TEHDI- Audiologic Evaluation Protocol
A group of Texas audiologists who regularly diagnose hearing loss in newborns and infants was assembled to write audiologic evaluation protocol for infants who fail the initial hearing screen at the hospital. The attached is the result of that effort. In Texas only seven percent (7%) of licensed audiologists have currently identified themselves to the Texas Department of State Health Services as professionals who work with early identification and diagnosis of hearing loss in newborns and infants. It is our hope that this protocol will help audiologists appropriately identify the type, degree, and configuration of an infant's hearing loss so that hearing aids can be fit appropriately.
The following people participated in the development of these protocols and have agreed to have their names published with the document.
|Angel de la Cruz
||Lisa C. Payne
This protocol is intended as a guide for audiologists who are performing audiometric evaluations of newborns and infants. It is assumed that these children did not pass an initial hearing screening in the nursery with either ABR or OAE.
ABR or OAE Re-Screening
- Re-screen well-babies as outpatients, within two weeks of discharge from the nursery.
- Re-screen NICU and Level II graduates as inpatients, if possible, immediately prior to discharge. Otherwise, re-screen as outpatients, within two weeks of discharge.
Audiologic Evaluation of Newborns and Infants
- Perform otoscopic examination.
- Perform click-evoked, diagnostic ABR via air conduction.
- Test at 70 to 80 dB nHL, to evaluate retrocochlear function.
- Evaluate absolute latencies for waves I, III and V
- Evaluate interpeak latencies for waves I to III, III to V, and I to V
- Evaluate waveform morphology
- Consider measuring wave V/I amplitude ratio
- Consider evaluating click-rate functions
- Perform click-evoked threshold search via air conduction.
NOTE: Each clinic will need to establish its own normative values. As a general guideline, normal sensitivity for clicks may be defined as a repeatable wave V threshold of less than 30 dB nHL.
- If a "borderline" response is obtained, confirmation via OAE is recommended.
- If uncertainty remains, confirmation via behavioral means is recommended, before six (6) months of age.
- If air conduction click thresholds are abnormal, perform threshold search via bone conduction. Air-bone gaps of 20 dB or more should be considered significant.
- If air conduction click thresholds are normal, perform OAE evaluation to obtain frequency-specific data. If click threshold and OAEs are normal, testing may be terminated. Given a normal click threshold, normal sensitivity may be ifnerred for all frequencies at which OAEs were present.
- If air and bone conduction click thresholds suggest sensorineural loss, evaluate OAEs to help determine the site of disorder.
- If the click ABR is abnormal; if DPOAES are abnormal, or if DPOAES cannot be evaluated because of degree of hearing loss, perform toneburst ABR at 4000Hz and 500 Hz.
- If sensorineural loss is detected, refer infant to ENT physician for examination and medical clearance. Begin amplification process and refer to your local Early Childhood Intervention program (ECI).
- If significant air-bone gaps are noted, or if other evidence of middle ear disease is seen, refer infants for ENT evaluation. Contact ECI. Repeat diagnostic evaluation following treatment.
- If results indicate a mixed loss, refer infant for ENT examination and contact ECI. Begin amplification process, and repeat diagnostic evaluation following ENT treatment.
- If ABR is normal, but OAE is abnormal, refer infant for ENT examination (results may indicate mild middle ear disorder). Re-test OAE following ENT treatment.
- If ABR suggests significant sensorineural loss (or prolonged interpeak latencies) and OAE is normal, refer infant to ENT physician for evaluation of retrocochlear dysfunction. Defer amplification process, but contact ECI and consider use of assistive listening device. Repeat diagnostic evaluation at six month intervals, to monitor neuromaturation.
- If the diagnostic battery is normal, retest infants at risk for delayed-onset hearing loss at six month intervals. Such risk factors include: CMV, rubella, ototoxic medication, syphilis, bacterial meningitis, and syndromes such as Usher, Alport, and Pendred.
- Incorporate behavioral testing as soon as possible. Ear-specific evaluation using VRA/COR is recommended.
- Incorporate an immittance battery with caution:
- For infants under approximately four (4) months of age, multi component/multi frequency testing is most appropriate, but normative data are lacking.
- For infants older than four months, the immittance battery becomes more reliable and valid.