Biomedical subjects

Dorothea M Brosi

Publications and source records attributed to Dorothea M Brosi.

4 recordsLinked to original sources

PubMed2006

Brain-stem auditory function in very preterm infants with chronic lung disease: delayed neural conduction.

OBJECTIVE: To examine brain-stem auditory function at term in very preterm infants who suffered chronic lung disease (CLD). METHODS: Brain-stem auditory evoked response (BAER) was recorded at term with clicks in 25 very preterm infants with CLD and no concomitant other major perinatal problems. RESULTS: Compared to those in normal term controls, BAER wave V latency and I-V and III-V interpeak intervals in the CLD infants increased significantly (ANOVA P<0.01-0.001). III-V/I-III interval ratio also increased significantly (P<0.01). The latencies of waves I and III did not differ significantly from the controls. However, no abnormalities were found in BAER wave amplitudes. These BAER findings, obtained at 21/s clicks, were also seen at the rates 51 and 91/s, although the increase in III-V interval tended to be more significant. Click rate-dependent changes in BAER variables in the CLD infants were generally similar to the controls, with slight differences. CONCLUSIONS: BAER components, mainly reflecting central auditory function, increased significantly. The increase in wave V latency and I-V interval is due to the increase in III-V interval. SIGNIFICANCE: Neural conduction in the more central portion of the brain-stem auditory pathway is delayed and thus brain-stem auditory function is impaired in CLD infants.

Acoustic Stimulation↗

PubMed2005

Brainstem auditory function at term in preterm babies with and without perinatal complications.

Functional integrity of the auditory brainstem was studied at term in babies born at 30-36 wk of gestation using maximum length sequence brainstem auditory evoked response (MLS BAER). Compared with normal term babies, preterm babies who had perinatal complications showed a tendency of an increase in wave V latency and I-V and III-V intervals at all 91-910/s clicks, with statistical significance at higher rates. Wave V latency and I-V interval increased significantly at 455/s and 910/s. III-V interval increased at all click rates, which was more significant at higher rates. III-V/I-III interval ratio increased at most rates. Waves III and V amplitudes reduced significantly mainly at 455/s and 910/s. In preterm babies who had no perinatal complications, there were no major MLS BAER abnormalities except an increase in III-V interval at 91-910/s. By comparison, the preterm babies with perinatal complications had a significant increase in wave V latency, I-V and III-V intervals, and III-V/I-III interval ratio at 455/s and 910/s clicks. These results suggest that although there are no major abnormalities in brainstem auditory function in preterm babies without perinatal complications, the auditory brainstem, mainly the more central part, in preterm babies with perinatal complications is impaired, which becomes more apparent at very high stimulus rates. We conclude that preterm babies with perinatal complications are at high risk of central auditory impairment.

Brain Stem↗

PubMed2003

Time course of brainstem pathophysiology during first month in term infants after perinatal asphyxia, revealed by MLS BAER latencies and intervals.

Dynamic changes in electrophysiology of brainstem auditory neurons during the first month after birth were studied in 51 term infants after perinatal asphyxia using maximum length sequence brainstem auditory evoked responses. The responses were recorded on d 1, 3, 5, 7, 10, 15, and 30 after birth. On d 1, wave III and V latencies and all interpeak intervals increased significantly at all repetition rates of clicks used (91-910/s), especially the higher rates (ANOVA, p < 0.05-0.0001). On d 3, all these latencies and intervals increased further and differed more significantly from the normal control subjects. Thereafter, the latencies and intervals decreased progressively. On d 7, wave V latency and all intervals still differed significantly from the control subjects. These dynamic changes were more significant at higher rates of clicks than at lower rates. On d 10 and 15, all intervals decreased significantly. On d 30, all wave latencies decreased to the values in the normal control subjects on the same day. The intervals also approached normal values, although the III-V and I-V intervals still increased slightly. These results indicate that hypoxic-ischemic brain damage persists during the first week, with a peak on d 3, and recovers progressively thereafter. By 1 mo, the damage has largely returned to normal. Maximum length sequence brainstem auditory evoked responses results correlated well with the stage of hypoxic-ischemic encephalopathy during the first week. The present study revealed a general time course of brainstem pathophysiology after asphyxia, although there were individual variations. Our findings can be used as a reference to monitor cerebral function and help judge the value of neuroprotective or therapeutic interventions. The first week, particularly the first 3 d, is a critical period of hypoxic-ischemic brain damage, and early intervention may prevent or reduce deterioration of the damage.

Asphyxia↗

PubMed2002

Auditory neural responses to click stimuli of different rates in the brainstem of very preterm babies at term.

Auditory neural responses to acoustic stimuli of different rates were studied by analyzing changes in brainstem auditory evoked responses (BAER) with increasing repetition rate of clicks, or rate-dependent changes, in 62 very preterm babies (gestation 24-32 wk). None had perinatal asphyxia or major complications at the time of testing (37-42 wk postconceptional age) to exclude their possible effects on the recorded BAER. As the rate of clicks was increased from 21/s to 51/s and 91/s, I-V interpeak interval in these babies increased similarly to that in normal term neonates. The rate-dependent change decreased significantly in I-III interval, but increased significantly in III-V intervals and III-V/I-III interval ratio (all p < 0.01). At all three rates of clicks, the I-V interval, the most commonly used BAER variable, tended to increase slightly but did not differ significantly from the term neonates. The I-III interval decreased significantly at higher click rates (ANOVA p < 0.05 at 51/s and < 0.001 at 91/s), whereas the III-V interval and III-V/I-III interval ratio increased significantly at all 21/s, 51/s, and particularly 91/s (p < 0.01-0.001). No abnormalities were found in wave V amplitude at any rates. These results suggest that very preterm babies have an advanced peripheral development of the brainstem auditory pathway but a retarded central development or central impairment. A nearly normal I-V interval does not exclude a possible abnormality in its subcomponents (I-III and III-V intervals). In babies who have a normal BAER at a conventionally used low rate of clicks, we cannot exclude an abnormal BAER at higher rates.

Acoustic Stimulation↗