Algorithmic overview of the diagnostic approach to identifying the etiology of pediatric hearing loss

AOM: acute otitis media; OME; otitis media with effusion; TM tympanic membrane; EAC: external auditory canal; SNHL: sensorineural hearing loss; CMV: cytomegalovirus; ABR: auditory brainstem response; OAE: otoacoustic emissions; CHARGE: coloboma, heart defects, choanal atresia, growth and/or developmental retardation, urogenital abnormalities, ear abnormalities and deafness; GJB: gap junction protein beta; NGS: next generation sequencing; MRI: magnetic resonance imaging; CT: computed tomography; ECG: electrocardiogram.
* Formal audiology is performed by an audiologist in a soundproof environment and provides detailed information about hearing ability. It consists of several different components, which may include pure tone audiometry, speech audiometry, behavioral audiometry, tympanometry, ABR, and/or OAE. The choice of which studies are performed is determined by the age of the child, the reason for the referral, the test environment, the equipment available, and the skill of the test administrator. No child is too young to have their hearing evaluated. For additional details on audiology testing, refer to UpToDate's topic on screening and evaluation of hearing loss in children.
¶ Hereditary hearing loss may be syndromic or nonsyndromic. Syndromic forms of hearing loss include Waardenburg, Usher, Pendred, Alport, hemifacial microsomia, and CHARGE syndromes, among others. Mutations in GJB2 and adjacent deletions in GJB6 account for >50% of nonsyndromic SNHL. For additional details, refer to separate UpToDate content on etiology of hearing loss in children.
Δ Congenital CMV infection can only be definitively diagnosed if testing is performed within 21 days after birth. Beyond 21 days, the likelihood that a positive test is due to postnatal exposure increases with increasing age. Detection of CMV between 3 weeks to 12 months after birth in conjunction with a finding of SNHL it is suggestive of congenital infection, though it is not definitive. Establishing a diagnosis of congenital CMV infection after the age of 12 months is generally not feasible. For further details, refer to separate UpToDate content on congenital CMV infection.
◊ Genetic testing should be directed by an otolaryngologist with expertise in genetic hearing loss or a clinical geneticist based upon the three-generation pedigree and specific clinical findings in the patient. Appropriate genetic counselling should be provided. If the child has syndromic findings, targeted genetic testing is performed. For children with bilateral SNHL without syndromic findings, comprehensive genetic testing is performed with NGS. Several NGS panels are available for evaluation of hereditary hearing loss. They differ somewhat with regard to the number and type of genes included and whether copy number variations are examined. Performance characteristics and analytic sensitivity also may vary.
§ Imaging can be performed using MRI or CT. The advantages of MRI is that it avoids radiation exposure, it is more sensitive for most peripheral auditory abnormalities, and it allows for simultaneous evaluation of the brain. The main disadvantage of MRI is that it generally requires sedation in young children. The anticipated clinical utility of imaging studies should be balanced against the risks associated with radiation exposure (for CT) and sedation (for MRI).
¥ The clinical evaluation is based on specific concerns in the individual patient. The evaluation begins with a detailed physical examination with attention to ear, head and neck, and cutaneous findings. In addition, all children with SNHL should undergo vision assessment. If hearing loss is profound or if there is a family history of sudden death or a personal history of syncope or cardiac arrhythmia, ECG should be performed. If there is a family history of kidney disease, urinalysis should be performed. Temporal bone imaging can be considered if the etiology remains uncertain after the initial evaluation. Temporal bone imaging is particularly useful in children with auditory neuropathy, which is characterized by the presence of OAE in the setting of absent or abnormal ABR.
‡ OME is the most common cause of conductive hearing loss in children. If a diagnosis of OME is made and the effusion and hearing loss persist, tympanostomy tube insertion may be warranted. Refer to UpToDate's topics on OME for further details.