Spontaneous thrombosis of an arteriovenous malformation.

Extensive thrombosis of a cerebral arteriovenous malformation, not associated with clinically recognizable hemorrhage, appears to be exceedingly rare. Angiographic and operative verification of such an occurrence is described in a 4-year-old child. Computed axial tomographic and ultrasonographic findings are discussed. It is proposed that thrombosis of the anomaly occurred as a result of intravascular turbulence, promoted by progressive elongation and increasing tortuosity of the lesion.