Coincidental cerebral venous thrombosis and subarachnoid haemorrhage related to ruptured anterior communicating artery aneurysm.

Aneurysmal subarachnoid haemorrhage (SAH) and cerebral venous thrombosis (CVT) are rare cerebrovascular pathologies. Here, we report the extremely rare coincidental presentation of both entities and discuss the likely relationship in aetiology and their optimal management. A female patient presented with headache and progressive neurological deficits. Cranial computed tomography and contrast-enhanced magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA) revealed dural venous sinus thrombosis, left-sided frontal and parietal infarcts, and left middle and anterior cerebral artery stenosis. In addition, left hemispheric subarachnoid haemosiderosis was seen on MRI. Following standard anticoagulation therapy for CVT, she represented with acute SAH. Digital subtraction angiography revealed a ruptured anterior communicating artery aneurysm and left middle cerebral artery/anterior cerebral artery vasospasms that were responsive to intra-arterial nimodipine. The latter were already present on the previous MRI, and had most likely prevented the detection of the aneurysm initially. The aneurysm was successfully coil embolised, and the patient improved clinically. Despite this case being an extremely rare coincidence, a ruptured aneurysm should be excluded in the presence of CVT and non-sulcal SAH. A careful consideration of treatment of both pathologies is required, since anticoagulation may have a potentially negative impact on aneurysmal bleeding.