Editing Sensorineural hearing loss (section)

==Diagnosis==

===Case history===
Before examination, a case history provides guidance about the context of the hearing loss.
* major concern
* pregnancy and childbirth information
* medical history
* development history
* family history

===Otoscopy===
Direct examination of the external canal and tympanic membrane (ear drum) with an [[otoscope]], a medical device inserted into the ear canal that uses light to examine the condition of the external ear and tympanic membrane, and
middle ear through the semi-translucent membrane.

===Differential testing===
Differential testing is most useful when there is unilateral hearing loss, and distinguishes conductive from sensorineural loss. These are conducted with a low frequency tuning fork, usually 512&nbsp;Hz, and contrast measures of air and bone conducted sound transmission.
* [[Weber test]], in which a tuning fork is touched to the midline of the forehead, localizes to the normal [[ear]] in people with unilateral sensorineural hearing loss.
* [[Rinne test]], which tests air conduction ''vs.'' bone conduction is positive, because both bone and air conduction are reduced equally.
* less common [[Bing test|Bing]] and Schwabach variants of the Rinne test.
* absolute bone conduction (ABC) test.

''Table 1''. A table comparing sensorineural to [[conductive hearing loss]]
{| cellspacing=0 cellpadding=10|
|  style="background:#ccc; text-align:center;"|'''''Criteria'''''
|  style="background:#eee; text-align:center;"|'''''Sensorineural hearing loss'''''
|  style="background:#eee; text-align:center;"|'''''Conductive hearing loss'''''
|-
| style="background:#eee;"|'''Anatomical site'''
|[[Inner ear]], [[cranial nerve]] VIII, or central processing centers
|[[Middle ear]] (ossicular chain), [[tympanic membrane]], or [[external ear]]
|-
| style="background:#eee;"|'''[[Weber test]]'''
|Sound localizes to normal [[ear]] in unilateral SNHL
|Sound localizes to affected ear (ear with conductive loss) in unilateral cases
|-
| style="background:#eee;"|'''[[Rinne test]]'''
|Positive Rinne; air conduction > bone conduction (both air and bone conduction are decreased equally, but the difference between them is unchanged).
|Negative Rinne; bone conduction > air conduction (bone/air gap)
|}
Other, more complex, tests of auditory function are required to distinguish the different types of hearing loss. Bone conduction thresholds can differentiate sensorineural hearing loss from conductive hearing loss. Other tests, such as oto-acoustic emissions, acoustic stapedial reflexes, speech audiometry and evoked response audiometry are needed to distinguish sensory, neural and auditory processing hearing impairments.

===Tympanometry===
A [[tympanogram]] is the result of a test with a tympanometer. It tests the function of the middle ear and mobility of the eardrum. It can help identify conductive hearing loss due to disease of the middle ear or eardrum from other kinds of hearing loss including SNHL.

===Audiometry===
An [[audiogram]] is the result of a hearing test. The most common type of hearing test is [[pure tone audiometry]] (PTA). It charts the thresholds of hearing sensitivity at a selection of standard frequencies between 250 and 8000&nbsp;Hz. There is also high frequency pure tone audiometry which tests frequencies from 8000 to 20,000&nbsp;Hz. PTA can be used to differentiate between conductive hearing loss, sensorineural hearing loss and mixed hearing loss. A hearing loss can be described by its degree i.e. mild, moderate, severe or profound, or by its shape i.e. high frequency or sloping, low frequency or rising, notched, U-shaped or 'cookie-bite', peaked or flat.

There are also other kinds of audiometry designed to test hearing acuity rather than sensitivity (speech audiometry), or to test
auditory neural pathway transmission (evoked response audiometry).

===Magnetic resonance imaging===
MRI scans can be used to identify gross structural causes of hearing loss. They are used for congenital hearing loss when changes to the shape of the inner ear or nerve of hearing may help diagnosis of the cause of the hearing loss. They are also useful in cases where a tumour is suspected or to determine the degree of damage in a hearing loss caused by bacterial infection or auto-immune disease. Scanning is of no value in age-related deafness.