Acoustic Neuroma
Acoustic neuroma is a noncancerous (benign) tumor that slowly grows in the nerve connecting the ear to the brain. Also known as vestibular schwannoma, acoustic neuroma grows behind the ear below the brain and affects a person’s hearing as well as sense of balance.
Acoustic neuroma accounts for a small portion of cases of unilateral hearing loss and dizziness as well as rarely other symptoms related to the brain.
What are the causes of acoustic neuroma?
Studies showed that an acoustic neuroma condition is not hereditary but is linked to a genetic defect possessed by some individuals. The typical individual possesses certain characteristics in their genes that prevent tumors from occurring. Those who have acoustic neuroma, however, normally do not possess this trait.
While there is an inheritable condition called neurofibromatosis type 2 (NF2) that can lead to acoustic neuroma formation, most acoustic neuromas occur spontaneously without any evidence that the condition can be inherited.
How common is this disease?
Acoustic neuroma cases are rare, with about ten tumors diagnosed each year per million persons. Put another way, the typical person has a one in 1,000 chance of developing an acoustic neuroma.
Only about one in every 1,000 has acoustic neuroma among patients with hearing asymmetry, although some report prevalence as high as 2.5 percent.
Most acoustic neuroma cases involve patients between the ages of 30 and 60. The condition is even rarer among children.
Who are at risk?
Those who are at risk of having the condition are those whose head and neck are exposed to radiation. While there are assumptions that those who are often exposed to radiofrequency radiation – such as frequent cellphone users – have a high risk of having acoustic neuroma, these are not conclusive. To date, however, no environmental factor (such as cell phones and diet) has been scientifically proven to cause this type of tumor. Experts, however, recommend that frequent cellular phone users use a hands-free device to enable separation of the device from the head.
What are the symptoms of acoustic neuroma?
Symptoms of acoustic neuroma are dependent on the location and size of the tumor. Because the tumor grows so slowly, symptoms typically show after the afflicted person reaches the age of 30.
Typical symptoms of acoustic neuroma include:
Abnormal sensation of movement (vertigo)
Loss of hearing in the affected ear
Ringing (tinnitus) in the affected ear
Less common symptoms include:
Dizziness
Headache upon waking up in the morning
Loss of balance
Numbness in the face or one ear
Facial pain
Vision problems
How is acoustic neuroma diagnosed?
The following signs may indicate an acoustic neuroma condition:
Drooling
Facial drooping on one side
Unsteady walk
Dilated pupil on one side only To detect acoustic neuroma, the healthcare provider may require the following:
MRI of the head
Head CT
Hearing test
Test of equilibrium and balance
Test of hearing and brainstem function
Test for vertigo What are my treatment options?
Conventional surgery. The objective of surgery is remove the tumor and prevent paralysis of the face. However, even if the tumor is removed, there is only a small chance that hearing will be restored. It is almost impossible to get back any hearing that is lost before surgery.
Radiosurgery. This type of surgery is often performed in elderly or sick patients who are unable to tolerate brain surgery.
Stereotactic radiosurgery, a form of radiation therapy whose goal is to slow or stop the tumor growth, not to cure or remove the tumor. Nearly half of all acoustic neuromas are treated by surgery, about a quarter with radiation, and about a quarter are under observation.
What are the risks involved?
Excising large tumors usually results in total loss of hearing on the side affected. Large tumors may also press down on nerves that play a role in movement and sensation in the face. While typically large tumors can be removed safely, surgery often leads to paralysis of some muscles of the face.
Extremely large tumors may also press on the brainstem, thus putting in danger other nerves and preventing the normal flow of cerebrospinal fluid. This can lead to a build-up of fluid (hydrocephalus), which can increase pressure in the head and can be life-threatening. Goals of surgery in these cases are to treat the hydrocephalus and relieve pressure on the brainstem.
