Preterm infants frequently experience pulmonary hemorrhage or cerebral intraventricular hemorrhage after birth. The immature myocardium of the left ventricle faces a high afterload after the baby is separated from the placenta. However, the preterm left ventricle has limited ability to respond to such an increase in afterload. This results in depressed cardiac function and a deterioration in hemodynamics. We speculated that the perinatal deterioration in cardiac performance would be closely related to serious hemorrhages. To prove our hypothesis, we studied the interrelationship between the perinatal changes in cardiac performance and the incidences of intraventricular and pulmonary hemorrhage. We obtained the stress-velocity relationship (rate-corrected mean fiber shortening velocity and end-systolic wall stress relationship) by M-mode echocardiography and arterial blood pressure measurement. We found that the incidences of intraventricular and/or pulmonary hemorrhages were higher in infants with an excessive afterload, which resulted in a decrease in the function of the left ventricle. We suggest that careful attention to keep the afterload at an acceptable level by vasodilator therapy and sedation may reduce or prevent these serious complications. In this review, we will discuss our data along with related literature.
Brain metabolite concentrations change dynamically throughout development, especially during early childhood. The purpose of this study was to investigate the brain metabolite concentrations of neonates (postconceptional age (PCA): 30 to 43 weeks) using single-voxel magnetic resonance spectroscopy (MRS) and to discuss the relationships between the changes in the concentrations of such metabolites and brain development during the neonatal period. A total of 83 neonatal subjects were included using the following criteria: the neonates had to be free of radiological abnormalities, organic illness, and neurological symptoms; the MR spectra had to have signal-to-noise ratios ≥ 4; and the estimated metabolite concentrations had to display Cramér-Rao lower bounds of ≤ 30%. MRS data (echo time/repetition time, 30/5000 ms; 3T) were acquired from the basal ganglia (BG), centrum semiovale (CS), and the cerebellum. The concentrations of five metabolites were measured: creatine, choline, N-acetylaspartate, myo-inositol, and glutamate/glutamine complex (Glx). One hundred and eighty-four MR spectra were obtained (83 BG, 77 CS, and 24 cerebellum spectra). Creatine, N-acetylaspartate, and Glx displayed increases in their concentrations with PCA. Choline was not correlated with PCA in any region. As for myo-inositol, its concentration decreased with PCA in the BG, whereas it increased with PCA in the cerebellum. Quantitative brain metabolite concentrations and their changes during the neonatal period were assessed. Although the observed changes were partly similar to those detected in previous reports, our results are with more subjects (n = 83), and higher magnetic field (3T). The metabolite concentrations examined in this study and their changes are clinically useful indices of neonatal brain development.
Purpose To investigate the time-course changes and predictive utility of brain metabolite concentrations in neonatal hypoxic-ischemic encephalopathy (HIE). Materials and Methods Sixty-eight neonates (age, 35-41 gestational weeks) with HIE were admitted to a neonatal intensive care unit between September 2009 and March 2016 and examined by using proton MR spectroscopy at 18-96 hours (n = 25) and 7-14 days (n = 64) after birth (35-43 postmenstrual weeks) to estimate metabolite concentrations in the deep gray matter. Adverse outcome was defined as death or neurodevelopmental impairment at 18-22 months of age. Areas under the receiver operating characteristic curves were calculated to evaluate the prognostic values of metabolites. Results At 18-96 hours, N-acetylaspartate and creatine concentrations were lower, whereas lactate, and glutamate and glutamine (Glx) concentrations were higher in neonates with adverse outcomes than in those with favorable outcomes. Metabolite concentrations at 18-96 hours decreased during days 7-14 in neonates with adverse outcomes but did not change in those with favorable outcomes. For N-acetylaspartate, creatine, lactate, and Glx concentrations measured at 18-96 hours to predict adverse outcomes, areas under the receiver operating characteristic curve were 0.98, 0.89, 0.96, and 0.88, respectively, whereas at 7-14 days, the areas under the receiver operating characteristic curve were 0.97, 0.97, 0.59, and 0.36, respectively. Conclusion Time-dependent reductions in N-acetylaspartate and creatine concentrations at both 18-96 hours and 7-14 days accurately predicted adverse outcomes. However, higher lactate and glutamate and glutamine concentrations were often transient.
Therapeutic hypothermia is recommended for moderate and severe neonatal encephalopathy, but is being applied to a wider range of neonates than originally envisaged. To examine the clinical use of therapeutic hypothermia, data collected during the first 3 years (2012–2014) of the Baby Cooling Registry of Japan were analysed. Of 485 cooled neonates, 96.5% were ≥36 weeks gestation and 99.4% weighed ≥1,800 g. Severe acidosis (pH < 7 or base deficit ≥16 mmol/L) was present in 68.9%, and 96.7% required resuscitation for >10 min. Stage II/III encephalopathy was evident in 88.3%; hypotonia, seizures and abnormal amplitude-integrated electroencephalogram were observed in the majority of the remainder. In-hospital mortality was 2.7%; 90.7% were discharged home. Apgar scores and severity of acidosis/encephalopathy did not change over time. The time to reach the target temperature was shorter in 2014 than in 2012. The proportion undergoing whole-body cooling rose from 45.4% to 81.6%, while selective head cooling fell over time. Mortality, duration of mechanical ventilation and requirement for tube feeding at discharge remained unchanged. Adherence to standard cooling protocols was high throughout, with a consistent trend towards cooling being achieved more promptly. The mortality rate of cooled neonates was considerably lower than that reported in previous studies.
Periventricular nodular heterotopia was seen in a relatively high proportion of children with Chiari II malformation, suggesting that it may be associated with severe hindbrain deformity.
Gamma‐aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the brain, and plays a key role in brain development. However, the in vivo levels of brain GABA in early life are unknown. Using edited MRS, in vivo GABA can be detected as GABA+ signal with contamination of macromolecule signals. GABA+ is evaluated as the peak ratio of GABA+/reference compound, for which creatine (Cr) or water is typically used. However, the concentrations and T 1 and T 2 relaxation times of these references change during development. Thus, the peak ratio comparison between neonates and children may be inaccurate. The aim of this study was to measure in vivo neonatal brain GABA+ levels, and to investigate the dependency of GABA levels on brain region and age. The basal ganglia and cerebellum of 38 neonates and 12 children were measured using GABA‐edited MRS. Two different approaches were used to obtain GABA+ levels: (i) multiplying the GABA/water ratio by the water concentration; and (ii) multiplying the GABA+/Cr by the Cr concentration. Neonates exhibited significantly lower GABA+ levels compared with children in both regions, regardless of the approach employed, consistent with previous ex vivo data. A similar finding of lower GABA+/water and GABA+/Cr in neonates compared with children was observed, except for GABA+/Cr in the cerebellum. This contrasting finding resulted from significantly lower Cr concentrations in the neonate cerebellum, which were approximately 52% of those of children. In conclusion, care should be taken to consider Cr concentrations when comparing GABA+/Cr levels between different‐aged subjects.
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