The authors thank Isobel Bowring for proofreading the article, and Nele Ruysschaert for the help with information on the anesthesia.

This protocol is used for a randomized controlled trial that is currently being carried out in the Netherlands. The trial compares endolymphatic duct blockage (EDB) to endolymphatic sac decompression (ESD)9. The protocol was approved by the medical ethics committee METC Leiden-Den Haag-Delft (number P20.118) and the board of the hospital, as well as the hospital&#39;s research ethics committee (Haga Hospital Research Board, T20-108). All patients who participated in the trial where this protocol is followed have provided written informed consent.&#160;The results of this trial are expected in late 2024.
1. Preoperative procedures
<ol>
	<li>Patient selection
	<ol>
		<li>Verify that all the diagnostic criteria for definite Meniere&#39;s disease according to the AAO-HNS criteria are met1. To be included in this study, select patients who have suffered more than three attacks in the previous 6 months. The attacks must meet the diagnostic criteria of an attack1.</li>
		<li>Rule out all the criteria of vestibular migraine reported by the consensus of the B&#225;r&#225;ny Society and the International Headache Society10.</li>
		<li>Due to its invasive nature, only consider this treatment in patients who have failed conservative treatment. This includes at least two intratympanic injections with (any type of) steroid and at least 6 weeks apart.</li>
		<li>In case of deafness of the contralateral ear, carefully consider this treatment option, as the effect of this surgery on hearing is not clear. This was reported to concern 2% of the patients by Saliba et al.5</li>
	</ol>
	</li>
	<li>Informed consent
	<ol>
		<li>Inform the patient about: potential benefits: reduction of vertigo attacks; risks: general risks of surgery (bleeding, wound infection, risks of general anesthesia), damage to the inner ear (deafness, disequilibrium), facial nerve damage, cerebrospinal fluid (CSF) leakage, and meningitis; and unknowns: effect on hearing loss, tinnitus, and aural fullness are currently unknown. The procedure seems to spare hearing function5,11, but the literature is limited.</li>
	</ol>
	</li>
	<li>Preoperative testing
	<ol>
		<li>Perform an MRI scan to rule out a retro-cochlear lesion, a CT scan, a hearing test (PTA), and electrocochleography preoperatively. Consider performing vestibular tests if the patient has complaints of chronic vertigo related to head movement.</li>
		<li>Check the CT scan for anomalies in the area of surgery, such as a high-riding jugular bulb. If a high-riding jugular bulb is present, this should be taken into account when operating. Also, assess the course of the vestibular aqueduct.</li>
	</ol>
	</li>
	<li>Consider using an operation room that is equipped with a CT scan.</li>
</ol>
2. Operative procedures
<ol>
	<li>Setting up the operation room
	<ol>
		<li>Place the anesthesia unit at the foot end of the patient to avoid problems with the CT scan.</li>
		<li>Place the control panel of the intraoperative neuromonitoring system as far away from the head of the patient as possible to avoid problems with the CT scan.</li>
	</ol>
	</li>
	<li>Perform regular safety checks and induce general anesthesia.
	<ol>
		<li>Using target-controlled anesthesia (TGA), administer propofol (2.5-4 mcg/mL) and remifentanil (0.3-0.5 mg/kg).</li>
		<li>Administer a low dose of the muscle relaxant rocuronium (0.3-0.5 mg/kg), as the facial nerve monitor is used during surgery.</li>
		<li>Intraoperatively, administer 4 mg of ondansetron and 4 mg of dexamethasone to prevent nausea postoperatively.</li>
		<li>Monitor the depth of anesthesia based upon hemodynamics-pulse, blood pressure, and CO2.</li>
		<li>Prepare analgesics to be administered at the end of surgery: 1 g of metamizole or 75 mg of diclofenac.</li>
	</ol>
	</li>
	<li>Position the patient as for a mastoidectomy: rotate the head to the contralateral side (45&#176; maximum) with the neck slightly in flexion.</li>
	<li>Preparation for surgery
	<ol>
		<li>If necessary, shave any hair around the ear. Check to confirm if the tympanic membrane is intact.</li>
		<li>Sterilize the outer ear, the external ear canal, and the skin around the ear with chlorohexidine or povidone. Infiltrate the retro-auricular skin with 2% lidocaine/1:80,000 adrenaline.</li>
		<li>Cover the patient with sterile sheets, leaving the surgery area free.</li>
	</ol>
	</li>
	<li>Surgery
	<ol>
		<li>Make a retroauricular incision of 7-8 cm just behind the auricle using a scalpel. Spread the subcutaneous layers until the temporal muscle is visible at the cranial side.</li>
		<li>Make a Palva flap (anterior based) by making a U-shaped incision to the petrous bone. Be careful not to damage the temporal muscle.</li>
		<li>Using forceps and a raspatorium, peel the periosteum off the cortex until the external auditory canal is found.</li>
		<li>Position two spreaders in the tissue layers so that the petrous bone is exposed. Place the spreaders in a position such that their handles are away from the operation site.</li>
		<li>Perform a canal wall up mastoidectomy using the burrs. Form a triangle and burr through the cortex and identify the mastoid cells. Identify the sigmoid sinus (caudal) and dura (cranial) as landmarks.</li>
		<li>Identify the dura of the posterior fossa and the curvature of the horizontal vestibular canal. Identify the posterior semicircular canal (PSCC) and the dura mater of the posterior fossa.</li>
		<li>Identify the prominence of the horizontal semicircular canal (HSCC) to determine Donaldson&#39;s line, to approximate the position of the ES (see Figure 1).</li>
		<li>Thin the bone over the sac and the dura with diamond burrs and skeletonize the ES completely.</li>
		<li>Remove the remaining bone and expose the dura. Using an elevator, lift the dura toward the brain, exposing the medial side of the posterior canal. Identify the ES caudally as a flat, thick, white structure. The medialization of the dura exposes the ED somewhere in Donaldson&#39;s line, where it connects with the sacculus and utriculus. 
		NOTE: Be careful not to damage the duct. If the duct is damaged or ruptured, use fascia or donor pericardium to plug the leak.</li>
		<li>Using the elevator, create a site to insert the tip of the instrument to clip the duct. At this level, in order to prevent any CSF leak, take care not to traumatize the dura, which is often thin.</li>
		<li>Using an elevator, try different clip sizes to determine which clip fits best. 
		NOTE: Thinning of the bone over the sigmoid sinus may be necessary to allow introduction of the clip instrument.</li>
		<li>If a CT scan is available in the operation room, follow the subsequent steps.
		<ol>
			<li>Without closing the clip, perform a CT scan. Cover the patient with a sterile cover. Position the scan so that the complete skull is scanned.</li>
			<li>Choose the protocol 20sDCT Head Micro under 3D head and follow the activate stand movements.</li>
			<li>Choose skull base and set up in the caudal-cranial direction. Follow the necessary 3D activate stand movement steps.</li>
			<li>After performing the scan, open Preset gallery and go to Head and neck. Select the preset DynaCTHead Petrosa.</li>
			<li>Assess the images to decide whether the clip is in the correct position. Do not forget to send the images to the patient file.</li>
			<li>If the clip is not placed correctly over the ED, replace the clip and/or consider using another size.</li>
			<li>Repeat step 2.5.12.2-2.5.12.6 of the CT-scan to assess the new clip position until satisfactory.</li>
		</ol>
		</li>
		<li>Remove the clip with an elevator and place the clip in the clip applier. Place the clip over the ED and close the clip. 
		NOTE: Clipping of the duct causes traction on the involved structures and may lead to tearing of the dura. If CSF leakage occurs, use fibrin sealant and fascia or donor pericardia to close the tear in the dura.</li>
		<li>Consider using a second clip to ensure the duct is tightly blocked. Ensure that the clips are positioned at the correct location and (completely) block the ED. If there is no CT scan available, check the clip position following the subsequent steps.
		<ol>
			<li>Make an incision along the inferior edge of the ES, starting from the posterior site of the newly positioned clip toward the sigmoid sinus using a knife.</li>
			<li>If the incision opens the sac, this confirms the correct placement of the clip. If a CSF leak is observed, continue the dissection medially in order to localize the sac.</li>
			<li>Repeat this procedure until correct placement of the clip is confirmed.</li>
		</ol>
		</li>
		<li>Completion of surgery
		<ol>
			<li>Close the tissue in layers, close the Palva flap and the subcutaneous layer using an absorbable polyfilament suture (70 cm), and close the skin with an absorbable monofilament suture by applying a subcutaneous continuous suture (70 cm).</li>
			<li>Cover the closed skin with plasters and a bandage. Wrap one bandage around the head to keep the plasters in place.</li>
			<li>Administer the analgesic that was prepared in step 2.2.5.</li>
		</ol>
		</li>
	</ol>
	</li>
</ol>
3. Postoperative care
<ol>
	<li>Examination of the patient after surgery
	<ol>
		<li>Determine if nystagmus is present. If spontaneous nystagmus is present, determine whether the fast phase is toward the operated ear or toward the contralateral side. If the fast phase is in the direction of the operated side, this indicates hyperexcitation of the operated ear and may be due to stimulation of the labyrinth from the surgery. This nystagmus is expected to fade out. If the fast phase is in the direction of the non-operated ear, this may indicate loss of function of the operated ear.</li>
		<li>Scratch the bandages to screen for loss of cochlear function. If the scratching on the operated side is not heard, and loss of hearing is suspected, consider administering steroids (1 mg/kg/day) for 7 days.</li>
		<li>Consider performing a bone conduction hearing on the day after surgery. If hearing loss is noticed, consider administering steroids (1 mg/kg/day) for 7 days.</li>
		<li>In case of pain, prescribe 1 g of acetaminophen (paracetamol) four times a day, and add 50 mg of diclofenac three times a day. In case of nausea, prescribe 4 mg of ondansetron.</li>
	</ol>
	</li>
	<li>Keep the patient under observation until they are mobile, can eat and drink, and can go to the toilet independently.</li>
	<li>Consider dismissal on the day of surgery if the patient feels confident and has assistance at home. If the patient does not feel well, or feels dizzy or unbalanced, keep the patient overnight for observation.
	<ol>
		<li>Upon dismissal, instruct the patient to keep the bandage around the head for 24 h, as well as the plasters underneath, keeping them dry until the next visit to the surgeon, 7 days after surgery.</li>
		<li>If bleeding or leakage of clear fluid occurs, ask the patient to contact the department immediately. In case of fever or excessive pain, ask the patient to contact the department.</li>
		<li>Explain what the patient can expect after the surgery-dizziness and vertigo attacks; dizziness and/or vertigo are common in the weeks after surgery. Inform the patient that having a vertigo attack does not mean that the surgery has failed. With regards to pain, most patients do not experience much pain after surgery, but acetaminophen (paracetamol) can be taken.</li>
	</ol>
	</li>
</ol>
4. Postoperative visits
<ol>
	<li>Ask the patient to visit the surgeon 1 week after surgery. During this visit, remove the bandages and assess the wound. In case of signs of infection, prescribe antibiotics. In case of motion-related, short-lasting vertigo, consider that it might be benign paroxysmal positional vertigo (BPPV). Perform the Dix-Hallpike test, and if positive, carry out the Epley maneuver.</li>
	<li>Plan a PTA 6 weeks after surgery. Plan a follow-up visit 6 months and 1 year after surgery. Perform a hearing test at each visit.</li>
</ol>

<ol>
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C., Cay&#233;-Thomasen, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+human+endolymphatic+sac+expresses+natriuretic+peptides.">The human endolymphatic sac expresses natriuretic peptides.</a> Laryngoscope. 127 (6), E201-E208 (2017).</li><li>Takumida, M., Bagger-Sj&#246;b&#228;ck, D., Wers&#228;ll, J., Rask-Andersen, H., Harada, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Three-dimensional+ultrastructure+of+the+endolymphatic+sac.">Three-dimensional ultrastructure of the endolymphatic sac.</a> Archives of Oto-Rhino-Laryngology. 244 (2), 117-122 (1987).</li><li>Friis, M., Thomsen, A. R., Poulsen, S. 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The authors have nothing to declare.

EDB is a potential new treatment modality, aiming to reduce vertigo attacks while sparing inner ear function in patients with intractable MD. In the current literature, the results seem promising, but little data is available.
Rationale of the technique 
Targeting the ES for relieving MD symptoms has been controversial for some decades. In the past, the general belief has been that the (ES) mainly has a role in the resorption of endolymph13,</...

M&#233;ni&#232;re&#39;s disease (MD) is an incapacitating disease characterized by vertigo bouts, aural symptoms, and hearing loss1. Endolymphatic hydrops in the inner ear is present in patients with MD, but the exact aetiology of the disease remains unclear. In most patients, the symptoms resolve over time2; despite this, the majority of patients seek active treatment because of the unpredictable pattern of attacks.
Treatment for MD aims to reduce vertigo attacks. In the past century, different treatment modalities have been proposed, both surgical and non-surgical. Destructive surgical interventions, such as labyrinthectomy or vestibular neurotomy, are effective in controlling vertigo but cause deafness and a loss of vestibular function on the operated ear3,4. Surgeries on the endolymphatic sac (ES) have been studied, such as decompression and shunting of the sac, but neither of the proposed interventions have been proven to be more effective than placebo surgery4.
In 2015, Saliba et al. published the results of a randomized controlled trial comparing a new technique, endolymphatic duct blockage (EDB), to endolymphatic sac decompression (ESD)5. The trial yielded promising results, with 96.5% of the patients in the EDB group being free of vertigo attacks after 2 years. The rationale behind this technique is that the ES is at least partially responsible for the disturbed homeostasis of endolymph and produces an overload of endolymph due to increased production. By blocking the endolymphatic duct (ED), the surplus of endolymph that is generated in the sac is hindered from flowing to the rest of the inner ear. This hypothesis is supported by histological studies6,7,8.
Whether EDB is the appropriate treatment for an individual patient depends on various factors. The patient&#39;s preference and the surgeon&#39;s preference play a role, but local health care regulations may also influence treatment choice. In our center, EDB is only considered in patients who suffer vertigo attacks despite treatment with intratympanic (IT) injections with corticosteroids, and if vestibular migraine has been ruled out. EDB is especially suitable for patients with good hearing function who reject ablative treatment. This article describes the surgical steps of this new technique and discusses the literature that is currently available.

<table><tbody><tr><td>Adson Forceps, Delicate, Smooth, 1 x 2 teeth, 12 0mm</td><td>Aesculap BV</td><td>BD511R</td><td></td></tr><tr><td>Adson-Brown Tissue Forceps, 7 x 8 teeth, 120 mm</td><td>Aesculap BV</td><td>BD700R</td><td></td></tr><tr><td>Baby Adson Retractor, hinged, semi-S tip, 3 x 4 prongs blade end, 140 mm</td><td>Aesculap BV</td><td>BV085R</td><td></td></tr><tr><td>Baby Senn-Miller RetractorFlat Handle, SHARP tip, 3 PRONGS blade end, blade size 8 x 7/22 x 7, 165 mm</td><td>Aesculap BV</td><td>BT006R</td><td></td></tr><tr><td>Bien Air Nano Micromotor OsseoDUO + NANOmicromotor</td><td>Bien air</td><td>1700524-001</td><td>Electronic motor used for mastoidectomy</td></tr><tr><td>Bien air tubing set for peristaltic pump</td><td>Bien air</td><td>1100037</td><td></td></tr><tr><td>Coagulation Forceps</td><td>Aesculap BV</td><td>E700246</td><td>Used for hemostasis</td></tr><tr><td>Cord, bipolar, 4.5 m</td><td>Valleylab BV</td><td>E360150L</td><td></td></tr><tr><td>Diamond burrs 0.8x 70 to 7.0x70</td><td>Bien air</td><td></td><td></td></tr><tr><td>Ear Curette, Pointed, Double Ended, cup size LARGE, 170 mm</td><td>Aseculap BV</td><td>OG189R</td><td></td></tr><tr><td>Ethicon hechtdraad 3/0 sh-1 vicryl 70 cm</td><td>Ethicon</td><td>3006273</td><td>Suture for deeper tissue layers</td></tr><tr><td>Fibrin Sealant</td><td>Baxter BV</td><td>BE-90-01-040</td><td>Tissue glue used in case of liquor leakage</td></tr><tr><td>Gillies Skin Hook, Tip 0.5/6mm, jaw STR, SERR</td><td>Aesculap BV</td><td>OL611R</td><td></td></tr><tr><td>Gillies Tissue Forceps, Delicate, X-SERR tip, 1 x 2 teeth, 155 mm</td><td>Aesculap BV</td><td>BD660R</td><td></td></tr><tr><td>Halsted Mosquito Forceps, Delicate, CVD jaw, 125 mm</td><td>Aesculap BV</td><td>BH111R</td><td></td></tr><tr><td>Handpiece for burr</td><td>Bien air</td><td>1600830-001</td><td></td></tr><tr><td>Hartmann Ear Forceps , Tip 4 mm, jaw STR</td><td>Aesculap BV</td><td>OG329R</td><td></td></tr><tr><td>Hartmann-Wullstein Ear Forceps</td><td>Aesculap BV</td><td>OF410R</td><td></td></tr><tr><td>Hejek Mallet, &amp;Oslash;27 220 mm</td><td>Aesculap BV</td><td>FL044R</td><td></td></tr><tr><td>Horizon Metal Ligation System - Clips size MICRO, SMALL, MEDIUM</td><td>Teleflex Medical</td><td>1201, 2200, 5200</td><td>Titanium clip used for blockage of endolymphatic duct</td></tr><tr><td>House Ear Curette</td><td>Aesculap BV</td><td>OG182R</td><td>Double Ended, cup size (mm) 1.5/1.8, tip ANG</td></tr><tr><td>Lucae Bayonet Forceps</td><td>Aesculap BV</td><td>BD878R</td><td>SERR tip, 140mm</td></tr><tr><td>Lucae Bayonet Forceps</td><td>Aesculap</td><td>BD878R</td><td>SERR tip, 140mm</td></tr><tr><td>Lucae Ear Hook Button</td><td>Aesculap BV</td><td>OF278R</td><td>Hook end SMALL, tip SHARP, 130mm</td></tr><tr><td>Mayo Dissecting Scissors</td><td>Aesculap BV</td><td>BC587R</td><td>Round Blade, B/B tip, CVD blade, 165mm</td></tr><tr><td>Mayo Dissecting Scissors, Round Blade, B/B tip, CVD blade, 165 mm</td><td>Aesculap BV</td><td>BC587R</td><td></td></tr><tr><td>McIndoe Thumb Forceps, Delicate</td><td>Aesculap BV</td><td>BD236R</td><td>SERR tip, 150 mm</td></tr><tr><td>Micro Adson Forceps, Delicate, SERR with platform tip Tip, 12 cm</td><td>Aesculap BV</td><td>BD220R/425.112</td><td></td></tr><tr><td>Monocryl 4-0 FS-2. 70 cm</td><td>Ethicon</td><td>Y422H</td><td>Suture for skin</td></tr><tr><td>NIM response 3.0</td><td>Medtronic</td><td>NIM4CM01</td><td>Nerve monitoring system</td></tr><tr><td>OSSEODUO control unit</td><td>Bien air</td><td>1600513-001</td><td></td></tr><tr><td>Paired Subdermal electrodes with subdermal ground electrode and subdermal stim return, 2 channel</td><td>Medtronic Xomed</td><td>8227410</td><td></td></tr><tr><td>Scalpel Handle #3&amp;nbsp; F/ Blades</td><td>Aesculap BV</td><td>BB070R</td><td></td></tr><tr><td>Steel burrs 0.8x 70 to 7.0x 70</td><td>Bien air</td><td></td><td></td></tr><tr><td>Volkmann Curette, tip size 3.6 mm, 170 mm</td><td>Aesculap BV</td><td>FK631R</td><td></td></tr><tr><td>Watertight, 2-button multifunction pedal</td><td>Bien air</td><td>1600517-001</td><td></td></tr><tr><td>Williger Bone Elevator, blade 6, 160 mm</td><td>Aesculap BV</td><td>FK300R</td><td></td></tr><tr><td>Wire bending forceps, curved downards, 80 mm, jaw length 3.50 mm, with tubular shaft</td><td>McGee</td><td>OG359R</td><td>Used to close clip</td></tr><tr><td>Wullstein Retractor, sharp tip, 3 x 3 prongs blade end, 130 mm</td><td>Aesculap BV</td><td>BV076R</td><td></td></tr></tbody></table>

endolymphatic duct blockage as a surgical treatment option for m&#233;ni&#232;re's disease

Endolymphatic duct blockage is a relatively new treatment option for M&#233;ni&#232;re's disease, aiming to reduce vertigo attacks while sparing hearing and equilibrium. After a regular mastoidectomy, the posterior semicircular canal is identified, and Donaldson's line is determined. This is a line through the horizontal semicircular canal, crossing the posterior semicircular canal. The endolymphatic sac is usually found at this site under the posterior semicircular canal. The bone of the endolymphatic sac and the dura are thinned until the sac is skeletonized, after which the endolymphatic duct is identified. The duct is then blocked with a titanium clip. Using a computerized tomography (CT) scan, the position is confirmed. Follow-up visits take place 1 week, 6 weeks and 1 year after surgery. To this day, only one prospective trial assessing this method has been conducted, comparing this new method to endolymphatic sac decompression. Results of the duct blockage are promising, with 96.5% of the patients free of vertigo after 2 years. However, further research is required.

Surgical factors 
This procedure was performed by one of the authors (HB) in both the Haga Hospital and the Antwerp University Hospital. Data from the Antwerp University Hospital could not be retrieved, but approximately 100 patients underwent EDB at that location. In the Haga Hospital, EBD is only allowed in the context of the aforementioned trial. In this trial, surgery was performed on 38 patients. Due to the blinded character of the trial, it is unknown how many and which of these patients under...

Watch this Scientific Journal Video about Endolymphatic Duct Blockage as a Surgical Treatment Option for MÃ©niÃ¨re's Disease at JoVE.com

Endolymphatic Duct Blockage as a Surgical Treatment Option for M&#233;ni&#232;re's Disease

Endolymphatic duct blockage is a relatively new surgical method for patients suffering from M&#233;ni&#232;re's disease. Following a regular mastoidectomy, the endolymphatic duct is identified and ligated using a regular titanium hemoclip. The effectiveness of this procedure is currently being assessed in a randomized trial.

Endolymphatic duct blockage is a relatively new treatment option for M&#233;ni&#232;re's disease, aiming to reduce vertigo attacks while sparing hearing ...

endolymphatic-duct-blockage-as-surgical-treatment-option-for-mnire-s

Research

JoVE Journal

Medicine

1.1K Views.  Haga Hospital. Endolymphatic duct blockage is a relatively new surgical method for patients suffering from Ménière's disease. Following a regular mastoidectomy, the endolymphatic duct is identified and ligated using a regular titanium hemoclip. The effectiveness of this procedure is currently being assessed in a randomized trial. 

Video: Endolymphatic Duct Blockage as a Surgical Treatment Option for Ménière's Disease

Canalostomy As a Surgical Approach to Local Drug Delivery into the Inner Ears of Adult and Neonatal Mice

Local delivery of therapeutic drugs into the inner ear is a promising therapy for inner ear diseases. Injection through semicircular canals (canalostomy) has been shown to be a useful approach to local drug delivery into the inner ear. The goal of this article is to describe, in detail, the surgical techniques involved in canalostomy in both adult and neonatal mice. As indicated by fast-green dye and adeno-associated virus serotype 8 with the green fluorescent protein gene, the canalostomy facilitated broad distribution of injected reagents in the cochlea and vestibular end-organs with minimal damage to hearing and vestibular function. The surgery was successfully implemented in both adult and neonatal mice; indeed, multiple surgeries could be performed if required. In conclusion, canalostomy is an effective and safe approach to drug delivery into the inner ears of adult and neonatal mice and may be used to treat human inner ear diseases in the future.

Here we describe canalostomy procedure which allows local drug delivery into the inner ears of adult and neonatal mice through the semicircular canal with minimum damage to hearing and vestibular function. This method can be used to inoculate viral vectors, pharmaceuticals, and small molecules into the mouse inner ear.

Local delivery of therapeutic drugs into the inner ear is a promising therapy for inner ear diseases. Injection through semicircular canals (canalostomy) ...

Genetics

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

Transcanalicular Diode Laser-assisted Dacryocystorhinostomy for the Treatment of Primary Acquired Nasolacrimal Duct Obstruction

Today&#39;s gold standard in the treatment of infrasaccal primary acquired nasolacrimal duct obstruction (PANDO) is external dacryocystorhinostomy (DCR), a relatively invasive procedure that can be performed after failure of recanalizing treatments. However, with progress in the field of diode laser technology, new approaches have emerged. Laser-assisted transcanalicular DCR with subsequent bicanalicular silicon intubation is a new option showing great promise as a viable minimally invasive procedure. Under permanent endoscopic visual control from the nasal cavity, a diode laser fiber is inserted into the lacrimal sac and laser energy is applied to create a bony ostium between the lacrimal sac and the nasal cavity. Since no skin incision needs to be made, advantages of this method comprise the sparing of the skin as well as the medial palpebral structures and the physiological palpebral-canalicular pump mechanism. The duration of surgery as well as reconvalescence is generally shorter than with external DCR. Complications include silicon tube prolapse, mild swelling and, rarely, canalicular infection and thermal injury. One-year functional success rates, defined as complete resolution of symptoms and ostium patency, are high, yet still range behind those of external DCR. However, secondary external DCR after failure of laser-assisted DCR can be performed without difficulty. Thus, laser-assisted transcanalicular DCR is a valid option that should be considered as a second-step procedure after failure of recanalization procedures and before external DCR.

The goal of this protocol is to present transcanalicular laser-assisted dacryocystorhinostomy as a minimally invasive approach in the treatment of primary acquired nasolacrimal duct obstruction.

Today&#39;s gold standard in the treatment of infrasaccal primary acquired nasolacrimal duct obstruction (PANDO) is external dacryocystorhinostomy (DCR), ...

Surgical Labyrinthectomy of the Rat to Study the Vestibular System

To study the vestibular system or the vestibular compensation process, a number of methods have been developed to cause vestibular damage, including surgical or chemical labyrinthectomy and vestibular neurectomy. Surgical labyrinthectomy is a relatively simple, reliable, and rapid method. Here, we describe the surgical technique for rat labyrinthectomy. A postauricular incision is made under general anesthesia to expose the external auditory canal and the tympanic membrane, after which the tympanic membrane and the ossicles are removed without the stapes. The stapes artery, which is located between the stapes and the oval window, is a vulnerable structure and must be preserved to obtain a clear surgical field. A hole to fenestrate the vestibule is made with a 2.1-mm drill bur superior to the stapes. Then, 100% ethanol is injected through this hole and aspirated several times. Meticulous dissection under a microscope and careful bleeding control are essential to obtain reliable results. Symptoms of vestibular loss, such as nystagmus, head tilting, and a rolling motion, are seen immediately after surgery. The rotarod or rotation chair test can be used to objectively and quantitatively evaluate the vestibular function.

This protocol describes the surgical labyrinthectomy of a rat, which is a useful method for studying the vestibular system.

To study the vestibular system or the vestibular compensation process, a number of methods have been developed to cause vestibular damage, including ...

A Revised Surgical Approach to Induce Endolymphatic Hydrops in the Guinea Pig

Endolymphatic hydrops is an enlargement of scala media that is most often associated with Meniere&#39;s disease, though the pathophysiologic mechanism(s) remain unclear. In order to adequately study the attributes of endolymphatic hydrops, such as the origins of low-frequency hearing loss, a reliable model is needed. The guinea pig is a&#160;good model because it hears in the low-frequency regions that are putatively affected by endolymphatic hydrops. Previous research has demonstrated that endolymphatic hydrops can be induced surgically via intradural or extradural approaches that involve drilling on the endolymphatic duct and sac. However, whether it was possible to create an endolymphatic hydrops model using an extradural approach that avoided dangerous drilling on the endolymphatic duct and sac was unknown. The objective of this study was to demonstrate a revised extradural approach to induce experimental endolymphatic hydrops at 30 days post-operatively by obliterating the endolymphatic sac and injuring the endolymphatic duct with a fine pick. The sample size consisted of seven guinea pigs. Functional measurements of hearing were made and temporal bones were subsequently harvested for histologic analysis. The approach had a success rate of 86% in achieving endolymphatic hydrops. The risk of cerebrospinal fluid leak was minimal. No perioperative deaths or injuries to the posterior semicircular canal occurred in the sample. The presented method demonstrates a safe and reliable way to induce endolymphatic hydrops at a relatively quick time point of 30 days. The clinical implications are that the presented method provides a reliable model to further explore the origins of low-frequency hearing loss that can be associated endolymphatic hydrops.

This article demonstrates an extradural approach to obliterate the guinea pig endolymphatic sac and injure the endolymphatic duct with a fine pick in order to induce experimental endolymphatic hydrops.

Endolymphatic hydrops is an enlargement of scala media that is most often associated with Meniere&#39;s disease, though the pathophysiologic mechanism(s) ...

Neuroscience

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 ...

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. ...

Microvascular Doppler Assisted Microsurgical Denervation of the Spermatic Cord in Treating Chronic Orchialgia

Chronic orchialgia is a common disease in department of urology and andrology. The etiology is complex, and the treatment is difficult. In severe cases, orchiectomy is even necessary. In recent years, microsurgical denervation of the spermatic cord (MDSC) is a minimally invasive and effective surgical method for the treatment of chronic orchialgia. Its greatest advantage is to preserve the testis and epididymis, avoid the possible organ resection. The key of the operation is to dissect all the fibrous tissues in the spermatic cord, while protecting the arteries (especially the testicular arteries) and several lymphatic vessels. Combined with the use of microvascular doppler in the operation, when separating the structure of spermatic cord under the microscope, the testicular arteries can be objectively and accurately protected (pulse &#8220;whistle&#8221; sound can be heard when the microvascular doppler probes the arterial surface), while artery injury and venous missed ligation can be avoided. The postoperative blood supply of the testis is also maximumly safeguarded. At the same time, we can be more fearless to cut the cremaster muscle, fatty and connective tissues surrounding the spermatic cord blood vessels and vas deferens after the arteries and lymphatic vessels being accurately protected under the microscope, finally achieve the spermatic cord completely &#34;skeletonized&#34; (only the testicular arteries, lymphatic vessels and vas deferens remained after the surgery). Thus we can better ensure the clinical curative effect (denervation thoroughly), avoid serious complications (testicular atrophy), and achieve better surgical results.

Here, we present a protocol to treat chronic orchialgia by microsurgical denervation of the spermatic cord. Combined with the use of a microvascular doppler, the procedures can be more easily implemented.

Chronic orchialgia is a common disease in department of urology and andrology. The etiology is complex, and the treatment is difficult. In severe cases, ...

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 ...

Harvest of Vestibular End-Organs under Physiologic Conditions during Labyrinthectomy

The living human inner ear is challenging to study because it is encased within dense otic capsule bone that limits access to biological tissue. Traditional temporal bone histopathology methods rely on lengthy, expensive decalcification protocols that take 9-10 months and reduce the types of tissue analysis possible due to RNA degradation. There is a critical need to develop methods to access fresh human inner ear tissue to better understand otologic diseases, such as M&#233;ni&#232;re's disease, at the cellular and molecular level. This paper describes a technique for the harvest of human vestibular end organs from a living donor under physiologic conditions. An individual with M&#233;ni&#232;re's disease and 'drops attacks' that were refractory to intratympanic gentamicin injection underwent labyrinthectomy. A traditional mastoidectomy was first performed, and the horizontal and superior semicircular canals (SCC) were identified. The mastoid cavity was filled with a balanced salt solution so that the labyrinth could be opened under more physiologic conditions to preserve cellular integrity. A zero-degree endoscope fit with a lens-cleaning sheath irrigation system was used to visualize the submerged mastoid cavity, and a 2 mm diamond burr was used to skeletonize and open the horizontal and superior SCCs, followed by the vestibule. The ampullae and portion of the canal ducts for the superior and lateral SCCs were harvested. The utricle was similarly harvested. Harvested tissue was immediately placed in an ice-cold buffer and then fixed for one hour in 4% paraformaldehyde in phosphate-buffered saline (PBS). The tissue was rinsed several times in 1x PBS and stored for 48 h at 4 &#176;C. The tissue samples underwent immunostaining with a combination of primary antibodies against tenascin-C (Calyx), oncomodulin (streolar hair cells), calretinin (Calyx and Type II hair cells), synaptic vesicle protein 2 (efferent fibers and boutons), &#946;-tubulin 1 (Calyx and afferent boutons), followed by incubation with fluorophore-conjugated secondary antibodies. The tissue samples were then rinsed and mounted for confocal microscopy examination. Images revealed the presence of ampullar and macular hair cells and neural structures. This protocol demonstrates that it is possible to harvest intact, high-quality human inner ear tissue from living donors and may provide an important tool for the study of otologic disease.

Here, we describe a technique for harvesting human vestibular end-organs under physiologic conditions during labyrinthectomy and their analysis using immunostaining.

Endolymphatic Duct Blockage as a Surgical Treatment Option for Ménière's Disease

Summary

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