Research Fact Sheets: Cause
Chickenpox and Stroke in Childhood, 7/2001
Stroke in childhood (SIC) can cause the disabilities usually identified with the occurrence of cerebral palsy: loss of muscle control and difficulty with speech and swallowing; it also can result in a seizure disorder such as epilepsy. SIC like cerebral palsy results in lifelong disabilities. Unlike stroke in adults, SIC is rarely caused by arterial atherosclerosis (plaque occluding an artery); it generally is caused by other types of injury to the arteries supplying blood to the brain. One potential risk factor for SIC is chickenpox, a common infectious disease of children.
In order to evaluate the relationship of chickenpox to SIC, two clinical research teams in Canada (Toronto and Hamilton) studied a group of young children (ages 6 months to 10 years) who had experienced a stroke due to lack of arterial blood to the brain (arterial ischemic stroke) during the period January 1992 to January 1999.1 The children studied were divided into two groups: those who had a history of chickenpox infection within 12 months of their stroke and those who did not. 31% of the children had a history of chickenpox in the preceding 1-11 months, with the average being 5.2 months. The children who had chickenpox were more likely to have hemiparesis (poor muscle control on one side of the body) and less likely to have seizures than the non-chickenpox group. The specific areas of the brain injured (basal ganglia), the type of arterial injury (large vessel occlusion) and the site of arterial injury were distinctive in the chickenpox-stroke group. The clinical neurological symptoms were essentially the same in both groups of children. The occurrence of subsequent strokes was more common in the chickenpox group (45%) than in the other group (20%), an important personal and public health finding.
As compared to SIC in non-measles related children, there was a 3 fold increase in the occurrence of SIC in children who had chickenpox within 12 months of the stroke; however, chickenpox related SIC is still relatively uncommon occurring in Canada in 1 out of 15,000 children. The reasons for both the occurrence of chickenpox related stroke and for its low occurrence are unknown. The authors suggest the reasons may be related to a child's specific immune system response to infection or to a particular type (strain) of chickenpox virus. Prevention of chickenpox related SIC by use of an available vaccine against chickenpox needs to be considered, but is probably not a priority public health measure (having to vaccinate 15,000 children to prevent one case). However, the authors suggest the use of long-term therapy with aspirin for children who have had a stroke in order to prevent subsequent strokes.
In many instances, cerebral palsy is the result of stroke: stroke in the fetus during pregnancy; stroke at the time of delivery; stroke in the early years of life. By stroke we mean brain damage due to an inadequate blood or oxygen supply to the brain or due to hemorrhage in the brain. These can occur in fetal life, in infancy and in childhood. We label the consequence, cerebral palsy. Cerebral palsy certainly can have other causes such as maternal illness or infant brain infection, but damage to the blood vessels of the developing and young brain is probably a major cause. Our Foundation is trying to influence the nation's stroke research experts, who generally only think about adult stroke, to also give serious attention to stroke in the fetus, infant and child. We need their expertise to prevent stroke related cerebral palsy and to more adequately treat its consequences. Stroke occurs at all ages and because in children we call its consequences cerebral palsy, should not interfere with their giving it the attention it requires.
1Askalan, R. et al. Chickenpox and Stroke in Childhood; A Study of Frequency and Causation. Stroke 2001;32: 1257-1261
, July 2001