Acoustic neuroma

Overview

Acoustic neuroma, also known as vestibular schwannoma, acoustic neurinoma and acoustic neurilemoma, is a tumor that develops from schwannom cells covering vestibular nerve of inner ear to brain. The tumor is noncancerous and also usually features as slow growing one, but it may rarely have rapidly growing features and the consequences of this growth is pressure against brain and interference with vital function. The patient can be alerted about his disease by loss of hearing on one side, ringing in ears, dizziness and balance problems.

What are the symptoms of Acoustic neuroma?

Signs and symptoms of acoustic neuroma are often appear gradually and take some years to be apparent. They are not usually causes by tumor itself, although the signs and symptoms are the consequences of the tumor size and its pressure on its surrounding structures. As the tumor becomes larger in size, its pressure on nerves (facial, trigeminal and vestibular), nearby blood vessels, or other brain structure may cause more  considerable or serious signs and symptoms.

Common signs and symptoms of acoustic neuroma include:

  • Hearing loss, often gradually – although in some cases occurs suddenly – and occurring on only one side or more pronounced on one side
  • Ringing (tinnitus) in the affected ear
  • Unsteadiness, loss of balance 
  • Dizziness (vertigo)
  • Facial numbness
  • Weakness or loss of facial muscle movement

What causes Acoustic neuroma?

Acoustic neuroma seems to be a genetic disease that means it’s existance came from malfunctioning of a specific gene on chromosome 22. Naturally, this gene produces some proteins to regulate Schwann cell, covering nerves growth but due to some unknown reasons this gene become corrupted and its function as a Schwann cell growth regulator disturbed so they can grow uncontrollably and form a tumor. This gene malfunctioning can also come from a rarely genetical disease called Neurofibromatosis type II, that is responsible for two sided tumor.

Who is at highest risk?

As mentioned, Neurofibromatosis type II is a well-known reason of this disease, although it is responsible for only 5% of cases. Recent studies demonstrate an elevated risk of acoustic neuroma amongst individuals with the history of leisure noise exposure, but not regular occupational exposure; and a lower risk among ever and current cigarette smoker than never smokers without any correlation for ex-smokers. 

When to seek urgent medical care?

You should seek medical care once each of the following symptoms are seen;

  • Hearing loss on one ear
  • Ringing in one ear
  • Balance disturbances

Diagnosis

Acoustic neuroma is difficult to diagnose in the primary stages since it has no signs and symptoms, unless it become lager and press against surrounding structure. Diagnosis usually triggered by patient’s symptoms. The most common symptom is unilateral hearing loss, that can be examined by audiometry tests such as “pure tone audiometry” that demonstrate progressive high frequency hearing loss. 

Other diagnosing tests include:

  • Brain audiometry evoked response (BAER) that can measure brain response to the heard sounds.
  • Scalp computerized tomography (CT) scan that can be used in order to find tumor even in its first stages but it can miss very small tumor. This test mostly applied when MRI is not available or you are not comfortable with that.
  • Magnetic resonance imaging (MRI) is the most accurate test and it is also used to confirm the diagnosis. 

Treatment options

Treatment of acoustic neuroma depends on the size and growth of the tumor. Treatment options include:

  • Surgery
  • Stereotactic radiosurgery; and
  • Observing

Each of mentioned above treatments options have its own privileges, for instance stereotactic radiosurgery can preserve hearing at least for several years but it can not be applied in tumor size more than about 3cm.

Observation may be a good option especially for older individuals with small tumor

Where to find medical care for Acoustic neuroma?

Ask our experts on Acoustic neuroma

Prevention of Acoustic neuroma

Prevention of the acoustic neuroma is not possible due to the nature of the condition.

What to expect (Outlook/Prognosis)?

Acoustic neuromas are not malignant and do not metastasis (spread) to other Organs. However, some untreated or even relapsed tumor can grow rapidly and invade surrounding structure such as nerves, ear and brain tissue, especially brain stem which is life-treating. Even after adequate treatment by surgery or radiation some complications such as hearing loss and balance problems caused by tumor may be persistent. The least permanent complication are seen when the tumor discovered in its primary stages when its really small therefore its more likely to preserve hearing.

Possible complications

  • Since each treatment option is chosen, vary of complication is expected such as:
    • Hearing loss
    • Facial numbness
    • Facial weakness
    • Ringing in ear
    • Balance problems
    • Persistent headache
    • Stroke or brain bleeding
    • Infection of cerebrospinal fluid (Meningitis)
    • Leakage of cerebrospinal fluid from the wound (may occur only after surgery)

Sources

  • Institute on Deafness and Other Communication Disorders
  • Medline Plus

References

Attribution

This article incorporates public domain material from Wikidoc and MedlinePlus. Please see licenses for further details.

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