Central venous thrombosis is uncommon. The superior sagittal and lateral sinuses are most commonly involved. Local factors important in the aetiology are infection, particularly of the bony structures of the head and neck( middle ear, sinuses), head injury, neurosurgical procedures and neoplasia. The most common site for an infective cause is the cavernous sinus. Middle ear and mastoid infections usually result in thrombosis of the lateral sinus and infections of the scalp may involve the superior sagittal sinus (Figure 17). Opportunistic infections may be involved in immunosuppressed individuals.
| Figure 17.|
Venous thrombosis. The picture shows a thrombosed superior sagittal sinus and haemorrhagic infarction of the adjacent grey and white matter in the adjacent brain in Figure 18.
General risk factors include pregnancy, the puerperium, oral contraception, haematological disorders associated with an increased risk of thrombosis (sickle cell disease, polycythaemia, clotting factor abnormalities, platelet disorders), severe dehydration, inflammation, connective tissue disorders, congestive or congenital cardiac disease.
Venous thrombosis results in haemorrhagic necrosis of adjacent cerebral tissue and may evolve to into major haemorrhage (Figure 18).
| Figure 18.|
Thrombosis of the superior sagittal sinus with infarction of the adjacent brain.