An intracranial hemorrhage, or brain bleed, occurs when a blood vessel ruptures or leaks within the skull. This causes bleeding directly into the brain tissue or the surrounding spaces. The accumulation of blood creates pressure inside the skull, which disrupts brain function and damages nerve cells. A brain bleed in a child is always a serious medical event requiring immediate attention. Causes fall into categories including external forces, internal defects, and systemic medical illnesses.
Hemorrhage Resulting from External Trauma
External physical force is the most common cause of brain bleeds in children beyond the neonatal period. This type of injury, classified as traumatic brain injury (TBI), results from a sudden, forceful impact or rapid acceleration and deceleration of the brain inside the skull. Injuries range from a contusion (a bruise on the brain tissue) to a hematoma (a collection of blood outside the brain tissue).
Accidental trauma, such as severe falls, motor vehicle accidents, or sporting injuries, causes the brain to strike the interior of the skull. This jarring motion creates a shearing force that tears delicate blood vessels, leading to bleeding. Subdural hematomas, occurring beneath the dura mater, often result from this venous tearing. Direct impact can also cause epidural hematomas, which typically result from arterial injury and can rapidly compress the brain.
Non-accidental trauma, often called abusive head trauma or Shaken Baby Syndrome, is a devastating injury mechanism in infants and young children. Violent, repetitive shaking creates extreme acceleration-deceleration and rotational forces. Because an infant’s head is proportionally larger and neck muscles are weaker, this motion severely stretches and tears the bridging veins, frequently resulting in a subdural hematoma. Abusive head trauma is a leading cause of traumatic death and serious neurological disability in children under two years of age.
Structural and Vascular Abnormalities
In the absence of external trauma, brain bleeds may be caused by inherent defects in the brain’s blood vessel structure that fail under normal pressure. The most common defect is an Arteriovenous Malformation (AVM). An AVM is an abnormal tangle where arteries connect directly to veins without the typical capillary network. This subjects the thinner-walled veins to high arterial pressure, making them susceptible to rupture.
AVMs are congenital, meaning they are present from birth, but they may not rupture until later in childhood or adolescence. Rupture causes a hemorrhagic stroke, which is a sudden bleed into the brain tissue. Another defect is a cavernous malformation, or cavernoma, which is a cluster of abnormally enlarged, thin-walled blood vessels.
Cavernomas can leak blood into the surrounding brain tissue, sometimes repeatedly. While AVMs often cause large, catastrophic hemorrhages, cavernomas tend to cause smaller, more isolated bleeds. These structural anomalies create points of weakness in the cerebrovascular system that can spontaneously fail.
Systemic Medical Conditions Affecting Clotting
Internal medical conditions that compromise the body’s ability to regulate clotting can lead to spontaneous intracranial hemorrhage. These conditions, known as coagulopathies, result in either an inability for blood to clot effectively or an increased tendency for vessels to rupture. Hereditary disorders like hemophilia, which involves a deficiency in specific clotting factors, significantly increase the risk of bleeding, including in the brain.
Von Willebrand disease is another inherited condition that affects clotting and platelet function, raising the risk of spontaneous or trauma-induced hemorrhage. Acquired clotting issues can stem from severe liver failure, as the liver produces most of the body’s clotting factors. A deficiency of Vitamin K, necessary for the synthesis of clotting proteins, can also lead to an acquired coagulopathy and subsequent bleeding risk.
Severe, uncontrolled hypertension (high blood pressure) is a less common cause of brain hemorrhage in children than in adults, but it is a factor in certain contexts. Sustained, extremely high blood pressure stresses vessel walls, leading to rupture, especially in weakened vessels.
Causes Specific to Newborns and Infants
The causes of brain bleeds in the neonatal period are unique, related to the immaturity of the infant’s brain and the stresses of birth. Intraventricular hemorrhage (IVH) is the most frequent type in premature infants, occurring inside or around the brain’s fluid-filled ventricles. The blood vessels in the germinal matrix, a highly vascular area, are exceptionally fragile in babies born very early.
These delicate vessels rupture easily in response to rapid fluctuations in blood flow or blood pressure, often occurring with respiratory distress. IVH is graded from one to four based on the amount of bleeding, with higher grades causing concern for long-term neurological injury. Nearly all cases of IVH happen within the first few days of life.
Mechanical stress during a difficult or prolonged delivery, especially involving vacuum extraction or forceps, can cause bleeding even in full-term infants. This mechanical trauma places excessive force on the head, resulting in various types of hemorrhage. Severe hypoxia (lack of oxygen around the time of birth) can also weaken blood vessel walls, making them more prone to rupture.