Cerebral venous thrombosis: new causes for an old syndrome? The range of disorders affecting the cerebral veins and sinuses is increasing and now includes blood disorders, abnormalities in the patterns of blood flow, and infiltrative or inflammatory conditions, all of which may promote thrombosis. We describe 10 patients with cerebral venous thrombosis: two had protein S deficiency, one had protein C deficiency, one was in early pregnancy, and there was a single case of each of the following: dural arteriovenous malformation, intracerebral arteriovenous malformation, bilateral glomus tumours, systemic lupus erythematosus, Wegener's granulomatosis, non-Hodgkin's lymphoma. The recognition of such diverse aetiology may be importance since clinical features are non-specific, and may consist only of raised intracranial pressure, allowing confusion with 'benign intracranial hypertension'. The existence of effective treatment both for the thrombosis and for many of the underlying disorders makes early diagnosis essential. The prognosis of treated patients may be favourable. 