Clinical History
A 41 year old male patient with known acute lymphoblastic leukaemia (ALL) had a seizure and new right hemiparesis. Initial CT showed bilateral frontal parietal haematomas. CT Venography confirms diagnosis of superior sagittal sinus thrombosis and bilateral venous infarction.
Imaging Findings
A 41 year old male with known ALL presented with severe headache and reduced consciousness. This was followed by a generalised seizure and he developed a new right hemiparesis after his seizure. Initial blood count, biochemical and clotting profiles were normal. Initial CT imaging showed bilateral frontal parietal intra-parenchymal haemorrhage with surrounding oedema and mass effect. The haemorrhage was confined to the near the top of the inner skull vault. The superior sagittal sinus was abnormal with a dense triangle anteriorly and posteriorly. Intravenous contrast was given and subsequent CT venogram was performed. This confirmed the presence of a thrombus with an empty delta sign posteriorly and a 'string' of thrombus in the sinus. The patient had areas of venous infarction either side of the sinus as the haemorrhagic areas did not fall into any specific arterial territory.
The cause of the thrombus was later shown to be due to a hyperviscosity state due to the ALL. The patient was later anticoagulated with haematological advice.
Discussion
Thrombosis of venous sinuses (VST) is less common when compared to arterial thrombosis, but still has severe morbidity. Both cerebral haemorrhage and infarction can result due to venous sinus thrombosis. Infarction is due to venous congestion and subsequent obstruction. The distribution of haemorrhage usually cannot be shown to be in a specific arterial territory.
Presenting symptoms can vary greatly depending on anatomical location of the thrombus. Another diagnosis may be initially suspected; severe headache occurs in both subarachnoid bleeds and VST. Focal neurological deficits and cranial nerve palsies are seen with areas of ischaemia/infarction due to arterial disease. Seizures can be due to tumours, VST and metabollic factors [1].
One study showed the presenting symptoms of patients with a diagnosed VST. These signs at presentation included headache (96%), focal neurological deficits (60%), seizures (40%) and papilloedema (43%) [3].
Causes include infection, trauma, pregnancy, blood dyscrasias, malignancy and collagen vascular diseases. Common medications, steroids and oral contraceptives are known to cause VST.
CT is the initial imaging technique to exclude an arterial territorial infarct. Subdural empyemas and intra-cerebral neoplasms can also be excluded. Sinuses can be assessed. The empty delta sign on contrast imaging appears as enhancement in veins adjacent to the superior sagittal sinus with non-enhanced thrombus in the centre of the sinus. There is a 'string' of thrombus, which is similar to the empty delta sign only a longitudinal view of the sinus is visible rather than a slice. The dense triangle sign from new thrombosis and the cord sign due to cortical vein thrombosis are rare [1].
CT venography (CTV) shows the cortical vein thrombosis better than MR venography. CTV is as good as MR Venography (MRV) and is an alternative diagnostic tool to MRV.
Treatment involves using anticoagulation in some patients, however the risk of worsening intra-cranial haemorrhage to taken into account in the eventual clinical decision. There is currently weak evidence for the effectiveness of anticoagulation. It is however a frequently used mode of treatment despite haemorrhage being present [2,3].
Differential Diagnosis List
Superior Sagittal Sinus Thrombosis on CT Venography.
Final Diagnosis
Superior Sagittal Sinus Thrombosis on CT Venography.
