A benign (non-cancerous) tumor that affects around 1 in 100,000 people every year.
Also known as vestibular schwannoma, acoustic neurinoma, or acoustic neurilemoma, an acoustic neuroma is a benign (non-cancerous) tumor that affects around 1 in 100,000 people every year. It grows from the Schwann cells that cover the vestibular nerve, which is the nerve connecting the inner ear to the brain, controlling balance and hearing. Although acoustic neuromas are not malignant and won’t spread to other areas of the body, as the tumor grows, it can begin to disturb other nerves of the brain, such as the nerves which are responsible for facial sensation and muscle movements.
Symptoms of an Acoustic Neuroma
In the early days, it can be difficult to pinpoint an acoustic neuroma as the cause behind your symptoms. This is because the typical symptoms of an acoustic neuroma are non-specific and can often be put down to other causes. Symptoms include:
- Hearing loss (this is the first symptom of an acoustic neuroma in around 90% of cases)
- Tinnitus (hearing a phantom ringing, clicking, buzzing, or other noise)
- Dizziness (vertigo)
- Loss of balance
- Loss of facial sensation or weakness in the facial muscles
If the acoustic neuroma develops only on the one side (unilaterally), then only the affected side will experience the symptoms of hearing loss, tinnitus, facial numbness, etc. Conversely, if the tumor is found affecting the vestibular nerves of both ears, you can expect symptoms on both sides.
In addition to the symptoms of an acoustic neuroma, if the tumor grows large enough to compress surrounding blood vessels or the brainstem, which controls vital bodily functions, the condition can become life-threatening.
What Causes Acoustic Neuromas?
Most cases of a one-sided acoustic neuroma occur spontaneously without any known cause or inherited family links. These cases commonly are diagnosed between the age of 30 and 60 years, though can arise at any age. Doctors believe that a dysfunction of a specific gene causes uncontrolled growth of Schwann cells, resulting in the vestibular schwannoma.
Acoustic neuromas that develop on both sides of the head (bilaterally) are commonly associated with a genetic disease called neurofibromatosis type 2. Neurofibromatosis type 2 is a disorder involving multiple tumors around the brain and spinal cord. There is also a link to the same dysfunctional gene as in one-sided acoustic neuromas, but in neurofibromatosis type 2, this problem is inherited. Compared to one-sided tumors, people with bilateral acoustic neuromas due to neurofibromatosis type 2 tend to become aware of their symptoms at an earlier age, around their teens to early adulthood.
Acoustic Neuroma Treatment and Management
The diagnosis of an acoustic neuroma can often be delayed due to the early symptoms being so subtle. Once investigations do begin, they typically involve:
- Hearing tests, such as audiometry
- Balance testing
- Physical ear examination
- MRI scans
The best treatment for you can be determined by a number of factors, such as the size and exact location of the tumor, your age and overall health, and how problematic your symptoms are. It’s important to note that all management strategies also come with risks, so your treating specialist will discuss with you which particular treatment has the best balance of risk versus benefit for your specific situation.
Treatment options for acoustic neuromas include:
- Observation/monitoring. This is appropriate for small tumors that demonstrate minimal or no growth, and are not causing particularly distressing symptoms. Elderly patients or other individuals who may be more at risk of complications from other interventions can also elect to just be monitored. You will need regular follow-up with imaging and hearing tests.
- The tumor may need to be surgically removed under general anesthetic if it’s very large, growing, or causing bothersome symptoms. People at risk of the acoustic neuroma damaging the facial nerve and causing facial paralysis are more likely to need surgery to remove the tumor. However, sometimes it’s not possible to get rid of the entire tumor if it carries too great a risk of damaging other nearby nerves or critical brain areas. Small tumors successfully removed through surgery can result in restoring hearing and improving your other symptoms.
- Radiation therapy. There are a few different types of radiation therapy that can be used to treat acoustic neuromas. These include stereotactic radiosurgery, stereotactic radiotherapy, and proton beam therapy. In each case, very precise doses of radiation are delivered to the target area (that is, the tumor), minimizing the impact on the surrounding tissues. The aim of radiation therapy is to prevent the acoustic neuroma from growing and, in some cases, can even shrink it. Radiation therapy may be most appropriate for people who are not suitable for surgery, such as the very elderly or those in ill-health who would not do well with surgery.
Symptoms of hearing loss, tinnitus, and vertigo shouldn’t be ignored. Though there are a number of other middle and inner ear conditions that can present with the same symptoms, always get these new-onset symptoms checked out with your family physician or ENT specialist.
Vestibular Schwannoma (Acoustic Neuroma) and Neurofibromatosis. https://www.nidcd.nih.gov/health/vestibular-schwannoma-acoustic-neuroma-and-neurofibromatosis
Acoustic Neuroma. https://www.mayoclinic.org/diseases-conditions/acoustic-neuroma/symptoms-causes/syc-20356127