Brain Growth Gains and Losses in Extremely Preterm Infants at Term

Abstract

Premature exposure to the extrauterine environment negatively affects the brains' developmental trajectory. Our aim was to determine whether extremely preterm (EPT) infants, with no evidence of focal brain lesions, show morphological brain differences when compared with term-born infants. Additionally, we investigated associations between perinatal factors and neuroanatomical alterations. Conventional magnetic resonance imaging was acquired at term-equivalent age (TEA) from 47 EPT infants born before 27 weeks of gestation, and 15 healthy, term-born controls. Automatic segmentation and voxel-based morphometry-Diffeomorphic Anatomical Registration through Exponentiated Lie algebra (DARTEL) were used. Compared with controls, EPT infants displayed global reductions in cortical and subcortical gray matter, brainstem, and an increased cerebrospinal fluid volume. Regionally, they showed decreased volumes of all brain tissues, in particular cortical gray matter. Increased volumes of cortical gray and white matter were observed in regions involved in visual processing. Increasing prematurity, intraventricular hemorrhage grade I-II, and patent ductus arteriosus ligation were associated with decreased volumes and had a particular effect on the cerebellum. Concluding, EPT infants without focal brain lesions had an altered brain growth at TEA that particularly affected the gray matter, and varied when it came to the presence of perinatal risk factors. Brain growth gains in EPT infants may be related to a longer extrauterine experience.

Patent Ductus Arteriosus and Brain Volume

“…[37][38][39] Although infants of the surgery group showed the lowest volumes in most brain regions, volumes were not significantly different between the 3 groups. This is in disagreement with our hypothesis and with Padilla et al, 40 who reported a significant reduction in MRI-measured global and regional brain volumes, especially cerebellar growth. Impairment of cerebellar growth associated with PDA was reported earlier, although differences in population and methods may hamper reliable comparison between the studies.…”

“…This tendency to postpone medical or surgical ductal closure 4,11,12 and thus accept a longer episode of suboptimal cerebral oxygenation may be a reason for the reported negative effects of PDA on brain growth. [40][41][42] As stated earlier, the result of the MLR analysis, showing a relationship between cerebellar volume and cerebral oxygenation in the surgery group, which had the highest postnatal age and lowest cerebral oxygenation (see also Fig 3), may substantiate this assumption. Thus, our active approach to a hemodynamically significant PDA may have largely prevented negative effects of suboptimal oxygenation on the immature brain 43 and in particular on the CB.…”

“…[40][41][42] We postulate that the amount of time elapsed between the diagnosis of PDA and actual surgical closure may have played a role here. In our institution we aim to close the duct early: When a PDA is clinically diagnosed and confirmed by echocardiographic investigation, noninvasive closure is always initiated.…”

Impaired Neurodevelopmental Outcome After Mild Germinal Matrix-Intraventricular Hemorrhage

“…15 However, it is noteworthy that the only significant deleterious anatomic effect of mild GMH-IVH detected by MRI studies at term equivalent age involved cortical and deep gray matter development. 16,17 Interestingly, and relevant to these MRI observations, recent studies of human premature brain show that during the developmental period of 25 to 34 weeks, the germinal matrix contributes to the generation and later migration of GABAergic interneurons to cerebral cortex and to association nuclei of the thalamus, both critical for higher-level cognitive functions. [18][19][20][21][22] Disturbance of these latter events could have deleterious consequences for neurodevelopment.…”

Stress : Clinical and Developmental Aspects of Salivary Cortisol in Infants

“…In preterm infants organ systems are already functional, but usually somewhat immature. The brain is no exception and in very preterm infants it is completely smooth at birth, with fewer convolutions by gestational week 40 than found among healthy full-term infants born at GA week 37-42 [40], a difference associated with poorer cognitive outcome [41,42]. Brain volume correlates with GA at birth and even among infants at low risk for neurodevelopmental deficits, prematurity impacts neurodevelopmental and cognitive outcome in children at 9 years of age [42].…”