📊 Definitions
• Conductive: problem in external/middle ear (cerumen, OME, ossicular chain). Often treatable.
• Sensorineural (SNHL): inner ear or auditory nerve (cochlea, CN VIII). Permanent.
• Mixed: both components.
• Universal newborn hearing screening: OAE and ABR by 1 month, diagnosis by 3 months, intervention by 6 months.
🦠 Sensorineural Hearing Loss Causes
• Genetic: 50% of SNHL (autosomal recessive 80%, autosomal dominant 15%, X-linked, mitochondrial). Connexin 26 (GJB2) most common.
• Congenital CMV: most common non-genetic cause (can be late-onset or progressive)
• Ototoxic drugs: aminoglycosides, cisplatin, loop diuretics, quinine
• Meningitis, trauma (temporal bone fracture), noise exposure, prematurity, hyperbilirubinemia
🩺 Conductive Hearing Loss Causes
• Otitis media with effusion (OME): most common cause in young children
• Cerumen impaction, foreign body
• Cholesteatoma, otosclerosis
• Congenital: aural atresia, microtia
📋 Evaluation
• Newborn: OAE (screening) and ABR (diagnostic)
• Older child: pure tone audiometry with bone and air conduction
• Tympanometry: middle ear function, effusion
• Genetics: GJB2 (connexin 26) testing, CMV PCR (saliva/urine within first 3 weeks for congenital CMV)
📌 Decision strategy: Conductive loss (air-bone gap) vs sensorineural (air and bone equally reduced). Congenital CMV is most common non-genetic SNHL; can present late. Universal newborn screening critical.