Acoustic neuroma

This page was reviewed under our medical and editorial policy by
Maurie Markman, MD, President, Medicine & Science at CTCA.

This page was updated on September 12, 2022.

An acoustic neuroma—also called a vestibular schwannoma—is a brain tumor, but it isn’t cancer. Unlike a cancerous tumor, acoustic neuromas don’t spread to other parts of the body or brain. However, as an acoustic neuroma grows, it presses upon essential parts of the brain that play a role in hearing and balance.

According to the Acoustic Neuroma Association, these tumors are rare and account for 6 to 10 percent of all brain tumors. In the United States, about 2,500 to 3,000 people are diagnosed with acoustic neuromas every year—or one in every 100,000 people. These tumors tend to occur in people between the ages of 30 and 60, although they may affect people of all ages.

Acoustic neuromas grow in cells surrounding the vestibulocochlear nerve, which connects the ear and the brain and helps control hearing and balance. These cells are called Schwann cells, and they form a protective layer around nerves. An acoustic neuroma may develop when there’s an overproduction of Schwann cells around this nerve.

Acoustic neuromas tend to be slow-growing, developing over many years without causing any problems. However, some of these tumors grow faster and cause more severe symptoms.

Symptoms of acoustic neuroma

The most common symptoms associated with acoustic neuromas are:

  • Hearing loss (on one side)
  • Ringing in the ears
  • Dizziness
  • Balance problems

These symptoms sometimes show up as the earliest sign of an acoustic neuroma. More severe symptoms that tend to appear later, as the tumor grows larger, include:

  • Numbness, paralysis or pain in the face
  • Headaches
  • Clumsiness
  • Confusion

Over time, if an acoustic neuroma grows large enough and starts putting pressure on the brain, it may become life-threatening. However, most cases are discovered and treated before they get to this point.

Early diagnosis of an acoustic neuroma isn’t always easy, as symptoms may be mild or confused with more common ear infections or other ear problems.

  • Ear exams, hearing tests and imaging tests are used to discover and diagnose an acoustic neuroma.
  • Magnetic resonance imaging (MRI) scans are an important part of the diagnostic process, as they produce detailed images of the area and reveal the size and location of the tumor.

Causes of acoustic neuroma

Acoustic neuromas are thought to be caused by a faulty gene on chromosome 22. This gene is supposed to regulate the production of Schwann cells, but in people with an acoustic neuroma, this gene doesn’t work properly. So Schwann cells grow out of control, forming a tumor.

Most acoustic neuromas aren’t caused by inherited genetic changes, meaning that the gene malfunction seems to arise randomly most of the time.

However, people with tumors that affect hearing in both ears often have an inherited condition called neurofibromatosis type 2 (NF2). Tumors on both nerves are called bilateral vestibular schwannomas, or bilateral acoustic neuromas, while a tumor affecting hearing on one side is referred to as unilateral.

NF2 causes affected individuals to inherit the faulty gene on chromosome 22 that is thought to be responsible for acoustic neuromas. Those who have this condition and go on to develop tumors on their hearing nerves usually experience symptoms earlier than others, when they are teenagers or young adults.

Treatment of acoustic neuroma

The three main treatment options for acoustic neuromas are:

The best treatment option depends on:

  • Size of the tumor
  • Severity of symptoms/hearing loss
  • Age and overall health
  • Personal preferences

Observation: Observation (or watchful waiting) is a treatment approach that doctors may recommend for small, slow-growing tumors. In this case, patients may undergo regular MRI scans to monitor the tumor and make sure it isn’t growing. If the tumor starts to cause problems, treatment options are reassessed.

Surgical removal: Some acoustic neuromas need to be surgically removed. This procedure may be complicated or relatively simple, depending on the tumor size and severity of hearing loss.

Surgery to remove a small tumor may stop the progression of hearing loss and relieve other symptoms. However, removing a larger tumor may not result in the same improvements, as the tumor may have already caused significant nerve damage. The surgery itself may also damage the nerves, potentially worsening symptoms.

Radiation therapy: Radiation therapy may shrink the tumor or slow its growth. Acoustic neuromas may be treated with a type of radiation therapy called radiosurgery, which sends a beam of radiation toward the tumor to destroy tumor cells and prevent them from growing.

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