Overview of Tympanoplasty
Chronic suppurative otitis media (CSOM) is a condition where a person has long-lasting or recurring ear infections lasting longer than 12 weeks. This can damage the eardrum, called the tympanic membrane (TM), and cause a persistent hole, or “perforation.” This condition is the most common infectious disease in children around the world. There are several things that could increase your chances of having it, such as respiratory infections, malnutrition, poor hygiene, family history, low birth weight, abnormalities in the head and face, and belonging to certain ethnic groups such as Native Americans, Native Alaskans, or Aboriginal Australians. The symptoms include fluid leaking out of the ear through the hole in the eardrum (otorrhoea) and hearing loss. The hearing loss can be mild but can be more severe if the hole is large or if the tiny bones in your ear that carry sound (the ossicular chain) are eroded. It’s important to check whether there’s a cholesteatoma, a type of growth, in these cases.
The eardrum hole can be located in different parts of the eardrum and may be moist or dry, depending on whether there’s an ongoing leak of fluid or not.
There’s a type of CSOM that involves a cholesteatoma, a sac of skin cells, usually in the upper part of the middle ear. This can grow beyond the eardrum, erode the bone, and destroy the ossicular chain. The symptoms are similar to CSOM and include a smelly discharge from the ear, hearing loss, a hole in the eardrum, and the upper part of the eardrum collapsing inward.
The operation to repair a hole in the eardrum is called a tympanoplasty, which may involve rebuilding the ossicular chain to prevent future infections and restore hearing. This operation is usually done for people with CSOM, but for large cholesteatomas, a different operation removing a part of the bone behind the ear (a mastoidectomy) and rebuilding the eardrum may be needed.
There are five types of tympanoplasty, classified by the Wullstein system:
* Type I: repairing the eardrum only, with no abnormalities in the middle ear.
* Type II: repairing the eardrum and middle ear where the malleus (one of the tiny bones in the ear) is eroded.
* Type III: repairing the eardrum onto the top of the stapes, another tiny ear bone, where both the malleus and another bone, the incus, have a defect.
* Type IV: grafting the eardrum to the stapes footplate, which is movable.
* Type V: repairing the eardrum where the stapes footplate is fixed.
Anatomy and Physiology of Tympanoplasty
The middle ear is a small space in your skull located behind your eardrum. It’s also called the tympanic cavity. This cavity is found inside your temporal bone, a bone at the side of your skull near your ear. It contains several important parts, including the inner layer of the eardrum (also known as the TM), the opening of the Eustachian tube, and the three tiny bones called the ossicles (malleus, incus, and stapes). These pieces all play a role in hearing.
The middle ear also has passages that lead to other parts of your ear and to your throat. Behind, it connects to air-filled cells in your skull (the mastoid air cells) through a passage called the tympanic antrum and the aditus ad antrum. In the front, it connects to the nasopharynx (the upper part of your throat behind your nose) via the Eustachian tube. This tube helps balance the pressure inside the middle ear with the outside air pressure.
The eardrum forms most of the side wall of the middle ear. Its outer layer is like the skin of the external ear canal. The middle layer is made of a fibrous material that gives the eardrum its shape and strength. The inner layer is continuous with the lining of the middle ear. Collagen fibers found in the middle layer of the eardrum help the eardrum to move, as it needs to respond to sounds, but also to resist extra stretching. Just for reference, the eardrum is about 10mm wide and it is so translucent, sometimes the ossicles behind it can be seen.
The eardrum has two main parts: the pars flaccida at the top, and the pars tensa at the bottom. The pars flaccida is a thinner, more flexible part compared to the pars tensa. Ear doctors, or otolaryngologists, often think about the eardrum in four parts, divided by imaginary horizontal and vertical lines. This helps them understand where problems may be in the ear. They need to be very familiar with the layout of the middle ear to perform surgeries effectively.
Now, how does all this help with hearing? When a sound wave enters your ear, it hits your eardrum and causes it to vibrate. These vibrations move the tiny bones in your middle ear, which then push on a small window into your inner ear, filling it with waves in the fluid. The eardrum and the small bones work together to make the sound louder when it gets to the inner ear. Special hair cells in the inner ear react to these waves and turn them into electrical signals. These signals are carried to your brain by the cochlear nerve, and your brain interprets them as sound.
Why do People Need Tympanoplasty
Tympanoplasty is a surgical procedure aimed at repairing the eardrum (also known as the tympanic membrane, or TM) and sometimes the tiny bones in the ear (ossicular chain). This can help to both avoid recurrent ear infections (known as otorrhoea) as well as improve hearing.
The main reasons to undergo this surgery are usually ongoing non-healing middle ear infections (referred to in medical terms as “chronic suppurative otitis media” or CSOM), or CSOM accompanied by a specific type of ear cyst called a cholesteatoma. Other potential reasons for having tympanoplasty include an accidental eardrum perforation (or hole) caused during a medical procedure in children receiving ‘ventilation tube’ insertions to treat otitis media with effusion (or fluid buildup). This is a common treatment for kids who have multiple ear infections or hearing loss.
In addition, some eardrum perforations caused by physical injuries might also require tympanoplasty. Typically, around 80% of eardrum tears will naturally heal on their own. However, if a tear doesn’t heal by itself, then surgery might be required to fix it.
When a Person Should Avoid Tympanoplasty
There are some circumstances or conditions in which a tympanoplasty operation might not be suggested. These can be loosely classified as relative or absolute. Relative contraindications include factors like the age of the patient (being very young or very old), having a Eustachian tube (a tube that links the middle ear with the back of the nose) that doesn’t work properly, or if the patient’s ear does not hear well or at all, or if the surgery is considered for the ear the patient hears better with.
Absolute contraindications are more serious, and include scenarios like the presence of an uncontrolled cholesteatoma, an abnormal skin growth in the middle ear behind the eardrum. Uncontrolled complications or prolonged effects of ear infections like intracranial abscess (a collection of pus in the brain), meningitis (infection of the protective layers of the brain and spinal cord), or lateral sinus thrombosis (a blood clot in the brain’s venous sinuses), can also make the operation too risky. If the patient has a tumor in the ear area or any condition that makes them unfit for anesthesia, the operation is strongly discouraged.
Equipment used for Tympanoplasty
A tympanoplasty is a surgical procedure to repair a hole in the eardrum. To do this, certain tools might be required such as:
A microscope and an otology instrument tray which contains specialized tools used for ear surgeries.
Now, if the tympanoplasty is being done endoscopically, which means using a special instrument called an endoscope to view the inside of the ear, a few other pieces of equipment would be needed. These could include:
A high-resolution camera, a light source, and a monitor to clearly see the inside of your ear during the surgery.
An endoscope, which can be set at 0, 30, or 45 degrees. This is a thin tube with a camera and light at the end that can be inserted into small openings like the ear to give the doctor a clear view of what they’re working on.
Who is needed to perform Tympanoplasty?
A tympanoplasty is a procedure that needs several medical professionals to complete it successfully. This involves a doctor known as an otologist, who is specifically trained to treat ear problems. They are the main person who will perform the operation.
Next, an anesthetist is also required. This is a doctor who is responsible for administering anesthesia, which is a medicine that makes you sleep or feel numb during the surgery, so you don’t feel any pain.
Lastly, a scrub team also plays a vital role in the procedure. They are usually made up of trained nurses or medical technicians. Their job is to assist the surgeon, keep the surgical instruments clean and organized, and ensure everything is ready and working correctly before and during the surgery.
Preparing for Tympanoplasty
Before having ear surgery, several tests are done to check how well the middle ear is working. The results of these tests can affect how the surgery is done and how well you might recover afterwards.
Firstly, if you go to the doctor with symptoms like ear discharge (otorrhoea) and hearing loss, they’ll do a careful check-up, which includes taking your health history and examining your ear with a special instrument called an otoscope or microscope. This examination gives important information about any hole in your eardrum (TM perforation), its size, and location. It also gives information about your ear discharge, whether it’s ‘wet’ or ‘dry’, and if there’s any ongoing inflammation.
Your doctor will also do some hearing tests before and after the surgery. These tests include the Rinne and Weber tests (done with a tuning fork) and the pure tone audiometry (PTA) test. They will compare the results of these tests after the surgery with the ones from before the surgery. This helps to measure any changes in your hearing.
Most of the time, you won’t need any imaging tests for simple holes in your eardrum. But if necessary, a type of scan called a CT scan can be used.
Additionally, doctors also use questionnaires that ask about your quality of life. These questionnaires measure how well you’re doing physically, mentally, and how your condition is affecting your day-to-day life and relationships. These questionnaires aren’t always included in the steps taken before surgery, but they’re becoming more common.
Before the surgery, you’ll need to give consent. This means understanding and agreeing to the risks tied to the surgery. These risks include pain, bleeding, the possibility of infection, the graft not working, needing more surgery, hearing loss or even deafness, dizziness, and nerve injury that could cause facial paralysis or taste disturbances. The surgery is usually done under general anesthetic, which means you’ll be asleep during the procedure. You’ll also have a chance to talk with the anesthesiologist before your surgery.
How is Tympanoplasty performed
Most ear surgeries involving the eardrum are traditionally done from behind the ear, but they can also be done through the ear canal. Both methods have their benefits and limitations. Surgeons will consider a few things when deciding on the best approach including how big the hole in the eardrum is, the size of the ear canal, and what they prefer to do. Nowadays, going through the ear canal for ear surgery is becoming more popular because it’s less invasive.
Regardless of the technique used for the surgery, standard preparations will be made in the operating theater. This may include giving preventative antibiotics, positioning the patient on their back with a comfortable headrest, and sometimes, shaving the hair behind the ear. The surgeon will also administer a local anesthetic for pain relief and to control bleeding. The surgeon will then examine and clean the ear canal, and carefully inspect the eardrum and the small hearing bones inside, before starting the surgery.
When repairing the eardrum, material called grafts are used. Autologous grafts are those taken from the patient’s own body and are generally preferred as they are natural, compatible with the body, and are not costly. These grafts are often taken from other parts of the ear or head, although there are other places they can be taken from too. While synthetic grafts are available, they don’t offer any additional benefit and are also relatively expensive and carry a small risk of infection when used.
Surgeons usually prefer grafts from the temporalis fascia, a muscle in the head, because they’ve shown good results in eardrum repair surgeries. However, for patients who might need more support like those with frequently recurring holes in their eardrum or high-risk patients, cartilage from the ear can be harvested for use in the graft. Some doubts have been raised about the use of cartilage, though, because it could potentially affect hearing and might be mistaken for a certain type of ear disease during follow-up.
Surgical repairs may be done through a microscope and either through a cut from behind the ear or through the ear canal. In the former, the surgeon makes a small cut behind the ear, peels back the muscle and skin layers to reach the ear canal, and then cuts a small flap in the eardrum to reach the middle ear. The edges of the hole in the eardrum will then be carefully trimmed and a graft will be placed under the drape of the eardrum to cover the hole. Additionally, the small bones within the ear may be repaired, if necessary.
Alternatively, endoscopic surgeries are less invasive and give the surgeon a wide view of the middle ear without having to make any cuts on the outside of the ear. Studies have shown it to be as effective as traditional microscopic surgery, with quicker operating and recovery times. The downside includes having to perform most of the surgical steps one-handed and the potential for nearby body parts to be affected by the heat produced by the light source on the endoscope.
For such procedures, the surgeon will access the middle ear through the ear canal, removing any excess skin from the hole in the eardrum as needed, and then elevate the ear canal and eardrum to reach the middle ear. The graft will be placed under the remnant of the eardrum and over one of the small bones of hearing. Absorbable gel sponges are inserted into the ear canals to support the graft and help with healing. In some cases, a technique called a ‘butterfly cartilage tympanoplasty’ is used which involves positioning a graft within the hole in the eardrum without the need to elevate the eardrum. Once the graft is in the right position, absorbable gel sponges are used to secure it.
Possible Complications of Tympanoplasty
Research has shown that over 93% of patients have successful outcomes after a tympanoplasty, which is a surgery to repair the eardrum using a part of a muscle near the ear (the temporalis fascia). However, like all surgeries, complications can occur. These might include the eardrum damage reappearing, having trouble hearing, tear in the eardrum, and needing to have a small tube called a ventilation tube inserted into the eardrum during or after the operation.
In a large case study involving over 1000 patients where surgeons used cartilage to repair the eardrums, it was found that eardrum damage reappeared in around 3.6% to 4.2% of patients (those with cholesteatoma – an abnormal skin growth in the middle ear – and those with a high risk of eardrum damage). About 1.9% to 11% of patients had trouble hearing after surgery.
Certain factors can affect the outcome of the surgery. These include having other health problems like diabetes, being a smoker, and having a weakened immune system.
The middle ear, which is the area surgeons work in during a tympanoplasty, contains important nerves, like the facial nerve and the chorda tympani. The facial nerve runs through a bone near the ear and then along the back wall of the middle ear. Damage to this nerve is rare because ear surgeons are highly trained. The chorda tympani nerve is always exposed during middle ear surgery. In cases where patients have cholesteatoma, this nerve might need to be removed to get rid of all the disease.
What Else Should I Know About Tympanoplasty?
Tympanoplasty is a surgical procedure that has been used since the 1950s to treat patients with chronic suppurative otitis media (CSOM), a long-term infection of the middle ear. The goal of this surgery is to decrease the chances of the infection coming back, improve hearing ability, and ultimately boost overall social development and quality of life.
As medical experience and knowledge have grown over the years, the methods used to perform tympanoplasty have changed and improved. Even though a newer technique involving the use of an endoscope (a special instrument to view inside the body) for middle ear surgery has become more popular, one traditional method still prevalent in many healthcare centers is the postauricular approach.
In the postauricular approach, a small cut is made behind the ear and a graft, typically a piece of tissue from the patient’s own body (autologous graft), is used to repair the ear. Despite the availability of newer techniques, this method remains widely used due to its effectiveness in treating chronic ear infections and improving hearing.