Initial symptoms of acoustic neuroma are difficult to distinguish from more common medical problems. In the beginning, 90 percent of people with an acoustic neuroma experience a reduction in hearing in one ear, often accompanied by tinnitus (ringing). Unsteadiness or balance problems may also be experienced, since the tumor originates on the eighth cranial nerve. As the tumor increases in size, it presses on other cranial nerves, including those that control facial movement and sensation.
Diagnosing an acoustic neuroma begins with specialized hearing tests, performed in the Koss Hearing and Balance Center at Froedtert & the Medical College of Wisconsin, to determine whether the cochlea and acoustic nerves are functioning properly. An Auditory Brainstem Response (ABR) test is performed to measure the passage of sound information from the ear to the brain.
If abnormalities are identified with audiologic testing, a Magnetic Resonance Imaging (MRI) test will be used to define whether an acoustic neuroma is present and to pinpoint its size and location. Sometimes, a facial nerve test is done to measure the tumor's impact on the nerve.