Audiology and hearing-test interpretation — branching viva

Opening question

This 5-week-old infant was referred on the newborn hearing screen. The diagnostic testing is now in front of you. Walk me through how you read a paediatric pure-tone audiogram, and tell me how you decide the degree and the type of hearing loss. [1]

Branch 1 — the tympanogram and the probe tone

You also have a tympanogram. Describe the three values it measures, give me the Jerger types in one line each, and tell me which probe-tone frequency you would use in a two-month-old and why. [3]

Branch 2 — OAE present, ABR absent

Now a harder case: in another infant the otoacoustic emissions are robustly present but the auditory brainstem response is absent with a preserved cochlear microphonic. What is the diagnosis, why does it occur, and why would an OAE-only screen have missed it? [11]

Branch 3 — the two-stage screen and loss to follow-up

The screening programme in your region uses a two-stage OAE then automated ABR protocol. What are the 1-3-6 milestones, and what are the common reasons a referred screen leads to a missed diagnosis through loss to follow-up? [2]

Closing — congenital cytomegalovirus and late-onset loss

A third infant passes the newborn screen and a diagnostic ABR at three weeks, but is then confirmed to have congenital cytomegalovirus. Does the normal audiogram guarantee future hearing, and what is your surveillance plan? Where does valganciclovir fit, and who supervises it? [6]