ANSD Flashcards
What is ANSD?
Auditory neuropathy spectrum disorder
Condition in which OHC integrity is normal but the afferent auditory pathway is abnormal
What is the site of lesion presumed to be with ANSD?
IHCS themselves
Synaptic dysfunction
Axonal loss or dys-synchrony due to demyelination of the auditory nerve
What are the etiologies related to ANSD?
Genetic and acquired
Genetic etiologies details
- Non-syndromic: single gene mutations that only cause hearing loss
- Syndromic: genetic mutations that cause more than just hearing loss
- Characterized by slow, progressive degeneration of hearing and other functions such as the muscles
Acquired etiologies details
Hypoxia: lack of oxygen
Prematurity: babies born earlier than 32 weeks are at risk for underdeveloped IHCs
Hyperbilirubinemia: jaundice, excessive bilirubin can be neurotoxic, crossing the blood-brain barrier and damage neural structures (auditory brainstem)
Treatment for ANSD is ….
Unique to the patient, what works for one patient will not work for everyone
Management options for ANSD include
- Amplification: hearing aids, about half benefit
- FM system: improve SNR, literature says it is the most helpful
- Cochlear implant: option if amplification is ineffective, only 1/3 experience improved speech perception
Management options to improve communication with ANSD include…
Listening strategies
Speech reading training
Manual communication training (ASL, cued speech)
All are very beneficial to the patient
ANSD effect on hearing thresholds (audiogram)
Range from normal to moderate SNHL
ANSD effect on speech recognition
Abnormally poor
Not consistent with the degree of hearing loss
Due to damage to the auditory nerve that affects the quality of the signal
ANSD effect on OAEs
Normal/present because there is normal OHC function
ANSD effect on ABR
Abnormal/absent because there is abnormality from IHCs onward meaning signal are impacted
What population is ANSD more common with?
Infants and young children but can happen with older adults as well
What are the subjective characteristics of ANSD?
- Fluctuating/progressive HL (varies day to day)
- Unable to understand speech especially in noise
- Strong visual orientation (hyperfocus on things)
- Little to no benefit from traditional amplification
ANSD effect on otoscopy
WNL, not a disorder of the outer or middle ear or TM
ANSD effect on tympanometry
WNLs meaning type A
ANSD effect on acoustic reflexes
Abnormal or absent/elevated that can be inconsistent with pure tone thresholds (example: absent when SNHL not greater than 50 dB)
ANSD presentation on the audiogram
Normal to profound SNHL
Typically bilaterally and fluctuating
ANSD presentation on speech perception tests
Poor performance (quiet and noise not consistent with degree of hearing loss)
ANSD presentation on ABR
- Whole lot of nothing
- May see cochlear microphonic: response that mimics input stimulus and is believed to be a response from the OHCs
Hallmark signs of ABR on testing
Present OAEs, absent acoustic reflexes, abnormal ABR with cochlear microphonic
