Endoscopic Ear surgery

Overview

In contrast to the simplicity with which the endoscope has been adopted for the practice of sinus surgery in recent decades, the use of the endoscope for middle ear surgery has been a very controversial topic within the field of otology. Currently, surgical operating microscopes are mostly utilized to examine the ear.

However, while modern equipment provides exceptional imaging of the surgical field while allowing both binocular vision and leaving both the surgeon's hands free, visualisation of cavities located far down the canal in the middle ear is clearly limited. 

In contrast to the otomicroscope, the otoendoscope's source of light is located at the distal end of the instrument, ensuring optimum visibility. Angled lenses provide a broader view of the operating region. The external ear canal (EAC) has been turned into an operational portal thanks to transcanal endoscopic procedures.

However, because the tool occupies part of the ear canal, it is only possible to operate with one hand, making dissection more difficult, especially when the surgical field gets flooded with blood. Although a variety of endoscope holders that should allow bimanual surgery have been created, the technological problems in establishing a holder with adequate precision for use in middle ear surgery have yet to be surmounted.Furthermore, owing to the heat generated by the endoscope when operating in the middle ear, concerns have been raised with regard to long-term safety aspects.

Initially, rigid endoscopes were used within the ear to assist microscopes in making diagnosis. Endoscopes' improved visual clarity, wide-angle imaging, and greater lighting made pictures of the middle ear cavity reasonably easy to obtain using a transmastoid, transtubal, or transtympanic route. As a result, previous studies on the use of the endoscope in middle ear surgery focused on the structures within the middle ear.

Following on from these anatomical investigations, surgeons investigated the use of endoscopes as experimental assistants in cholesteatoma revision surgery in the 1990s, with the goal of determining their usefulness in identifying remaining or recurring disease.

However, during the last 15 years, there has been an increasing trend to employ the endoscope as an observation device as well as the only equipment adequate for imaging the middle ear and surgical dissection, similar to how paranasal sinus surgeries are now conducted. Endoscopes are used in ear surgery for imaging as well as surgical procedures.

Benefits of Ear Endoscopic Procedures

There are several advantages of using endoscopy for ear surgeries. These include:

No incision: There is generally less pain and a quicker healing time because there is no cut behind your ear. Furthermore, you will not have a scar.

Your doctor has a better view: Because the endoscope is flexible, your doctor can view what's causing your ear troubles more clearly. Because a typical scope does not bend, physicians can only view what is in a straight line when using the traditional technique.

Your doctor can treat different problems: Since the endoscope can get into all the tiny recesses of the middle ear, doctors are able to perform surgeries that aren’t possible with the traditional approach.

You can see the issue as well. Your doctor will capture high-definition photos of your inner ear during an endoscopic ear treatment. As a consequence, your doctor can utilize the photos to describe what they observe within your ear, the therapy they propose, or the surgical results.

Safety aspects of Ear Endoscopic Surgery

It has been stated that, given the notable absence of data to the contrary, employing an endoscope in patients of any age has established an appropriate safety profile. Similarly, there is undeniable potential for the endoscope to be employed in the identification of ear pathology. Based on the information acquired thus far, it is acceptable to recommend that the endoscope be used frequently for inspection, both intra-operatively and in the clinic.

So far, the reviews of surgical endoscopic ear surgery have been insufficient. This field of study is still in its early stages, and more information must be acquired before the endoscope can be considered a viable alternative for the microscope. Endoscopic ear surgery is now performed by a small number of surgeons, presumably after specialized training. With the potential benefits in mind, experimental trials of endoscopic ear surgery may lead to a greater variety of uses for the procedure, preferably accompanied by a broader range of published research.

The tip of the endoscope has the potential to induce thermal tissue harm since light energy is passed from the source to the tissue. It is highly encouraged, in accordance with the manufacturer's guideline, to keep the light intensity below 50%. 

Uses of Ear Endoscopic Surgery

Experienced specialists use TEES to treat children and adults with conditions such as:

1. Acoustic neuroma: This noncancerous tumor, also known as vestibular schwannoma, develops on the vestibular nerve, which connects the inner ear to the brain. In some circumstances, TEES can be utilized to remove acoustic neuromas.
2. Cerebrospinal fluid (CSF) leak: The fluid that surrounds and protects the brain and spinal cord might leak through a hole in the meninges, the brain's membrane. CSF leaks that produce ear problems are most commonly found in the temporal bone along the sides and base of the skull. CSF leaks can be congenital flaws that exist from birth or acquired leaks that occur as a result of trauma, surgery, infection, or spontaneously.
3. Cholesteatoma: In the middle ear, a benign skin cyst composed of skin and dead skin cells can form. Cholesteatomas can be congenital, or they can develop as a result of an ear injury or persistent ear infections. TEES is frequently used to treat early cholesteatomas because it provides improved visibility, eliminates the need for an incision behind the ear, and allows for a faster recovery.
4. Cholesterol granuloma: A rare, benign cyst can occur in the petrous apex, a section of skull bone near the middle ear. These cysts contain fluid, cholesterol, and other lipids.
5. Congenital or acquired ossicular chain fixation or discontinuity: The malleus (hammer), incus (anvil), and stirrup are three little bones in the middle ear (the ossicles) (stapes). One or more ossicles can be repaired (fused together), deformed, or absent when a person is born. Trauma, surgery, infection, or malignancies can all result in acquired diseases. Because the ossicles carry vibrations from the eardrum to the inner ear, any issues with them might result in hearing loss.
6. Facial nerve disorders: These problems can develop as a result of an infection, an accident, or another condition, such as a tumor. Facial nerve tumors, such as schwannoma or hemangioma, an aberrant cluster of blood vessels, can press on facial nerves, causing symptoms such as twitching or facial paralysis. TEES can be used to treat face nerve problems on occasion.
7. Osteoma: A benign, slow-growing tumor can form in the bones around the ear canal. Osteomas can result in pain, hearing loss, and recurrent ear infections.
8. Otosclerosis: In this inherited disease, the stapes bone becomes fixed and no longer vibrates to transmit sounds to the inner ear.
9. Paraganglioma: This unusual tumor, also known as a glomus tumor, most commonly originates in the temporal bone or the middle ear and is usually benign, presenting with patients feeling their heartbeat in their ear. Many glomus tympanicum tumors can be removed using TEES.
10. Ruptured eardrum: A hole or tear in the eardrum, also known as a tympanic membrane perforation, can occur as a result of a foreign object in the ear, head trauma, a middle ear infection, or fast pressure fluctuations, such as those experienced during air travel or scuba diving.
11. Temporal bone encephalocele: An encephalocele arises when brain tissue protrudes through a hole in the skull, which can happen as a result of an injury, surgery, or an ear infection. A temporal bone encephalocele develops in the skull bone along the sides and base of the head.
12. Tympanosclerosis: Chronic ear infections can cause scar tissue, calcium deposits, or new bone tissue to form in the middle ear. When the condition affects only the eardrum, it is called myringosclerosis.

Is Ear Endoscopic Surgery difficult?

The surgeon may face some challenges as follow:

1. Poor bleeding management: in early cases spending time to control the bleeding is one of the most important factors in getting comfortable with the endoscopic methods
2. Trauma to the canal with angled scope and instrument movement: early on with angled scope insertion this should be performed in a two handed manner. Slowly progressing to single handed making sure to identify and treat any canal trauma.
3. Understanding the limitations of the equipment: the endoscopic otologic equipment is slightly different to the usual otologic tray and takes time to understand its limitations, such the reach and angulation of Thomassin instruments.
4. Short tympanomeatal flap: Because of the decreased depth perception in EES, an untrained otologist may create a tympanomeatal flap that is too short for the desired surgery. A sufficient flap length is especially crucial when doing an extensive atticotomy, for example. In early EES, the diameter of the round knife (about 3 mm) can be utilized as a reference to obtain a sufficient tympanomeatal flap length. In most circumstances, a 5–6 mm tympanomeatal flap, roughly twice the diameter of the round knife, is sufficient.
5. Failing to convert earlier to a mastoidectomy: When first beginning the endoscopic technique, especially with attic and antral disease, the temptation is to spend a lot of time pursuing cholesteatoma in order to prevent a mastoidectomy. Consider introducing a "10-minute rule by the clock." If the surgeon is chasing the same antral disease for more than 10 minutes as monitored by the scrub nurse's clock, he considers converting to mastoidectomy.
6. Overdoing the atticotomy: Typically, a minor atticotomy combined with angled scopes provides the endoscopic surgeon with a sufficient view of the illness. The temptation is to keep extending the atticotomy when chasing posterior attic and antral disease. The issue is the reconstruction of major deformities, which is difficult following extensive atticotomies. A little atticotomy and canal wall up mastoidectomy may be preferable in some cases.

Contraindications for Endoscopic Ear Surgery

Extensive middle ear cholesteatoma involving the mastoid, presence of obstruction and exostosis in the external ear canal preventing endoscopic access, insufficient equipment availability.

How challenges & limitations are overcomed?

One of EES's biggest disadvantages, particularly among those who prefer microscopic methods, is its one-handed methodology. Similar to functional endoscopic sinus surgery (FESS), the non-dominant hand holds the endoscope while the dominant hand performs the operation, resulting in a one-handed approach. Endoscopic surgery is conducted transcanally, using the external auditory canal as a natural channel to the middle ear, reducing the loss of healthy tissue.

In microscopic ear surgery, the dominant hand suctions the operating field of blood, while the non-dominant hand conducts the great majority of the critical surgical dissection. As a result, haemostasis is critical in the context of one-handed surgical procedures. EES's minimally invasive approach promotes less local tissue stress (less dissection, fewer incisions required) and hence less bothersome bleeding. To minimize the risk, the surgeon may:

1. Take a hands-on course on EES or visit an International Working Group of Endoscopic Ear Surgery member (www.iwgees.org) to gain experience.
2. Start with a graded approach to case complexity (start with cerumen debridement, tubes, myringoplasty, and advance to tympanoplasty and cholesteatoma surgery over time).
3. Initial cases should be selected with favourable anatomy (i.e. widely patent ear canal, absence of infection / granulation tissue).
4. Start with a zero-degree endoscope, and advance to angled scopes as experience increases.
5. Proper operative positioning with arm rests to provide support for both elbows throughout the case (Figure 1) to avoid fatigue and improve manual dexterity.
6. Proper positioning of the monitor in a “neck neutral” position to avoid fatigue.
7. Trimming the ear canal hairs can limit repeated smearing of the endoscope.
8. Inject the ear canal before scrubbing to provide time for the epinephrine to work. Apply neuro-patties soaked in topical epinephrine to the bony ear canal.
9. Advocate for hypotensive anesthesia and slightly elevate the head of the bed.
10. Acknowledge that the most difficult step in EES is the elevation of the tympanomeatal flap as this causes the most bleeding.
11. If necessary when starting with the technique for the first time elevate the tympanomeatal flap with the microscope and then switch to the endoscope upon entering the middle ear.
12. Use neuro-patties or gelfoam soaked with topical epinephrine throughout the flap elevation. Irrigate with saline, remove blood from the field before application of topical epinephrine, and be patient and wait for the topical epinephrine to take effect before proceeding.
13. Consider having an experienced colleague assist with suctioning when learning EES.
14. Consider purchasing a suction round knife, an instrument that permits dissection and suction simultaneously.

Conclusion

Endoscopic ear surgery (EES) is a less invasive alternative to standard ear surgery that involves using a rigid endoscope rather than a surgical microscope to see the middle and inner ear during otologic surgery. During endoscopic ear surgery, the surgeon uses one hand to hold the endoscope and the other to work in the ear. 

Different surgical equipment must be utilized to enable for this type of single-handed surgery. Endoscopic visualization has improved thanks to high-definition video imaging and wide-field endoscopy, and since it is less invasive, EES is becoming more popular as an auxiliary to microscopic ear surgery.

Endoscopes enable for better surgical visibility. The distal portion of the equipment is illuminated and has lenses that are tilted to provide a better view of the operational region. The external ear canal (EAC) has been turned into an operational portal thanks to transcanal endoscopic procedures. EES can provide larger views, greater imaging capabilities, higher magnification, and techniques to study normally inaccessible areas of the middle ear.

EES enables surgeons to use less invasive otological methods. Endoscopic tympanoplasty has been proven to need less operating time than microscope-assisted surgery in some cases. However, there are a number of disadvantages to EES, including the fact that it is a one-handed method, that the light source may cause thermal harm, and that vision with the endoscope is severely limited if bleeding is copious.

Endoscopic ear surgery is indicated in the following issues: External ear (Canalplasty, repair of exostosis, cholesteatoma, debridement and biopsy), Middle ear (myringotomy, lateral graft tympanoplasty, retraction of the tympanic membrane, acquired cholesteatoma, congenital cholesteatoma), Inner ear/skullbase (Intracochlear schwannoma, small symptomatic neoplasms of the facial nerve in the internal auditory canal fundus), Middle cranial fossa (repair of superior canal dehiscence), Posterior fossa/cerebello-pontine angle (Establishing the existence of enduring schwannoma in the IAC fundus, localization and sealing of externalized air cells during the decompression of IAC to reduce the risk of CSF leaks).

In most cases, patients who undergo endoscopic ear surgery can usually go home the same day of their procedure. Patients who are having a tumor removed typically stay in the hospital for two to three days.