An intracranial hemorrhage, or brain bleed, is bleeding that occurs within the brain tissue or the spaces surrounding it inside the skull. This is a serious medical emergency because the rigid skull prevents expansion, meaning accumulating blood quickly increases pressure on delicate brain tissue. This increased pressure can damage brain cells, interrupt blood flow, and lead to permanent neurological impairment or death. Understanding the causes of bleeding in the pediatric brain is essential for recognizing the severity and necessity of immediate medical intervention.
Causes Related to Physical Trauma
External mechanical forces are a frequent cause of brain bleeds in children, particularly in older, active populations. These traumatic injuries account for a large percentage of cases and are categorized by the force applied to the head. High-impact accidental injuries, such as severe motor vehicle collisions, falls from heights, or forceful sports impacts, generate immense kinetic energy.
Accidental Trauma
High-impact injuries often result in an epidural hematoma (EDH), where bleeding occurs between the skull and the dura mater. EDH typically results from a skull fracture tearing an underlying artery, such as the middle meningeal artery, leading to rapid blood accumulation. Severe accidental trauma can also cause a subdural hematoma (SDH), which is bleeding between the dura mater and the arachnoid membrane. SDH is often caused by the shearing of small veins as the brain moves inside the skull.
Abusive Head Trauma (AHT)
Non-accidental trauma (NAT), or abusive head trauma (AHT), involves violent acceleration-deceleration or rotational forces, such as forceful shaking. AHT creates powerful shear forces that tear the bridging veins connecting the brain’s surface to the dura. This mechanism results in a subdural hematoma, the most common intracranial finding in infants with AHT. The rotational force also causes diffuse axonal injury, damaging nerve fibers throughout the brain. The presence of bilateral or interhemispheric subdural hematomas, especially without a history of severe accidental trauma, raises suspicion for AHT.
Congenital and Acquired Vascular Abnormalities
Structural defects in the brain’s blood vessels can rupture spontaneously, causing a sudden brain bleed. These abnormalities are often congenital but may not cause symptoms until childhood or adolescence. Arteriovenous malformations (AVMs) are a recognized cause of spontaneous intracranial hemorrhage in children. An AVM is an abnormal tangle where arteries connect directly to veins, bypassing the capillary network. This subjects the thin-walled veins to high arterial pressure, weakening the vessel walls and making them prone to rupture and hemorrhagic stroke.
Cerebral aneurysms are another form of vascular weakness, appearing as a balloon-like bulge on a blood vessel wall. Though rare in children, they pose a serious risk for subarachnoid hemorrhage if they burst. Pediatric aneurysms can be congenital or acquired due to trauma, infections that weaken the artery wall, or underlying genetic disorders affecting connective tissue. Cavernous malformations (cavernomas) are clusters of small, thin-walled capillaries that lack normal structural support. These vessels are fragile and susceptible to leakage. While bleeding from a cavernoma is often slow, a significant hemorrhage can occur, causing neurological symptoms or a stroke.
Hematological and Systemic Disorders
Medical conditions that affect the blood’s ability to clot or compromise vessel wall integrity can cause spontaneous brain bleeds. Inherited clotting disorders, such as hemophilia, involve a lack of specific clotting factors necessary to stop bleeding. Children with severe hemophilia A (Factor VIII deficiency) or hemophilia B (Factor IX deficiency) are at significant risk for spontaneous intracranial hemorrhage, even following minor trauma.
Acquired clotting deficiencies include Vitamin K Deficiency Bleeding (VKDB) in infants. Vitamin K is necessary for the liver to produce key coagulation factors (II, VII, IX, and X). Newborns have low Vitamin K stores. Failure to receive the standard prophylactic injection at birth puts them at risk for late-onset VKDB, which often presents as a brain bleed between two weeks and six months of age.
Systemic infections and cancers also disrupt the balance required to prevent hemorrhage. Severe bacterial infections like sepsis or meningitis cause inflammation that damages blood vessel linings. This inflammation can trigger Disseminated Intravascular Coagulation (DIC), consuming clotting factors and platelets, leading to widespread bleeding, including in the brain. Blood cancers, such as leukemia, can crowd out the production of healthy blood components in the bone marrow. This results in thrombocytopenia (low platelet count), impairing the body’s ability to form clots and increasing the risk for spontaneous bleeding into the brain tissue.
Causes Specific to Newborns and Infants
Newborns and infants have unique vulnerabilities stemming from prematurity and delivery stress. Intraventricular hemorrhage (IVH) is the most common brain bleed in premature infants, especially those born before 32 weeks. IVH originates in the germinal matrix, a highly vascular structure near the brain’s ventricles. The vessels in the germinal matrix are fragile, lacking mature support cells. This fragility, combined with the premature infant’s inability to regulate cerebral blood flow, makes the vessels susceptible to rupture from sudden blood pressure changes. The hemorrhage starts in this matrix and often extends into the ventricles.
In full-term infants, brain bleeds are often associated with birth trauma or oxygen deprivation during complicated deliveries. Excessive mechanical force from difficult labor or the use of delivery instruments (forceps or vacuum extractors) can tear the dural membranes. These tears may rupture underlying veins, causing a subdural hemorrhage. Furthermore, a lack of oxygen and blood flow (hypoxic-ischemic encephalopathy, or HIE) compromises the structural integrity of blood vessel walls. This breakdown makes vessels leaky and prone to rupture, leading to various types of intracranial hemorrhage in the newborn.