Purpose: To describe a method for the preoperative embolization of arteriovenous malformations (AVM) containing vessels en passage (VeP). First, before embolization of the primary AVM, the distal portion of the VeP beyond the AVM, which supplies the parenchymal compartment, is blocked through placement of an endovascular ligature (fibered coils). This protects the post lesional parenchymal tissue and isolates malformational compartments before embolization. Thus the proximal AVM-supplying segment of the VeP can be safely embolized.
Patients and methods: Five of 204 AVM patients admitted for preoperative embolization between 1989 and 1997 fulfilled the following treatment criteria for the placement of an endovascular ligature in a VeP before embolization: 1. The diameter of the distal portion of the VeP behind the AVM was large whereas the parenchymal blush was poor; 2. The VeP fed a large portion of the AVM; 3. The VeP was judged to be accessible only late in the surgical procedure; 4. The VeP and its off branches were an integral part of the AVM periphery and thus not suitable for microdissection.
Results: In all five cases the leptomeningeal collateral perfusion (the arterial supply to parenchymal brain areas) served to supply brain areas distal to the AVM after primary blockage of a VeP by endovascular ligature with fibered coils. Embolization and complete surgical dissection of the AVM was then achieved in all cases. No neurological deficits occurred.
Conclusion: Experience with our five cases indicates that a preparatory endovascular ligature of a VeP between parenchyma and the malformational compartment followed by embolization of the AVM can serve as an alternative to open surgical dissection of a vessel en passage and that it safely allows effective preoperative embolization.