Acoustic neuroma Health Article

Definition

An acoustic neuroma is a noncancerous (benign), often slow-growing tumor of the nerve that connects the ear to the brain.

Alternative Names

Vestibular schwannoma; Tumor - acoustic; Cerebellopontine angle tumor; Angle tumor

Causes, incidence, and risk factors

These tumors are thought to occur when there is a defect in a gene that normally prevents tumors from forming. The cause of the genetic defect is not known. However, acoustic neuroma is often linked with the genetic disorder neurofibromatosis type 2 (NF2).

Acoustic neuromas are relatively uncommon, but they are one of the most common types of brain tumors.

The tumor is usually found at the base of the brain.

Symptoms

The symptoms vary based on the size and location of the tumor. Because the tumors grow so slowly, symptoms usually start after the age of 30.

Common symptoms include:

• Abnormal sensation of movement (vertigo)
• Hearing loss in the affected ear
• Ringing (tinnitus) in the affected ear

Less common symptoms include:

• Difficulty understanding speech
• Dizziness
• Headache
  • Upon waking up in the morning
  • Wakes you from sleep
  • Worse when lying down
  • Worse when standing up
  • Worse when coughing, sneezing, straining, or lifting (Valsalva maneuver)
  • With nausea or vomiting
• Loss of balance
• Numbness in the face or one ear
• Pain in the face or one ear
• Vision abnormalities that are temporary
• Weakness of the face

Signs and tests

The health care provider may diagnose an acoustic neuroma based on your medical history, an examination of your nervous system, or tests. A physical examination may show the following signs:

• Drooling
• Facial drooping on one side
• Unsteady walk

If the tumor is large, there may also be signs of increased pressure on the brain (increased intracranial pressure), including the following:

• Dilated pupil on one side only (see eyes, pupils different size)
• Nausea and vomiting
• Sleepiness

The most useful test to identify acoustic neuromas is an MRI of the head. Other useful tests used to diagnose acoustic neuroma and to tell it apart from other causes of dizziness or vertigo include:

• Head CT
• Hearing test (audiology)
• Test of equilibrium and balance (electronystagmography)
• Test of hearing and brainstem function (brainstem auditory evoked response)
• Test for vertigo (caloric stimulation)