Unilateral parenchymal haemorrhagic infarction in the preterm infant.

A unilateral parenchymal haemorrhage associated with a germinal matrix-intraventricular haemorrhage (GMH-IVH) is still an important problem in the preterm infant and especially in those who are very immature. This type of lesion is now considered mainly to be caused by impaired drainage of the veins in the periventricular white matter and is often referred to as a venous infarction. The risk factors and neonatal imaging findings, as well as neurodevelopmental outcome and imaging data in infancy, of this type of lesion differ from those found in children with bilateral periventricular leukomalacia. An effort should, therefore, always be made to make a distinction between these two types of lesions. In our experience it is possible to make this distinction in most cases, when performing both sequential ultrasonography as well as selective magnetic resonance imaging during the neonatal period.

Parenchymal brain injury in the preterm infant: comparison of cranial ultrasound, MRI and neurodevelopmental outcome.

AIM: Magnetic resonance imaging (MRI) is increasingly being used in high-risk preterm neonates. Cranial ultrasound (US) was compared with MRI in preterm patients with parenchymal injury and related to neurodevelopmental outcome. PATIENTS AND METHODS: Studies were performed in 61 patients. Twelve infants with normal US (Group 1) had an MRI within the first 4 weeks of life (early MRI), and 10 also at term age (late MRI). Eight out of 20 infants with intraventricular haemorrhage with parenchymal involvement (IVH + PI) (Group 2) had an early as well as a late MRI and 12 a late MRI. Of the 20 patients with cystic-periventricular leukomalacia (c-PVL) (Group 3), 7 had an early MRI, 1 had an MRI on both occasions and 12 had a late MRI. All 9 children with focal infarction (FI) (Group 4) had a late MRI. RESULTS: MRI was conform with cranial US in Group 1. Early MRI in Group 2 showed contralateral c-PVL in one infant and an additional contralateral occipital parenchymal haemorrhage and blood in the posterior fossa in another infant. Late MRI showed an asymmetrical posterior limb of the internal capsule (PLIC) (n=6), which predicted later hemiplegia. Early MRI in Group 3 showed more cysts (n = 5), punctate white matter lesions (n = 6), lesions in the basal ganglia (n = 1) and once involvement of the cerebellum. Late MRI showed involvement of the centrum semiovale (n = 2) lesions in the basal ganglia (n = 2) and bilateral abnormal signal intensity of the PLIC in 7 infants who all went on to develop cerebral palsy. In Group 4 MRI showed signal intensity changes suggestive of cystic lesions compared to persisting echogenicity on US (n = 3) and an asymmetrical PLIC (n = 5), which predicted hemiplegia in 4. CONCLUSION: Early MRI especially provided additional information in those with c-PVL. MRI at term age could assess the PLIC, which was useful in children with unilateral parenchymal involvement, for prediction of subsequent hemiplegia and, to a lesser degree, in bilateral c-PVL for prediction of diplegia or quadriplegia.

Value of (1)H-MRS using different echo times in neonates with cerebral hypoxia-ischemia.

Previous studies have shown altered brain metabolism after cerebral hypoxia-ischemia, using magnetic resonance spectroscopy with echo times (TE) of 272 and 136 ms, based on peak-area or peak-height ratios. The present study examined the additional value of proton magnetic resonance spectroscopy with a short TE (31 ms) to predict a poor outcome in neonates with brain hypoxia-ischemia. Studies were performed in 21 full-term neonates with perinatal asphyxia in a 1.5 tesla magnetic field. Proton magnetic resonance spectroscopy was performed in a single volume of interest including the basal ganglia. TE of 272, 136 and 31 ms were used. After curve-fitting procedures, peak-areas as well as peak-height ratios of different brain metabolites were calculated, comparing patients with a poor versus a good outcome. Seven neonates out of 21 had a poor outcome. Neonates with a poor outcome showed a significantly lower N:-acetylaspartate/choline (NAA/Cho) and a significantly raised lactate/NAA (Lac/NAA) ratio using TE of 272 and 136 ms. Using a TE of 31 ms, no differences were found in glutamate/NAA (Glx/NAA), Glx/Cho, myo-inositol/NAA (mI/NAA), and mI/Cho ratios between neonates with a good and those with a poor outcome. Highest predictive values could be achieved for NAA/Cho with a TE of 136 ms. We conclude that low NAA/Cho and high Lac/NAA ratios predict a poor outcome in neonates with cerebral hypoxia-ischemia. TE of 272 and 136 ms have a better predictive value than a TE of 31 ms.

Glutamate in cerebral tissue of asphyxiated neonates during the first week of life demonstrated in vivo using proton magnetic resonance spectroscopy.

We tested the hypothesis that glutamate (Glx) levels as demonstrated by proton magnetic resonance spectroscopy ((1)H-MRS) are elevated in brain tissue of neonates with severe hypoxic-ischemic encephalopathy (HIE). Studies were performed in 26 neonates (median gestational age 40.5 weeks, range 36.7-42.4 weeks; median birth weight 3,360 g, range 2,180-4,200 g). The median postnatal age at the time of testing was 2.5 days (range 1-7 days). HIE was scored according to Sarnat as grade I (n = 4), grade II (n = 15) or grade III (n = 7). Results for neonates with mild to moderate HIE (group 1) were compared to those with severe HIE (group 2). After magnetic resonance imaging, (1)H-MRS was performed in a single volume of interest including the basal ganglia. An echo time of 31 ms was used. After curve-fitting procedures, peak area ratios of different brain metabolites were calculated. The median total Glx/N-acetylaspartate ratio was 1.21 (range 0.64-3.25) in group 1 versus 1.55 (range 1.10-2.75) in group 2 (p = 0.035). The median total Glx/choline ratio was 1.33 (range 0.71-2.52) in group 1 versus 2.14 (range 1.21-3.55) in group 2 (p = 0.019). We concluded that during the first days of life, Glx was elevated in the basal ganglia of neonates with severe HIE.

Cerebral proton magnetic resonance spectroscopy of neonates after extracorporeal membrane oxygenation.

UNLABELLED: During venoarterial extracorporeal membrane oxygenation the right carotid artery is ligated in a hypoxic neonate. The aim of the present study was to compare the morphology and metabolism of the left and right basal ganglia in 10 neonates after extracorporeal membrane oxygenation, using proton magnetic resonance imaging and spectroscopy. Data could be obtained in 9 neonates. No significant metabolic differences were found between either the left or right basal ganglia, despite a small right-sided thalamic infarct in one child. Metabolism was normal in all cases. All the infants showed symmetrical neurodevelopment. CONCLUSION: Ligation of the right carotid artery for venoarterial extracorporeal membrane oxygenation did not produce persistent changes in brain metabolism in the basal ganglia in this small group of patients.

Neonatal diffusion-weighted MR imaging: relation with histopathology or follow-up MR examination.

PURPOSE: Diffusion-weighted imaging (DWI) has become a standard method for early evaluation of stroke in adults, but its value in neonates is less well established. In this study neonatal DWI was compared with histopathology in those patients who died, or with sequelae seen on a second MR in the surviving neonates. PATIENTS AND METHODS: DWI was performed in 2 groups. Group 1: seven neonates who died and had a post-mortem ex-amination (perinatal asphyxia [n=5], symptomatic hypoglycemia [n= 11, periventricular leukomalacia [n= 1]). Group 2: six surviving neonates with a second MR examination at three months of age (perinatal asphyxia [n= 21, neonatal stroke[n= 3], meningo-encephalitis [n= 1]). RESULTS: In group l neonatal DWI showed more extensive involvement than conventional MRI in 6 out of 7 patients. These changes were less extensive,however, than seen post-mortem by histopathology in 5 out of 7. In group 2 neonatal DWI showed more extensive involvement than conventional MRI in 2 out of 6; 4 out of 6, however, showed less extensive cystic evolution on follow-up MRI at 3 months than expected from neonatal imaging. CONCLUSION: There was a good relation between hyperintense areas on DWI and areas of cytotoxic edema and neuronal damage on histopathology. In the survivors a second MRI showed cystic evolution in all, but the volume of the cysts was smaller than expected on the basis of the neonatal DWI findings.