Abstract
The transmastoid branch of the occipital artery is an important supply to posterior fossa vascular malformations and tumors and is often difficult to catheterize due to tortuosity and a transforaminal course. In very difficult situations, we can try to induce spasm of the occipital artery just beyond the origin of the mastoid branch by repeated passages of the microcatheter/wire. This induces a temporary 'ligation' like effect so that the microcatheter can then be manipulated into the mastoid branch via the mastoid foramen. Rarely, the occipital artery has to be sacrificed if spasm cannot be induced or is short living, following which particles can be injected from a distance without entering the mastoid foramen. Occluding the occipital artery proximally has no effect on distal perfusion, as collaterals and anastomoses from superficial temporal artery, posterior auricular artery, and opposite occipital artery take over the supply.