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Biomedical subjects

R Otto

Publications and source records attributed to R Otto.

At least 145 records · Page 8Linked to original sources
PubMedDate not supplied

Cochlear microphonics recorded from fetal and newborn sheep.

PURPOSE: Sounds present within the uterus stimulate the fetal inner ear and central auditory pathway. This study was undertaken to determine the efficiency of transmission of exogenous airborne stimuli to the fetal inner ear. In this way, we may quantify the extent to which the fetal auditory system is isolated from sounds produced outside the mother. MATERIALS AND METHODS: Cochlear microphonics were recorded from fetal and newborn sheep to evaluate the extent to which the fetus is isolated from sounds exogenous to the ewe. Electrodes were surgically placed in contact with the round window membrane in nine near-term fetal sheep. Cochlear microphonics were recorded in response to 1/3 octave-band noises (0.125 to 2.0 kHz) delivered through a loudspeaker 1.8 m from one side of the pregnant ewe. Sound pressure levels generated by the noises were simultaneously recorded ex utero with a microphone and in utero with a hydrophone previously sutured to the fetal neck. After cochlear microphonic amplitudes were recorded, the fetus was delivered through an abdominal incision. Recordings were repeated from the newborn lamb. Fetal sound isolation was calculated as the difference between the sound pressure levels that were necessary to evoke equal cochlear microphonic amplitudes from the fetus and from the newborn lamb. RESULTS: The sound attenuation observed was variable for all frequencies. The fetus was isolated from external sounds by 11.1 dB for 0.125 kHz, 19.8 dB for 0.25 kHz, 35.3 dB for 0.5 kHz, 38.2 dB for 1.0 kHz, and 45.0 dB for 2.0 kHz. CONCLUSIONS: Other investigators have demonstrated that the immature auditory system is more susceptible to damage produced by noise exposure than is the mature auditory system. Low-frequency noise produces damaged cells that later in life code higher frequencies. A possibility of fetal hearing loss produced by intense noise exposure needs more careful evaluation.

Animals↗
PubMedDate not supplied

Cranial sonography of the occipital horns and gyral patterns in the occipital lobes.

Cranial sonographic examinations of 199 neonates were evaluated to determine the incidence of an echogenic pattern in the occipital lobe that simulated a mass, to relate that finding to the birth weight, and to correlate it with the gyral development of the occipital lobe. This echogenic pattern was seen in infants weighing less than 1750 g at birth and was identified on both sides of the midline on the most medial paramedian sagittal sonogram scans of the head. This pseudomass was found to be due to close approximation of a large occipital horn and calcarine fissure joining other adjacent secondary fissures. The multiple fissures formed an echogenic star, and the proximity of the occipital horn and premature brain tissue texture contributed to the relatively hypoechoic background of the pseudomass. The pseudomass is limited superiorly by the parietooccipital fissure and inferiorly by the tentorium. This sonographic pattern should be recognized as a normal variant.

Birth Weight↗