Investigations of sensorineural hearing loss (SNHL) involve a history, physical exam of the ear, tuning fork tests, audiological evaluations including pure tone audiometry and speech discrimination tests, tympanometry, otoacoustic emissions testing, auditory brainstem response testing, and imaging studies with CT and MRI to evaluate the ear structures and rule out other causes. The evaluations assess the nature, progression, laterality of the hearing loss and examine cochlear and retrocochlear function.

1. INVESTIGATIONS OF
SENSORINEURAL HEARING LOSS
(SNHL)
BY: KAREEM HUSSIEN

2. SNHL INVESTIGATIONS
1. HISTORY
2. PHYSICAL EXAMINATION
• Examination of the ear & other structures
• Evaluation with a tuning fork
3. AUDIOLOGICAL EVALUATION
• Pure tone audiometry (PTA)
• Speech discrimination audiometry.
• Tympanometry
• Otoacoustic emissions (OAE) test screening
• Auditory brainstem response
• Electrocochleography (ECoG)
4. IMAGING STUDIES
• CT
• MRI

3. HISTORY
• duration of deafness
• the nature of the onset (sudden or insidious)
• the rate of progression (rapid or slow)
• involvement of the ear (unilateral or bilateral)
• presence or absence of other conditions: tinnitus, vertigo, imbalance, aural fullness, otorrhea,
headache, facial nerve dysfunction, and head and neck paresthesia

4. PHYSICAL EXAMINATION
• Examination of the ear
• Examination of other structures

5. Evaluation with a tuning fork
• Rinne's test
• Weber's test

6. AUDIOLOGICAL EVALUATION

7. 1. PURE TONE AUDIOMETRY (PTA)

8. 2. SPEECH DISCRIMINATION AUDIOMETRY.
• The ability to understand speech is obviously reduced with all hearing loss but particularly with
sensorineural loss in which the high tones are involved
• Sensory score 70-90%
• Neural scores are very poor (0-50%)

9. 3.TYMPANOMETRY
• measuring the pressure in the middle
ear & the compliance of the TM
• Test result is usually normal in case if
SNHL
(If cochlear or retrochochlear)
(not on top of mid ear disease)
• Type A, As and Ad
• Type B
• Type C

10. 4.OTOACOUSTIC EMISSIONS (OAE) TEST
• It is widely used for neonatal screening of hearing loss
• This phenomenon measures the active sounds produced by the outer hair cells which are
recorded in response to tone clicks applied to the ear
• This test measures the function of the cochlea

11. 5. AUDITORY BRAINSTEM RESPONSE ABR
• The ABR is generally used to evaluate for a retrocochlear process, or
pathology that occurs downstream of the auditory process from the
cochlea.
• the signal electrodes are positioned to measure the components of the
pathway
• The signals are measured after an acoustic stimulus, usually a “click,”
and filtered to record five specific ABR waves.

12. IMAGING STUDIES
• CT scans
• caliber of the external auditory canal, the integrity of the ossicular chain
• presence or absence of middle ear or mastoid disease
• detecting inner ear malformations
• measurement of the cochlear height, lateral semicircular canal bony island width, and the vestibular
aqueduct
• detection of bone erosion often seen in the presence of chronic otitis media and cholesteatoma.

13. • MRI
It is superior for imaging
retrocochlear pathology such as
vestibular schwannomas,
meningiomas, other lesions of
the cerebellopontine angle that
may present with hearing loss,
demyelinating lesions of the
central nervous system, and
brain tumors.