Clinical implications of associated venous drainage in patients with cavernous malformation.

OBJECT The authors reviewed angiograms obtained in patients with cavernous malformations to identify and characterize coexisting venous drainage. METHODS Fifty-seven patients with cavernous malformations treated at the authors' institutions between 1994 and 2002 were classified into three groups according to the venous system adjacent to the malformation on angiography studies. In Group A patients (23 patients) the malformations had no venous drainage; in Group B patients (14 patients) the lesions were associated with typical venous malformations; and in Group C patients (20 patients) the lesions had atypical venous drainage (AVD). The risk of hemorrhage based on the type of associated venous drainage was analyzed, and the usefulness of magnetic resonance (MR) imaging compared with digital subtraction (DS) angiography in demonstrating associated AVD was determined. Fifty-seven patients harbored 67 cavernous malformations: Group A patients had 29 cavernous malformations with no associated venous drainage; Group B patients had 17 lesions associated with venous malformations; and Group C patients harbored 21 lesions, 20 of which manifested AVD. Symptomatic hemorrhage was present in 10 (43.5%) of 23 Group A patients and in 28 (82.4%) of 34 Groups B and C patients. Although high-resolution MR imaging revealed the presence of associated venous malformations in 11 (78.6%) of 14 Group B patients, such studies demonstrated AVD in only two (10%) of 20 Group C patients. CONCLUSIONS Patients harboring cavernous malformations plus venous malformations or AVD are more likely to present with symptomatic hemorrhage than are patients with cavernous malformation alone. The actual incidence of associated venous drainage may be underestimated when MR imaging alone is used rather than combined with DS angiography.