Tumours have a variable blood supply which can make surgery more difficult because of excessive bleeding. It is possible in many cases to reduce the amount of bleeding during the operation by occluding the blood vessels supplying the tumour. This is achieved by passing a catheter (tube) into the blood vessels supplying the tumour and injecting an "embolysate" - a substance to obstruct blood flow, which may be in the form of small particles that visually resemble grains of sand (polyvinyl alcohol), or a liquid embolic which sets in the blood vessel (n-butyl cyanoacrylate or a non-adhesive liquid embolic). This may be combined with the use of metallic coils or other materials to occlude larger arteries.
For head and neck tumours complications include those described for diagnostic cerebral angiography. There may be an additional risk of complications occurring as a result of the embolysate going into normal arteries supply the brain and nerves resulting in a stroke. Detailed mapping of the vessels to be embolised are taken before any embolysates are injected to minimise this risk. In some cases the Interventional Neuroradiologist may further test the safety of obliterating a particular vessel by performing transvascular neurophysiological testing through injecting medications which are designed to cause temporary neural non-function.
Similar operations may be performed for patients with epistaxis (nose-bleed) and chronic subdural haematoma. In this setting the embolysate is injected into the blood supply leading to the source of bleeding, whether that be the lining of the nasal cavity or the dural membranes. There are again similar risks, and in this setting, specifically that of blindness. However, NIISwa Interventional Neuroradiologists perform all such operations in WA, ensuring that the expertise is centralised.
The procedure usually takes several hours. It may be performed under sedation although in some cases a general anaesthetic is more appropriate.