Acoustic neuroma other diagnostic studies
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Other diagnostic studies
Hearing test (audiometry)
- Audiometry can detect whether the hearing loss is sensorineural or conductive.
- During the test, the patient wears earphones and hears sounds directed to one ear at a time.
- A range of sounds of various tones are heard and the patient has to indicate each time they hear the sound.
- Each tone is repeated at faint levels to find out when the patient can barely hear.
Auditory brainstem response test
- An auditory brainstem response test (ABR, BAER, or BSER) may be done in some cases.
- This test provides information on the passage of an electrical impulse along the circuit from the inner ear to thebrainstem pathways.
- An acoustic neuroma can interfere with the passage of this electrical impulse through the hearing nerve at the site of tumor growth in the internal auditory canal, even when the hearing is still essentially normal.
- This implies the possible diagnosis of an acoustic neuroma when the test result is abnormal. 20-35% of acoustic neuroma tumors smaller than 1 cm are missed by ABR screening techniques.
- An abnormal auditory brainstem response test should be followed by an MRI.
- If an MRI is not available or cannot be performed, a computerized tomography scan (CT scan) with contrast is suggested for patients in whom an acoustic neuroma is suspected.
- The combination of CT scan and audiogram approach the reliability of MRI in making the diagnosis of acoustic neuroma.
- Electronystagmography (ENG) is a test in which eye movements are recorded with small electrodes placed on the skin around the eyes.
- This test evaluates patient's balance by detecting eye movements while stressing the balance in various ways.
- Electronystagmography (ENG testing) is frequently abnormal in patients with acoustic neuroma.
- Unilateral loss of calorics is associated in about 50% of all tumors.
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