Periventricular leukomalacia: evaluation with MR imaging

Susceptibility-weighted and diffusion kurtosis imaging to evaluate encephalomalacia with epilepsy after traumatic brain injury

Objective

Encephalomalacia after traumatic brain injury (TBI) is one of the factors leading to epilepsy. In this study, magnetic resonance imaging (MRI) was used to explore the brain image features of epilepsy after traumatic encephalomalacia, and to provide objective evidence for predicting the possible occurrence of epilepsy after traumatic encephalomalacia.

Methods

Two‐hundred‐fifty‐two patients with traumatic encephalomalacia were prospectively enrolled in the study. All patients underwent MRI after discharge from the hospital. At the 1‐year follow‐up, participants were divided into epilepsy and nonepilepsy groups. All participants underwent MRI including conventional imaging, susceptibility‐weighted imaging (SWI), and diffusion kurtosis imaging (DKI). The lesion volume, iron deposition, mean diffusion (MD), and mean kurtosis (MK) around the lesions were calculated for each group and compared using t‐tests. P values < 0.05 were considered statistically significant.

Results

Sixty patients with epilepsy and 91 without epilepsy were reported. There were no significant differences in Glasgow Coma Scale (GCS), lesion volume, encephalomalacia, or MD values between the two groups. Iron deposition was significantly higher in the epilepsy group (P < 0.05). The MK values were significantly different (P < 0.05).

Interpretation

Advanced MRI is an important means of evaluating risk of developing epilepsy at 1 year due to encephalomalacia in patients with TBI. SWI and DKI could be used to assess the microstructural changes around the encephalomalacia, and therefore be used to evaluate risk of developing epilepsy at 1 year.

The attenuation of retinal nerve fiber layer thickness and cognitive deterioration

Thinner retinal nerve fiber layer (RNFL) has been reported in Alzheimer's disease (AD) patient. However, whether changes in RNFL thickness can predict the cognitive deterioration remains unknown. We therefore set out a prospective clinical investigation to determine the potential association between the attenuation of RNFL thickness and the deterioration of cognitive function over a period of 25 months. We assessed cognitive function using the Repeatable Battery for the Assessment of Neuropsychological Status and measured RNFL thickness employing optical coherence tomography in 78 participants (mean age 72.31 ± 3.98 years, 52% men). The participants were categorized as stable participants whose cognitive status remained no change (N = 60) and converted participants whose cognitive status deteriorated (N = 18). We found that there was an association between the attenuation of superior quadrant RNFL thickness and the deterioration of cognitive function in the stable participants. In the converted participants, however, there was an inverse association between the reduction of inferior quadrant RNFL thickness and decline of cognitive functions [scores of list recall (R = -0.670, P = 0.002), adjusted (R = -0.493, P = 0.031)]. These data showed that less reduction in the inferior quadrant of RNFL thickness might indicate a higher risk for the patients to develop cognitive deterioration. These findings have established a system to embark a larger scale study to further test whether changes in RNFL thickness can serve as a biomarker of AD, and would lead to mechanistic studies to determine the cellular mechanisms of cognitive deterioration.

Young adults born preterm with very low birth weight demonstrate widespread white matter alterations on brain DTI

Preterm birth with very low birth weight (VLBW, ≤1500 g) is connected to reduced white matter (WM) integrity in childhood and adolescence. These changes in WM are correlated to motor, sensory and neuropsychological impairments. CNS myelination continues into the early twenties, but the consequences of this for WM integrity in VLBWs have not been explored. DTI and tract based spatial statistics (TBSS) was carried out to test for voxelwise differences in fractional anisotropy (FA), eigenvalues and mean diffusivity (MD) between a preterm VLBW group (n=49) and a control group born at term (n=59) at 18-22 years of age. TBSS was also used to explore the relationship between perinatal clinical data and general cognitive ability (total IQ), respectively, and the DTI metrics (FA and MD), with gender and age as a confounder. In the VLBW group several major WM tracts particularly in the posterior region had significantly reduced FA caused by an increase in the two lowest eigenvalues. MD was significantly increased in the VLBWs in 50% of the same regions as the FA changes, but encompassing also more peripheral WM. In the VLBW group, FA was found to correlate positively with birth weight and negatively with number of days in intensive care and on mechanical ventilator, particularly in the corpus callosum. FA was found to correlate positively with total IQ in the young preterm adults. In the controls there was no correlation between FA and total IQ. Our results indicate that the neurologic sequelae of preterm birth with VLBW are a lifelong condition inducing structural and functional impairments also in adulthood in VLBW survivors. The greatest risk of having reduced WM integrity in adulthood was found in the most immature VLBW neonates requiring mechanical ventilation and long-term intensive care.

Abnormal cerebral MRI findings and neuroimpairments in very low birth weight (VLBW) adolescents

BACKGROUND

High prevalence of abnormal cerebral MRI findings as well as major and minor motor, perceptual and cognitive impairments has been reported in very low birth weight (VLBW) children.

AIM

To investigate whether cerebral MRI pathology relates to different types of neuroimpairments in adolescents with VLBW.

METHODS

At age 15, 55 adolescents with birth weight < or = 1500 g (VLBW) were examined. Motor function was evaluated by Movement Assessment Battery for Children (ABC) and the Grooved Pegboard (GP) test, cognitive function by Wechsler Intelligence Scales, and visuo-motor and visual perceptual function by The Developmental Test of Visual-Motor Integration (VMI) with the supplementary tests of Visual Perception (VP), and Motor Coordination (MC). Executive functions were assessed by Wisconsin Card Sorting Test (WCST) and the Stroop test. Cerebral MRI was assessed semi-quantitatively for ventricular, white and grey matter pathology.

RESULTS

There was a rather weak relationship between MRI pathology and neuroimpairments. Poor performance on the WCST was related with ventricular dilatation (VD), white matter reduction and corpus callosum thinning. There was a correlation between results on the VMI test and the Movement ABC test and MRI pathology, but the correlation became much weaker when children with cerebral palsy were excluded. There was no relationship between MRI findings and estimated intelligence quotient (IQ) scores. Normal MRI predicted normal or near normal neuropsychological functioning.

CONCLUSION

Cerebral MRI pathology suggestive of perinatal white matter injury was related to disadvantages in performances on executive functions, to a lesser degree to motor and visual perceptual problems, but not to cognitive impairments in VLBW adolescents.

Cerebral MRI findings in very-low-birth-weight and small-for-gestational-age children at 15 years of age

BACKGROUND

A high prevalence of abnormal cerebral MRI findings has been reported in low-birth-weight children.

OBJECTIVE

To compare MRI findings in very-low-birth-weight (VLBW) and term small-for-gestational-age (SGA) children with controls in early adolescence.

MATERIALS AND METHODS

Cerebral MRI was used to examine 55 VLBW, 54 SGA and 66 controls at 15 years of age. The MR images were qualitatively assessed, and size of ventricles, white-matter and grey-matter abnormalities were reported.

RESULTS

The VLBW teenagers had a higher prevalence of various MRI abnormalities than SGA children and controls. Dilation of the ventricular system, especially of the occipital horns, was found in 82% of the VLBW group, in 19% of the SGA group and in 21% of controls. White-matter reduction was found in 53% of the VLBW, in 6% of the SGA and in 2% of controls. Corpus callosum thinning was found in 47% of the VLBW, in 2% of the SGA and in 6% of controls. Periventricular gliosis was found in 29% of the VLBW, in 4% of the SGA and in 8% of controls.

CONCLUSIONS

Cerebral MRI pathology in white matter is a common finding in VLBW teenagers. The findings may indicate minor perinatal PVL with resulting loss of white-matter tissue and ventricular dilation.

Imaging perinatal brain injury in premature infants

The primary methods currently in use for imaging the infant brain are cranial ultrasound (CUS), computed tomography (CT) and magnetic resonance imaging (MRI). This review outlines the relative strengths and weaknesses of these modalities in relation to the premature infant, with specific focus on the correlations between imaging findings and neurodevelopmental outcome. Since MRI is undergoing rapid development at this time, the newer MRI methods of brain volume measurement and diffusion tensor imaging are reviewed in more detail. Current guidelines regarding the application of these neuroimaging methods to the premature infant are discussed.

Correlation between neuroimaging and neurological outcome in periventricular leukomalacia: diagnostic criteria

BACKGROUND

Periventricular leukomalacia (PVL) is the most important factor in cerebral palsy in preterm infants.

METHODS

In the present study, we investigated 747 preterm infants of less than 36 weeks gestation who were repeatedly examined by cranial ultrasonography and computed tomography (CT) scanning at around 40 weeks of corrected post-menstrual age. The clinical course of these infants was followed for more than 3 years and they were examined by magnetic resonance imaging (MRI) between 12 and 18 months of age.

RESULTS

Single examinations in early infancy were not sufficient to diagnose PVL, but the combination of ultrasonography, CT and MRI examinations allowed the clinical diagnosis of PVL. In preterm infants, clinical PVL could be predicted from cystic PVL and periventricular echogenicity (PVE) 3 or PVE 2 prolonged over 3 weeks on ultrasonography and confirmed by MRI after 11 months of corrected age.

CONCLUSIONS

We tried to determine diagnostic criteria for PVL by neuroimaging. Such criteria from neuroimaging for PVL may be useful for determining the exact occurrence rate of and clinical risk factors for PVL.

Human oligodendroglial development: relationship to periventricular leukomalacia

Periventricular leukomalacia in the premature infant is a lesion of cerebral white matter with its greatest period of risk when white matter is immature, that is, when oligodendrocyte precursors are proliferating and differentiating, and before myelin sheaths are actively synthesized. Although the pathogenesis of perinatal cerebral white matter damage involves multiple factors, the correlation of the timing of the lesion with dominance of oligodendrocyte precursors in cerebral white matter suggests that intrinsic factors related to oligodendrocyte precursors are critical. Ischemia and infection have both been implicated as causes of perinatal white matter damage. Major mechanisms underlying oligodendrocyte injury in ischemia include glutamate toxicity, free-radical injury, and cytokine damage mediated by macrophages accompanying ischemia-induced inflammation. Factors related to a vulnerability of immature oligodendrocytes to ischemia potentially include a developmental lack of antioxidant enzymes to mediate oxidative stress. Cytokine-mediated injury to oligodendrocytes is also potentially important. A complete understanding of the role of immature white matter in the pathogenesis of periventricular leukomalacia is essential for developing strategies to prevent it.

Immunohistochemical study of myelination and oligodendrocyte in infants with periventricular leukomalacia

Eighteen patients with periventricular leukomalacia (PVL) of the focal or widespread type were immunohistochemically studied with respect to myelination and ferritin-containing oligodendrocytes and compared with 23 controls. Morphometric examination of myelination and ferritin-containing oligodendrocytes revealed normal development in the nonnecrotic cerebral white matter of the focal PVL brains. Myelination was mainly impaired in the necrotic or gliotic periventricular white matter of the widespread PVL brains. The expression of lipid components was poorer than that of myelin basic protein and the number of ferritin-containing oligodendrocytes was decreased in the necrotic or diffuse gliotic region of the widespread PVL brains compared to the controls. There was a significant relationship between the number of ferritin-containing oligodendrocytes and the degree of myelination. The impaired myelination in the PVL brains occurred in the necrotic as well as gliotic regions in the cerebral white matter, and may be related to the decrease of normal oligodendrocytes.

Periventricular leukomalacia, glial development and myelination

In perinatal leukomalacia, the brain pathology exhibits several different distribution patterns, according to cerebrovascular and glial maturity or various causal factors. Periventricular leukomalacia occurs in the prenatal as well as the postnatal period, and is caused by, in addition to predisposing factors, cerebral hypoperfusion which is in turn caused by systemic hypotension or intracranial vascular constriction and circulatory disturbance. Oligodendroglial damage or diffuse astrogliosis associated with leukomalacia may lead to delayed or reduced myelination in the cerebral white matter.

A comparative magnetic resonance imaging study of the corpus callosum in neurologically normal children and children with spastic diplegia

To determine the extent of brain damage in children with spastic diplegia, we analyzed the true midsagittal magnetic resonance imaging findings for the corpus callosum in 43 children with spastic diplegia and in 69 neurologically normal children. In the normal children, the thicknesses of the genu, midbody, splenium and the entire corpus callosum were found to increase with age, while the ratios of the thickness of the splenium and of the midbody to the length were constant, regardless of age. Both ratios were significantly reduced in diplegic children and the ratio for the splenium was highly correlated with the extent of motor impairment. Assessment of the morphometric changes in the corpus callosum using magnetic resonance imaging may contribute to the determination of the extent of brain damage in diplegic children.

Anatomy of diplegia: an hypothesis

Periventricular leukomalacia (PVL) occurring in relation to the body of the lateral ventricle could account for damage to the corticospinal tracts. However, PVL in this location is relatively rare, and the view that it causes the diplegia of preterm birth is challenged on the anatomical grounds that the corticospinal tracts to the legs are some distance away from the main sites of PVL, which are at the collateral trigone and near to the interventricular foramen. If PVL lesions do cause permanent nerve damage, it is surprising that cortical blindness in diplegia is so uncommon. A dying-back neuropathy caused by selective damage to corticospinal neurons could be considered as an alternative hypothesis to account for the paralysis of diplegia.

MRI changes and deficits of higher brain functions in preterm diplegia

Forty-one preterm children (29 with spastic diplegia and 12 without motor deficits) who had a normal verbal IQ were studied to clarify the clinical significance of neuroanatomical abnormalities disclosed by T1-weighted and T2-weighted magnetic resonance imaging (MRI). Both types of images clearly showed abnormalities in the frontal corona radiata of the children with spastic diplegia, while there were no abnormalities in the children without motor deficits. We compared the T1-weighted imaging findings with deficits of higher brain functions, evaluated by the performance subtests of the Wechsler Intelligence Scale. Thinning of the parietal and/or occipital white matter was noted in children with visuospatial cognitive deficits. Thus, MRI may be helpful in confirming early clinical suspicions of visuospatial cognitive deficits as well as motor deficits in preterm children, especially those with spastic diplegia.

MRI in motor delay: important adjunct to classification of cerebral palsy

Cranial magnetic resonance imaging (MRI) was performed prospectively in 45 children (ages 3-27 months) with clinically documented motor delay to evaluate the ability of MRI to determine etiologic factors, to determine whether myelination correlated with motor delay, and whether the clinical category corresponded with the imaging findings. Of the 22 children diagnosed clinically as having major motor delay (i.e., cerebral palsy), 77% had magnetic resonance imaging abnormalities. In 23%, etiologic associations were established from MRI alone and in 32% a clinically suspected etiology was supported. No children had myelination delay as the sole abnormality. In 23 children with minor motor delay, only 17% had abnormal scans. Clearly, MRI provided useful information in the majority of children with cerebral palsy; therefore, a classification system is proposed in which MRI can be used in conjunction with clinical assessment to specify more precisely the etiologic factors in cerebral palsy.

Neuropathologic study of newborns with prenatal-onset leukomalacia

The distribution of leukomalacia and glial fibrillary acidic protein (GFAP)-positive glial cells in prenatal- and postnatal-onset leukomalacia were compared and diagnosed histologically in 128 autopsied infants and the different pathogeneses were examined. Prenatal-onset leukomalacia was diagnosed in 12 of 71 still-births and neonates surviving less than 3 days (16.9%). All 4 preterm infants of less than 32 gestational weeks had widespread white matter necrosis and 4 of 5 term infants had focal necrosis. GFAP-positive glial cells were more increased in the deep and intermediate white matter in both forms of leukomalacia than in the controls, although in the subcortical white matter they were less increased in prenatal- than postnatal-onset leukomalacia. These differences may indicate different pathogeneses, including vascular maturity and causal factors, in prenatal- and postnatal-onset leukomalacia.

Periventricular hyperintensity on magnetic resonance imaging correlated with brain ageing and atrophy

Fifty-two patients with cerebrovascular risk factors without neurological abnormalities were reviewed with respect to periventricular hyperintensity (PVH) on T2-weighted magnetic resonance imaging (MRI); brain atrophy was also assessed by CT and T1-weighted MRI. Extensive PVH showed a stronger correlation with age-related atrophy than mild or absent PVH. The relative volume of brain affected by PVH, calculated by computer, also correlated with brain atrophy, especially ventricular enlargement. The effects of PVH on brain ageing and atrophy is discussed.

Early pattern recognition in severe perinatal asphyxia: a prospective MRI study

On the basis of MRI examinations in 88 neonates and infants with perinatal asphyxia, we defined 6 different patterns on T2-weighted images: pattern A--scattered hyperintensity of both hemispheres of the telencephalon with blurred border zones between cortex and white matter, indicating diffuse brain injury; pattern B--parasagittal hyperintensity extending into the corona radiata, corresponding to the watershed zones; pattern C--hyper- and hypointense lesions in thalamus and basal ganglia, which relate to haemorrhagic necrosis or iron deposition in these areas; pattern D--periventricular hyperintensity, mainly along the lateral ventricles, i.e. periventricular leukomalacia (PVL), originating from the matrix zone; pattern E--small multifocal lesions varying from hyper--to hypointense, interpreted as necrosis and haemorrhage; pattern F--periventricular centrifugal hypointense stripes in the centrum semiovale and deep white matter of the frontal and occipital lobes. Contrast was effectively inverted on T1-weighted images. Patterns A, B and C were found in 17%, 25% and 37% of patients, and patterns D, E and F in 19%, 17% and 35%, respectively. In 49 patients a combination of patterns was observed, but 30% of the initial images were normal. At follow-up, persistent abnormalities were seen in all children with patterns A and D, but in only 52% of those with pattern C. Myelination was retarded most often in patients with diffuse brain injury and PVL (patterns A and D).

Etiologies and distribution of neonatal leukomalacia

Neonatal leukomalacia was classified into 4 groups: focal (F), widespread (W), diffuse (D), and multicystic encephalomalacia (MCE) according to the distribution of ischemic necrosis in the cerebral hemisphere. The highest and lowest values of PaCO2, PaO2, and pH and the lowest systolic and diastolic blood pressures were compared among each group and controls. The lowest PaCO2 values were significantly lower in MCE than in the F, W, and D (F + W + D) group or controls. The lowest values of systolic and diastolic blood pressures in the W and F + W + D groups were significantly lower than in the controls; therefore, hypocarbia can be an etiologic factor of MCE rather than periventricular leukomalacia. Hypotension may be closely related to a causal factor of neonatal leukomalacia.

MRI of patients with cerebral palsy and normal CT scan

Three children with clinical evidence of cerebral palsy (CP) and normal cerebral computed tomography (CT) scans were evaluated by magnetic resonance imaging (MRI) to identify CT-undetectable white matter lesions in the watershed zones of arterial territories. The two patients with spastic diplegia showed bilateral lesions either in the subcortical regions or in the occipital periventricular regions. The patient with congenital hemiplegia exhibited unilateral lesions in the periventricular region. We conclude that MRI is more informative than CT for the evaluation of patients with CP.

Cerebral magnetic resonance imaging (MRI) of very low birth weight infants at one year of corrected age

Cerebral MRI was performed at 1.5 T in 27 infants with birth weight below 1500 grams at 1 year of corrected age. The images were compared to those reported on normal development at the same age. On T1 weighted images, 20 (74.1%) of the 27 infants showed myelin deposition different from what has been reported to be normal. Areas most affected were the central occipital white matter and the centrum semiovale. Both correspond to "watershed areas" known to be at risk for periventricular leukomalacia in preterm infants. T2-weighted images showed delayed myelination in the same areas as described for T1. In addition, two infants showed delayed myelination in the central occipital white matter and one in the centrum semiovale. Patchy focal abnormalities involving the white matter were seen in seven (25.9%) infants. Mild cerebral atrophy, mainly of the cortex was found in 10 (37.0%) infants. Irregular shape of the lateral ventricles, especially of the occipital horns was present in 12 infants (44.4%). 11 of these infants also had deviating changes in myelination. Only 2 infants (7.4%) had a normal MRI examination. Follow-up MRI examinations are needed to determine whether the high percentage of changes in myelination represent delayed development or brain damage in preterm infants.

Myelination as an expression of the functional maturity of the brain

A prospective cross-sectional study was performed on hydrocephalic infants and children. MRI was used to assess the state of myelination and to quantify the intracranial cerebrospinal fluid (CSF) volume repeatedly in all children. At the same time, neurodevelopmental testing was performed. A positive correlation was found between the progress of myelination and psychomotor development, but there were no significant correlations between CSF volume and myelination or between CSF volume and psychomotor development. This study provides strong evidence in favour of Flechsig's thesis that myelination expresses the functional maturity of the brain. The interdependency of neuronal maturation and progress of myelination are discussed.

Magnetic resonance imaging in children with spastic diplegia: correlation with the severity of their motor and mental abnormality

Magnetic resonance imaging (MRI) findings for 34 children with spastic diplegia, examined between two and 10 years of age, were analysed. Dilatation of the trigone, atrophy of the peritrigonal white matter and prominent deep cortical sulci were seen. On T2-weighted images, periventricular high-intensity areas in the white matter adjacent to the trigones and bodies of the lateral ventricles were seen in many children. These MRI features may reflect the pathological changes of periventricular leukomalacia in children with spastic diplegia. Among the MRI findings, only the amount of white matter correlated with severity of disability: white matter reduction corresponded to the more severe motor disabilities.

Periventricular hyperintensity detected by magnetic resonance imaging in infancy

Twenty-one infants younger than 12 months of age were diagnosed as having periventricular hyperintensity (PVH) on T2-weighted magnetic resonance imaging. Ten infants had experienced neonatal asphyxia, 6 intracranial hemorrhage, 2 bacterial meningitis, and 3 apnea. PVH was classified according to its extent. Round foci of PVH surrounding the frontal and occipital horns of the lateral ventricles were observed in 4 infants (PVH pattern I). Continuous PVH was observed in 17 infants (PVH patterns II and III). Fourteen infants with continuous PVH had spastic diplegia or quadriplegia. Developmental delay was demonstrated in 15 infants with continuous PVH. No PVH pattern I infants had cerebral palsy; only 1 such infant had mild developmental delay. Our study suggests that the extent of PVH reflects the severity of brain damage in neonates with cerebral injuries.

Myelination patterns on magnetic resonance of children with developmental delay

Magnetic resonance (MR) imaging was performed in 30 children with unexplained developmental delay who had associated neurological abnormalities such as seizures, spasticity, hypotonia, ataxia or poor vision. No child had a history of regression, preterm birth or neonatal cerebral injury. CT scans were performed before MR in all cases and were either normal or showed only mild atrophy. At least two MR sequences were obtained for all patients. Nine children had delayed or absent myelination on MR, one had patchy white-matter abnormalities, and in one patient myelination was topographically normal, but of inappropriately low signal intensity. MR was abnormal in six of seven children who had abnormal brainstem auditory evoked potentials (BAEP), and was normal in nine of 11 patients who had a normal BAEP. MR may have a useful rôle in demonstrating abnormal white-matter maturation in children with unexplained neurodevelopmental delay, particularly when abnormalities are found on BAEP studies.

Mapping of normal brain maturation in infants on phase-sensitive inversion--recovery MR images

It is illustrated that phase-sensitive inversion-recovery MR images are particularly well suited for the monitoring of brain maturation and myelination in the neonate and young infant. Provided appropriate timings are applied with the inversion-recovery MR pulse sequence, the myelinated areas show up as bright spots in the phase-sensitive images. The chronology of the appearance, and the location of these hyperintense zones correlate well with the chronology of brain maturation, as assessed by other means. In particular, the progressive functional capabilities of the infant correlate well with the progress of myelination, as exhibited by the MR images.

Neurologic sequelae and MRI in low-birth weight patients

Periventricular hyperintensity was detected using long repetition and echo time on spin-echo magnetic resonance imaging in 24 of 32 children with birth weights less than 2,500 gm. Functionally, 11 children were normal, 6 mildly handicapped, 7 moderately handicapped, and 8 severely handicapped. The functional handicaps were correlated to the degree of periventricular hyperintensity observed on magnetic resonance imaging when periventricular hyperintensity was divided into 4 grades; therefore, the extent of periventricular hyperintensity observed on magnetic resonance imaging has been proved to be of value in the clinical assessment of low-birth weight infants and children and may contribute to the prediction of later functional deficits.

Visual and neurological outcome of infants with periventricular leukomalacia

Visual acuity, visual fields and neurological status were assessed in 10 infants with periventricular leukomalacia (PVL), tested at 16, 36, 48 and 72 weeks from the expected date of confinement. Monocular acuity development was normal in eight of the 10 infants, but was below normal in one infant at eight months and in another at 18 months. Over half the infants tested at 16, 36 and 48 weeks had smaller visual fields than those of 95 per cent of healthy preterm infants tested at the same ages, but by 72 weeks only two of six infants tested had restricted visual fields. Nine of the 10 infants were neurologically abnormal at ages under one year, but only four remained so beyond one year. These results indicate more favourable outcomes for visual acuity and neurological status in infants with non-cavitary PVL than have been reported in infants with cavitary PVL. The most compromised infants were one with cavitary PVL and another with extensive non-cavitary PVL who had the longest-lasting EEG abnormalities of all 10 infants.

Extensive cystic leucomalacia: correlation of cranial ultrasound, magnetic resonance imaging and clinical findings in sequential studies

Cranial ultrasound (US) was used in 14 neonates to define three categories of extensive cystic leucomalacia, namely periventricular, mixed, and subcortical. The initial US findings were compared with serial magnetic resonance imaging (MRI) and the neurodevelopmental outcome of the children. In the infants with periventricular leucomalacia, MRI showed a decrease in the size of the cystic areas with age. Six of these seven children showed an increase in the level of myelination upon follow-up examination, although white matter development was slower in the vicinity of the cysts. The lateral ventricles of these children were slightly enlarged and the occipital horns showed an irregular angular outline. In the infants with mixed leucomalacia, MRI showed cystic areas which remained obvious at the final examination. Myelination was grossly delayed in these patients. The lateral ventricles were enlarged and remained unchanged, with the exception of one infant whose ventricles collapsed after shunt revision. In the three children with subcortical leucomalacia, MRI confirmed shrinkage of the cysts in two of the three infants upon the first follow-up examination but thereafter the cysts remained unchanged. No supratentorial myelination was demonstrated in these patients. The ventricles were enlarged and the cortical sulci were prominent in all these infants. A strong correlation was shown between the MRI appearances and the clinical outcome in these children. MRI may be most useful for making the diagnosis of cystic leucomalacia in children not submitted to US examination as neonates or in whom only some of the classical US features have been identified.

Computed tomographic findings in children with spastic diplegia: correlation with the severity of their motor abnormality

Computed tomographic findings of 46 children with spastic diplegia examined at nine months to three years of age corrected for preterm births were analyzed. Both the size of the lateral ventricles measured by the width of the anterior horns, and the volume of the extracerebral low-density areas were enlarged in some patients. Both enlargements did not, however, correlate to the severity of the motor abnormality in the patients. The low-density areas of the periventricular white matter, especially adjacent to the trigone, were reduced in many children, probably due to the atrophy of the cerebral white matter having periventricular leukomalacia. The anterior expansion of the white matter reduction from the trigone corresponded to the severe motor abnormality in the children with spastic diplegia.