1,916 research outputs found
Study of the Term Neonatal Brain Injury with combined Diffuse Optical Tomography and Electroencephalography
This thesis describes the application of combined diffuse optical tomography (DOT) and electroencephalography (EEG) in the investigation of neonatal term brain injury. With hypoxic ischaemic encephalopathy (HIE) and perinatal stroke being the most frequent contributors to brain injury in the term neonatal population, the first part of the thesis focuses on the description and ongoing requirement for their further investigation. In continuation to that, the characteristics and unique properties of both DOT and EEG are described and explored.
The combination of these two modalities was utilised in elucidating the relationship between neuronal activity and cerebral haemodynamics both in physiological processes as well as in disease, by the infant’s cot side. This work differs to previous studies using near-infrared technologies and EEG, as a denser whole head array was used, offering the potential of 3-dimensional image reconstruction of the cortical haemodynamic events in relation to electro-cortical activity. These methods were applied in the study of critically ill infants presenting with seizures in the first few days of life.
The relevant results are presented in three separate chapters of the thesis. Distinct neurophysiological phenomena such as seizures and burst suppression were detected and studied in association to underlying HIE. On the grounds of a pre-existing pilot study of our research group, distinct prolonged de-oxygenated cortical areas were identified following electrical seizure activity. Further exploration of infants with seizures provided limited supporting evidence. The investigation of burst suppression in HIE led to the first ever identification of repeated, waveform, cortical haemodynamic events in response to bursts of electrical activity with some spatial correlation to regions of brain injury. Further analysis of the low frequencies within the diffuse optical signal in cases of perinatal stroke, showed a consistent interhemispheric difference between the healthy and stroke-affected brain regions.
The limitations, prospects and conclusions are presented in the final chapter. The use of simultaneous DOT and EEG offers a unique neuro-monitoring and neuro-investigating tool in the neonatal intensive care environment, which is safe, portable, and cost-effective, Ongoing research is required for the exploration and development of the methodology and its potential diagnostic properties
Role of the advanced MRI sequences in predicting the outcome of preterm neonates
AIM
The aim of the project is to evaluate the role of advanced MRI sequences
(susceptibility weight imaging (SWI), diffusion tensor imaging (DTI), and arterial
spin labeling (ASL) perfusion) in detecting early changes that affect preterm neonatal
brain, especially in those patients without lesions at conventional MRI or with small
brain injuries (i.e. low grade germinal matrix-intraventricular hemorrhage (GMHIVH)),
and to correlate these subtle brain abnormalities with neurodevelopmental
outcome at 24 months.
METHODS
Since November 2015 until June 2017, 287 preterm neonates and 108 term neonates
underwent a 3T or 1.5T MRI study at term corrected age (40\ub11 weeks). SWI, DTI
and ASL sequences were performed in all neonates. SWI sequences were evaluated
using both a qualitative (SWI venography) and quantitative (Quantitative
Susceptibility Map analysis (SWI-QSM)) approach. DTI data were analyzed using a
Tract-Based Spatial Statistics analysis (TBSS). ASL studies were processed to
estimate Cerebral Blood Flow (CBF) maps. Perinatal clinical data were collected for
all neonates. Neurodevelopmental data were evaluated at 24 months in 175 neonates
using 0-2 Griffiths Developmental Scales.
RESULTS
The analysis performed on SWI-venography revealed differences in subependymal
veins morphology between preterm and term neonates with normal brain MRI, with
a higher variability from the typical anatomical pattern in preterm neonates. The same
analysis performed in preterm neonates with GMH-IVH revealed that the anatomical
features of subependymal veins may play a potential role as predisposing factor for
GMH-IVH. Moreover, the SWI-QSM analysis revealed a greater paramagnetic
susceptibility in several periventricular white matter (WM) regions in preterm
neonates with GMH-IVH than in healthy controls. This finding is likely related to the
accumulation of hemosiderin/ferritin following the diffusion of large amounts of
intraventricular blood products into the WM, and it is also supposed to trigger the
cascade of lipid peroxidation and free radical formation that promote oxidative and
inflammatory injury of the WM in neonatal brain after GMH-IVH. The TBSS
analysis confirmed that microstructural WM injury can occur in preterm neonates
with low grade GMH-IVH even in the absence of overt signal changes on
conventional MRI, with different patterns of WM involvement depending on
gestational age. Moreover, the distribution of these WM microstructural alterations after GMH-IVH correlates with specific neurodevelopmental impairments at 24
months of age. Finally, the analysis of brain perfusion at term-corrected age revealed
lower CBF in preterms with sub-optimal neuromotor development, reinforcing the
hypothesis that impaired autoregulation of CBF may contribute to the development
of brain damage in preterm neonates.
CONCLUSION
Advanced MRI sequences can assist the standard perinatal brain imaging in the early
diagnosis of preterm neonatal brain lesions and can provide new insights for
predicting the neurodevelopmental trajectory. However, detailed and serial imaging
of carefully chosen cohorts of neonates coupled with longer clinical follow-up are
essential to ensure the clinical significance of these novel findings
Brain Injury and Inflammation and Placental Inflammation in Response to Repetitive Umbilical Cord Occlusions in the Near Term Ovine Fetus
We hypothesized that repetitive umbilical cord occlusions (UCOs) leading to severe acidemia will stimulate a placental and fetal inflammatory response associated with brain injury, which will be exacerbated by chronic hypoxemia and low-grade infection. Chronically instrumented fetal sheep served as controls or underwent repetitive UCOs for up to 4 hours or until fetal arterial pH was2saturation pre-UCOs of \u3e55% an
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