The condition is also relatively common in the retina, and can cause partial or total loss of vision.
[1][2] Some medical procedures, such as embolisation, involve occluding a blood vessel to treat a particular condition.
This can be to reduce pressure on aneurysms (weakened blood vessels) or to restrict a haemorrhage.
It can also be used to reduce blood supply to tumours or growths in the body, and therefore restrict their development.
Occlusion can be carried out using a ligature; by implanting small coils which stimulate the formation of clots; or, particularly in the case of cerebral aneurysms, by clipping.