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Stroke is brain damage that occurs secondary to the blockage or breakage of blood vessels in the brain. The causes of stroke in children are many and often not well understood. Diagnosis requires careful clinical examination combined with brain imaging. Early treatment focuses on protecting the brain and keeping blood vessels open to prevent more strokes. Most children experience neurologic deficits with long-term treatments focused on physical, developmental, and psychosocial complications. The study of pediatric stroke has been growing rapidly, from understanding the main causes to supporting children and families.
Strokes in children are of three primary types. Two are ischemic strokes in which blockage of blood vessels results in lack of blood flow and damage. When an artery is blocked, the term arterial ischemic stroke (AIS) is used. When a vein is blocked, the term used is cerebral sinovenous thrombosis (CSVT). In the third form, hemorrhagic stroke (HS), the blood vessel breaks instead of being blocked. Each of the three childhood stroke types are described further below.
Arteries are the blood vessels that carry blood from the heart to the brain. Two major pairs of arteries carry blood in the neck:
After reaching the middle of the brain, these arteries connect with each other in a circle (Circle of Willis). From here, most of the major brain arteries arise and spread out like branches of a tree to supply the brain. The largest and most common site for childhood stroke is the middle cerebral artery. AIS involves the blockage of one or more of these arteries, usually by a blood clot. Within minutes of blockage, the brain tissue supplied by the artery becomes damaged due to lack of oxygen and sugar. AIS is the most common type of childhood stroke. Cerebral Sinovenous Thrombosis (CSVT)
Veins carry blood from the body back to the heart. In the brain, veins first drain into larger passages called the venous sinuses. Superficial and deep venous systems merge to drain blood from the brain. In CSVT, abnormal blood clots form in the veins or sinuses to block this drainage. Impaired drainage of blood from a brain region decreases the supply of blood to that area, resulting in ischemic stroke. Due to the "back pressure" that occurs in such strokes, they often bleed. CSVT is less common than AIS in children, accounting for about 1 in 4 ischemic strokes. Hemorrhagic Stroke (HS)
Bleeding in the brain and skull is described by location within certain compartments or spaces. In children, the most common is intracerebral hemorrhage where blood spills directly into brain tissue. Other hemorrhages can occur in spaces beside the brain such as the ventricles (intraventricular hemorrhage) or the fluid-filled space the brain rests in (subarachnoid hemorrhage). Bleeding further outside the brain such as subdural or epidural hemorrhage is usually due to trauma. Hemorrhagic strokes occur with similar frequency to AIS in children.
Many of the clinical signs and symptoms, diagnostic tests, treatments, and outcomes are similar across these three diseases. Each are therefore summarized collectively in the sections below. However, important differences also exist and are described.
Several conditions similar to stroke are not discussed here. The period before and around birth carries a particularly high risk for stroke. Such perinatal stroke differs in many regards from stroke in older infants and children; and is therefore not reviewed here. When such injuries around birth result in physical motor disabilities, the term cerebral palsy is appropriate. In contrast, motor disabilities acquired later in childhood stroke would not use this term even though the problems can appear very similar. A lack of blood supply to the entire brain, rather than due to the blockage of a single blood vessel as in stroke, also occurs regularly in children but is not considered "stroke". Examples include global hypoxic-ischemic encephalopathy (HIE) or watershed infarction.
Most strokes in children present with the SUDDEN ONSET of neurologic problems. The sudden onset of neurologic symptoms should be considered stroke until proven otherwise, regardless of age. These are often focal neurological deficits - affecting one specific function. Common examples include:
Less specific neurologic symptoms can also be the first manifestation of stroke, particularly in young children. Examples include:
Signs and symptoms can also occur briefly and resolve. This happening is called a transient ischemic attack (TIA). Such symptoms should be taken seriously as they may be a warning sign of a possible larger stroke.
Failure to recognize the signs and symptoms of stroke in children often contributes to delays in diagnosis.
The diagnosis of stroke in children requires recognition of presenting signs and symptoms leading to a careful clinical history and examination combined with appropriate brain imaging studies. Two main forms of imaging are used to assess the brain and brain blood vessels:
CT (computer assisted tomography or "CAT") scans are often the initial test. CT imaging of the brain is widely available. Studies can be done within minutes, avoiding the need for sedation or anesthesia. They can demonstrate ischemic strokes, but may miss them if done very early or if strokes are small. CT scans are good at detecting hemorrhagic strokes. Addition of intravenous contrast can also accurately assess brain blood vessels. Pictures of the arteries called CT angiograms (CTA) can detect blockages and specific causes. Pictures of the veins and sinuses called CT venograms (CTV) are good at detecting cerebral sinovenous thrombosis. CT scans include a low risk dose of radiation.
MRI is required in most children with stroke. For acute diagnosis, MRI is the most sensitive test. Diffusion weighted images (DWI) can detect very small and very early ischemic strokes. Other MRI pictures are very sensitive to blood and hemorrhage.
MRI can image the arteries; the result is called an MR angiogram (MRA). When MRI is used to image the veins it is called an MRV; both types help diagnose AIS and CSVT. There is no radiation associated with MRI but longer scan times require sedation for preschool children.
A) CT head shows arterial strokes as dark areas within an arterial territory. (B) Diffusion MRI shows arterial strokes very clearly and early, (C) MR angiograms (MRA) can image the major cerebral arteries and show problems like an occluded branch (arrow). (D) CT venograms (CTV) show filling defects in the venous sinuses (arrows) to diagnose CSVT. (E) CT head is very good at demonstrating hemorrhagic strokes and the immediate life-threatening complications of increased pressure.
Conventional angiography (CA) is another diagnostic imaging test required in some children. CA involves insertion of a small tube (catheter) into an artery in the groin which is passed upwards toward the major brain blood vessels. A dye is injected to then create detailed pictures of the brain arteries. CA is only required in certain circumstances, usually to help determine specific causes for arterial ischemic or hemorrhagic strokes.
The causes of strokes in children are not well understood. However, it is unlikely that a child, parent, or anyone could have done something to directly cause a child's stroke. Genetic problems are responsible for a relative minority of known causes.
A risk factor implies an association with stroke, but not necessarily the cause. Many children possess multiple risk factors which may have to combine in order for stroke to occur. A significant number of children will have no risk factors identified despite extensive investigation and are termed idiopathic.
Most possible causes are distinct to each type of childhood stroke (AIS, CSVT, HS) so they are listed separately below.
