Sinovenous thrombosis in children

Epidemiology

The Canadian Pediatric Ischemic Stroke Registry, a population-based national registry, provides the first data on the incidence of sinovenous thrombosis in children [1]. In the Registry, based on 160 pediatric patients with CSVT, the incidence is 0.6 per 100,000 children per year aged term birth to 18 years. Neonates comprise 43% of patients in the Registry, resulting in an incidence for neonatal CSVT of 40.7 per 100,000 live births per year. No prior estimates are available; however, the

Anatomy and physiology

As in adults, the venous drainage of the brain via the “superficial” or “deep” sinovenous systems consist of networks of cerebral sinuses and veins. The location of venous sinuses along suture lines makes them susceptible to mechanical injury during birth in the neonate. The rigid attachment of sinuses and lack of venous valves results in a passive drainage of blood flow in the cerebral venous system [5]. As a result of these anatomic factors, reduction in systemic blood pressure can result in

Pathophysiology of venous infarction

In sinovenous thrombosis, the mechanism for venous infarction is obstruction of venous drainage with increasing venous pressure in the affected region of the brain. The venous congestion results in significant extravasation of fluid into the brain, producing focal cerebral edema and hemorrhage. The edema may be transient, if venous flow is re-established, or be associated with permanent tissue infarction if the increased venous blood pressure eventually exceeds the arterial blood pressure. In

Clinical features

The clinical features of childhood CSVT are subtle, diffuse, and, in very young infants and children, dominated by seizures. Signs of raised intracranial pressure typically develop gradually over hours, days, or even weeks. The clinical presentation is influenced by the age of the child, the extent and location of the thrombus, and the presence or absence of associated venous infarction. In some infants and children, accompanying asphyxia or meningitis may produce neurologic signs that

Risk factors

In childhood CSVT, thrombosis results from a combination of intravascular and vascular factors. Within individual patients, certain underlying risk factors including prothrombotic states may predispose to thrombosis, and other states including acute illnesses or prothrombotic medications act as triggering factors. Dehydration is a major intravascular risk factor at all ages. Vascular malformations including vein of Galen or cerebral arteriovenous malformations can also be associated with CSVT.

Imaging

The diagnosis of sinovenous thrombosis in infants and children is challenging. Findings and radiologic appearances are more variable and nonspecific compared with adults.

A number of radiographic techniques are available to study the cerebral veins and sinuses, and each has advantages and disadvantages (Table 2). But there have been very few systematic studies assessing diagnostic strategies, including magnetic resonance and CT techniques, against a gold standard. The recent advent of

Treatment

Therapy for sinovenous thrombosis includes nonantithrombotic and antithrombotic therapy. In the acute phase of CSVT, nonantithrombotic therapy is aimed at maintaining adequate perfusion of the brain and minimizing the metabolic demands within cerebral tissue in order to minimize the extent of cerebral damage. Approaches include maintenance of blood pressure, correction of hyper- or hypo-glycemia, and prevention of recurrent seizures. In addition, specific primary treatment for all reversible

Outcome

The outcome of CSVT in children is difficult to assess because no standardized outcome measures have been developed, and most studies have had an insufficient duration of follow-up. In addition, given the inconsistent use of anticoagulants and other treatments, it is difficult to adjust for the potential influence of treatment on outcome. A number of factors influence outcome from CSVT, including age at the time of the event, the rapidity of diagnosis, extent of the thrombosis, presence of

Summary

Sinus thrombosis in children is increasingly recognized; however, the diagnosis is still frequently missed. Children may have an increased incidence of this disorder compared with adults, and neonates are at greatly increased risk compared with older children. Childhood CSVT carries significant long-term sequelae that include death or neurologic deficits in nearly 50% of cases. Neonates are not spared from these sequelae. At present, the approach to treatment is empiric but in the past decade

Acknowledgements

The authors are grateful to Dr. Susan Blaser, Staff Neuroradiologist at The Hospital for Sick Children, for her help and expert advice in the preparation of this article.