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ASSESSMENT & DIAGNOSIS OF ANSD - Coggle Diagram
ASSESSMENT & DIAGNOSIS OF ANSD
What is ANSD?
have a hard time understanding speech especially in noisy environment
inconsistent responses to speech
people with ANSD are able to detects sounds normally by the ears, but has problem sending it to the brain
based on functional components affected (
site of lesion
)
auditory nerve
synapse
a problem with trasmission of sounds to the brain due to problem at the IHC, or the synapses between IHC and auditory nerve or the nerve itself
prevalence
bilateral 75-79 %
unilateral 21-25 %
risk factors
adult
early-onset
same as paediatrics' risk factors
clinical symptoms
vestibular problems
tinnitus
difficulty hearing in noise
difficulty in understanding speech
late-onset / acquired
predisposing factors & aetiologies
low socioeconomic status
hormonal variation
temperature-dependent changes
Charcot-Marie tooth disease
gene mutation
neural damage
traumatic brain injury
exposure to toxic chemicals & solvents
hereditary motor-sensory neuropathy
clinical symptoms
vertigo
headache
tinnitus
defective vision
difficulty in understanding speech
paediatric
36 %
lack of oxygen at birth/ mechanical ventilation
9-15 %
cerebral palsy
36-38 %
family history of hearing loss
41-80 %
ototoxic drug exposure
30-46 %
prematurity (<28 weeks)
50-73 %
presence of hyperbilirubinemia associated with severe jaundice in newborn period
autoimmune disorders/ genetic factors
What are the assessments?
Pure Tone Audiometry
To detrmine if the patient has hearing loss
To know the severity/degree of hearing loss
Laterality of hearing loss
Tympanometry
To rule out any middle ear pathology
ASR
Acoustic reflexes always nearly absent in patients with ANSD
OAE
Patients with ANSD will have normal OHC functions But not necessarily in everyone, as some will have 2 different conditions at the same time.
ABR
Electrophysiological recording of responses of the distal auditory pathway (eighth nerve and brainstem) to sounds.
Objective test battery before CM can be done
CM
A preneural potential generated predominantly from OHCs
To differentiate ANSD from cochlear loss
When OAEs are not recordable due to high noise floor or presence of CHL
Additional assessments
ASSR
Assessing infants and difficult to test populations and in determination of threshold estimations
Detect more accurately physiologic thresholds for hearing aid amplification or cochlear implantation.
CAEP
Assesses the integrity of the auditory pathways from the cochlea to the auditory cortex.
Presence or absence provide an insight into the degree of an individual’s dys-synchrony.
ECochG
Reliable tool in evaluating the auditory peripheral function in the presence of a desynchronized ABR.
Examining the origins and magnitude of the potentials recorded with ECochG.
Speech perception test
ANSD is characterized by an abnormal speech perception that does not necessarily correlate with their hearing abilities.
It evaluates the practical impact of the disorder on everyday communication skills
How to diagnose?
minimal requirement
presence of normal/ near normal OAEs or CM
absent or markedly abnormal ABR
https://www.thebsa.org.uk/wp-content/uploads/2023/10/OD104-85-Recommended-Procedure-Assessment-and-Management-of-ANSD-in-Young-Infants.pdf
managed by expert multidisciplinary team
(pediatric) Audiologist
medical professionals
otolaryngologist
neurologist
speech-language pathologist
teacher of the deaf
ongoing and regular monitoring of
speech and language development
general development
auditory and hearing status
electrophysiological
functional
behavioural
middle ear
hearing threshold
Possible results
ASR
absent of ASRT across frequencies tested
OAE
present OAE (often have normal OHC function) (Starr et al., 2000)
can be absent of OAE (if there is a conductive element to the hearing loss)
Tympanometry
type A tympanogram suggestive of normal middle ear function
ABR
complete absence or abnormal ABR
Cochlear Microphonic (CM)
a response predominantly generated by OHC, which occurs before W1 of ABR
obtain separate replicated waveforms using single polarity rarefaction and condensation click stimuli
result with a present of CM
Behavioral assessment
result with hearing loss
fluctuations are more frequent in children than in adults
associated cognitive impairments may also complicate the hearing thresholds estimation
the hearing thresholds frequently fluctuate and could reach variations of over 40dB
hearing fatigue may be present for high intensities and/or long-duration tonal stimuli and may impede the threshold investigation
Other assessments
ASSR
Auditory steady-state responses can be detected in auditory neuropathy patients.
Auditory steady state response thresholds are higher than PTA threshold (Emara & Gabr 2010)
Cortical auditory evoked potentials (CAEPs)
Can be evoked in patients with ANSD even with absent ABR
ECochG
ECochG may also be recorded intraoperatively during cochlear implantation.
ANSD patient produce larger CM (Ulukan & Ciprut 2023)
Speech perception tests
Poor speech discrimination abilities, out of proportion compared to the PTA thresholds
