High frequency immittance for neonates: a normative study.

CONCLUSION High frequency immittance measurements demonstrate promise in clarifying middle ear status for neonates but age- and gender-specific norms should be consulted. OBJECTIVE To describe high frequency immittance measurements using a 1000 Hz probe tone for a sample of 278 neonatal ears (0-4 weeks of age) in order to compile normative tympanometric and acoustic reflex criteria. SUBJECTS AND METHODS Assessment of neonatal ears included 1000 Hz probe tone immittance measurements (tympanograms and ipsilateral acoustic reflexes), and distortion product oto-acoustic emission (DPOAE) screening. Results were compared and normative values were compiled for immittance measures in ears controlled for normal middle ear functioning (n=250). RESULTS Comparison of immittance results to OAE screening outcome provides estimates of sensitivity and specificity for middle ear fluid with tympanometry of 57% and 95%, and 57% and 90% for acoustic reflex presence, and 58% and 87% for combined tympanogram and acoustic reflex results, respectively. Normative data indicate that static peak admittance values differ significantly across gender and age with the 5th percentile cut-off value for the entire sample at 1.4 mmho. The 90% range of tympanic peak pressure normative values increases with increasing age from 140 daPa for neonates 1 week of age to 210 daPa for neonates 2-4 weeks of age. Acoustic reflexes were elicited at 93+/-9 dB with a 90% normality range of 80-105 dB.