Overview of Stapedectomy
A stapes procedure, such as a stapedectomy, is aimed at improving your hearing. This is done by restoring the vibration of the fluids within a part of your ear known as the cochlea – think of this like fixing a traffic jam to improve the flow of sound. The first stapedectomy surgery, which replaces a tiny bone in the ear known as the stapes, was done back in 1892. Today, it involves using a prosthetic replacement, an idea that kickstarted in the 1950s by Doctor John Shea.
The main aim of this surgery is to improve the transmission of sound in those who have a condition called otosclerosis. Otosclerosis is a disease that stiffens the chain of tiny bones in your ear responsible for transmitting sound, due to the growth of abnormal bony tissue. The condition is the most common reason people end up losing their hearing later in life.
People with otosclerosis usually experience a gradual loss of hearing which continues to worsen over time. They might find it hard to follow conversations, more so when chewing or in noisy rooms. An ear examination might show a soft reddish glow in the middle-ear space, which doctors call the Schwartze sign.
The exact cause of otosclerosis is unclear. The disease seems to be a mix of inherited genes and environmental factors. Nine specific genes have been linked to the disease. Different populations are affected differently: it’s more common in white people, compared to African Americans, Asians, or Native Americans, and it tends to affect more women than men.
A Stapedectomy is an effective treatment for the hearing loss resulting from otosclerosis. It does this by reconstructing the sound-conducting mechanism in the ear. To measure the success of the procedure, doctors typically observe the improvement on an audiometric test, which measures the difference in hearing of sounds transmitted through bone and air.
There are two main methods of this procedure: stapedectomy and a smaller operation called small fenestra stapedotomy. While the former involves complete removal of the stapes bone, the latter makes a small hole for the placement of a prosthetic replacement. There’s no noticeable difference in outcome between these two methods – what’s most critical for success is the experience of the surgeon performing the procedure.
Anatomy and Physiology of Stapedectomy
The temporal bone, which is part of the skull, is divided into four main sections; the tympanic, squamous, petrous, mastoid, and styloid bones. Notably, the tympanic section is the area that houses the external, middle, and inner ear. If a surgeon were to work on this area, they would first come across the external ear which includes the parts of the ear we can see from the outside (the pinnae), the ear canal, and the eardrum. Behind the eardrum, we have the middle ear space – an air-filled area that’s bordered by the eardrum and the promontory (the part of the ear where the bone sticks out). A lot of ear surgeries like a stapedectomy (a surgery to improve hearing) are performed here. The oval window, a delicate membrane that separates the middle ear from the inner ear, marks the starting point of the inner ear. The inner ear, which is surrounded by dense bone, contains structures such as the cochlea, vestibule, saccule, utricle, and the three semicircular canals which are all important for hearing and balance.
The middle ear is divided up into three sections: the mesotympanum (middle section), epitympanum (upper section), and hypotympanum (lower section). It contains a chain of three small bones (ossicles) – the malleus, incus, and stapes – which help transmit sound from the eardrum to the inner ear. The lining of this space is similar to the lining of the respiratory tract as it’s connected to the eustachian tube (a tube that links the middle ear with the back of the nose). Inside a healthy middle ear, a surgeon would find structures like the manubrium of the malleus, the stapes, the chorda tympani nerve, the long process of the incus, the stapes tendon, and other smaller parts.
The epitympanum is located above the mesotympanum and is divided into a front and a back part by a bone called the “cog”. This bone is a handy marker for surgeons when they want to find the facial nerve during surgery. The back part of the epitympanum contains the top of the malleus and the body of the incus. The hypotympanum is located below the mesotympanum and is separated by the lower wall of the ear canal.
The size of the lower section of the ear can vary and it’s important for surgeons to keep that in mind as it might occasionally contain a jugular bulb (a large vein in your neck) or an odd position of the carotid artery (a major blood vessel in the neck).
The role of the ossicular chain is to transport sound from the eardrum to the cochlea. The chain begins with the eardrum, then moves to the malleus, proceeds to the incus (which is the largest out of the three ossicles), and then finally to the stapes (the smallest ossicle). The stapes consists of a head, anterior and posterior crura (the back of the stapes is where a tendon stretches from a bony prominence to attach), and footplate. The footplate sits on top of the oval window separated by a ring-shaped ligament which forms a joint between them. Hardening of this ligament results in a condition called otosclerosis, which can cause hearing loss.
Why do People Need Stapedectomy
If you’re being considered for a specific ear surgery called a stapes procedure – because you might have otosclerosis, a disease that leads to hearing loss – your doctor will confirm that you don’t have other conditions like a superior semicircular canal dehiscence (SSCD) or a dilated vestibular aqueduct. Both these conditions can cause a type of hearing loss at lower frequencies and might have similar symptoms like hearing your own voice unusually loud (autophony), being overly sensitive to noises (hyperacusis) or dizziness triggered by high volume or pressure changes. Doctors have tools and methods to tell these conditions apart.
The acoustic reflex arc is one such tool. It’s a mechanism in your ear that helps protect it from loud sounds. If someone has otosclerosis, the acoustic reflex might be missing. But if they have SSCD or a dilated vestibular aqueduct, the reflex should be present and normal.
Another helpful tool in these cases might be a high-resolution computed tomography (CT) scan. This is a type of advanced imaging that can take very detailed pictures of your ear. However, it’s not always used because it can be costly and exposes you to some amount of radiation. But when it is used, it can diagnose otosclerosis with over 95% certainty. On the scan, otosclerosis shows up as a spotty area near the stapes bone in your ear, which can cause hearing loss. But otosclerosis might also cause a different kind of hearing loss, signaled by a “halo sign” around the cochlea (a part of your inner ear). If there’s a hearing loss of this type, it might be treated with medications like sodium fluoride or bisphosphonates.
A high-resolution CT scan is also the go-to tool to diagnose SSCD, although it only correctly identifies the disease around 67% of the time. In these cases, other specialized tests might be used, but that’s beyond the scope of our discussion here.
Before you go in for the stapes procedure, it’s important that you fully understand and are okay with everything involved in the operation, the risks, the process for admission to the hospital, as well as the process after the operation and discharge from the hospital. The doctor will also consider a few things before the surgery.
– First, you need to be healthy enough to endure the procedure, especially if general anesthesia will be used.
– Ideally, the surgery will be performed on the ear that has poorer hearing first. This is decided based on what you report, not the hearing tests. If required, the other ear can be operated on after six months or later, as long as it now has poorer hearing. In children, it might be important to operate on the worse ear first to avoid using a hearing aid before school starts. Operation on the other ear can be delayed until the child is old enough to decide for themselves.
A surgery is a good idea for you if you have a confirmed diagnosis of otosclerosis and a hearing loss of 25 dB or greater at certain frequencies, revealed by hearing tests. These tests use tuning forks of different frequencies, and how you perceive these sounds in air or through bone conduction can provide clues about the type of hearing loss you have. Other factors like what type of hearing loss you have, mixed or conductive, can also guide the decision about the surgery.
When a Person Should Avoid Stapedectomy
Stapes surgery, a procedure to improve hearing, may not be suitable for everyone. Here are some reasons why certain people may not be able to have the surgery:
Firstly, if a person is not healthy enough or can’t handle being put to sleep with anesthesia, then they can’t undergo stapes surgery. This procedure requires you to be under anesthesia, which means you’ll be completely asleep and won’t feel pain during the operation.
Secondly, if a person only has one functioning ear, this surgery isn’t advisable. The risk involves potential complications that could impact the healthy ear.
Thirdly, if a person has an active ear infection, either on the outer or middle part of their ear, the operation can’t proceed. An infection could make surgery more complicated and riskier.
Fourthly, if a person is currently experiencing balance problems, like Meniere’s disease, a condition that causes vertigo (a sensation of feeling off balance) and tinnitus (ringing in the ears), they can’t have the surgery. This is especially the case for those who have a hearing loss of 45 dB or more at 500 Hz and with a serious loss of high-frequency hearing. The surgical procedure could amplify these balance issues, making it harder for the person to move about safely.
Lastly, if a person does work that requires unimpaired balance (intact vestibular function), like construction workers or firefighters, for example, this procedure would not be recommended. Stapes surgery could potentially interfere with this balance, which could impact the person’s job performance and safety.
Equipment used for Stapedectomy
Stapes surgery, particularly a procedure known as a stapedectomy, needs specific instruments. These include:
A complete set of middle-ear tools, which contains a sickle knife and a round knife for precise cutting. It also includes a device called a fascia press, used to flatten tissue, and various sizes of a tool called an otologic specula, which helps the surgeon see inside your ear.
Depending on the surgeon, they may like to use a speculum holder so they can work with both hands.
An operative microscope, with a 200 to 250 mm objective lens, is used to allow the surgeon to see the operation clearly. Usually, this microscope is covered with a sterile cover to prevent any contamination during surgery.
How the surgeon decides to remove the stapes crura and footplate – parts of the ear that can cause hearing problems – can vary. Some might choose to use a special type of small, precise drill, while others might prefer to use a specific laser. These types of lasers – usually argon, KTP, or CO2 – are chosen with the intention of reducing the risk of any vibratory sound trauma to your cochlea, a part of your ear that is key in hearing.
The surgeon also will use a stapes prosthesis – an artificial part to replace the removed stapes – that they are comfortable and experienced with using.
Who is needed to perform Stapedectomy?
When a surgeon is performing a delicate operation using a special microscope, it’s usually a one-person job. But there’s another vital team member involved called the scrub technician. This person is trained to make sure everything runs smoothly in the operating room. By assisting the surgeon, the scrub technician allows the surgeon to focus solely on the operation without needing to look away from the microscope.
Sometimes, depending on the specific components required for the operation, an assistant might be needed. For example, they might have to carefully take a strip of vein from the back of the hand that’s not being operated on. Alternatively, the surgeon might use a special tissue from the side of your head, known as a ‘temporalis fascia graft’, which they would have prepared before the surgery started. Whether it’s a vein or this special tissue being used, the scrub technician is responsible for keeping it safe and prepared until it’s needed during the surgery.
Preparing for Stapedectomy
A stapedectomy is a surgery that can be done under local or general anesthesia. The doctor who performs the surgery talks with the anesthesiologist about the best kinds of medicine to use. They try to avoid using medicine that would make it hard to monitor how the nerves in the face are doing. It’s important to keep an eye on these nerves during the operation. When deciding which local anesthetic to use for numbing the skin in the ear canal, many pick lidocaine or bupivacaine with epinephrine. Epinephrine might be the safer option because it won’t affect the facial nerves. This, however, is not widely agreed upon in medical literature.
When performing a stapedectomy, it’s very important to position the patient in a way that makes it easy for the doctor to do the surgery. After the anesthesia starts working, the patient is positioned as close to the doctor as the operating table allows. If the patient has a short neck or a large chest, it might help to very slightly tilt the table. If a vein from the back of the hand will be used during this surgery, the opposite hand is placed out on a board. To keep the patient comfortable during the operation, support for the arm, knee, and lower back is provided as needed.
Before surgery begins, the area is cleaned with alcohol or a solution called povidone-iodine (also known as Betadine). The patient and the microscope used for the surgery are both covered with clean sheets. Any leftover cleaning solution is removed from the ear canal, along with any earwax that might be in the way.
How is Stapedectomy performed
To operate successfully on the ear, the patient gets positioned so that the surgeon can easily look down the ear canal while sitting. The area is typically numbed using a small needle, starting at the back wall of the canal or the bottom. The numbing medicine needs to be given slowly, especially if it’s the only form of anesthesia being used, as the skin is very close to the bone or cartilage in this area. If the medication is given too quickly, it can cause the skin to balloon up, creating a pocket of fluid. If that happens, the doctor will drain it with a needle.
The surgeon needs to insert small amounts of anesthetic as they move around the ear canal, in order to still see everything clearly. Different materials can be used during the operation including a vein, fascia (a band of connective tissue), perichondrium (the layer that surrounds cartilage), or fat. These materials can be accessed before or after the operation has started, but they need to be prepared before the stapes footplate, a small bone in the ear, is opened up. This is done to limit the amount of time the vestibule (a part of the inner ear) is exposed.
For the procedure, the surgeon will use the largest ear speculum (a tool used to hold open body parts) that fits into the ear canal. Depending on their preference, they may use a tool to hold the speculum in place. The procedure outlined here involves a one-handed approach, allowing the patient the freedom to move their head if they wish to. It’s best to use regular metal tools, as black materials can make it harder to see.
When working on the middle ear, it’s essential to see everything clearly. To ensure this, a tympanomeatal flap (a replacement ear drum) is created. This begins with a cut 1mm from the tympanic membrane (the eardrum), and is extended from the lower back annulus (the outer edge of the eardrum) to a point well above the pars flaccida (a small, slack part of the eardrum). It might be necessary to repeat this process to ensure the periosteum (a layer of tissue that covers bones) has been cut. The flap should be about 5-7 mm and is then carefully peeled back until the fibrous annulus is seen below, and the notch of Rivinus (a small depression in the bone) is seen above. The surgeon will know when the incision was successful when the tympanic membrane can be pulled back completely.
When doing a stapedectomy (a surgical procedure) for suspected otosclerosis (abnormal bone growth in the ear), or working in the middle ear to improve hearing impairment, the surgeon should be able to see four landmarks: the handle of the malleus (the hammer-shaped bone) at the front, the round window below, the pyramidal process (a small, cone-shaped part of the bone) at the back, and the horizontal part of the facial nerve above. These landmarks are visible after the successful removal of the bony scutum (a protective shield of bone), which usually involves removal in the notch of Rivinus, moving downwards. The surgeon needs to be careful to avoid damaging the chorda tympani nerve during this process.
Once everything is clearly visible, the ossicular chain (the three smallest bones in the body that help transmit sound) must be checked to locate the problem. In a healthy ear, touching the malleus will cause a reflex in the round window, showing that the ossicular chain is intact and fluid is moving normally within the perilymph (a fluid in the inner ear). However, in otosclerosis, this reflex will be absent because the stapes, another small bone in the ear, is stuck and can’t move. Once the doctor knows how much of the stapes needs to be fixed, the incudostapedial joint (the joint that connects two of the small bones in the ear) is separated.
The stapes footplate, a small bone in the ear, is opened up, at its thinnest point, with a fine needle. This helps to relieve pressure in the vestibule (a part of the inner ear) and provide an area where tools can be used, in case this bone starts to float. The stapedial tendon, a band of tissue that connect the stapes to the muscles of the middle ear, is severed and the stapes is fractured using a quick, downward pressure towards the promontory (a rounded prominence of bone). A small, angled hook is then used to remove parts of the central footplate.
The next steps are to measure the distance from the footplate to the top of the incus (the anvil-shaped small bone in the middle of the ear). This will usually result in a prosthesis (an artificial body part) of about 4.5 mm, but the distance can vary from 3.5 to 5.5 mm. When the correct prosthesis has been chosen, the graft is gently placed over the oval window and pressed into the hole created to help determine where the prosthesis will be placed. Then, the ossicular chain must be touched to ensure that it is still connected to the prosthesis. Once in place, the skin flaps from the surgery can be returned to their original position and packed with antibiotic-soaked small cotton balls.
Possible Complications of Stapedectomy
During surgeries that deal with the middle ear, like the stapedectomy, the main objective is always to keep the auditory nerve working if we can. Even when there could be some complications during the operation, stopping the procedure to avoid total hearing loss is usually the best course of action. Having the option to use a hearing aid is a better alternative than risking losing all hearing ability.
A variety of complications can arise during this surgery like damage to the eardrum or certain nerves, dislocation of tiny bones in the middle ear, issues with certain parts of the ear called the stapes and the footplate, and several others. Many of these complications can lead to severe hearing loss, or what doctors call a “dead ear.”
A torn eardrum, for example, can happen when the surgeon is preparing the ear for surgery. Small tears can be repaired during the operation and larger tears may require additional treatment using tissue from the same operation. It is important to check the ear carefully before surgery, as sometimes opening up the eardrum to fix it requires another surgery. These complications rarely affect the overall result of the main operation, the stapedectomy.
The stapedectomy procedure involves careful exposure of the stapes, which is a bone in the ear. If not done properly, it can damage a nerve that is often preserved in about 90% of cases. While some damage can be fixed, total damage might sometimes be unavoidable. Interestingly, patients whose nerve had to be completely cut have experienced fewer symptoms related to taste disorders compared to those who only had part of their nerve affected.
Another uncommon complication is the dislocation of bones in the ear. While this might make it harder to place the prosthesis (an artificial device that helps hearing), it usually still yields good results with hearing.
The stapes has a structure that can sometimes break away from its surrounding attachment. This happens rarely but is a serious complication. If the surgeon fails to make a tiny hole in the footplate (part of the stapes) before removing its top structure, this problem might happen. This can be fixed, but it requires careful handling of this part of the ear.
When large pieces of the footplate get displaced, they can be removed. However, trying to retrieve those that have moved into the vestibule (a part of the ear) could cause damage. While large fragments can cause a condition like persistent dizziness, small fragments usually do not affect hearing and can be left alone.
There is also another rare condition where fluid from the inner ear suddenly flows out. This happens usually in children having their stapes fixed, but could also occur in adults. Patients who experience this uncontrolled leakage of ear fluid tend to have sensorineural hearing loss, a type of hearing loss caused by damage to the inner ear.
When it comes to children who need a stapedectomy, a CT scan might be necessary before the surgery to identify any abnormalities in the ear. If the fluid leakage happens, it can be controlled by various methods, including raising the head, draining the fluid, and using a prosthesis.
There are some rare instances where it’s necessary to abandon the stapedectomy. A persistent artery can be worked around, for example, but if it’s blocking an important part of the ear, the surgery must be stopped. Instead, the patient should use a hearing aid to improve their hearing.
During the surgery, complications like abnormal positioning of a nerve can be encountered. It’s very crucial to avoid damaging the nerve in such scenarios. If the nerve is displacing the footplate of the stapes, the surgery must be stopped.
Patients undergoing the procedure may feel dizzy; this could be a warning of potential damage to the inner ear. A drug called droperidol can be helpful in these cases, but it should be administered carefully due to its impact on the heart.
A serious issue after the stapedectomy is reactive tissue growth around the part of the ear where the surgery was performed. This problem typically develops after a week and results in hearing loss and dizziness. An immediate second operation is usually necessary to replace the prosthesis to treat this issue.
What Else Should I Know About Stapedectomy?
John J. Shae has been doing a procedure to improve hearing, called a stapedectomy, for over 40 years. His success rate has always been good, and it’s only gotten better as the tools he uses have improved. These tools include things like microscopes, implants used in the ear, drills, and lasers. About 90% of the people have improved hearing after the first surgery, and around 70% get better hearing with a second try. However, there is a slight chance that the procedure could make a person’s hearing worse, about 1.8% on the first attempt, and 4% on a repeat attempt.
Stapedectomy and stapedotomy are the latest and best treatment options for a condition called otosclerosis, which can lead to hearing loss. Most people who choose to undergo surgery today opt for a type of procedure known as a small fenestra stapedotomy. This procedure uses a microdrill or a laser, and it is preferred because it often leads to better hearing (especially for high frequency sounds) and fewer complications afterward. However, the success and safety of this ear surgery depend greatly on the surgeon’s skills and experience.
To effectively treat otosclerosis, it is crucial for the surgeon to understand the disease well and be able to adjust the surgical technique as needed. The stapedectomy is a particularly tricky operation, and this becomes even more challenging when a second surgery is needed. There is a higher risk of severe hearing loss, also referred to as ‘dead ear,’ in these revision cases. Thus, it is recommended to proceed with caution when dealing with inner ear problems after surgery.
Despite these risks and the need for a high level of skill, there is currently no better way to improve hearing and close the gap between air conduction and bone conduction – two ways our body can convey sound to the brain – especially in cases of otosclerosis. This is why it’s crucial to pick a surgeon who has a lot of experience and is comfortable with the procedure.
