Acoustic Neuroma/Vestibular Schwannoma
An acoustic neuroma may also be called a vestibular schwannoma. It is a benign tumor that may affect your hearing or balance. You have 12 paired, cranial nerves (one for your left and right side) that arise directly from your brain or brainstem. Each cranial nerve is involved with a specific function. An acoustic neuroma (vestibular schwannoma) arises from your eighth cranial nerve, which actually is composed of two nerves: (1) the vestibular nerve that carries messages from your inner ear to your brainstem to help regulate your body balance and eye movements, and (2) the cochlear nerve that is involved with your hearing.
Signs and Symptoms
Because of the typically slow growth pattern of an acoustic neuroma, the initial symptoms involving hearing or steadiness may be subtle. If the tumor grows large enough, it can put pressure on other nearby nerves, blood vessels and brain structures. Symptoms of an acoustic neuroma may include:
- Hearing loss that is usually gradual and present, or more noticeable, in one ear
- Ringing in the ear
- Loss of balance or steadiness
- Dizziness (vertigo)
- Facial numbness or, less commonly, facial pain on one side
Schwann cells form a sheath around your eighth cranial nerve. A faulty gene on chromosome 22 leads to abnormal growth of Schwann cells which results in acoustic neuroma. Patients with a condition called neurofibromatosis may have acoustic neuromas on both sides.
Many other conditions can produce the same type of symptoms that are seen with an acoustic neuroma. It is important to check with a doctor (such as a neurosurgeon or ear, nose and throat [ENT] surgeon) who is experienced in recognizing the exact combination of signs and symptoms to establish an accurate diagnosis.
A customized treatment plan is designed for you based on:
- The size of the tumor
- Your age and general health
- Your ability to tolerate a specific treatment
- Your goals and preferences
Treatment for an acoustic neuroma may include one or a combination of the following options:
- Observation If the tumor is not big or growing rapidly, observing the tumor by monitoring your symptoms and checking scans may be considered or recommended.
- Microscopic surgical resection Microsurgical resection of an acoustic neuroma is typically performed by highly specialized neurological and ENT surgeons. The operation is done using general anesthesia. Intra-operative monitoring of your nerve function and the use of real-time image guidance may be used to help achieve the safest resection possible. Several different approaches or trajectories can be chosen based upon the size and location of the tumor. You will need to stay in the hospital for a few days after surgery, with the length of stay usually depending on the size of your tumor and the extent of surgery. You will undergo a post-operative brain MRI (with and without contrast) to evaluate the tumor removal.
- Stereotactic radiosurgery This is a very precise form of radiation treatment. The acoustic neuroma is outlined on a 3-D image of your brain. Small beams of radiation are directed to the tumor target from many different angles. Each individual beam has minimal effect on your normal brain tissue. However, a very high dose of radiation hits the targeted area where all the different beams intersect. Certain stereotactic radiosurgery procedures may require the use of a reference frame placed on your skull, but many do not.
Follow-up care includes regular monitoring to check for any worsening symptoms or the effectiveness of treatment. Follow-up brain scans (usually MRIs) will be obtained to look for any growth or recurrence of the acoustic neuroma.