L.T.L. Sie

Functional MRI of visual cortex in sedated 18 month-old infants with or without periventricular leukomalacia.

Functional MRI (fMRI) of the visual cortex was evaluated in 42 sedated 18‐month‐old infants (mean corrected age; 31 males, 11 females) with or without periventricular leukomalacia (PVL). Data from 14 infants could not be evaluated because of movement artefacts. Ten of the remaining 28 infants showed no significant fMRI response upon visual stimulation. In 18 infants, a significant signal change upon stimulation was found in the visual cortex: in 17 a signal decrease and in one a signal increase. Functional changes were located mainly in the anterior part of the visual cortex. Seven of the 28 infants had normal MRI and 21 showed variable occipital PVL. An fMRI response was equally frequent in infants without PVL (4 of 7 infants) and with PVL (14 of 21 infants). In conclusion, fMRI was shown to be feasible in sedated infants. No correlation was found between functional activation and the presence or absence of occipital PVL. Type of fMRI response (signal decrease) and localization (anterior part of the visual cortex) are different from those seen in adults, probably reflecting a combination of sedation effects and immaturity of the visual system. At present, fMRI is a highly promising research tool; its clinical relevance still has to be established.

Predictive value of EEG in neonates with periventricular leukomalacia

The aim of this study was to evaluate whether EEG (i.e. positive Rolandic sharp waves) can be used to predict neurodevelopment in newborn infants with periventricular leukomalacia and compare the predictive value with that of MRI. A sequential cohort of neonates (n=45; 33 males, 12 females; mean gestational age 31.2 weeks, SD 2.7, range 27 to 37.8 weeks; mean birthweight 1592g, SD 601g) with periventricular hyperechogenicities on cranial ultrasound was recruited for this study. EEGs were analyzed for positive Rolandic sharp waves. Neurodevelopment was evaluated at the ages of 12 and 18 months. In the whole group the probability of a poor outcome was 24% and the probability of any impairment was 33%. If the number of positive Rolandic sharp waves was no more than 0.1 per minute, the probability of a poor outcome was reduced to 9% (95% confidence interval [95% CI] 2 to 27%) and the probability of any impairment was reduced to 13% (95% CI 4 to 32%). In all infants with more than 0.1 positive Rolandic sharp waves per minute the probability of a poor outcome was 41% (95% CI 23 to 61%) and of any impairment was 55% (95% CI 34 to 73%). In these infants MRI identified infants with a poor outcome with a sensitivity of 1.00 (95% CI 0.70 to 1.00) and a specificity of 0.92 (95% CI 0.67 to 0.99), and infants with any impairment with a sensitivity of 0.83 (95% CI 0.55 to 0.95) and a specificity of 1.00 (95% CI 0.72 to 1.00). Results suggest that if an EEG of an infant with periventricular leukomalacia contains no more than 0.1 positive Rolandic sharp waves per minute the probability of a normal or mildly delayed development is high (0.91, 95% CI 0.73 to 0.98). MRI enhances the accuracy of the outcome prediction slightly; however, owing to a wide confidence interval, this advantage is negligible. However, if the frequency of the positive Rolandic sharp waves exceeds 0.1 per minute, MRI can significantly enhance the precision of the prediction of outcome.

Value of fluid-attenuated inversion recovery sequences in early MRI of the brain in neonates with a perinatal hypoxic-ischemic encephalopathy

Abstract. The aim of our study was to assess the usefulness of fluid-attenuated inversion recovery (FLAIR) sequences in comparison with conventional spin-echo and inversion MR imaging in neonates for evaluation of myelination and for detection of hypoxic-ischemic brain injury. We reviewed early MR scans of 18 neonates with suspected hypoxic-ischemic brain damage. Myelination could be evaluated with confidence using conventional MR imaging in all but 2 infants; however, the presence of myelin was very difficult to assess on FLAIR images. Overall, 53 lesions or groups of lesions were identified. The FLAIR technique was more sensitive in 11 of the lesions; especially (pre)cystic lesions could be identified much better and more cysts were found. Conventional MR imaging failed to identify 2 of the lesions and was more sensitive in 14 of the lesions; especially punctate hemorrhages and lesions in basal ganglia or thalami could be better determined. The FLAIR technique missed 3 of these lesions. In the remaining 28 lesions conventional MR and FLAIR images were equally diagnostic. The FLAIR technique and conventional MR imaging are complementary in detecting early sequelae of hypoxic-ischemic brain injury in neonates. The FLAIR technique is not suitable for assessing myelination of the neonatal brain; therefore, FLAIR cannot replace conventional MR imaging.

Walking and periventricular leukomalacia: Locomotor characteristics and brain imaging (MRI)

The aim of the present study was to compare the walking abilities in infants with and without periventricular leukomalacia and to see whether the severity of the brain damage was related to locomotor outcome of the infants at 12 and 18 months. 47 newborns were included in the study based on white matter abnormalities on ultrasound. Magnetic resonance imaging (MRI) recordings during the neonatal period were used to identify and quantify the location and severity of the brain lesions. Locomotor outcome was assessed in terms of disability at 12 and 18 months. The quality of walking, including global and segmental gait parameters, was measured for the infants who could walk independently at 18 months and compared to a group of healthy control infants. The number of children who could walk was related to the extent of white matter abnormalities seen on the neonatal MRI, but the quality of walking was not.