Search

Aims: To detect any functional abnormality in the brainstem auditory pathway in late preterm babies born of small-for-gestational age (SGA) using maximum length sequence brainstem evoked response., Study Design: The response was recorded and analyzed at term in 38 SGA (birthweight <3rd centile) babies born at 33-36 week gestation. The results were compared with 40 age-matched babies born of appropriate-for-gestational age (AGA) (birthweight >10th centile). None of the subjects had major perinatal problems., Results: All wave latencies and interpeak intervals in the SGA group were slightly longer than those in the AGA group at most click rates. Wave III latency was significantly longer than that in the AGA group at 227/s (P < 0.05), and wave V latency was at 227 and 910/s (P < 0.05 and 0.05). Of the interpeak intervals, only the I-V interval in the SGA group was significantly longer than that in the AGA group at the highest rate 910/s (P < 0.05). The amplitudes of waves I, III and V in the SGA group all tended to be smaller than those in the AGA group at all click rates 91-910/s. The wave V amplitude was significantly smaller at most click rates (227-910/s, all P < 0.05). The slopes of all wave latency-, interval-, and amplitude-rate functions were similar in SGA and AGA groups., Conclusions: There were marginal abnormalities in MLS BAER of low-risk late preterm SGA babies, suggesting a mild degree of maturational delay in the brainstem. Intrauterine growth retardation occurring in late preterm babies has a minor effect on neural maturation of the immature brainstem., (Copyright © 2015. Published by Elsevier Ireland Ltd.)

The development of rifaximin- and rifampicin-resistant intestinal coliforms was studied in 27 subjects receiving rifaximin for 3 days by plating stool samples on media containing rifaximin 200 mg/L or rifampicin 64 mg/L before treatment (day 0), after treatment was completed (day 3), and after a further 2 days (day 5). The susceptibility of enterococci grown on day 0 and day 3 was also studied in 71 subjects. Significant increases in antimicrobial-resistant coliform flora were not seen in either the rifaximin-treated or the placebo-treated subjects. Enterococci recovered pre- and post-treatment showed similar susceptibilities. Rifaximin did not select for significant resistance in the Gram-negative and Gram-positive intestinal flora during therapy.

The lipid extract of the temperate red alga Rhodymenia pertusa has yielded four eicosanoid metabolites, three of which are new natural products. Using principally NMR and MS techniques, their structures were deduced as 5R,6S-dihydroxy-7(E),9(E),11(Z),14(Z)-eicosatetraenoic acid (5R,6S-diHETE), 5R*,6S*-dihydroxy-7(E),9(E),11(Z),14(Z),17(Z)-eicosapentaenoic acid (5R*,6S*-diHEPE), 5-hydroxy-6(E),8(Z),11(Z),14(Z)-eicosatetraenoic acid (5-HETE), 5-hydroxy-6(E),8(Z),11(Z),14(Z),17(Z)-eicosapentaenoic acid (5-HEPE). The co-occurrence of these metabolites strongly suggests that R. pertusa contains a unique 5R-lipoxygenase system acting on both arachidonic and eicosapentaenoic acids.

Data from 213 cases of simultaneous carotid endarterectomy and coronary artery bypass grafting (CEN/CABG) were analyzed (1980-1996). There were 154 males (72.3%), and 59 females (27.7%), (mean age: 65. 6 years, range: 42-83). One hundred and thirty-two patients (62.0%) had angina, 58 (37.2%) had myocardial infarction, and 23 (10.8%) had congestive heart failure. Symptomatic cerebrovascular disease was present in 89 patients (41.7%). One hundred and twenty-two patients (57.2%) had three-vessel coronary artery disease, 41 (19.2%) had left main disease, and 27 (12.6%) had a low ejection fraction (ejection fraction /=75% diameter reduction) stenosis was present in 168 (78.8%) of the operated carotid arteries. The contralateral internal carotid artery was severely stenosed or occluded in 35 patients (16.4%). The hospital mortality rate was 5. 6% (12 patients). The cause of death was cardiac in ten patients (4. 6%), and neurologic in two (1%). Eleven patients (5.1%) developed a stroke postoperatively; eight strokes were ipsilateral to the operated artery, and six were permanent. Myocardial infarction occurred in five patients (2.3%). Independent predictors of early mortality were age >62 years, hypertension, and postoperative stroke (p < 0.05). Male sex was the only independent predictor of neurologic morbidity (p < 0.05). Late follow-up data were obtained for 163 (81.0%) patients (mean: 54.8 months, range: 1-168). Four (9. 3%) out of the 43 late deaths were attributed to strokes. There were three (1.8%) late ipsilateral strokes, and five (3.1%) contralateral strokes. The 5- and 10-year survival probabilities were 75 +/- 4%, and 52 +/- 6.9%. The freedom from late ipsilateral neurologic morbidity at 5 and 10 years were 97 +/- 1.7% and 90 +/- 4.0%, respectively. Taken together, the results indicate that combined carotid endarterectomy and coronary artery bypass grafting can be performed safely in this high-risk group of patients. Excellent long-term freedom from stroke can be expected.

Changes in brainstem auditory evoked response (BAER) with varying stimulus repetition primarily represent neural processes concerning the efficacy of synaptic transmission in the brainstem auditory pathway. In this study the BAER to different rates of clicks was recorded from 16 term neonates. The results were compared with those from 16 adults to examine whether the degree of maturation of synaptic transmission of the neonatal brainstem auditory pathway parallels that of general function of the pathway. All BAER wave latencies and interpeak intervals increased linearly and wave amplitudes reduced with increasing click rate. The absolute rate-dependent changes in BAER measures were much greater in the neonates than in the adults, reflecting a significant immaturity in the efficacy of synaptic transmission in the neonatal auditory brainstem and in the ability of the neonatal brainstem to process rapid acoustic stimulation. When the data obtained at higher click rates at various age groups were analyzed as percentages, using the BAER measurements at conventionally used slow rate (21/s) of clicks as the denominators, the changing rates (%), or relative changes, of most BAER measures at higher rates in the neonates were still greater than those in the adults. Therefore, the rate-dependent BAER changes in the neonates are relatively less mature than general aspects of the BAER, reflected by the BAER elicited with conventionally used slow rates of clicks. These findings suggest that synaptic efficacy in the neonatal brainstem auditory pathway is relatively less mature than general function of the pathway and thus may be more susceptible to unfavourable perinatal conditions.

Purpose: The role of continuous electroencephalographic (EEG) monitoring during carotid endarterectomy was evaluated in this retrospective review., Methods: We analyzed data from 902 consecutive carotid endarterectomy procedures performed with vein patch angioplasty. In 591 operations from 1980 to 1988 we did not use intraoperative EEG monitoring or shunting (non-EEG group). Continuous intraoperative EEG monitoring and selective shunting were used in 311 procedures from 1988 to 1994 (EEG group). The patients' mean age was higher in the EEG group (68.8 years; range, 41 to 87 years) than in the non-EEG group (66.2 years; range, 34 to 90 years; p < 0.001). There was also a significantly higher incidence of hypertension (56.2% vs 41.9%) and redo operations (5.4% vs 2.54%) in the EEG group than in the non-EEG group (p < 0.05). The operative technique was identical in both groups. We defined a significant EEG change as a greater than 50% reduction of the amplitude of the faster frequencies, a persistent increase of delta activity, or both., Results: In the EEG group, acute EEG changes occurred in 40 patients (12.8%); 31 (77.5%) unilateral and ipsilateral to the operated carotid artery, and nine (22.5%) bilateral. In five patients (12.5%) the changes correlated with an intraoperative episode of hypotension, and after normal blood pressure was restored the EEG returned to normal. In 35 procedures (87.5%) a carotid shunt was inserted. In 33 of those patients the EEG returned to baseline, in one patient there was a significant improvement, and in one patient the EEG changes persisted. Postoperative hospital strokes occurred in one patient (0.32%) in the EEG group and in 13 patients (2.19%) in the non-EEG group (p < 0.05). All strokes (n = 14) were ipsilateral to the operated carotid artery. Of the 13 strokes in the non-EEG group nine were major and four were minor. The one stroke in the EEG group was embolic in origin and occurred before carotid cross-clamping; it was associated with profound EEG changes that did not reverse after placement of a shunt. In the total group (n = 902), intraoperative EEG monitoring was inversely associated with postoperative stroke (p < 0.05)., Conclusion: The overall neurologic morbidity rate was significantly lower in the EEG group than in the non-EEG group, therapy demonstrating the value of intraoperative EEG monitoring in carotid endarterectomy.

Binaural interaction (BI) components in brain-stem auditory evoked potential (BAEP) and their changes with stimulus intensity and repetition rate were examined in human adult. Seven BI components were identified, which occurred between the latency range of 5 and 11 ms and coincided consistently with the latency range of BAEP waves IV-VII. Waves DV and DVII, occurring at the downslopes of BAEP waves V and VII, respectively, were the two most prominent and reproducible BI components. Wave DVII existed consistently at high, moderate and, in most cases, low stimulus intensities, suggesting that this component is neurogenic although acoustic cross-talk may account for a part of its waveform at high stimulus intensities. The latencies of all BI components increased as a function of decreasing stimulus intensity, while the interpeak intervals, especially DV-DVII, were essentially constant at different intensity levels. The amplitudes of BI components decreased slightly with decreasing intensity. As click repetition rate increased, BI wave latencies and interpeak intervals increased slightly and amplitudes decreased slightly. When repetition rate increased to above 20/s, BI components became poorly differentiated. Lower repetition rates, e.g. 10/s, are therefore preferred for routine derivation of the BI. The changes in the latency and amplitude of BI components with stimulus intensity and repetition rate were associated or concomitant with those of the corresponding BAEP components in monaural and binaural potentials. In view of the concomitant relationship between BI and BAEP latency, we designate BI components in association with the corresponding BAEP components.

Whether preterm birth has a significant effect on the maturation of the human brain remains an equivocal issue. Since experience plays a crucial role in the development of the brain, it is conceivable that extra-uterine preterm exposure could exert some effects on the maturation of the developing human brain. The present study compared the post-term maturation of the central components of brainstem auditory evoked response (BAER) in low risk preterm infants with that of age-matched full term infants up to 6 years. The preterm infants demonstrated similar maturational profiles to those of the term infants in both interpeak intervals and amplitude measures. No systematic, statistically significant differences were found between the preterm and term infants in any of the BAER variables although the I-V interval tended to be slightly shortened in the prematurely born infants. These results suggest that preterm birth or earlier exposure to sound environment extra utero is unlikely to lead to significant neurophysiological consequence in the developing auditory brainstem of low risk infants.

Low birthweight (LBW) and perinatal asphyxia are known to be high-risk factors for a number of neurodevelopmental deficits. In this study, we analyzed brainstem auditory evoked response (BAER) in 18 LBW and 36 perinatally asphyxiated children with non-progressive neurological sequelae after the age of 6 months to inspect and compare the long-term influence of LBW and perinatal asphyxia on the brainstem auditory pathway. The typical changes in the BAER of children born with LBW were slightly shorter III-V interpeak interval and smaller III-V/I-III interval ratio than normal controls. On the contrary, the abnormalities in the BAER of 36 children surviving perinatal asphyxia were characterized by a reduction of the amplitude of wave V with normal intervals. This discrepancy in the BAER between the children born with LBW and those with perinatal asphyxia implies that the two high-risk factors exert different long-term influences on the development of the brainstem auditory pathway. It is hypothesized that these characteristic changes may be indicative of a major influence of LBW on the generators contributing to wave III and that of asphyxia on the generators contributing to wave V. An increase in response threshold with abnormal latency-intensity function was found in 11% of the LBW children and 19% of the asphyxiated children, suggesting that sensorineural hearing impairment occurred more frequently in children surviving perinatal asphyxia than in those born with LBW. Follow-up study demonstrates that the abnormalities in the brainstem auditory pathway of LBW and asphyxiated children after the age of 6 months is likely to be persistent.

Latency and interpeak interval of the brain-stem auditory evoked potentials at different click rates were measured in 80 healthy children from birth to 6 years, and 21 adults. Clicks were presented at 10, 30, 50, 70 and 90/sec, and 70, 40 and 20 dB HL. At high stimulus intensity (70 dB SL), all latencies of waves I, III and V and the I-V, I-III and III-V intervals showed a progressive prolongation with increasing repetition rate. The latency- and the interval-rate functions were similar for all age groups but their slopes were slightly steeper in younger than in older. As click rate increased from 10/sec to 90/sec, the latencies of waves I, III and V at different age groups were prolonged by 4-10%, 9-13% and 12-15% respectively, and the intervals of I-V, I-III and III-V were prolonged by 15-16%, 8-16% and 14-24% respectively. The mean increments of wave V latency and I-V interval in different age groups were 0.404-0.575 and 0.332-0.526 msec respectively with increasing click rate from 10 to 50/sec, and 0.697-1.009 and 0.629-0.776 msec respectively with increasing click rate from 10 to 90/sec. The younger the age the larger the absolute increments for all these BAEP parameters, but the increasing rates for a BAEP measure were similar among different age groups, exhibiting no age-dependent differences.(ABSTRACT TRUNCATED AT 250 WORDS)

Early development of brainstem auditory pathway was studied in 14 children with Down's syndrome (age range from 1 month to 3 years). The brainstem auditory evoked potentials (BAEP) during infancy was characterized by elevated threshold and poorly differentiated wave I. All children within 2 years had elevated threshold in one or both ears, suggesting a high incidence of peripheral hearing deficits. Follow-up tests showed that as age increased up to 3 years the elevated threshold gradually decreased and the differentiation of wave I improved. The I-V interpeak interval was slightly shorter and the amplitude of wave V was smaller than the normal controls, which existed continuously during follow-up studies. Our findings suggest that the development of peripheral hearing is delayed, although persistent hearing deficits cannot be excluded, and the functioning and development of the brainstem auditory pathway may also be abnormal in Down's syndrome children.