Repeated childhood stroke and venous thrombosis: the risks

Professor Ulrike Nowak-Göttl, Department of Paediatric Haematology and Oncology, University Hospital of Münster, Germany, and colleagues did a study of 396 children who had suffered a first cerebral venous thrombosis (CVT/stroke), and monitored them for an average of 36 months to determine the risk of a second cerebral or systemic venous thrombosis. The study is the largest and longest follow-up study of children with a first onset of stroke.

They found that 12 of the children died immediately, while 22 had recurrent VT, of which 13 were cerebral. Recurrent VT only occurred in children over two-years-old, and children who did not receive anti-coagulant drugs were 11 times for likely to have recurrent VT. Children suffering from venous occlusion (blocking of the veins to any blood flow) were over four times more likely to have recurrent VT, as were children with a genetic mutation already known to increase risk of VT.

The authors say: “Although cerebral venous thrombosis is associated with substantial mortality and morbidity, its causes in children have not been extensively investigated.”

Children older than two years who had a second VT did so at an average age of 13 years – the authors propose that this is because after the high risk first year of life, the next highest risk period of a child’s life relating to VT is puberty, probably due to hormonal changes and the down-regulation of the fibrinolytic system. This finding is backed by previous studies.

However the authors caution that continued use of anticoagulants in children has to be balanced against the risks of them suffering haemorrhages due to being physically active, and each case has to be considered individually. Where the risk of repeated VT is high, the benefit of anticoagulant therapy could clearly outweigh the risk of possible haemorrhage.

The authors conclude by calling for larger randomised studies into repeated VTs. They say: “Until data from such studies are available, the message of this follow-up study is clearly that administration of secondary anticoagulation prophylaxis should be considered on an individual patient basis in children with newly identified CVT in situations where the risk of VT is high.”

In an accompanying Comment, Dr Meredith Golomb, Indiana University School of Medicine, Riley Hospital for Children, Indianapolis, USA, says: “Recurrent venous thromboembolism after cerebral sinovenous thrombosis can be devastating.”

She then asks: “Which patients absolutely need to be on anticoagulation, and which ones can be safely weaned off? How can we tell the parents of an otherwise healthy five-year-old that he can never sled, perform gymnastics, or wrestle with his siblings? What doses of anticoagulation will keep the risk of recurrence and bleeding to a minimum?”

She concludes: “This paper provides some important answers; however, physicians, patients, and the patients’ families have many more questions.”