Acoustic neuroma is an uncommon tumor that grows in the brain. It is also known as a vestibular schwannoma. It usually grows in size but does not spread to other areas. This means the tumor is benign.
The tumor grows near to the ear area on a nerve in the brain. This can cause problems with balance and hearing. It also causes ringing in the ears known as tinnitus. Generally the cause of this tumor is unknown. Sometimes acoustic neuromas can be associated with the disease known as neurofibromatosis type 2.
Acoustic neuromas will generally grow slowly and are not life-threatening. The most common treatment is with surgery, however radiotherapy may also be used. After treatment for a acoustic neuroma, one of the most common symptoms is permanent deafness in the treated ear.
What causes an acoustic neuroma?
It is unknown how most acoustic neuromas are developed. Approximately 7% of acoustic neuromas are caused by neurofibromatosis type 2 (NF2). This is an uncommon genetic disorder that causes benign tumours of the nervous system. 1 in 350,000 people are affected. Almost anyone with neurofibromatosis type 2 will develop an acoustic neuroma on both of the hearing nerves otherwise known as acoustic nerves. Since they occur on both sides it is known as a bilateral tumor. Sometimes, people with neurofibromatosis type 2 may also develop tumors on the spinal cord and the lining of the brain. These are usually benign.
Are acoustic neuromas common?
Acoustic neuromas are not common. The incidence is approximately 10 to 20 per 1,000,000 people in the United States. Brain tumors are even considered rare. There are two types of Brain tumors. Non-cancerous tumors are known as benign while cancerous tumors are known as malignant. Brain tumours are split into two main categories:
- A Primary brain tumor originates in the brain. Acoustic neuroma is considered a primary brain tumor.
- A Secondary brain tumor is a tumor that has spread from other parts of the body to the brain. These tumors are often referred to as brain metastases. These tumors are considered malignant.
- Acoustic neuromas are common in middle-aged adults and very rare in children. Acoustic neuromas appear to be more common in females than in males.
What are the most common symptoms of an acoustic neuroma?
The most common symptom is hearing loss. A certain degree of deafness will occur in most people with an acoustic neuroma. The loss of hearing is usually gradual and affects one ear. This type of deafness caused is called sensorineural deafness. This means the acoustic nerve which is the nerve for hearing is damaged.
Another common symptom is ringing in the ears or Tinnitus. About 70% of people with an acoustic neuroma will have tinnitus in one ear. The sounds can vary and does not have to be ringing like a bell. Any sounds heard within the ear when there is no external sound being made is known as Tinnitus. Tinnitus is not a disease in itself and is very common. Earwax, ear infections, aging and noise-induced hearing loss can cause tinnitus.
Other symptoms of acoustic neuroma include:
Vertigo. This is the sensation or feeling of a room spinning, usually described as dizziness. Vertigo can even occur when standing still. Other conditions affecting the inner ear can cause Vertigo. Almost half of people with an acoustic neuroma have Vertigo, but less than 10 percent have it as their first symptom.
Facial numbness, pain or tingling. Pressure from the acoustic neuroma on other nerves typically symptoms cause these symptoms . The trigeminal nerve controls feeling in the face and is the most commonly affected nerve. About 25% of people diagnosed with acoustic neuroma will have some facial numbness – which is a more common symptom than weakness of the facial muscles. However, this symptom usually goes unnoticed. Similar symptoms can occur with other problems, trigeminal neuralgia or a facial neuroma which is a tumor growing on the facial nerve is a similar symptom.
Less common symptoms of acoustic neuroma are:
Headache is a rare symptom of an acoustic neuroma. Headaches from acoustic neuromas can occur if the tumor is large enough to block the flow of cerebrospinal fluid in the brain. Cerebrospinal fluid or CSF is a clear, nourishing fluid that flows around the spinal cord and brain. CSF protects these delicate structures from chemical and physical harm. When the flow and drainage of cerebrospinal fluid is onstructed, it can cause hydrocephalus which is a problem known as “water on the brain”. This results in increased swelling and pressure, and the brain basically becomes squashed within the skull. This can cause headaches and, if untreated, this can cause brain damage.
Another rare symptom of acoustic neuroma is Earache. There are many more common causes of earache.
Visual problems is another rare symptom. Hydrocephalus usually plays a role in visual problems.(see above).
Lack of energy and tiredness. These are can be due to many causes and are nonspecific symptoms. There is possibility that a benign brain tumour could lead to this.
What tests can be performed to diagnose an acoustic neuroma?
An MRI or Magnetic Resonance Imaging scan of the brain is the best test to diagnose an acoustic neuroma. An MRI uses a strong magnetic field and radio waves to take a detailed picture of your brain including the structures inside it. It is painless test, but it can be noisy.
Another test that can be performed is a hearing test if an acoustic neuroma is suspected. This is because hearing loss is one of the most common symptoms of an acoustic neuroma. If an acoustic neuroma is found on an MRI scan, it is helpful to know what your hearing in both ears is like before getting treatment.
What treatment options are available for acoustic neuroma?
Acoustic neuromas are grow very slowly and may not cause any symptoms for a long time. If you have a very small acoustic neuroma, your physician may decide to just to observe and monitor it closely. Treatments can have complications and side-effects so the risks and benefits of treatment should be balanced. If observation is recommended, your condition will be monitored regularly.
Surgery or Stereotactic Radiosurgery are the main treatments for Acoustic Neuroma. The treatment you are offered will depend on several factors:
Your age and overall health will determine if you are suited for surgery or radiotherapy.
The size and location of your acoustic neuroma will determine the type of treatment offered.
The results of the scans and tests you receive will help determine which treatment is right for you.
A neurosurgeon or an ENT (Ear Nose Throat) surgeon can operate to remove an acoustic neuroma. This is dependent on its size and location on the vestibulocochlear nerve in the brain. The surgery is performed under General Anesthesia.
Surgery is the main treatment option for people with acoustic neuromas. About 95% of these tumors can be completely removed. In a small number of cases, a small part of the tumor can be left behind. If the tumor is located near critical or nearby structures and can cause more damage to the nerve, sometimes the complete tumor is not removed.
If some of the acoustic neuroma is left remaining, it can usually be treated with radiotherapy. After surgery for an acoustic neuroma, you will most likely remain in the hospital for several days for monitoring. You should be fully recovered within 6-12 weeks, and, if your tumor was removed completely, you should not need additional treatment.
Stereotactic radio surgery
is a newer type of treatment that can be used for acoustic neuromas. This involves delivering a very precise single dose of radiation to a well-defined area within the brain to treat the acoustic neuroma.
Stereotactic is defined as locating a point using three-dimensional (3D) coordinates. In this instance, the point is the acoustic neuroma within the brain. A halo-like metal frame is attached to your scalp and a series of scans are taken to show the exact location of the tumor.
Stereotactic radiosurgery is a very specialised type of treatment and is available at Premier Brain and Spine. The main advantage of this focal treatment is to preserve any remaining hearing and prevent tumor growth. This focal treatment tends to shrink rather than destroy or remove the acoustic neuroma. It can be used for small tumors.
Are there any complications from an acoustic neuroma?
Possible complications due to the acoustic neuroma include but are not limited to:
Hearing loss. This is the most common symptom of an acoustic neuroma. The acoustic neuroma grows on the vestibulocochlear nerve and damages it causing hear loss. If the acoustic neuroma is removed with surgery, or destroyed by radiotherapy, a certain degree of permanent hearing loss in one ear is usual. The extent to which you will be affected by hearing loss varies depending on the tumor size, how much damage has been caused by the tumor, and how difficult the treatment was. Severe or even complete deafness on the side of the acoustic neuroma is possible.
Hydrocephalus (water on the brain). If the acoustic neuroma grows large in size, a complication known as hydrocephalus can occur. When the flow of cerebrospinal fluid (CSF) is obstructed (see above, under ‘Less common symptoms of acoustic neuroma’)pressure can build up inside the brain, leading to permanent brain damage if not identified and treated. This condition can be treated by inserting a shunt or drainage tube to relieve the pressure and allow the CSF to flow normally. Hydrocephalus is very unlikely if you have treatment for an acoustic neuroma.
Damage caused by pressure on other nerves in the brain, or on the brainstem. If the acoustic neuroma is growing and untreated, it can cause problems by pressing on nearby structures in the brain. This can lead to some of the symptoms of acoustic neuroma, listed earlier. Long-term pressure can cause permanent damage. It is possible that the trigeminal nerve (which controls feeling in the face) or the facial nerve (which controls movements of the muscles of the face) can be affected. The brainstem is the lower part of your brain that connects to the spinal cord. It controls vital bodily functions. If the brainstem is affected (very rare) then it is possible to have problems with breathing, consciousness, the circulation, co-ordination and balance, and your arm and leg function. Again, if you have treatment for your acoustic neuroma before it has had the chance to grow very big (remember, it is a slow-growing tumour), this sort of complication is very unlikely.
Possible complications due to treatments for acoustic neuroma:
Facial nerve palsy from damage to the facial nerve. Movements in the muscles of the face is controlled by the facial nerve. If an acoustic neuroma has grown very large, surgical removal can potentially lead to damage of this nearby nerve. Paralysis of part of the face can occur if the nerve is damaged. This can cause a problem with drooping of one side of the face. In some cases, physiotherapy will help but, in others, the damage may be permanent. Great care is taken during surgery to identify and avoid damage to surrounding nerves.
Damage to the vestibulocochlear nerve, leading to deafness. A certain degree of hearing loss is normal after treatment for acoustic neuroma. If you have bilateral tumors and NF2, there is a strong chance that after surgery, you will lose hearing in both of your ears.
Facial numbness due to damage of the trigeminal nerve. In the same way that the facial nerve can be damaged during surgery to remove an acoustic neuroma, the trigeminal nerve can also be injured. If this occurs, there is loss of feeling to parts of the face.
Recurrence of acoustic neuroma
Fewer than 5% of all acoustic neuromas come back. It is more likely if you have neurofibromatosis type 2 or NF2. It could cause any of the symptoms mentioned earlier, or any of the complications. After treatment of an acoustic neuroma, you will generally be followed up by your physician for any symptoms or signs of a recurrence.
What is the outlook for an acoustic neuroma?
The outlook is normally very good since it is a non-cancerous tumour. It is generally very suitable for treatment and complications are uncommon. There is usually some degree of hearing loss in the affected ear after treatment.