## 4 Results
_Note._ N.b.—newborn, 0.5 \(\times\) 1.0 cm—millimeter ischemic foci, 1.0 \(\times\) 3.0 cm—small-sized ischemic foci, 3.0 \(\times\) 5.0 cm—medium-sized ischemic foci, >5.0 cm—ischemic foci of large size, diffuse—large ischemic lesions with diffuse encephalomalacia and ischemic destructive-necrotic lesions. According to the results of MRI in children and newborns, the most frequent additional stroke-associated cerebral MRI changes in children were dilatation of the ventricular system and nonspecific glioependymal foci (Figure 6). Comparing with newborns, the results of MRI showed that the most common additional stroke-associated cerebral changes in newborns are represented by myelination deficiency, on first place and on the second place by the cortical atrophy (Figure 6). Below are some developmental anomalies of the brain found in children with IS, such as a developmental anomaly of the ventricular system (\(n=3\); 8.1%; 95% CI [3.61-12.59]), hypogenesis of the corpus callosum (\(n=2\); 5.4%; 95% CI [1.68-9.12]), hypogenesis of the cerebellar vermis, retrocerebellar cyst, Arnold Chiari malformation, and hypogenesis of the cerebellar hemispheres, each one case (2.7%; 95% CI [0.03-5.37]). Thus, brain developmental abnormalities detected in children with stroke were present in nine (\(n=9\); 24.3%; 95% CI [17.25-31.35]) cases (Figure 7). Figure 5: Other changes detected in cerebral MRI examination associated with IS in children aged 28 days to 18 years (%). _Note._ DVS—dilatation of the ventricular system, NGF—nonspecific glioependymal foci, CA—cortical atrophy, DSS—dilation of subarachnoid spaces, MD—myleination deficiency, ICF—intracerebral cystic formations, IFSE—intracerebral foci with nonspecific subcortical extension. Figure 6: Comparison of the most commonly encountered additional stroke-associated cerebral MRI changes in newborns and children (%). Here, the results of the comparison of cerebral structural changes according to age are shown. _Note._ DVS—dilatation of the ventricular system, NGF—nonspecific glioependymal foci, CA—cortical atrophy, DSS—dilation of subarachnoid spaces, MD—myleination deficiency, ICF—intracerebral cystic formations, IFSE—intracerebral foci with nonspecific subcortical extension. Brain MRI results associated with the age of the child and the topographic location of the ischemic focus were analyzed (Figure 8). Brain MRI was performed in the acute period of the stroke and at six months after the disease in all children included in the prospective study group. In contrast to CT, MRI images were much more informative and allowed for the assessment of the dimensions of the pathological focus at a distance compared to the acute period of the disease. It was found that the ischemic changes in the brain tissue detected during the acute period evolved into gliotic foci or cysts of various sizes, with a statistically significant difference being attested in that case (Table 6). Evolution towards normality was found only in the case of very small ischemic foci (3.7%). Additionally, a slight reduction in medium-sized ischemic foci was observed in 17 (31.5%) cases, possibly due to tissue recovery from the ischemic penumbra. Large lesions underwent cystic transformation. Angio-CT and angio-MRI were applied in exceptional cases to eight children with suspected vascular malformations (Figure 9). Figure 8: The results of the cerebral MRI examination regarding the location of the ischemic focus according to age and the involved artery in newborns and children with IS (%). Figure 7: Developmental abnormalities of the brain in children with stroke (brain MRI examination %). _Note._ AVS—developmental abnormality of the ventricular system, HCC—hypogenesis of the corpus callosum, HCV—hypogenesis of the cerebellar vermis, RC—retrocerebellar cyst, ACM—Arnold, Chiari malformation, HCH—hypogenesis of the cerebellar hemispheres.