BRAIN DAMAGE AT THE EARLIEST AGE

The area of damage (in the brain) depends on the gestational age of the child, and is explained by changes in the blood flow to the central nervous system during maturation. In premature babies born before the 35th week of gestation the damage is located in the deeper parts of the brain (in the periventricular area) while in newborns born after the 35th week of gestation the damage is usually located in the cerebral cortex or under it. The most common causes of brain damage in newborns are intracranial haemorrhaging and hypoxic-ischaemic injuries (injuries that occur as a result of insufficient oxygen supply). Neurological development depends on the point in time when the injuries were incurred, the area in the brain that was damaged and the extent of the injuries.

INTRACRANIAL HAEMORRHAGE

Intracranial haemorrhage (bleeding in the tissue under the skull) is common in newborns. The frequency and type of haemorrhaging depends on gestational age – the lower the gestational age, the higher the frequency of haemorrhaging. The frequency of intracranial haemorrhaging in newborns is from 2 to 30 per cent or more according to some sources.

Intracranial haemorrhage is divided into extracerebral and intracerebral haemorrhage.

Extracerebral haemorrhage is bleeding that occurs outside of the brain tissue but within the skull and depending on the meningeal layer affected can be classified as epidural, subdural or subarachnoid.

Epidural haemorrhage is usually linked to a skull fracture. It is accompanied by progressive worsening of neurological symptoms and unfortunately the outcome is usually fatal.

Subdural haemorrhage is rare today and it is primarily caused by trauma during delivery, especially in conditions that require a surgical delivery (for example, a narrow pelvis in first-time mothers, an older mother who has given birth several times, cephalopelvic disproportion, i.e. disproportion between the head of the baby and the mother’s pelvis, breech presentation, shoulder presentation). This type of haemorrhage usually occurs in full-term newborns. Depending on the localisation and intensity of haemorrhaging, symptoms can be minimal or absent, or the outcome can even be fatal.

Subarachnoid haemorrhage of all types of haemorrhage is the one with the best prognosis. It occurs more often in premature babies. The cause is usually hypoxia (lack of oxygen), or, more rarely, trauma. It presents with various symptoms which can be very mild, or which can follow a progressive course leading to death.

We distinguish between periventricular haemorrhage and intraventricular haemorrhage, depending on the relation to the cerebral ventricles (chambers). Although intracerebral haemorrhage is considered to occur primarily in premature babies, it is being recognised more and more often in full-term newborns. It is usually caused by hypoxia or trauma. The ideal method for diagnosing peri- and intraventricular haemorrhage is ultrasound, by which changes (to the brain) can be detected with 95% accuracy compared to CT scans, and the results correlate well with MR scans of the child’s brain.

The extent of haemorrhage is graded according to the Papille scale. There are four grades of haemorrhage. Grade I haemorrhage is localised on the so-called germinal matrix, the most common place where haemorrhage occurs. In grade II haemorrhage, blood penetrates into the lateral ventricles, but without ventricular enlargement. First and second grade haemorrhages are also called uncomplicated haemorrhages.

Grade III haemorrhage develops if blood extends into the lateral ventricles to a substantial extent causing ventricular enlargement. Grade IV haemorrhage develops when blood penetrates from the cerebral cortex into the cerebral tissue. Third and fourth grade haemorrhages are so-called complicated haemorrhages. They manifest themselves through considerable structural changes in the cerebral tissue and disorders in the neurological development of children.

The main factor that influences the prognosis is the extent of haemorrhage and the development of complications. Minor haemorrhage causes a milder clinical picture, while major haemorrhage a more sever clinical picture. It is necessary to monitor children with cranial haemorrhage during their development in order to assess the extent to which their neurological development, and later mental (cognitive) development, deviates from normal development.

First and second grade haemorrhages cause motor or cognitive effects less often (than higher grade haemorrhages) , although according to some authors up to 30% of children with these grades of haemorrhage show some kind of developmental disorder. Up to 20% of newborns with third grade haemorrhage suffer a fatal outcome, and in the others a high number develop cerebral palsy or some other form of neuromotor deviation. In children with fourth grade haemorrhage the mortality rate is high (81%) or, if the child survives, there is severe neurological damage in the form of considerable motor damage, often accompanied by cognitive damage.

HYPOXIC-ISCHAEMIC ENCEPHALOPATHY

Hypoxic-ischaemic encephalopathy is a non-progressive encephalopathy that arises as a result of a lack of oxygen in the blood (hypoxia) and/or a deficiency in the supply of blood or oxygen to the brain (ischaemia). The exact frequency of hypoxic-ishaemic encephalopathy in infants is not known, however, it is higher in premature infants. Hypoxic-ishaemic encephalopathy in newborns often results in permanent brain damage, cerebral palsy, mental retardation and epilepsy. The frequent association of hypoxic-ishaemic brain injury and intracranial haemorrhage links the cause of both types of injury; it is most likely a case of two episodes during the same, primary illness/disorder of the newborn.

Hypoxic-ischaemic encephalopathy can be divided into three grades.

Of the different types of hypoxic-ischaemic injuries to the brain, we will mention only focal and multifocal injuries and periventricular leukomalacia.

The most common causes of focal and multifocal brain injuries are thromboembolic events linked to placental infarction, infection, injury, thrombosis creation, clotting disorders, and so on. In 50% of newborns with focal ischaemic injuries the middle cerebral artery (arteria cerebri media) is affected – the left more often than the right. Venous thromboses are less common. Focal and multifocal injuries can arise in different phases of the development of the brain and they lead to the death of cells with a loss of cerebral tissue and cavity formation. Focal epileptic seizures and hemiparetic cerebral palsy dominate the clinical picture; spastic tetraparetic cerebral palsy results if there is generalised injury.

Periventricular leukomalacia is a hypoxic-ischaemic injury that usually emerges in premature babies with low gestational age, precisely because of the degree of development of the brains of these infants. The death of cells results in the formation of cavities located near the cerebral ventricles (chambers), and this is usually accompanied by dilation of the ventricles (ventriculomegaly). The fibre pathways of the brain responsible for motor control pass through the part of the brain in which periventricular leukomalacia usually occurs. The clinical picture of periventricular leukomalacia in later life is usually spastic diparesis, with vision impairment, loss of hearing and cognitive disorders.