[Effects of intrauterine hypotrophy and perinatal hypoxia on cochlear function evaluated by click evoked otoacoustic emissions (TEOAE)].

The authors evaluated mutual relationships between transiently evoked otoacoustic emissions (TEOAE) and various parameters defining perinatal period focusing mostly on hypotrophic newborns. TEOAE was collected using 2.5-12.5 msec time-window. TEOAE amplitude and responses (S/N ratio) from various frequency bands calculated using off-line analysis were collected using ILO 88 ECHOPORT Otodynamics. Half-octave frequency bands centered at 1.0, 1.5, 2.0, 3.0, and 4.0 kHz were included to this study. All 370 newborns, 1 to 5 days old, were tested bilaterally. The relationship between TEOAE and birth weight in all newborns showed positive correlation. Weaker TEOAE amplitudes and off-line calculated responses at low and middle frequency bands were associated with middle ear status and with immaturity of the cochlea. This tendency was specifically strong in preterm neonates with very low birth weight. The separated subgroup of hypotrophic newborns with Apgar score <7 was characterized by statistically significant weakening TEOAE amplitude and off-line calculated responses at the whole frequency band. Such results may suggest that perinatal hypoxia affect the outer hair cell function at the whole length of the basilar membrane. Co-existing factors such as intrauterine hypotrophy and perinatal hypoxia affect the cochlear function significantly deeper than each of them working separately.