This study was supported by Youth Fund of National Natural Science Foundation of China (Grant No. 81400460), Youth Fund of National Natural Science Foundation of China (Grant No. 81900932), and Clinical Research Plan of SHDC (Grant No. SHDC2020CR1049B).

NOTE: This study was approved and performed according to the guidelines of the ethical committee of Fudan University.
1. Anesthesia and surgical field preparation
<ol>
	<li>Induce intravenous anesthesia and perform orotracheal intubation or use a laryngeal mask.</li>
	<li>Place the patient in a supine position with the head rotated to the contralateral side.</li>
	<li>Sterilize the auricle and the external ear canal (EAC) with a povidone iodine solution; drape the surgical field with a blanket sparing the EAC.</li>
	<li>Check the optical clarity of the endoscope and adjust its white balance.</li>
	<li>Introduce the 0&#176;, 3 mm diameter, and 15 cm length endoscope into the EAC. Remove the cerumen from the EAC with microscopic forceps and sterilize the EAC with the povidone iodine solution again.</li>
</ol>
2. Establishment of a minimal invasive endaural approach
<ol>
	<li>Administer local anesthesia to the EAC by injecting 1% lidocaine with adrenaline (1:100,000) at 7 and 11-o&#39;clock positions.</li>
	<li>Under the endoscope, make a circumferential incision with a round knife from 2 to 6-o&#39;clock position, counterclockwise (right ear), approximately 8 mm from the tympanic membrane. 
	NOTE: Use povidone iodine to clean the lens of the endoscope.</li>
	<li>Raise the tympanomeatal flap with a 1 mm diameter suction tube and a small piece of gauze soaked with adrenaline (1:1,000).</li>
	<li>Under direct vision, make an intercartilaginous incision with a scalpel at the 12-o&#39;clock position, from the previously made circumferential incision towards the meatus and through the stretched intercartilaginous incisura.</li>
	<li>Make another radial incision with the scalpel at the 6-o&#39;clock position, from the previously made circumferential incision towards the meatus.</li>
	<li>Raise the flap enclosed by the medial circumferential incision and the two radial incisions outward with a curette. Check the exposure of the lateral wall of the attic and the posterior wall of the EAC. 
	NOTE: The edge of the incision can be subjected to bipolar coagulation so that it shrinks, providing better exposure.</li>
	<li>Place a self-retaining retractor to widen the meatus of the EAC and hold the lateral-based skin flap in place.</li>
</ol>
3. Bone drilling and lesion removal
<ol>
	<li>Tailor the tube of a disposable venous infusion needle to make a soft suction tube, which will be used in the bone-drilling stage. Make several side holes at its distal end with scissors (Figure 1).</li>
	<li>Cut a small section of the tube of a disposable infusion set to make an electrodrill shaft sleeve that will protect the lens of the endoscope during bone drilling. Fix the sleeve to the drill handle with a sterile transparent sticker (Figure 1).</li>
	<li>Put the distal end of the soft suction tube (with the side holes) into the tympanic cavity, and connect the other end of the tube to a vacuum aspirator.</li>
	<li>Execute bone drilling in an inside-out direction starting from the posterior part of the scutum. 
	NOTE: Here, a 1.8 mm diamond burr is used in the beginning to avoid tearing the tympanomeatal flap. After removing the posterior part of the scutum, lesions around the incudostapedial joint can be fully exposed. Drilling of the posterior lateral attic wall can be expanded If the lesion cannot be removed entirely.</li>
	<li>Instruct the assistant to irrigate the meatus of the EAC with saline continuously. 
	NOTE: If necessary, additional clearance of bone sludge can also be done intermittently with the surgical suction tube.</li>
	<li>Remove the anterior part of the lateral attic wall by bone drilling if the lesion extends anteriorly. 
	NOTE: The malleus head can be removed to facilitate the lesion removal.</li>
	<li>Perform an extended atticoantrotomy if the lesion extends further into the antrum. 
	NOTE: The whole attic and antrum can be opened to facilitate lesion removal. Sometimes, the direct approach can be applied to the retrotympanum to remove the lesion with minimal bone-drilling5. In such an approach, the surgeon stands opposite to the affected ear and uses a 45&#176; endoscope. The operating table should be tilted ~30&#176; toward the surgeon to facilitate the introduction of the endoscope and the instruments. After lesion removal, lens fogging can be observed in some patients when the constant suction is stopped. This phenomenon will disappear if the tympanic orifice of the eustachian tube is blocked by a small piece of gauze. Of note, such a phenomenon could be used to assess eustachian tube function (fogging is a sign of good function). To observe this phenomenon, the balloon should not be too tight when endotracheal intubation is established.</li>
</ol>
4. Reconstruction and closure
<ol>
	<li>Check the integrity and mobility of the ossicular chain after lesion removal. Correct ossicular abnormalities with various mature surgical techniques6.</li>
	<li>Harvest a large piece of tragus cartilage with perichondrium on both sides.</li>
	<li>On one side, detach the perichondrium from the cartilage with a round knife, leaving the perichondrium on the other side to form a cartilage-perichondrium graft. Tailor the cartilage-perichondrium graft for reconstruction.</li>
	<li>Use the cartilage-perichondrium graft and the perichondrium to reconstruct the lateral wall of the attic and the tympanic membrane. 
	NOTE: If an extended atticoantrotomy is performed, part of the cartilage-perichondrium graft can also be used to reconstruct the posterior wall of the EAC.</li>
	<li>Tailor and reposition the tympanomeatal flap and the lateral-based skin flap; pack the EAC with a gelatin sponge.</li>
	<li>Suture the intercartilaginous incision and pack it with gauze.</li>
</ol>
5. Postoperative management
<ol>
	<li>Administer intravenous antibiotics for 2 days postoperatively during hospitalization.</li>
	<li>Remove the dressing 2 days after the surgery, just before discharge.</li>
	<li>Apply oral antibiotics and ciprofloxacin drops for 2 weeks after discharge.</li>
	<li>Remove the stitches and the remaining gelatin sponge at the first visit, usually 7 to 10 days after discharge.</li>
	<li>Organize future follow-ups according to the pathology and type of surgery.</li>
</ol>

<ol>
	<li>Yong, M., Mijovic, T., Lea, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+ear+surgery+in+Canada:+a+cross-sectional+study.">Endoscopic ear surgery in Canada: a cross-sectional study.</a> Journal of Otolaryngology-Head &amp; Neck Surgery. 45, 4 (2016).</li><li>Kapadiya, M., Tarabichi, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+overview+of+endoscopic+ear+surgery+in+2018.">An overview of endoscopic ear surgery in 2018.</a> Laryngoscope Investigative Otolaryngology. 4 (3), 365-373 (2019).</li><li>Tseng, C. C., Lai, M. T., Wu, C. C., Yuan, S. P., Ding, Y. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+transcanal+myringoplasty+for+anterior+perforations+of+the+tympanic+membrane.">Endoscopic transcanal myringoplasty for anterior perforations of the tympanic membrane.</a> JAMA Otolaryngology-Head &amp; Neck Surgery. 142, 1088-1093 (2016).</li><li>Huang, Y. B., Hu, L. L., Ren, D. D., Han, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myringoplasty+with+an+ultrathin+cartilage-perichondrium+complex+graft+versus+temporalis+fascia+graft:+a+propensity+score-matched+analysis.">Myringoplasty with an ultrathin cartilage-perichondrium complex graft versus temporalis fascia graft: a propensity score-matched analysis.</a> Otolaryngology-Head and Neck Surgery. , 19459982096540 (2020).</li><li>Presutti, L., Marchioni, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Endoscopic ear surgery: principles, indications, and techniques. , (2015).</li><li>Slater, P. W., Rizer, F. M., Schuring, A. G., Lippy, W. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Practical+use+of+total+and+partial+ossicular+replacement+prostheses+in+ossiculoplasty.">Practical use of total and partial ossicular replacement prostheses in ossiculoplasty.</a> Laryngoscope. 107 (9), 1193-1198 (1997).</li><li>Thomassin, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+ear+surgery.">Endoscopic ear surgery.</a> Annales d' Oto-laryngologie et de Chirurgie Cervico Faciale. 107 (8), 564-570 (1990).</li><li>Pollak, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+and+minimally-invasive+ear+surgery:+A+path+to+better+outcomes.">Endoscopic and minimally-invasive ear surgery: A path to better outcomes.</a> World Journal of Otorhinolaryngology-Head and Neck Surgery. 3 (3), 129-135 (2017).</li><li>Dornhoffer, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retrograde+mastoidectomy.">Retrograde mastoidectomy.</a> Otolaryngologic Clinics of North America. 39 (6), 1115-1127 (2006).</li><li>Hatano, M., Ito, M., Yoshizaki, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retrograde+mastoidectomy+on+demand+with+soft-wall+reconstruction+in+pediatric+cholesteatoma.">Retrograde mastoidectomy on demand with soft-wall reconstruction in pediatric cholesteatoma.</a> Acta Oto-laryngologica. 130 (10), 1113-1118 (2010).</li><li>Vaughan, C., Jufas, N., Patel, N. P., Saxby, A. J., Kong, J. H. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+"Chopstick+Drilling+Technique":+A+novel+solution+to+drilling+bone+in+endoscopic+ear+surgery.">The "Chopstick Drilling Technique": A novel solution to drilling bone in endoscopic ear surgery.</a> Clinical Otolaryngology. 44 (6), 1231-1233 (2019).</li></ol>

The authors declare that there are no conflicts of interest regarding the publication of this article.

Since the introduction of the endoscope in middle ear surgery in the 1990s7,8, endoscopic ear surgery has gained great popularity around the world. This is partially because the endoscope can provide high-quality images and help visualize poorly seen structures such as the hypotympanum and sinus tympani. Moreover, the EAC, which is a much more direct and natural approach than the retroauricular approach to the middle ear, confers the advantages of less trauma and quick recovery. The accompanying video provides a detailed protocol of endaural exclusive endoscopic atticoantrotomy using a constant-suction bone-drilling technique adopted at this hospital. The procedure mentioned above is an endoscopic modification of the inside-out transmeatal mastoidectomy (retrograde mastoidectomy), which has already been developed in the microscope era9,10. In the current technique, we retain the advantages of the primary microscopic inside-out technique, such as a direct and natural approach, less bone removal, and following the lesion along the direction of its growth. The use of the endoscope eliminates the original disadvantages such as inadequate exposure and limited visualization.
The surgical technique mentioned above provides an endoscopic solution to various middle ear lesions, especially different degrees of cholesteatoma. Bone drilling can be gradually expanded safely by following the pathology from the tympanic cavity to the attic and the antrum. Cholesteatoma in the tympanic cavity is first recognized after the elevation of the tympanomeatal flap. If the lesion extends superiorly through the tympanic isthmus to the attic, the posterior part of the scutum can be removed first. If the cholesteatoma cannot be removed entirely, drilling could be expanded posteriorly and superiorly toward the aditus and the posterior part of the attic. If the lesion further extends anteriorly, the atticotomy could be expanded by drilling the lateral attic wall anteriorly to expose the malleus head. In case of further posterior extension of the cholesteatoma into the antrum, drilling is continued posteriorly along the tegmen tympani and tegmen antri, with a typical atticoantrotomy being performed. In summary, the extent of endaural endoscopic atticoantrotomy (retrograde mastoidectomy) is flexible and based on the requirement. 
In the authors' department, this technique is mainly used in selected patients with cholesteatoma confined to the attic and the antrum, especially in the ones with sclerotic mastoid. This surgical technique can also be used to enlarge the posterior bony part of the EAC, which is quite helpful for some patients with EAC stenosis. Currently, bone drilling is a key technical challenge of endoscopic middle ear surgery. This is mainly due to the narrow feature of the EAC, which makes it almost impossible to insert multiple instruments simultaneously. In addition, the surgeon must hold the endoscope constantly in one hand, making drilling while irrigating quite difficult. When drilling is required, some surgeons advocate switching to a microscope to enable the use of both hands. Several drilling techniques have also been developed for endoscopic middle ear surgery, such as drilling in a watered field and the "chopstick" technique5,11. 
In this video, we show methods to achieve bone drilling while irrigating and suctioning at the same time. This technique has several advantages. First, it is a simple but efficient method. After establishing a tiny endaural incision and simply modifying the electrodrill handpiece, the traditional otological electrodrill can be as effective as the specially designed microdrill or an ultrasonic bone curette for bone removal in endoscopic middle ear surgery. Second, the suction tube placed in the EAC is soft and flexible, providing great agility and maneuverability that facilitates operation in tight spaces. Finally, the soft sleeve around the drill shaft is also quite useful. It can prevent the high-speed rotating shaft from damaging the lens of the endoscope. Thus, the drilling technique mentioned in this paper is practical and efficient and can be successfully adopted in endoscopic middle ear surgery.

Since the endoscope was introduced as a powerful tool in ear surgery over 20 years ago, endoscopic middle ear surgery or endoscopic middle ear surgery adjunct to conventional microscopic ear surgery has quickly become a widely employed surgical technique to address middle ear and mastoid pathology1,2. The main advantages of the endoscope are its panoramic and wide-angle vision. The use of the endoscope reveals the entire structure of the middle ear through the confined external auditory canal. The use of angle endoscopes (30&#176; and 45&#176;) further facilitates the exposure of the surgical field and allows dissection into the most hidden areas of the middle ear. Multiple studies have demonstrated the advantages of the superior visibility of endoscopic procedures over traditional microscopic approaches and confirmed that the major outcomes, such as the recurrence of the lesion and the changes in hearing levels, were not different between the two approaches3,4. The advances in technology and surgical instruments are still pushing the boundaries of endoscopic middle ear surgery to manage more disorders of the middle ear and even of the lateral skull base.
However, during transcanal endoscopic ear surgery, as one hand needs to hold the endoscope firmly, all surgical procedures must be performed by the other hand. As a result, surgical techniques of endoscopic ear surgery require some effort, especially the bone drilling technique poses a great technical challenge in endoscopic middle ear surgery. Due to the lack of an efficient endoscopic bone drill technique, some surgeons consider any pathology extending beyond an imaginary line, which bisects the lateral semicircular canal, not to be suitable for an exclusive endoscopic approach. Moreover, when drilling is required, some surgeons would instead switch to a microscope to enable the use of both hands, which may require additional postauricular or endaural incisions to improve access. 
To address this problem, a constant-suction bone-drilling technique has been developed in these authors' department for endaural exclusive endoscopic atticoantrotomy (retrograde mastoidectomy). From April 2020 to August 2020, 11 cases of endaural exclusive endoscopic atticoantrotomy have been successfully performed with this technique in the department. The purpose of this video is to describe the detailed procedure of this constant-suction bone-drilling technique and endaural exclusive endoscopic atticoantrotomy using this technique.

<table><tbody><tr><td>Bipolar electrocoagulation</td><td>Hutong</td><td>GD350-B</td><td></td></tr><tr><td>Curved dissecting scissors</td><td>Jinzhong</td><td></td><td></td></tr><tr><td>Disposable infusion set and venous infusion needle</td><td>KDL</td><td></td><td></td></tr><tr><td>Endoscopes: 3 mm diameter, 15 cm length, 0&amp;deg; and 45&amp;deg;</td><td>Karl Storz</td><td></td><td></td></tr><tr><td>BASCH&amp;nbsp;Micromotor/PM 1600207-001 Handpiece</td><td>Bienair</td><td></td><td>High-speed electrodrill</td></tr><tr><td>No 11 bland and its handle</td><td>Jinzhong</td><td></td><td></td></tr><tr><td>Otological microsurgical instruments</td><td>Tiansong</td><td></td><td></td></tr><tr><td>Self-retaining retractor</td><td>Tiansong</td><td></td><td></td></tr><tr><td>Toothed forceps</td><td>Jinzhong</td><td></td><td></td></tr><tr><td>Video Equipment (HD screen; CCD camera; Xenon light source)</td><td>Karl Storz</td><td></td><td></td></tr></tbody></table>

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.

From April 2020 to August 2020, the senior surgeon performed endaural exclusive endoscopic atticoantrotomy on 11 patients using the above-mentioned constant-suction bone-drilling technique. The patients&#39; characteristics are described in Table 1. There were 10 men (90.9%) and 1 woman (9.1%). The patients&#39; age ranged from 9 to 63 years, with a mean age of 41 years. Most of these cases were cholesteatoma (8 cases), followed by chronic suppurative otitis media (3 cases). Of the 8 patients with cholesteatoma, the most common sites of involvement were attic (n=8, 100 %), followed by antrum (n=7, 87.5%) and tympanic cavity (n=3, 37.5%).
Intraoperative ossicular chain reconstruction was performed in 8 cases (72.7%) using methods including titanium partial ossicular replacement prostheses (4 cases) and titanium total ossicular replacement prostheses (4 cases). The results of short-term follow-up seem promising. Until the revisit at 3 months after the surgery, no sign of recurrence was noticed by clinical examination. However, the results of long-term follow-up are still unclear, which indicates further investigation is still needed.
With respect to the hearing outcome, a better postoperative air-bone gap (ABG) was observed in 5 patients, no significant change was observed in ABG in 5 patients, and a worse postoperative ABG was noted in 1 patient. The postoperative facial nerve function was normal in all the patients. No other complications were noticed postoperatively. The photographs of typical cases are shown in Figure 2.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/62450/62450fig01.jpg" /> 
Figure 1: Tailoring of a disposable infusion set and venous infusion needle and modification of electrodrill handpiece. (A) The disposable infusion set and venous infusion needle before tailoring. (B) The components cut out of the disposable infusion set and venous infusion needle: (a) electrodrill shaft sleeve, which is fixed on the handpiece with a sterile transparent sticker, (b) the soft suction tube, which will be inserted into the tympanic cavity, (c) side holes on the suction tube. <a href="https://jove.unicartagenaproxy.elogim.com/files/ftp_upload/62450/62450fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/62450/62450fig02.jpg" /> 
Figure 2: Typical cases. (A) Axial CT image of one patient shows cholesteatoma (arrowhead) in the attic and antrum. Note that the extent of the lesion goes beyond the imaginary line that bisects the lateral semicircular canal. (B) Establishment of constant-suction bone-drilling technique. Arrow indicates the soft suction tube; arrowhead indicates the electrodrill shaft sleeve. (C) The operative cavity of the same patient in (A) after completion of the endaural endoscopic atticoantrotomy. (D) Preoperative endoscopic image of the tympanic membrane. (E) Endoscopic image of the tympanic membrane of the same patient in (D) at 6 months after the operation. (F) One month after the surgery, the endaural incision (indicated by the arrowhead) is almost invisible. Abbreviations: CT = computed tomography; et = eustachian tube; hs = head of stape; ct = chorda tympani; fn = facial nerve; lsc = lateral semicircular canal. <a href="https://jove.unicartagenaproxy.elogim.com/files/ftp_upload/62450/62450fig02large.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>No</td>
			<td>Sex</td>
			<td>age</td>
			<td>side</td>
			<td colspan="2">lesion</td>
			<td colspan="2">extent</td>
			<td colspan="2">Ossicular chain reconstruction</td>
			<td colspan="2">ABG preoperative</td>
			<td>ABG 3 months later</td>
		</tr>
		<tr>
			<td>1</td>
			<td>M</td>
			<td>33</td>
			<td>R</td>
			<td colspan="2">cholesteatoma</td>
			<td colspan="2">tympanic cavity,attic,antrum</td>
			<td colspan="2">TORP</td>
			<td colspan="2">34</td>
			<td>20</td>
		</tr>
		<tr>
			<td>2</td>
			<td>M</td>
			<td>47</td>
			<td>L</td>
			<td colspan="2">cholesteatoma</td>
			<td colspan="2">attic,antrum</td>
			<td colspan="2">TORP</td>
			<td colspan="2">32</td>
			<td>22</td>
		</tr>
		<tr>
			<td>3</td>
			<td>M</td>
			<td>28</td>
			<td>L</td>
			<td colspan="2">cholesteatoma</td>
			<td colspan="2">tympanic cavity,attic,antrum</td>
			<td colspan="2">TORP</td>
			<td colspan="2">38</td>
			<td>43</td>
		</tr>
		<tr>
			<td>4</td>
			<td>M</td>
			<td>59</td>
			<td>L</td>
			<td colspan="2">cholesteatoma</td>
			<td colspan="2">tympanic cavity,attic,antrum</td>
			<td colspan="2">PORP</td>
			<td colspan="2">27</td>
			<td>22</td>
		</tr>
		<tr>
			<td>5</td>
			<td>M</td>
			<td>62</td>
			<td>R</td>
			<td colspan="2">CSOM</td>
			<td colspan="2">tympanic cavity,attic,antrum</td>
			<td colspan="2">not reconstructed</td>
			<td colspan="2">profound deafness</td>
			<td>profound deafness</td>
		</tr>
		<tr>
			<td>6</td>
			<td>F</td>
			<td>53</td>
			<td>L</td>
			<td colspan="2">CSOM</td>
			<td colspan="2">tympanic cavity,attic,antrum</td>
			<td colspan="2">not reconstructed</td>
			<td colspan="2">25</td>
			<td>15</td>
		</tr>
		<tr>
			<td>7</td>
			<td>M</td>
			<td>33</td>
			<td>L</td>
			<td colspan="2">cholesteatoma</td>
			<td colspan="2">attic,antrum</td>
			<td colspan="2">PORP</td>
			<td colspan="2">43</td>
			<td>23</td>
		</tr>
		<tr>
			<td>8</td>
			<td>M</td>
			<td>9</td>
			<td>L</td>
			<td colspan="2">cholesteatoma</td>
			<td colspan="2">attic,antrum</td>
			<td colspan="2">PORP</td>
			<td colspan="2">20</td>
			<td>21</td>
		</tr>
		<tr>
			<td>9</td>
			<td>M</td>
			<td>41</td>
			<td>L</td>
			<td colspan="2">cholesteatoma</td>
			<td colspan="2">attic</td>
			<td colspan="2">TORP</td>
			<td colspan="2">10</td>
			<td>34</td>
		</tr>
		<tr>
			<td>10</td>
			<td>M</td>
			<td>28</td>
			<td>L</td>
			<td colspan="2">cholesteatoma</td>
			<td colspan="2">attic,antrum</td>
			<td colspan="2">not reconstructed</td>
			<td colspan="2">10</td>
			<td>13</td>
		</tr>
		<tr>
			<td>11</td>
			<td>M</td>
			<td>63</td>
			<td>R</td>
			<td colspan="2">CSOM</td>
			<td colspan="2">tympanic cavity,attic,antrum</td>
			<td colspan="2">PORP</td>
			<td colspan="2">45</td>
			<td>23</td>
		</tr>
	</tbody>
</table>
Table 1: Characteristics and short-term outcomes of patients who underwent endaural endoscopic atticoantrotomy with the constant-suction bone-drilling technique. Abbreviations: M = male; F = female; R = right; L = left; CSOM = chronic suppurative otitis media; TORP = total ossicular replacement prostheses; PORP = partial ossicular replacement prostheses; ABG = air bone gap.

Watch this Scientific Journal Video about Endaural Endoscopic Atticoantrotomy Retrograde Mastoidectomy using a Constant Suction Bone-drilling Technique at JoVE.com

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.

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 ...

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3.6K Views.  Fudan University. In this paper, we present the protocol and short-term outcomes of endaural exclusive endoscopic atticoantrotomy using a constant suction bone-drilling technique.

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

Surgical Induction of Endolymphatic Hydrops by Obliteration of the Endolymphatic Duct

Surgical induction of endolymphatic hydrops (ELH) in the guinea pig by obliteration and obstruction of the endolymphatic duct is a well-accepted animal model of the condition and an important correlate for human Meniere's disease. In 1965, Robert Kimura and Harold Schuknecht first described an intradural approach for obstruction of the endolymphatic duct (Kimura 1965). Although effective, this technique, which requires penetration of the brain's protective covering, incurred an undesirable level of morbidity and mortality in the animal subjects. Consequently, Andrews and Bohmer developed an extradural approach, which predictably produces fewer of the complications associated with central nervous system (CNS) penetration.(Andrews and Bohmer 1989) 
The extradural approach described here first requires a midline incision in the region of the occiput to expose the underlying muscular layer. We operate only on the right side. After appropriate retraction of the overlying tissue, a horizontal incision is made into the musculature of the right occiput to expose the right temporo-occipital suture line. The bone immediately inferio-lateral the suture line (Fig 1) is then drilled with an otologic drill until the sigmoid sinus becomes visible. Medial retraction of the sigmoid sinus reveals the operculum of the endolymphatic duct, which houses the endolymphatic sac. Drilling medial to the operculum into the area of the endolymphatic sac reveals the endolymphatic duct, which is then packed with bone wax to produce obstruction and ultimately ELH. 
In the following weeks, the animal will demonstrate the progressive, fluctuating hearing loss and histologic evidence of ELH.

This video shows how to surgically obstruct the guinea pig's endolymphatic duct to produce endolymphatic hydrops.

Surgical induction of endolymphatic hydrops (ELH) in the guinea pig by obliteration and obstruction of the endolymphatic duct is a well-accepted animal ...

Biology

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 ...

A Bedside, Single Burr Hole Approach to Multimodality Monitoring in Severe Brain Injury

Intracranial pressure (ICP) monitoring is a cornerstone of the intensive care management of patients with severe acute brain injuries, including traumatic brain injury. While elevations in ICP are common, data regarding the measurement and treatment of these ICP elevations are conflicting. There is increasing recognition that changes in the balance between supply and demand of brain tissue are critically important and therefore the measurement of multiple modalities is required. Approaches are not standard, and therefore this article provides a description of a bedside, single burr hole approach to multimodality monitoring that allows the passage of probes designed to measure not only ICP but brain tissue oxygen, blood flow, and intracranial electroencephalography. Patient selection criteria, operative procedures, and practical considerations for securing probes during critical care are described. This method is readily performed, safe, secure, and flexible for the adoption of a variety of multimodality monitoring approaches aimed at detecting or preventing secondary brain injuries.

A method of recording multimodality monitoring signals in patients with severe brain injuries using a bedside, single burr hole technique is described.

Intracranial pressure (ICP) monitoring is a cornerstone of the intensive care management of patients with severe acute brain injuries, including traumatic ...

Neuroscience

An Integrated (Microscopic/Endoscopic) Dissection Ear Surgery Course

Traditionally, otologic surgical training consisted of microscopic cadaveric dissections. However, during the last decades the endoscope has significantly changed the surgical perspective in the otologic field. Thus, the modern ear and lateral skull base surgeon should master the entire spectrum of endoscopic and microscopic approaches, with the aim of tailoring the procedure and guaranteeing the best possible functional outcome. This work proposes a step-by-step guided and illustrated dissection course, including indications for the setup of the cadaver lab and the integration of the microscope and endoscope to enhance the use of both instruments. The alternation of the endoscope and microscope allows the novice to train the correct handling of the instruments in the surgical field under both optical views. This aspect is of utmost importance since it is not advisable to start off a technique without practicing the other one, as both are important and complementary in the modern otologic surgery setting.

An Integrated Microscopic/Endoscopic Dissection Ear Surgery Course

Traditionally, otologic surgical training consisted of microscopic cadaveric dissections. However, during the last decades the endoscope has significantly ...

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. ...

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.

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. ...

A Cost-Effective, Versatile Probe Implant System for Electrophysiology in Mice

The DREAM Implant: A Lightweight, Modular, and Cost-Effective Implant System for Chronic Electrophysiology in Head-Fixed and Freely Behaving Mice

Chronic electrophysiological recordings in rodents have significantly improved our understanding of neuronal dynamics and their behavioral relevance. However, current methods for chronically implanting probes present steep trade-offs between cost, ease of use, size, adaptability, and long-term stability.
This protocol introduces a novel chronic probe implant system for mice called the DREAM (Dynamic, Recoverable, Economical, Adaptable, and Modular), designed to overcome the trade-offs associated with currently available options. The system provides a lightweight, modular and cost-effective solution with standardized hardware elements that can be combined and implanted in straightforward steps and explanted safely for recovery and multiple reuse of probes, significantly reducing experimental costs.
The DREAM implant system integrates three hardware modules: (1) a microdrive that can carry all standard silicon probes, allowing experimenters to adjust recording depth across a travel distance of up to 7 mm; (2) a three-dimensional (3D)-printable, open-source design for a wearable Faraday cage covered in copper mesh for electrical shielding, impact protection, and connector placement, and (3) a miniaturized head-fixation system for improved animal welfare and ease of use. The corresponding surgery protocol was optimized for speed (total duration: 2 h), probe safety, and animal welfare.
The implants had minimal impact on animals&#39; behavioral repertoire, were easily applicable in freely moving and head-fixed contexts, and delivered clearly identifiable spike waveforms and healthy neuronal responses for weeks of post-implant data collection. Infections and other surgery complications were extremely rare.
As such, the DREAM implant system is a versatile, cost-effective solution for chronic electrophysiology in mice, enhancing animal well-being, and enabling more ethologically sound experiments. Its design simplifies experimental procedures across various research needs, increasing accessibility of chronic electrophysiology in rodents to a wide range of research labs.

Here, we introduce a lightweight, cost-effective probe implant system for chronic electrophysiology in rodents optimized for ease of use, probe recovery, experimental versatility, and compatibility with behavior.

Chronic electrophysiological recordings in rodents have significantly improved our understanding of neuronal dynamics and their behavioral relevance. ...

Extracting the Cochlea from a Human Temporal Bone: A Cadaveric Protocol

The extraction of the cochlea from a cadaver human temporal bone may be required for different studies of the inner ear. For histological evaluations, the inner ear must be extracted from the temporal bone to facilitate histologic processing; likewise, some micro-computed tomography devices are too small to accommodate the complete temporal bones; additionally, the image quality can be enhanced when the cochlea is isolated.
The inner ear is located within the petrous part of the temporal bone. The inner ear can be divided into the osseous labyrinth or otic capsule and the membranous labyrinth inside the otic capsule. Furthermore, the inner ear can be divided into the vestibular system (the semicircular canals and the vestibule) and the cochlea. The appreciation of the location and orientation of the cochlea within the temporal bone is difficult, as it is embedded within bony structures and thus cannot be directly visualized. Nevertheless, there are distinct anatomical structures that can help guide the process to allow a reliable drill-out of the cochlea. The landmarks in the posterior parts of the cochlea are the facial nerve, semicircular canals, and the vestibule. In the middle, the inferior borders of the cochlea are identified by the round window and the basal turn of the cochlea. In the anterior border, one encounters the carotid artery; the landmark for the superior border is the genicular ganglion (GG) of the facial nerve. The medial structures are determined by the locations of the internal auditory canal, the superior semicircular canal, and the canal of the internal carotid artery.
In this article, we present a method for extracting the cochlea reliably out of the temporal bone by drill-out while following several anatomical landmarks.

This article presents a reliable method for extracting the human cochlea from the cadaver temporal bone by drill-out while following distinct anatomical landmarks.

The extraction of the cochlea from a cadaver human temporal bone may be required for different studies of the inner ear. For histological evaluations, the ...

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.