ANSD

Question 1

What is ANSD?

Answer 1

Auditory neuropathy spectrum disorder

Condition in which OHC integrity is normal but the afferent auditory pathway is abnormal

Question 2

What is the site of lesion presumed to be with ANSD?

Answer 2

IHCS themselves
Synaptic dysfunction
Axonal loss or dys-synchrony due to demyelination of the auditory nerve

Question 3

What are the etiologies related to ANSD?

Answer 3

Genetic and acquired

Question 4

Genetic etiologies details

Answer 4

• 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

Question 5

Acquired etiologies details

Answer 5

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)

Question 6

Treatment for ANSD is ….

Answer 6

Unique to the patient, what works for one patient will not work for everyone

Question 7

Management options for ANSD include

Answer 7

• 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

Question 8

Management options to improve communication with ANSD include…

Answer 8

Listening strategies
Speech reading training
Manual communication training (ASL, cued speech)

All are very beneficial to the patient

Question 9

ANSD effect on hearing thresholds (audiogram)

Answer 9

Range from normal to moderate SNHL

Question 10

ANSD effect on speech recognition

Answer 10

Abnormally poor
Not consistent with the degree of hearing loss
Due to damage to the auditory nerve that affects the quality of the signal

Question 11

ANSD effect on OAEs

Answer 11

Normal/present because there is normal OHC function

Question 12

ANSD effect on ABR

Answer 12

Abnormal/absent because there is abnormality from IHCs onward meaning signal are impacted

Question 13

What population is ANSD more common with?

Answer 13

Infants and young children but can happen with older adults as well

Question 14

What are the subjective characteristics of ANSD?

Answer 14

• 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

Question 15

ANSD effect on otoscopy

Answer 15

WNL, not a disorder of the outer or middle ear or TM

Question 16

ANSD effect on tympanometry

Answer 16

WNLs meaning type A

Question 17

ANSD effect on acoustic reflexes

Answer 17

Abnormal or absent/elevated that can be inconsistent with pure tone thresholds (example: absent when SNHL not greater than 50 dB)

Question 18

ANSD presentation on the audiogram

Answer 18

Normal to profound SNHL

Typically bilaterally and fluctuating

Question 19

ANSD presentation on speech perception tests

Answer 19

Poor performance (quiet and noise not consistent with degree of hearing loss)

Question 20

ANSD presentation on ABR

Answer 20

• Whole lot of nothing

- May see cochlear microphonic: response that mimics input stimulus and is believed to be a response from the OHCs

Question 21

Hallmark signs of ABR on testing

Answer 21

Present OAEs, absent acoustic reflexes, abnormal ABR with cochlear microphonic