Russian Scientists Investigate Age-Related Differences in Brain Damage Volume Following Childhood Stroke

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A team of Russian scientists and clinicians, including Sofya Kulikova from HSE University in Perm, compared the extent and characteristics of brain damage in children who experienced a stroke either within the first four weeks of life or before the age of two. The researchers found that the younger the child, the more extensive the brain damage—particularly in the frontal and parietal lobes, which are responsible for movement, language, and thinking. The study, published in Neuroscience and Behavioral Physiology, provides insights into how age can influence the nature and extent of brain lesions and lays the groundwork for developing personalised rehabilitation programmes for children who experience a stroke early in life.

A stroke is an acute disruption of blood flow in the brain: it occurs either when a blood vessel is blocked by a clot or embolus (ischaemic stroke) or when a vessel ruptures, causing bleeding (haemorrhagic stroke). Paediatric stroke has distinct characteristics, as a child’s brain is continuously growing and developing. Although the mechanism of stroke in children and adults is the same—rupture or blockage of a blood vessel—the nature of the pathology differs. In adults, strokes are usually caused by emboli (blood clots that block blood flow) or by atherosclerosis, in which cholesterol builds up on vessel walls and obstructs circulation. Children, however, typically have neither of these conditions.

Sofya Kulikova

'Paediatric strokes most often occur in infants with congenital heart defects, including those who have undergone surgery. This is because their cardiovascular system does not function properly. Moreover, in some cases of perinatal stroke, it is impossible to determine the exact timing—whether it occurred before, during, or shortly after birth,' explains Sofya Kulikova, Director of the Centre for Cognitive Neuroscience at HSE University in Perm and co-author of the article.

Extensive brain lesions are generally associated with a poor prognosis, but it remains unclear whether this holds true for children, whose brains exhibit exceptional plasticity. To explore this question, scientists from several Russian universities and medical institutions—including HSE University, Ural Federal University, Moscow State University, the Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, Ural State Medical University, the Skolkovo Institute of Science and Technology, as well as Children's City Clinical Hospital No. 9 and the Regional Children's Clinical Hospital in Yekaterinburg—compared the size of stroke-related brain lesions in children of different ages. 

The researchers analysed MRI data from 35 children who experienced an ischemic stroke before the age of two and were treated in hospitals in Yekaterinburg, Perm, Chelyabinsk, and Tyumen between 2015 and 2019. The children’s ages at the time of the stroke ranged from four days to 23 months.

To assess the effects of stroke, the researchers used a modern imaging analysis technique known as voxel-based morphometry. Simply put, this method involves manually tracing the boundaries of brain damage on each MRI slice, layer by layer. A specialised computer program then calculates the precise volume of the affected area in cubic millimetres. This technology provides more objective data than traditional MRI reports, which typically focus on qualitative characteristics such as the stroke’s boundaries and location. Voxel-based morphometry, by contrast, yields quantitative data—including the absolute size of the lesion and its proportion relative to total brain volume. As a result, this method produces precise numerical values that can be used for statistical analysis and comparison.

The researchers divided the cases into two age groups: perinatal and paediatric strokes. Perinatal strokes occurred within the first 28 days of life, while paediatric strokes occurred before the age of two. 

The study found that strokes in infants and in children older than one month differ both in the size and nature of brain lesions. In infants with perinatal stroke, the volume of brain damage was significantly greater than in older children—7.9% versus 1.6% of total brain volume. Newborns were also more likely to experience cortical disorders, mixed and bilateral strokes, whereas in children aged 28 days to two years, strokes were more often localised in subcortical regions and affected only the left hemisphere.

Ischemic lesion in the area supplied by the right middle cerebral artery (a) and its manual delineation (b) on the MRI slice.

© Korotkova, E.V., Kulikova, S.P., Kotyusov, A.I. et al. Voxel-based morphometry of brain MRI: first results in pediatric ischemic stroke cohort. Neurosci Behav Physi 55, 327–339 (2025).

'Children’s brains are highly plastic, and this plasticity is greater the younger the child. On one hand, an earlier stroke leads to more extensive lesions, but it remains unclear how this will impact the child’s subsequent development. A large volume of lesions does not necessarily predict a poor outcome. In some cases, nearly half of the brain may be affected, yet the child later performs well at school. Conversely, even a small lesion of just a few millimetres can result in lifelong disability,' notes Kulikova.

The analysis also showed that nearly half of the strokes (48.6%) occurred on the left side, consistent with findings from other studies. According to Sofya Kulikova, left-sided strokes are more common in adults. This is due to the asymmetry of the cardiovascular system: the carotid arteries branch unevenly from the aorta, making it more likely for a blood clot to form in the left side of the brain than in the right. It is also possible that the left side of the brain, being more involved in language, makes related disorders more noticeable than those caused by right-sided lesions. In other words, left-sided strokes may simply be diagnosed more frequently. However, the factors influencing this localisation in children remain unknown.

The second, less obvious finding related to the specific areas affected. The study revealed that the frontal lobe (68.6% of cases) and the parietal lobe (54.3%) were most frequently involved in children. These regions, critical for a child's development, are responsible for movement, planning, language, reasoning, and spatial perception.

However, the regions supplied by the middle cerebral artery proved to be the most vulnerable, affected in 94.3% of cases. Nearly 63% of the children also had damage to the internal capsule, which often results in cognitive impairments such as inattention, apathy, abulia (lack of will or drive), and memory problems. On average, the volume of brain damage was approximately 20,000 cubic millimetres, or about 3.4% of the total brain volume.

In the next stage of their research, the scientists plan to examine the effects of strokes that occurred at different ages in the same children. Many of these children are now in school, while others continue to experience developmental delays. The researchers aim to compare the children’s cognitive abilities with the location and size of the brain lesions they sustained in early childhood. Ultimately, the goal of this work is to develop a programme for predicting and rehabilitating strokes in both adults and children.