Hearing loss in high-risk neonates — structured oral (viva)

Branch 1 — Screening rationale

Examiner: "Why was this infant screened with AABR rather than otoacoustic emissions?" Candidate: Automated auditory brainstem response was used because the NICU population carries the highest burden of auditory neuropathy spectrum disorder. Otoacoustic emissions test only the cochlear outer hair cells and return a normal result in auditory neuropathy, where the cochlea is intact but the nerve or brainstem misfires. AABR tests the entire pathway from sound to brainstem and therefore detects auditory neuropathy, which is why it is the mandated screen for the NICU infant. [1] [2]

Examiner: "How do you interpret a bilateral refer?" Candidate: A refer means the screen did not detect a clear brainstem response in either ear. It is not a diagnosis of hearing loss — a proportion of refers reflect transient causes such as middle-ear fluid or ambient noise. The protocol is to repeat the screen once, and if it refers again, to refer for a full diagnostic assessment. The priority is to ensure the infant is not lost to follow-up, because loss to follow-up is the commonest failure of the pathway. [1]

Branch 2 — Risk indicators and the meaning of a pass

Examiner: "What risk indicators does this infant carry, and if the repeat screen passes, is the infant then discharged from audiology?" Candidate: This infant carries a prolonged NICU stay beyond five days, repeated ototoxic drug exposure with gentamicin and furosemide, severe hyperbilirubinaemia at exchange level, and prolonged assisted ventilation. These are all recognised JCIH risk indicators. [1]

Even if the repeat screen passes, the infant is not discharged from audiology. A meaningful fraction of permanent loss is progressive or late-onset, and congenital CMV in particular can produce loss that is absent at birth and emerges in the first year. Infants with risk indicators therefore require ongoing surveillance to at least 30 months, because a pass at one point in time does not exclude loss that develops later. [3]

Branch 3 — Diagnostic confirmation and auditory neuropathy

Examiner: "The diagnostic ABR shows an absent response with a present otoacoustic emission. What is the diagnosis and why?" Candidate: This is the signature of auditory neuropathy spectrum disorder — a present OAE indicating an intact cochlea, with an absent or markedly abnormal ABR indicating that the auditory nerve or brainstem is not transmitting a coherent signal. The causes are the signature NICU insults this infant has experienced: severe hyperbilirubinaemia, perinatal asphyxia, and extreme prematurity. I would also consider congenital infection and genetic causes such as OTOF mutations. [4]

Examiner: "How is auditory neuropathy managed?" Candidate: Management begins with a trial of amplification and close monitoring, because some infants with ANSD derive usable hearing from hearing aids. Those who do not develop usable hearing progress to cochlear implantation, which can be highly effective when the spiral ganglion and auditory nerve are intact. The family is enrolled in early intervention from confirmation, because language outcomes depend on intervention within the sensitive period. [4]

Branch 4 — Congenital CMV and the time window

Examiner: "If you suspect congenital CMV, what investigation must you do, and when?" Candidate: I would send a urine or saliva CMV PCR before 21 days of life. After three weeks, a positive test cannot distinguish congenital from later-acquired infection, so the window to confirm a congenital diagnosis — and the chance to treat a potentially progressive loss — is lost. This time limit is critical and is one of the favourite exam points in this area. [3]

Examiner: "If CMV is confirmed with end-organ disease, what treatment is offered?" Candidate: Symptomatic congenital CMV disease is treated with valganciclovir, dosed at 16 milligrams per kilogram twice daily for up to six months, which improves both audiologic and developmental outcomes. The decision is made with infectious diseases input, and the early urine PCR that enabled the diagnosis is the investigation that made the treatment possible. [3]

Branch 5 — Prognosis and disposition

Examiner: "What do you tell the parents about long-term outlook?" Candidate: The prognosis for language is excellent when the loss is identified early and habilitated within the sensitive period. The 1-3-6 framework — screen by one month, diagnose by three, intervene by six — is the standard that protects language, and children identified and habilitated within it acquire language at rates comparable to hearing peers. The discharge plan therefore includes a booked audiology appointment and a documented surveillance schedule, because this infant goes home not with a cleared screen but with an ongoing commitment to monitoring. [1]