. Here an in-depth demonstration of this surgical procedure is provided, involving transection and subsequent repair of the flexor digitorum longus (FDL) tendon in the murine hind paw.&#160;This technique can be used to conduct lineage analysis of different cell types, assess the effects of gene gain or loss-of-function, and to test the efficacy of pharmacological interventions in the healing process. However, there are two primary limitations to this model: i) the FDL tendon in the mid-portion of the murine hind paw, where the transection and repair occur, is not surrounded by a synovial sheath. Therefore this model does not account for the potential contribution of the sheath to the scar formation process. ii) To protect the integrity of the repair site, the FT is released at the myotendinous junction, decreasing the mechanical forces of the tendon, likely contributing to increased scar formation. Isolation of sufficient cells from the granulation tissue of the FT during the healing process for flow cytometric analysis has proved challenging; cytology centrifugation to concentrate these cells is an alternate method used, and allows for generation of cell preparations on which immunofluorescent labeling can be performed. With this method, quantification of cells or proteins of interest during FT healing becomes possible.

Flexor tendons in the hand are commonly injured, leading to impaired hand function. However, the scar-tissue healing response is not well characterized. A murine model of flexor tendon healing is demonstrated here. This model can enhance overall understanding of the healing process and assess therapeutic approaches to improve healing.

Tendon connects skeletal muscle and bone, facilitating movement of nearly the entire body. In the hand, flexor tendons (FTs) enable flexion of the fingers ...

Discovering Middle Ear Anatomy by Transcanal Endoscopic Ear Surgery: A Dissection Manual

The middle ear is located in the center of the temporal bone and bears a highly complex anatomy. The recently introduced exclusively endoscopic transcanal approach to the middle ear is a minimally invasive technique sparing the bone and mucosa of the mastoid bone, since the middle ear is accessed through the external auditory canal. This emerging method has several advantages over the traditional (microscopic) approaches to the middle ear such as the panoramic wide-angle views of the anatomy, the possibility to approach and magnify tiny structures, and the possibility of looking around the corner using angled endoscopes.
The cadaveric dissection method presented here consists of an overview on the technical requirements and a precise description of a step-by-step protocol to discover the anatomy of the middle ear. Each step and anatomical structure is carefully described in order to provide a comprehensive guide to endoscopic ear anatomy. In our opinion, this is particularly important to any novice in endoscopic ear surgery as it provides thorough anatomical knowledge and may improve surgical skills.

The aim of this article is to describe the methodology of exclusively endoscopic cadaveric middle ear dissection. Moreover, we aim to provide a comprehensive guide to endoscopic middle ear anatomy.

The middle ear is located in the center of the temporal bone and bears a highly complex anatomy. The recently introduced exclusively endoscopic transcanal ...

An Endoscopic Transcanal Transpromontorial Approach for Vestibular Schwannomas using a Computer-Based Three-Dimensional Imaging System

A 2D monocular endoscope has been used in transcanal transpromontory vestibular schwannoma surgery instead of craniotomy. However, the absence of depth perception is the limitation of this approach. With the loss of depth perception, the surgeon will be not able to perform delicate and particularly complicated surgery. A binocular endoscope has been developed to provide stereoscopic vision with better depth perception for complicated anatomic structures and has been applied in some endoscopic surgeries. However, the diameter of the endoscope is a limitation in the performance of transcanal otologic surgeries. A small diameter endoscope facilitates easier surgery in a restricted space. A computer-based 3D imaging system can obtain 3D images in real-time using a small monocular endoscope. In this study, to evaluate the feasibility of a computer-based 3D imaging system for endoscopic lateral skull base surgery, we applied this 3D imaging system in a transcanal transpromontorial approach in two patients with vestibular schwannomas. The surgical procedure was completed without complication in these two cases. There was no mortality, perioperative complications, nor notable postoperative complications. Using this computer-based 3D imaging system, a better depth perception and stereoscopic vision was observed compared to a conventional 2D endoscope. The improvement in depth perception offers superior management of the complicated surgical anatomy.

Here, we present a transcanal transpromontorial approach for vestibular schwannomas using a computer-based three-dimensional (3D) imaging system combined with a two-dimensional (2D) endoscope. This system provided stereoscopic vision, better depth perception and reduced visual fatigue. This 3D imaging system enabled the application of 3D vision technology in endoscopic lateral skull base surgery.

A 2D monocular endoscope has been used in transcanal transpromontory vestibular schwannoma surgery instead of craniotomy. However, the absence of depth ...

Endaural Endoscopic Atticoantrotomy (Retrograde Mastoidectomy) using a Constant Suction Bone-drilling Technique

Endoscopic middle ear surgery is a widely employed minimally invasive surgical technique to address middle ear and mastoid pathology. Bone drilling is the main technical challenge of endoscopic middle ear surgery. The accompanying video describes the detailed protocol of a constant-suction bone-drilling technique and the procedure of endaural exclusive endoscopic atticoantrotomy (retrograde mastoidectomy) using this technique. The main components of this bone-drilling technique include a soft and flexible suction tube, which is placed into the tympanic cavity to provide constant suction, and a soft sleeve, which is wrapped around the drill shaft to prevent the high-speed rotating shaft from damaging the lens of the endoscope. With these simple modifications, the traditional otological electrodrill can be used for drilling a tiny endaural incision in endoscopic middle ear surgery. Based on this bone-drilling technique, endaural endoscopic atticoantrotomy (retrograde mastoidectomy) can be successfully established for the removal of various amounts of bone, depending on the extent of the lesion. The short-term postoperative outcome seems promising.

Endaural Endoscopic Atticoantrotomy Retrograde Mastoidectomy using a Constant Suction Bone-drilling Technique

In this paper, we present the protocol and short-term outcomes of endaural exclusive endoscopic atticoantrotomy using a constant suction bone-drilling technique.

Endoscopic middle ear surgery is a widely employed minimally invasive surgical technique to address middle ear and mastoid pathology. Bone drilling is the ...

The Microscopic Transcanal Approach in Stapes Surgery Revisited

The microscopic transcanal (aka transmeatal) surgical approach was first described in the 60s, offering a minimally invasive means of reaching the external auditory canal, the middle ear, and epitympanon. Such an approach avoids a retroauricular or endaural skin incision; however, working through a narrow space needs angled microsurgical instruments and specific training in otologic surgery. The transcanal approach restricts the working space; however, it offers a binocular microscopic vision into the middle ear without extended skin incisions and thus, reducing post-operative pain and bleeding. In addition, this minimally invasive approach avoids scar tissue complications, hypoesthesia of the auricle, and potential protrusion of the pinna. Despite its numerous advantages, this method is still not routinely performed by otologic surgeons. Since this minimally invasive technique is more challenging, there is a need for extensive training in order for it to be widely adopted by otologic surgeons. This article provides step-by-step surgical instructions for stapes surgery and reports possible indications, pitfalls, and limitations using this microscopic transcanal technique.

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

The microscopic transcanal (aka transmeatal) surgical approach was first described in the 60s, offering a minimally invasive means of reaching the ...

Step-by-Step Stapedotomy through Transcanal Exclusive Endoscopic Approach

In recent years there has been an increasing trend in the use of the endoscope to treat a variety of middle ear pathologies, including otosclerosis. Several studies comparing traditional microscopic and endoscopic stapes surgery have reported similar hearing results and an overall low rate of complications. The endoscope has unraveled its full potential in demanding settings of stapes surgery, such as unfavorable anatomy of the oval window niche or revision cases. Reduced manipulation of the chorda tympani and low rate of post-operative dysgeusia are further benefits to mention for endoscopic stapes surgery.
Being a one-handed technique, management of bleeding, positioning, and crimping of the prosthesis may be challenging for novice endoscopic surgeons, so some training in endoscopic ear surgery is recommended before performing endoscopic stapedotomy. The problem of sharing the surgical field between the endoscope and the operating instruments could be easily overcome if proper instruments positioning is understood. One-handed bleeding control in the narrow space of the ear canal may represent an issue during the elevation of the tympano-meatal flap, possibly discouraging the surgeon since the preliminary steps of surgery. Following appropriate technique to raise the flap and the collaboration with the anesthesiology team in keeping the blood pressure low guarantee an adequate bleeding control in most cases.
The aim of this article is to describe the entire surgical procedure of a transcanal exclusive endoscopic stapedotomy, from operating room set up and patient positioning to post-operative care. A step-by-step description of the surgical maneuvers with technical hints is reported, to guide the surgeon across the procedure and allow any ear surgeon to perform stapes surgery endoscopically.

The aim of this article is to provide a step-by-step method for endoscopic stapes surgery from operating room setting and patient positioning to post-operative care. This work would represent a guide for any otologic surgeon who is willing to treat otosclerosis with endoscopic transcanal technique.

In recent years there has been an increasing trend in the use of the endoscope to treat a variety of middle ear pathologies, including otosclerosis. ...

Surgical Treatment of an Endolymphatic Sac Tumor

Endolymphatic sac tumors (ELST) are low-grade papillary adenocarcinoma originating from the endolymphatic sac. Usually slow-growing, with local aggressiveness and a low risk of distant metastases, ELST can be sporadic but also frequently associated with von Hippel Lindau disease. The current treatment of ELST is primarily surgical resection. A 55-year-old woman accessed our otologic tertiary level referral center for a sudden worsening of hearing loss in her left ear and vertigo. A magnetic resonance (MRI) and computer tomography scan study subsequently showed a mass in the petrous bone; hence, the presence of an ELST was hypothesized. After embolization of the mass, the patient underwent surgical removal of the lesion. The resection of the mass was done through a translabirinthine approach, with an uneventful procedure. No residual disease remained after surgery. After 24 months of radiologic follow up with MRI, there are no signs of recurrence disease. This paper reports the management of this sporadic ELST, as well as the follow up results, providing clinicians this protocol for the handling of such a challenging otologic skull base surgery and rare disease.

Here, we discuss clinical and radiological features of endolymphatic sac tumors and report the methodology and results of a surgical removal in a case in care at our otologic referral center.

Endolymphatic sac tumors (ELST) are low-grade papillary adenocarcinoma originating from the endolymphatic sac. Usually slow-growing, with local ...

Robot-Assisted Transcanal Endoscopic Ear Surgery for Congenital Cholesteatoma

Congenital cholesteatoma accounts for 25% of cholesteatoma cases in children. Transcanal Endoscopic Ear Surgery (TEES) is ideal for these patients because it offers a wide endoscopic view of the middle ear and a minimally invasive approach. The two main limitations are the loss of one operative hand and a narrow external auditory canal in younger children. Here, we present the case of a 3-year-old patient with a Potsic stage III congenital cholesteatoma adherent to the incus and branches of the stapes. A robotic-assisted TEES procedure was performed, during which a robotic arm with 6 degrees of freedom held a 0&#176;, 2.9 mm wide endoscope, enabling the surgeon to work in a narrow environment with both hands. The procedure's duration was 2 h and 9 min, including 16 min for the installation and draping of the robotic arm. After a trans-canal approach, the cholesteatoma was dissected from the ossicles using both a needle (or sickle knife) and suction to stabilize the ossicles and limit the risk of hearing trauma. The cholesteatoma was debulked to reduce its size, allowing it to be pushed under the malleus anteriorly and then separated from other adherences before removal. A tragal cartilage graft was used to reinforce the tympanic membrane.

This protocol describes the removal of congenital cholesteatoma using minimally invasive transcanal endoscopic ear surgery with a two-handed approach and a robotic endoscope holder.

Congenital cholesteatoma accounts for 25% of cholesteatoma cases in children. Transcanal Endoscopic Ear Surgery (TEES) is ideal for these patients because ...

A Comprehensive Step-By-Step Guide for Exclusive Endoscopic Ossiculoplasty

Techniques of Endoscopic Ossiculoplasty

The utilization of endoscopes in modern otology has evolved from diagnostic purposes to the development of exclusive endoscopic ear surgery. This technique offers a panoramic view of the middle ear and provides an optimal magnification of the oval window region, the stapes' suprastructure, and the footplate, allowing great precision in prosthesis positioning during ossiculoplasty (OPL). Various techniques for ossicular chain reconstruction have been described in the literature. Either autologous or synthetic materials can be used for reconstruction. The use of a patient's own tissue minimizes the risk of implant rejection or extrusion of the prosthesis through the tympanic membrane. On the other hand, synthetic materials like titanium are light and rigid and do not require time-consuming prosthesis remodeling. The main objective of this article is to present a comprehensive step-by-step guide that serves as a surgical manual for exclusive endoscopic OPL. This guide will explain various forms of OPL using synthetic and autologous materials. The goal is to provide a comprehensive understanding of the various surgical techniques and support the integration into clinical practice.

Author Spotlight: Advancing Endoscopic Ossiculoplasty &#8211; Techniques, Innovations, and Practical Guidance for Clinical Integration

Exclusive Endoscopic ossiculoplasty (EEO) is a promising and minimally invasive approach for the treatment of conductive hearing loss due to ossicular chain disruptions and associated middle ear pathologies. Herein, step-by-step instructions and a discussion of various endoscopic ossiculoplasty techniques are presented.

The utilization of endoscopes in modern otology has evolved from diagnostic purposes to the development of exclusive endoscopic ear surgery. This ...

Endoscopic Approach for Colloid Cyst Resection

This protocol describes a minimally invasive endoscopic technique for the removal of colloid cysts located in the third ventricle. These cysts are a rare type of intracranial lesion that can obstruct cerebrospinal fluid flow. If left untreated, they may cause hydrocephalus or, in severe cases, even sudden death. The objective of this approach is to provide a safe and effective alternative to traditional microsurgical methods. It does so by reducing postoperative pain, surgical morbidity, and hospital stays. The protocol delineates meticulous preoperative preparations, encompassing patient positioning and equipment setup, followed by a systematic step-by-step guide to the endoscopic surgical procedure. This protocol involves the use of intraoperative ultrasound guidance for precise navigation, incision of the cyst wall, aspiration of cyst contents, and meticulous hemostasis. Special care is taken to minimize damage to surrounding neural structures, ensuring complete cyst removal while reducing the risk of complications. The efficacy of this minimally invasive approach is substantiated by the observation that it is associated with reduced operation times, minimal neurological deficits, and rapid postoperative recovery. Typically, patients are able to resume mobilization the day after surgery and are discharged within two days. This protocol serves as a comprehensive guide for neurosurgeons aiming to enhance surgical precision while maximizing patient outcomes. The successful utilization of this protocol is dependent on meticulous preoperative planning, advanced intraoperative navigation techniques, and the employment of specialized endoscopic instruments.

This protocol details a minimally invasive endoscopic technique for the removal of third ventricular colloid cysts. It provides a comprehensive overview of preoperative preparations, surgical steps, and postoperative outcomes, emphasizing reduced recovery time, minimal complications, and total cyst removal. This approach is a safe and effective alternative to traditional microsurgery.

 This protocol describes a minimally invasive endoscopic technique for the removal of colloid cysts located in the third ventricle. These cysts are a rare ...