Why Screen Children for Hearing Loss
Overall in the school-aged population, as many as 9 to 10 of every 1000 children have a permanent hearing loss and about 1 in 7 (14%) will have either permanent or temporary hearing problems that impact on school performance.
There are numerous risk factors that can help pediatricians identify patients aged younger than 3 years who warrant close monitoring or hearing screening. These are listed below.
- Caregiver concern regarding hearing, speech, language, or developmental delay.
- Family history of permanent childhood h
- Neonatal intensive care of longer than 5 days or any of the following, regardless of length of stay: extracorporeal membrane oxygenation; assisted ventilation; exposure to ototoxic medications (gentamycin and tobramycin) or loop diuretics (furosemide/Lasix); and hyperbilirubinemia that requires exchange transfusion.
- In utero infections (eg, cytomegalovirus, herpes, rubella, syphilis, and toxoplasmosis).
- Craniofacial anomalies, including those that involve the pinna, ear canal, ear tags, ear pits, and temporal bone anomalies.
- Physical findings (eg, white forelock) associated with a syndrome known to include a sensorineural or permanent conductive hearing loss.
- Syndromes associated with hearing loss or progressive or late-onset hearing loss: neurofibromatosis; osteopetrosis; Usher syndrome; Waardenburg syndrome; Alport syndrome; Pendred syndrome; Jervell and Lange-Nielson syndrome.
- Neurodegenerative disorders (eg, Hunter syndrome) or sensory motor neuropathies (eg, Friedreich ataxia, Charcot-Marie-Tooth disease).
- Culture-positive postnatal infections associated with sensorineural hearing loss, including confirmed bacterial and viral (eg, herpes viruses, varicella) meningitis.
- Head trauma, especially basal skull/temporal bone fracture that requires hospitalization.
- Recurrent or persistent otitis media for at least 3 months.
Several studies have shown that OAE hearing screening can be easily performed in pediatric practice and it will identify children with hearing problems. Otoacoustic emissions can be used as a screening test for any age. The technology is especially convenient with infants and toddlers, for whom audiometry can be difficult or impossible to perform. It is also helpful in deciding if surgical management is needed for bilateral middle ear effusion of longer than 3 months’ duration.
When sound enters the ear canal, the tympanic membrane vibrates and the middle ear ossicular chain transmits the sound to the cochlea. The sound waves in the cochlea excite the outer hair cells and a backwash of sound energy–otoacoustic emissions (OAEs)–travels in the reverse direction, from the cochlea through the middle ear into the ear canal. In an abnormal ear, the intensity of the emissions is much weaker than in a normal ear.
Transient OAEs are produced by the outer hair cells of the cochlea when a “click” sound stimulus is presented to the ear. In contrast, distortion product otoacoustic emissions (DPOAEs) are the emissions produced by the outer hair cells in the cochlea when sound stimulus is provided by the simultaneous presentation of 2 pure tones of equal intensity but different frequencies. In either situation, an OAE screening instrument, using a sensitive microphone in the ear canal, assigns a pass or fail grade for the child’s hearing based on an algorithm stored in memory.
Otoacoustic emissions screeners test hearing at 2, 3, 4, and 5 kHz in a matter of minutes. An infant or child who “refers” should be examined for evidence of ear canal obstruction with cerumen, otitis media, or serous otitis, with treatment as indicated. In the absence of a treatable cause, or watchful waiting in the case of a serous otitis, repeat testing should occur in 2 to 4 weeks’ time, and if there is no improvement, the child should be referred to a pediatric audiologist. Pediatricians should screen children for hearing problems throughout childhood as per the Bright Futures guidelines. This means screening children at ages 4, 5, 6, 8, and 10 years and whenever risk factors are identified. Additionally, those children who are being monitored for developmental delays or speech problems also should be subjected to hearing screening.
There are many OAE and hearing screeners on the market. Otometrics, a division of Natus Medical, distributes an excellent device called the Bio-logic AuDX Pro Flex, that performs tympanometry, as well as DPOAE and pure tone audiometry. The device has a small foot print, can perform simultaneous OAE screening from both ears, and has a cartoon mode for tympanometry and OAE screening that encourages young children to cooperate. Prices range from the mid $4000 to $8000 range depending on configuration. Considering that practices are paid $10 for Audiometry and Tympanometry and $25 for OAEs, the cost of the device is usually recovered within 6 months to a year.
If a practice is interested in just OAE screening as well as integrated audiometer capability the Bio-logic AuDX is a good choice. It is portable, durable, easy to use, and also features a cartoon mode like the AuDx Pro Flex above. Both devices have very durable ear probe cables that withstand breaking with frequent use. The AuDXis very affordable as well, selling for about $4000 to $5400.
Please see the video above with Diane Sabo, from Natus for a great discussion and presentation of the Bio-logic AuDX and Bio-logic AuDX Pro Flex!