Overview of Mastoidectomy
A mastoidectomy is a surgical procedure that involves opening the small air-filled spaces in the bone behind the ear (the temporal bone). This is done by removing the thin sections of bone that separate these spaces. Each mastoidectomy is unique because the pattern of these air-filled spaces can vary from person to person. The presence of any disease can affect the formation of these spaces and make the mastoidectomy procedure more complicated.
Anatomy and Physiology of Mastoidectomy
The temporal bone is a critical part of the body that doctors need to understand well before they can safely perform surgery on the mastoid, a part of the ear. The temporal bone is shaped like a pyramid and points towards the front and middle of the skull. It connects to several other bones in the skull: the parietal, occipital, zygomatic, and sphenoid bones.
The temporal bone has three main sections: the petrous, squamous, and mastoid. A mastoidectomy, a type of surgery, involves creating an open space within the mastoid part of the temporal bone. The front border of this open space is marked by the back of the bony ear canal. The ‘spine of Henle’, is a specific point found at the back, top edge of the ear canal. This point denotes the level of the antrum of the mastoid, which is part of the middle ear.
The top part of the open space created in mastoid surgery is marked by the temporal line, which is found at the lower limit of a muscle in the temple area called the temporalis muscle. This line also marks the level of the middle fossa floor, which is a depression in the skull where certain parts of the brain rest. The back border of the open space is limited by the sigmoid sinus, a vein-like structure that is responsible for draining blood from the brain.
On the inside, the Koerner septum, a flat piece of bone, marks the boundary between the petrous and squamous parts of the temporal bone. Going further inside, the lateral semicircular canal and the mastoid antrum are reliable landmarks that surgeons use to gauge how deep they are dissecting compared to the middle ear space.
Why do People Need Mastoidectomy
A mastoidectomy is a surgery performed to create a safe and dry ear, particularly if the patient is dealing with severe or chronic infections in the mastoid bone, found behind the ear. Illnesses that may require this type of operation include severe mastoiditis (an infection of the mastoid bone), persistent ear infections that lead to other complications, or a growth known as a cholesteatoma. This procedure might also be used when a patient needs a tube placed in their ear drum to help drain fluid, or when other ear surgeries – such as cochlear implantation or facial nerve surgery, among others – need to be performed.
There are generally two main types of mastoidectomy. In the first kind, called ‘canal wall up’ mastoidectomy, the back wall of the ear canal is kept intact. This procedure is usually performed on patients experiencing their first episode of acute mastoiditis. The second type is ‘canal wall down’ mastoidectomy. This is generally performed on patients with long-term chronic ear infections or persistent cholesteatoma. In this surgery, the back wall of the ear canal is removed. Which type of operation is chosen depends on several factors, such as a patient’s individual anatomy, the extent of the disease, risks to hearing or balance, and the patient’s ability to attend consistent follow-up appointments. If the canal wall down option is selected, patients must commit to regular follow-up visits for cleaning of the mastoid cavity.
When a Person Should Avoid Mastoidectomy
People who are not in good enough health to safely go through planned surgery should not have a mastoidectomy. A mastoidectomy is a surgical procedure to remove an infected part of the bone behind the ear when medications don’t work.
Equipment used for Mastoidectomy
A mastoidectomy is a type of surgery often done while the patient is under general anesthesia, which means you’re asleep and won’t feel anything. This procedure is carried out in an operating room. In order to complete the mastoidectomy, surgeons use a variety of tools.
One essential tool is an operating microscope, which lets the surgeon see small, detailed areas clearly during the surgery. Another key instrument is a high-speed drill that comes with cutting pieces and burrs that are diamond-like in nature. “Burrs” here refer to the small rotating tools used for cutting or shaping hard materials. The drill, with its special burrs, is used to safely and carefully remove certain parts of the bone.
The surgeons also use otologic instruments, which are specially designed tools for operations concerning the ear. There are additional minor surgical instruments involved as well.
Although it isn’t mandatory, a tool often used for this kind of operation is facial nerve monitoring. This tool helps to increase the safety of the mastoidectomy by allowing surgeons to watch the facial nerves closely during the procedure. This way, they are able to perform the surgery more quickly and efficiently.
Who is needed to perform Mastoidectomy?
Every surgery needs a team working together to make sure everything goes well. This team doesn’t just include the doctor who does the operation, it also includes a special kind of doctor called an anesthesiologist, or a CRNA (a nurse who is trained to administer anesthesia). In addition to them, there is also a nurse who helps during the surgery, a surgical technician, and sometimes even a video technician. There is a procedure called a ‘surgical time-out’ where everyone in the room makes sure they have the right patient and they all understand the plan for the surgery.
Preparing for Mastoidectomy
Before proceeding with a mastoidectomy, which is a surgical operation on the ear, some doctors prefer to check a specific type of scan known as a CT temporal bone. This is not required, but can be very useful. This scan helps them understand the structure of the ear and look out for any unusual or irregular features that might affect the surgery, especially if it’s a subsequent operation.
This scan may help identify any deformities that were present at birth, or any weak spots along the facial nerve canal, which is a pathway where a crucial nerve (the facial nerve) runs. It’s important to know about these things before the surgery so that there are no surprises during the procedure.
Before the patient is put to sleep with anesthesia, the doctors need to discuss how they will monitor the facial nerve during the surgery. This is very important because they want to make sure not to damage this nerve. They will also make arrangements with the anesthesiologists to ensure they don’t use any anesthesia that could interfere with the nerve monitoring.
Once the patient is asleep and comfortably set up for the surgery, the doctor will make sure the work area around the ear is clean and sterile. They might shave off any hair behind the ear and use special sticky sheets to keep any hairy areas separate and clean. They will then set up the equipment to monitor the facial nerve during the surgical procedure.
Unless there are any issues that prevent it, the surgeons will often inject a local anesthetic too. This helps to reduce any pain and also to narrow the blood vessels in the area, which can limit bleeding during the operation and make the surgeon’s work easier.
How is Mastoidectomy performed
The procedure starts with a cut being made behind the ear, a method popularized by Sir William Wilde. In more complex cases, a longer cut can be used to enable better visibility. A special surgical tool known as a cautery is used to cut down to the level of the fascia, a layer of fibrous tissue that wraps around structures like muscles and bones. After this, flaps of skin are lifted so that a piece of the fascia (the sheath that encloses a muscle) can be obtained if necessary. A ‘T’ or ‘7’ shaped cut is then made into the periosteum (a dense layer of connective tissue that envelopes bones) with the top of the ‘T’ at the temporalis (a broad muscle that covers parts of the side of the skull). The periosteum is then lifted to expose a region of the ear known as the spine of Henle and the ear canal. A Wietlander, a surgical instrument, can be used to keep the soft tissue away from the area of surgery.
Next, a surgical drill is used to mark out the boundaries of the mastoidectomy, a procedure to remove part of the skull bone behind the ear. The boundaries include specific areas of the skull: the tegmen (the roof of the mastoid bone), the sigmoid sinus (a vein that drains blood from the brain), the posterior bony part of the ear canal, and the digastric ridge (a ridge at the lower part of the mastoid bone). Bone is carefully removed evenly from top to bottom, with the deepest part of the surgical area being the superior and anterior part. To improve visibility and avoid working behind the bony ledges, the bone is saucerized (made concave). The lateral semicircular canal, a part of the inner ear, serves as a landmark to show that the surgery has reached the depth of the facial nerve. The antrum, a cavity inside the mastoid bone is usually discovered at the deepest and most forward part of the operation. By opening the antrum, a path for air is created between the mastoid and the middle ear.
Cholesteatoma, an abnormal skin growth in the middle ear, can extend from the middle ear to the mastoid through this area too. A facial recess may be created as needed. The facial recess provides another ventilation pathway between the mastoid and the middle ear. It also enables access for any required middle ear work like cholesteatoma dissection, ossicular chain reconstruction, or cochlear implant insertion. The facial recess is a triangular-shaped opening into the middle ear bordered by the facial nerve at the back, the chorda tympani at the front, and the incus buttress at the top. There are variations and modifications of the mastoidectomy, but once the lateral mastoid cells have been removed and the correct landmarks identified, the drilling can be concluded for a canal-wall-up mastoidectomy. In a canal-wall-down procedure, the posterior bony external ear canal is removed to create a large cavity that can be accessed in a non-surgical setting.
Finally, the wound is typically closed using absorbable deep stitches to bring the periosteum back together. Another layer of buried interrupting stitches is placed in the deep dermal layer. Then the epidermis (the outermost layer of the skin) can be joined together using a superficial running stitch or a tissue adhesive. A bandage dressing can then be placed over the ear for one to two days.
Possible Complications of Mastoidectomy
Mastoidectomy, a surgical procedure to remove infected parts of the bone behind the ear, can lead to several complications. These may include damage to the facial nerves, hearing loss, an unsteady feeling called vertigo, changes in taste, leakage of brain fluid, a need for another surgery, infection after surgery, and bleeding. A facial nerve injury, although rare, can have severe and lifelong effects.
Similarly, if acute or chronic mastoiditis (an infection in the mastoid bone) isn’t treated correctly, it can lead to more severe complications. To reduce the risk of damage to the facial nerves during surgery, surgeons need a deep understanding of the body’s structure and the skills to perform the surgery safely.
What Else Should I Know About Mastoidectomy?
When someone has acute mastoiditis, which is a serious bacterial infection, they may undergo a procedure known as a mastoidectomy. This surgical procedure helps fast-track the elimination of the infection rather than relying on antibiotics alone. This way, they can prevent any potential complications related to mastoiditis.
On the other hand, those suffering from chronic diseases, like ongoing infections or cholesteatoma — that’s a skin cyst located in the middle of the ear — also benefit from a mastoidectomy. The procedure provides them with relief from persistent ear drainage and discomfort, and they also often find that their hearing improves. It’s worth noting that this surgery helps prevent potentially harmful complications that could include the spread of the disease beyond the ear, specifically towards the brain.
