Localized convexity subarachnoid haemorrhage – a sign of early cerebral venous sinus thrombosis

Abstract

The diagnosis of cerebral venous sinus thrombosis (CVST) requires a high index of suspicion owing to the wide spectrum of clinical manifestations. Amongst the different presentations, radiological evidence of subarachnoid haemorrhage (SAH) often leads to diagnostic errors. Between March 2005 and December 2007, 233 patients with CVST were reviewed at our centre, and this report summarizes 10 cases that presented with SAH. The early clinico-radiological pointers towards a diagnosis of CVST are highlighted and previously published reports are reviewed. The mean age at presentation was 33 years (range 25-50), and the median duration from onset of symptoms to admission was 5 days (range 2-15). In all cases, there was radiological evidence of SAH with or without associated parenchymal bleeding or other signs of CVST. SAH was usually localized, involving the sulci of the cerebral convexity and sparing the basal cisterns. Aetiologically, there were two cases with both hyperhomocysteinaemia and polycythaemia and one case each of antiphospholipid antibody (APLA) syndrome, post-partum state, oral contraceptive use and dehydration because of diarrhoea. Eight patients improved with anticoagulant therapy despite the presence of SAH. Localized SAH (whether focal, unilateral or bilateral), especially when confined to the parasagittal or dorsolateral convexity of the brain and without involvement of the basal cisterns, may provide an early pointer towards an underlying CVST. The presence of predisposing factors for CVST accords a further diagnostic hint.