Overview of Labyrinthectomy
Labyrinthectomy is a type of surgery carried out on a part of the ear known as the temporal bone. This operation is normally performed to help treat severe vertigo that can’t be managed through other treatments. During the surgery, certain parts of the ear — specifically the semicircular canals and vestibule — are removed. These parts are responsible for balance and spatial orientation. The main purpose of this surgery is to remove any irregular signals coming from a damaged balance system in the ear to make it easier for the brain to adjust and stabilize balance.
This operation is generally very well executed and successful. One thing to remember, though, is that this procedure can lead to the loss of all remaining hearing in the ear that is operated on.
Anatomy and Physiology of Labyrinthectomy
The vestibular system, which is found in our inner ears, is a critical part of our balance and orientation. The design of these organs is complex and maze-like, leading people to often call this part of the inner ear the “labyrinth.”
This “labyrinth” in each ear contains five key parts: the superior, lateral, and posterior semicircular canals, along with the utricle and the saccule. These semicircular canals help us process how our head is rotating or turning. On the other hand, the utricle and saccule are responsible for detecting straight, or linear, movements of our head.
All five of these parts work together like a super-smart navigation tool, tracking the position and movements of our head. Our brain combines this information with input from our eyes and body to help us keep our balance. If any of these signals disagree with each other, it could lead to feelings of unsteadiness or even dizziness.
Why do People Need Labyrinthectomy
When someone experience dizziness due to a one-time injury or loss of a part of the inner ear (a condition called “stable vestibulopathy”), this issue can often be improved by the body’s own healing processes, which can be helped along by physiotherapy and rehabilitation. However, there are certain diseases that can cause ongoing or continually changing issues with the inner ear (which is called an “unstable vestibulopathy). An example of this is Meniere’s disease. These types of issues aren’t as likely to be improved by the body’s own healing processes.
If medical treatments and lengthy periods of physiotherapy aren’t successful in improving an unstable vestibulopathy, it might be necessary to consider a procedure that destroys the affected part of the inner ear – this is called “vestibular ablation”.
One possible surgery for this procedure is labyrinthectomy, which removes the affected part of the inner ear and essentially reverts the condition from unstable to stable. Other options for this procedure include using gentamicin, a specific kind of medication that can intentionally cause damage to the affected part of the inner ear (this is sometimes referred to as a “chemical labyrinthectomy”); or a surgery that cuts the vestibular nerve.
When a Person Should Avoid Labyrinthectomy
A labyrinthectomy is a type of surgery that can cause complete hearing loss in the operated ear. Therefore, if a patient still has usable hearing in the ear that is potentially being operated on, it is usually suggested not to have the operation. Especially if it’s the only ear the patient can hear with. However, this recommendation has relaxed a bit as cochlear implants — devices that help users understand speech better — have proven successful in restoring hearing in an ear that underwent labyrinthectomy.
Usually, patients with a particular level of hearing loss (measured as a pure tone average threshold of 70 dB or more) and a word discrimination score of 30% or less may be suitable for a labyrinthectomy surgery. However, what is considered “usable” hearing can vary from person to person, so the decision to go through with the surgery should be made after the patient and doctor discuss the risks and benefits.
For the labyrinthectomy to be successful, it’s not only essential to remove the diseased tissue from all five vestibular organs, but the other ear must also compensate adequately for the loss. That’s why it is crucial to test the healthy ear’s function before surgery. Also, patients with Meniere’s disease undergoing labyrinthectomy need to be aware that there’s a 10 to 40% chance that the disease might affect their healthy ear, even though it’s functioning well at the time of surgery.
The pre-surgery evaluation should check for ‘poor central compensation’ too—mainly, the patient’s ability to benefit from vestibular rehabilitative physical therapy. Factors that could lower the chances of this include increased age, visual issues, cognitive impairment, or factors leading to a sedentary lifestyle like obesity, arthritis, or problems with the lower limbs.
Equipment used for Labyrinthectomy
A labyrinthectomy is a type of surgery which is performed in an operating room under general anesthesia, so you will be completely unconscious and won’t feel any pain during the procedure. During this operation, the surgeon uses special equipment which includes an operative microscope (a special microscope used for surgical procedures), an otologic drill (a specific type of drill used for ear surgeries) equipped with suitably sized cutting and diamond burrs (tools for cutting and smoothing) and a special set of instruments designed for ear surgery.
Furthermore, a facial nerve monitor is also used during the procedure. This device monitors the nerves in your face to make sure they are not damaged during surgery. The use of this device helps to increase the safety of the procedure and allows the surgeon to operate more quickly.
Who is needed to perform Labyrinthectomy?
Just like with any surgery, a labyrinthectomy (a procedure to treat severe and disabling vertigo, or dizziness) requires teamwork to get the best results. The surgeon (the doctor who performs the surgery) must stay in contact and work together with a variety of other health professionals. These include the anesthesiologist or nurse anesthetist (who handles your anesthesia or medication to make you sleep during the operation), the circulating nurse (who helps during the surgery), and the surgical technician (who assists the surgeon).
These professionals carry out a “surgical time-out” before the procedure. This is a pause they take to make absolutely sure that they’re operating on the correct patient and on the correct side of the body. During this time-out, they also make sure that everyone in the team is on the same page about how the surgery is going to go. This is done to make your surgery go as smoothly and quickly as possible.
Preparing for Labyrinthectomy
Before starting the surgery, the doctor and the anesthesiologist (the person who puts you to sleep during the operation) talk about putting special monitoring devices on your facial nerves. These are nerves in your face that control things like blinking and smiling. The monitors help to make sure nothing goes wrong with these nerves during surgery. The anesthesiologist might also decide not to use a really strong sleeping medicine when first putting you under anesthesia (putting you to sleep for the surgery).
Before the surgery, you’ll also be given an antibiotics to help prevent any infections, and the doctor might also choose to give you steroids through an IV (a tube inserted into your veins). These medicines can help with inflammation and other issues related to the surgery.
When you’re fully under anesthesia, you’ll be moved onto your side, facing away from the doctors and nurses. This is so that they can get a good view of the ear that needs surgery. A special machine called a microscope is also used to get a closer look.
The nurses will also start to prep the surgery area. They might shave away or section off any hair near to where they’ll be operating. This helps maintain a clean environment during the surgery. They’ll also place the facial nerve monitoring devices and double-check that everything is working correctly.
Before making the first incision (cut), you’ll be given more local anesthesia (numbing medicine), in and around your ear. This helps to constrict (narrow) your blood vessels, which can help reduce bleeding during surgery, and also helps to lower any pain you might feel after the operation.
How is Labyrinthectomy performed
The labyrinthectomy procedure is a type of surgery where the inner ear, or the labyrinth, is removed. The surgeon can perform this surgery in two different ways: through the ear canal (transcanal approach) or through the mastoid bone behind the ear (transmastoid approach). The transcanal approach is less intense and takes less time, but there might be a bigger risk of not removing all of the damaged tissue. The transmastoid approach is considered the most effective method for this surgery. In both cases, the goal is to control vertigo, or the feeling of being unsteady or spinning. However, patients might still feel slightly unsteady after the surgery, which seems to happen more frequently with the transcanal approach.
Transcanal Labyrinthectomy
In a transcanal labyrinthectomy, the surgeon first makes a cut in the ear canal, over the back upper part of the eardrum. The surgeon then gently clears away bone to fully see the stapes footplate and the round window niche; these are two structures in the inner ear. During the surgery, the surgeon takes extra care to avoid injuring a nerve that affects taste sensation.
They then separate a joint between two tiny bones in the inner ear, remove one of these bones, and take out the stapes bone and its footplate. The surgeon then removes a part of the bone that allows for a good look into the vestibule, which is a part of the inner ear that helps control balance. The surgeon then carefully excises, or removes, a nerve and associated tissue in the upper part of the vestibule. They also ease out ampullae, which are sac-like dilations in the superior and lateral semicircular canals.
The surgeon uses soft suction to remove more nerve tissue from another part of the inner ear, being extra careful to avoid injuries. Finally, they remove an ampulla in the posterior semicircular canal, another part of the ear responsible for balance. At the end of the surgery, the middle ear is packed with gel-foam that has been soaked in a drug called gentamicin which helps get rid of any remaining tissue that could cause future problems.
Transmastoid Labyrinthectomy
The transmastoid labyrinthectomy begins with a mastoidectomy, which involves removing the mastoid bone located behind the ear. The surgeon obtains exposure by making a curved cut behind the ear and raising tissue flaps. A mastoidectomy is then performed to identify significant landmarks surrounding tissue. Once these structures have been identified, the labyrinthectomy procedure begins. A burr, which is a tool that grinds bone, removes the air cells surrounding the otic capsule of the semicircular canals. These are parts of the ear that help with balance and hearing. The surgeon will then venture into the labyrinth by entering the lateral semicircular canal, one of three loop-shaped structures in the ear integral to keeping balance.
The semicircular canals are then followed to their wider ends, also known as ampullae, in a careful fashion to avoid any nerve injuries. The PSC, or posterior semicircular canal, is followed until the back of the SSC, or superior semicircular canal, is located. This part of the ear is then drilled into, taking additional care to avoid injuring the parts of the ear located above it. At this point in the surgery, a small suction is used to scrape out all the nerve and tissues from the vestibule as well as all three ampullae. Gelfoam soaked with gentamicin can be used to pack the vestibule and the ampullae to chemically cleanse any leftover nerves and tissues.
Possible Complications of Labyrinthectomy
A CSF Leak is usually caused by damage to the macula cribrosa, a delicate area on the inner side of the vestibule (part of the inner ear). This allows cerebrospinal fluid, or CSF, which typically flows around the brain and spinal cord, to leak into the vestibule from the internal auditory canal, which is the tube that connects the inner ear to the brain.
Facial Nerve Injury is another possible complication. The vestibule and the PSC, part of the inner ear, are located close to the facial nerve. Thus, while operating in these areas, the utmost care must be taken to prevent damage to the facial nerve. It’s recommended to avoid using powered instruments during this part of the surgery to minimize this risk.
Disabling Chronic Disequilibrium, a long-term balance disorder, is a rare but serious side effect. This can significantly impact a person’s ability to maintain stability and balance.
Cochlear Ossification, or hardening of the cochlea – a part of the inner ear, could potentially prevent restoring hearing through cochlear implants, a procedure that helps deaf or hard-of-hearing people. This is a lesser-known complication of labyrinthectomy, a surgery to remove the innermost part of the ear. Typically, the cochlea remains patent (open and unblocked) for many years post-surgery. However, damage to the internal auditory canal and the labyrinthine artery, which supplies blood to the inner ear, could raise the chances of cochlear ossification.
What Else Should I Know About Labyrinthectomy?
The purpose of the procedure called labyrinthectomy is to correct issues within the inner ear that lead to problems with balance and create feelings of dizziness. This is done for patients who experience sudden bouts of dizziness (episodic vertigo) or continuous balance problems (baseline disequilibrium). It’s important to note that total hearing loss in the ear that has been operated on is expected. The procedure is highly effective in controlling dizziness (95 to 100% success rate), but there’s a notable chance that some persistent balance problems may continue.
