DSA confirms the presence of a 14 mm vascular tumour receiving arterial supply from a single hypertrophied muscular branch of the left V3/V4 junction arising at the level of the dural entry. This follows a tortuous course and is directed caudally. There is no definite arteriovenous shunt. A single draining vein, directed cranially, is also tortuous travelling around the left dorsal CSF space to drain into the left IPS. The left PICA is remote to the lesion throughout its length.