Diagnosis and Management of Arteriovenous Malformations in Children

Arteriovenous malformation (AVM) is the most common cause of spontaneous intraparenchymal hemorrhage in children, excluding hemorrhages of prematurity and early infancy. Because most children diagnosed with an AVM undergo initial treatment emergently, the natural history of AVMs in the pediatric population is not well understood. Most pediatric AVMs do not come to clinical attention unless they hemorrhage. Therefore, their optimal management remains controversial. Children with intracranial AVMs represent a special challenge in that they harbor unacceptable lifelong risks of hemorrhage and potential neurologic deficits. Patients should be evaluated on a case-by-case basis to determine the best multidisciplinary treatment regimen that can be used to preserve neurologic function and eradicate the AVM with the lowest risk of mortality. Successful treatment depends on the location and size of the AVM, its hemodynamic properties, the clinical condition of the patient, and the treatment modality selected. The armamentarium for AVM management has grown with technological advances and now includes microsurgical resection, endovascular embolization, radiosurgery, or any combination of these modalities. Microsurgical resection remains the gold standard for treatment of accessible pediatric AVMs, especially in cases that present with intracranial hemorrhage. Newer modalities, such as embolization and radiosurgery, have provided additional tools to help children with large or deep-seated lesions that would be deemed unresectable with microsurgical techniques alone. Long-term follow-up with repeated diagnostic imaging is important despite complete obliteration of the lesion to rule out the small possibility of AVM recurrence.

Cerebral arteriovenous malformations (AVMs) are congenital lesions thought to arise because of failure of embryogenesis during the differentiation of vascular channels into mature arteries, capillaries, and veins, which results in direct arteriovenous shunts without intervening capillary beds. Three major types of AVMs have been identified: (1) the more common high-flow variant with a compact nidus and few arterial feeders and draining veins; (2) the rarer diffuse variant with low-flow and multiple en-passage arterial feeders and draining veins ; and (3) the recently described linear, vein-based configuration with multiple arterial feeders draining into a single, usually superficial, vein. Cerebral AVMs most often become symptomatic in the second to fourth decades of life, presenting with hemorrhage, seizures, or progressive neurologic deficits. Despite the congenital nature of the disease, cerebral AVMs are less commonly discovered in children than in adults, with children composing only 3% to 19% of AVM patients.

Intracranial hemorrhage is the most frequent clinical presentation of AVMs in children and adults, and 80% to 85% of pediatric patients suffer a hemorrhagic event as the initial presenting symptom compared with their adult counterparts who present with hemorrhage in 50% to 65% of cases. Hemorrhagic events from an AVM in children have been associated with a 25% mortality rate, whereas the mortality rate from hemorrhage in adults is 6% to 10%. One explanation for this discrepancy is the propensity of posterior fossa ( Fig. 1 ) and deep-seated AVMs (eg, in the basal ganglia) to hemorrhage in children. The annual rate of rebleeding in the pediatric population may be higher than that seen in the adult population (2%–4% in children vs 1%–3% in adults), although not all investigators are in agreement with this assertion. If this risk of hemorrhage or rehemorrhage is stratified (projected) over a 50-year horizon to account for a child’s longer life expectancy, the probability of rehemorrhage is in the order of 65%. The high cumulative risk of hemorrhage during the long potential life span of the pediatric patient with an AVM underscores the importance of treating even asymptomatic AVMs in children. The natural history, pathology, diagnosis, and treatment of cerebral AVMs are discussed in this article.