Surgery for Acoustic Neuroma
Doctors at NYU Langone may recommend surgery to treat people who have an acoustic neuroma, also called vestibular schwannoma. The goal is to remove the tumor entirely, if possible, while sparing important nerves involved in hearing, balance, and facial movement and sensation.
Physicians may choose surgery for people with large tumors or tumors that are causing serious problems with balance; persistent headaches or facial pain; or hydrocephalus, a buildup of fluid in the brain.
Hydrocephalus occurs when an acoustic neuroma grows large enough to press on the brain stem, the lower portion of the brain that connects to the spinal cord. This blocks the flow of cerebrospinal fluid—the liquid that surrounds and cushions the brain and spinal cord—from draining properly.
Very small tumors can also be treated with surgery when doctors observe growth or when preservation of hearing is a goal.
Surgery to remove an acoustic neuroma is often guided by computer software that incorporates MRI scans and CT scans, which create three-dimensional images of the brain. The imaging tests help surgeons remove tumors with great precision, while avoiding damage to nerves responsible for hearing, balance, and facial movement.
A team of clinical neurophysiologists—doctors who specialize in how the nervous system works—monitors these nerves during surgery to see how they are tolerating the procedure. This helps to preserve the nerves’ function.
The surgical approach your doctor uses depends on the tumor size and location and whether preserving your hearing is a priority or an option. All procedures require general anesthesia.
Doctors may use translabyrinthine surgery for any size of tumor that has caused significant hearing loss or where hearing preservation is not possible. During this procedure, the surgeon makes an incision behind the ear and opens the mastoid bone, as well as a portion of the inner ear, which contains structures important for hearing and balance. This gives the surgeon access to the tumor in the internal auditory canal, which acts as the passageway for the eighth cranial nerve—the nerve that runs from the brain to the inner ears—and provides a good view of the nerves so the surgeon can preserve facial function.
The surgeon removes the entire tumor, or as much of it as is safely possible. To reach the tumor, surgeons occasionally remove the cochlea, the part of the inner ear that processes sound, or the otic capsule, which is the bony structure that surrounds the inner ear.
Because a portion of the inner ear is removed during this procedure, hearing is lost in that ear. Balance is usually not a problem because the opposite ear can take over this function, although rehabilitation therapy may be necessary to help you compensate for some loss of balance.
In general, the translabyrinthine approach is the best option when hearing has already been severely affected from the tumor or when tumors are large and hearing preservation is not possible.
Our surgeons may use a retrosigmoid approach for smaller acoustic neuromas, when hearing preservation is possible. They use this approach for tumors that are growing out of the internal auditory canal and approaching the brainstem.
During this surgery, a surgeon makes an incision further behind the ear to open a portion of the skull called the occipital bone, located behind the mastoid. The cerebellum, a part of the brain located above the brain stem, falls back out of the way, and surgeons remove the bone over the internal auditory canal to fully access the tumor. The surgeons can view the facial nerve, the hearing nerve, and the brainstem.
If removing the entire tumor could damage nerves or brain tissue, the doctor may leave some small bits of the tumor behind. The section of the skull opened to perform this surgery is replaced after tumor removal. Fat from the periumbilical region, meaning the area surrounding the belly button, is removed and used to seal the closure to prevent spinal fluid leaks.
Middle Fossa Approach
The middle fossa approach is an option for smaller tumors that have not grown beyond the internal auditory canal. As with the retrosigmoid approach, it is used to help preserve hearing. The surgeon makes an incision above the ear in the lateral skull bone, and then uncovers the internal auditory canal, and removes the acoustic neuroma. This approach is the best for saving hearing, which is possible in the majority of people who have the procedure. Then surgeons replace the skull bone and use fat from elsewhere in the body to help close the opening.
What to Expect after Surgery
After surgery, you may spend a few days recovering in the hospital while your doctor monitors you and manages any pain, dizziness, and other symptoms you may be experiencing. If your hearing has been affected by the surgery, your doctor can work with you to explore your options for hearing rehabilitation. Balance is recovered slowly, and most people can return to work in 8 to 12 weeks.