Acoustic neuroma other diagnostic studies: Difference between revisions
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__NOTOC__ | __NOTOC__ | ||
{{Acoustic neuroma}} | {{Acoustic neuroma}} | ||
{{CMG}}{{AE}}{{Simrat}} | {{CMG}}{{AE}}{{Simrat}} {{M.B}} | ||
==Overview== | ==Overview== | ||
[[Audiometry]] as the best initial [[Screening (medicine)|screening]] [[test]] for the [[diagnosis]] of acoustic neuroma. It can detect asymmetric [[Sensorineural hearing loss|sensorineural hearing impairment]] in about 95% of the [[Patient|patients]]. Brain stem-evoked response audiometry (ABR, BAER, or BSER) may be done in some cases with unexplained asymmetries in standard [[Audiometry|audiometric testing]] as a further [[screening]] measure and an abnormal [[Hearing (sense)|auditory]] [[brain stem]] response [[test]] should be followed by an [[MRI]]. | |||
==Other | |||
===Hearing | ==Other Diagnostic Studies== | ||
[[Audiometry]] | ===Hearing Test (Audiometry)=== | ||
===Auditory | * [[Audiometry]] as the best initial [[Screening (medicine)|screening]] [[test]] for the [[diagnosis]] of acoustic neuroma. | ||
* It can detect asymmetric [[Sensorineural hearing loss|sensorineural hearing impairment]] in about 95% of the [[Patient|patients]]. | |||
* [[Speech]] [[audiometry]] includes [[speech]] reception threshold (SRT) and the word discrimination score. The word discrimination score is noticeably decreased in the affected [[ear]] and out of proportion to the measured [[Hearing impairment|hearing loss]]. | |||
[[ | |||
===Auditory Brainstem Response Test=== | |||
* [[Brain stem|Brainstem]]-evoked response [[audiometry]] (ABR, BAER, or BSER) may be done in some cases with unexplained asymmetries in standard [[Audiometry|audiometric testing]] as a further [[Screening (medicine)|screening]] measure. | |||
* This [[test]] provides information on the passage of an electrical impulse along the circuit from the [[inner ear]] to the [[brainstem]] pathways. An acoustic neuroma can interfere with the passage of this electrical impulse through the [[cochlear nerve]] at the site of [[tumor]] growth in the [[Internal auditory meatus|internal auditory canal]], even when the [[Hearing (sense)|hearing]] is not necessarily impaired. | |||
* This implies the possible [[diagnosis]] of an acoustic neuroma when the [[test]] result is abnormal. 20 - 35% of acoustic neuroma [[Tumor|tumors]] smaller than 1 cm are missed by ABR [[Screening (medicine)|screening]] techniques. The [[Type I and type II errors|false negative]] rate can be as high as 30% with small vestibular schwannomas, and there is a 10% [[Type I and type II errors|false positive]] rate. | |||
* An abnormal [[Hearing (sense)|auditory]] [[brain stem]] response [[test]] should be followed by an [[MRI]]. | |||
* If an [[Magnetic resonance imaging|MRI]] is not available or cannot be performed, a [[CT scan|computerized tomography scan (CT scan)]] with [[Contrast medium|contrast]] is suggested for [[Patient|patients]] suspected of having the [[tumor]]. | |||
* The combination of [[Computed tomography|CT scan]] and [[audiogram]] can approach the reliability of [[Magnetic resonance imaging|MRI]] in making the [[diagnosis]] of acoustic neuroma. | |||
==References== | ==References== | ||
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Latest revision as of 19:28, 26 April 2019
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Simrat Sarai, M.D. [2] Mohsen Basiri M.D.
Overview
Audiometry as the best initial screening test for the diagnosis of acoustic neuroma. It can detect asymmetric sensorineural hearing impairment in about 95% of the patients. Brain stem-evoked response audiometry (ABR, BAER, or BSER) may be done in some cases with unexplained asymmetries in standard audiometric testing as a further screening measure and an abnormal auditory brain stem response test should be followed by an MRI.
Other Diagnostic Studies
Hearing Test (Audiometry)
- Audiometry as the best initial screening test for the diagnosis of acoustic neuroma.
- It can detect asymmetric sensorineural hearing impairment in about 95% of the patients.
- Speech audiometry includes speech reception threshold (SRT) and the word discrimination score. The word discrimination score is noticeably decreased in the affected ear and out of proportion to the measured hearing loss.
Auditory Brainstem Response Test
- Brainstem-evoked response audiometry (ABR, BAER, or BSER) may be done in some cases with unexplained asymmetries in standard audiometric testing as a further screening measure.
- This test provides information on the passage of an electrical impulse along the circuit from the inner ear to the brainstem pathways. An acoustic neuroma can interfere with the passage of this electrical impulse through the cochlear nerve at the site of tumor growth in the internal auditory canal, even when the hearing is not necessarily impaired.
- 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. The false negative rate can be as high as 30% with small vestibular schwannomas, and there is a 10% false positive rate.
- An abnormal auditory brain stem 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 suspected of having the tumor.
- The combination of CT scan and audiogram can approach the reliability of MRI in making the diagnosis of acoustic neuroma.