An acoustic neuroma is a benign (noncancerous) usually slow growing tumor of the cranial nerve that can affect hearing and balance controlled by the brain. These tumors grow outside of the brain on the cranial nerve and can grow large enough that they may grow into the canal that connects the ear to the brain. They may also press on the brain stem and cranial nerves, which control facial movement and sensation.
Acoustic Neuroma is an old term for what is more accurately known as vestibular schwannoma. This name arises because it is an overgrowth of the schwann cells that insulate the nerve of the brain and the cranial nerves. It is vestibular because it grows off of the eighth cranial nerve, the vestibulocochlear nerve.
The eighth cranial nerve is made up of three nerves: the cochlear nerve, which transmits sounds from the hearing apparatus, and the superior and inferior vestibular branches. This arises specifically from one of the vestibular branches, most often the superior vestibular branch of the eighth cranial nerve.
Anyone is at risk for developing an acoustic neuroma. There are two known risk factors for developing acoustic neuroma, otherwise these are sporadic:
Often times, patients are examined by their primary care physician and they receive an audiogram, which is a hearing test that graphically displays the results of serviceable hearing in each ear. If it is determined that there is diminished hearing, the patient may undergo an MRI, CT scan or other diagnostic imaging procedure to determine if a mass is present.
Once an acoustic neuroma is found, the patient is seen by a neuro-otologist, a doctor who specializes in the ears, nose & throat (Otolaryngology or ENT) that specializes in that hearing apparatus. Patients commonly get sent to a neurosurgeon as well. Here at the Neurosciences Center at Brigham and Women’s Hospital, we have the Skull Base Surgery program which is a multi-disciplinary program. This program coordinates care so the patient can see the neuro-otologist and the neurosurgeon together in the same clinic.
There are three major treatment approaches for an acoustic neuroma:
Conservative management: Watchful waiting with a series of MRIs. Since these are benign tumors, watchful waiting is a perfectly reasonable way to follow acoustic neuromas, especially if the patient receives an MRI and there is no natural history.
Radiation Therapy: Advanced focused radiation, known as Gamma Knife radiosurgery, shows a great success rate. Focused radiation can be an optimal treatment choice especially in the older population or for someone who is not healthy enough to undergo surgery. Even though it is called radiosurgery and “knife” is in the title, the goal of focused radiation is not to remove the acoustic neuromas. The goal of targeted radiation is to hit the acoustic neuroma hard enough so that it stunts it into submission and it does not continue to grow. A small patient population may also benefit from tumor shrinkage through this procedure.
The advantages of the surgical removal of acoustic neuromas are twofold. The first benefit to surgery is the advantage of a pathologic diagnosis. By removing the tumor, neuropathologists are able to examine and conduct a number of genetic tests on the tumor tissue to determine the variant of the tumor and learn more about its origin. The other advantage of surgery is that the acoustic neuroma is completely removed. Once taken out, the chances of an acoustic neuroma recurring (occurring again) are greatly diminished.
There are three approaches to the surgical removal of an acoustic neuroma. The best option will be determined by a number of factors, including the patient’s overall health:
Translabyrinthine Craniotomy: This surgical procedure is completed by a neuro-otologist, who approaches the surgery by entering through the hearing apparatus. Through this method, there is no attempt to save hearing and it is guaranteed to sacrifice hearing. Translabyrinthine is ideal if the patient has no serviceable hearing when they are diagnosed with an acoustic neuroma.
Middle Fossa Craniotomy: This surgical procedure doesn’t necessarily sacrifice hearing, but it’s not as good as preserving hearing as the third approach. Middle fossa is not done very frequently.
Retro-Sigmoid Craniotomy: This procedure is frequently done by our expert fellowship trained skull base neurosurgeons in the Department of Neurosurgery and often in conjunction with experienced neuro-otologists (ENT) in a multidisciplinary team based approach. Neurosurgeons routinely operate with neuro-otologists because they are experts in neurological disorders of the ear. Through this procedure, the team has clear access to the sides of the brain where the seventh and eighth cranial nerve disappears into the canal. For masses outside of the canal, it is really the only approach to surgery because the Middle Fossa and Translabyrinthine approaches don’t allow you to access the brain easily.
The procedure begins with a line incision behind the mastoid, where there is a large blood vessel called the sigmoid sinus, arising to the procedure’s name (behind the sigmoid sinus). The neuro-otologists remove a piece of bone from the canal, which gives the neurosurgeon access to the rest of the tumor.
During surgery the neurosurgeon attempts to peel and free the tumor from the nerves, which may have become damaged due to pressure from the mass.
Many important things are monitored during surgery. This includes the function of the seventh cranial nerve, which controls facial movement on the same side that is being operated on (via a process called neuromonitoring). The seventh cranial nerve is able to be stimulated electrically to monitor how the facial nerve and how the cochlear apparatus are doing. Using a device that sits in the ear, the neurosurgeon can register whether or not signal is being sent down the nerve and into the brain stem.
Even if the patient has no serviceable hearing at the time of surgery, the neurosurgeon will still preserve the cochlear nerve even if there is a chance hearing may get better.
The recovery time after surgery depends on the patient’s overall health prior to and after surgery. Routine hospitalization can usually range anywhere between three and five days after surgery. Immediately following surgery, patients can expect to stay one to two days in the Intensive Care Unit (ICU) and two to three days on a hospital floor with specialized neuro trained nurses and physician assistants.
An important part of surgery for the removal of an acoustic neuroma is preserving the functionality of the facial nerve. While the facial nerve controls facial movement, it is also responsible for closing the eyelid. Closing the eyelid is so important because doing so protects the eye and specifically the cornea. If the cornea is not protected, it can lead to a cornea ulcer and potential blindness.
After surgery, if the facial nerve is not working and cannot close the eyelid completely, a plastic surgeon may complete a temporary procedure where a gold or platinum weight is surgically placed into the upper eyelid to give the eyelid more mass to close fully. Neuro-Ophthalmologists (eye doctors that specialize in neurological disorders) are also a part of the multidisciplinary team approach here at the Neurosciences Center and will be part of your care after surgery to ensure the eye is cared for properly (if necessary).
Like all cranial surgeries, there is a risk of bleeding, infection, injury to the brain, and risk of injury to one of the blood vessels in the brain that may result in a stroke, coma or even death which is why having a well trained and experienced care team is vital. The goal of the surgical procedure is about removing the acoustic neuroma while simultaneously preserving the facial nerve and hearing.
Depending on your age and current state of health, the recovery period for surgical removal of the acoustic neuroma is four to eight weeks. Your dedicated skull base physician assistant will guide you through each step of the surgical process and is available to answer any questions and concerns you may have throughout and during the follow-up process of your surgery.
It is important to note that none of the areas that the team is operating on has anything to do with personality, memory, language or movement and you will be the same person you were prior to surgery. You will be up and walking around the day after surgery with assistance from our dedicated neuro trained nurses during your hospitalization. Most people recover very well from cranial surgery and you may experience pain from the incision and potentially some neck stiffness, but you will get stronger each day.
Our surgeons, as part of work with a multidisciplinary team of physicians to create an individualized treatment plan for each patient in order to provide the best possible treatment. The multidisciplinary team includes specialists in neurosurgery, neuro-otology, and radiology.
Learn more about our team by visiting their physician profiles below:
Within the Department of Neurosurgery at Brigham and Women’s Hospital, we have an established Skull Base Program within the Neurosciences Center that utilizes a multidisciplinary team approach for the best treatment of each particular case of acoustic neuroma. In addition to being neurosurgeons, our team received extra training in the treatment of base of the skull surgeries, like acoustic neuromas. Our neurosurgeons are world-renowned for their expertise and advanced approaches to skull base surgery and have a routine method in which they determine the best approach to treatment on a case by case basis. Our neurosurgeons commonly work with experienced neuro-otologists, neuro-oncologists, neuro-pathologists and radiation oncologists to complete surgical procedures and determine the best method of treatment for your acoustic neuroma.
With our Neurosciences Center clinic, we have the capability to coordinate your surgeon visits with other specialists along with your specialized imaging (CT, MRI, etc) on the same day and in the same space.
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Department of Neurosurgery
Brigham and Women's Hospital
60 Fenwood Road
Boston, MA 02115
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