Superior sagittal sinus thrombosis: subtle signs on neuroimaging.

INTRODUCTION The aim of this study was to review the clinical, computed tomography (CT) and magnetic resonance imaging (MRI) diagnosis and the frequency of positive neuroimaging findings in patients with cerebral venous thrombosis (CVT) involving the superior sagittal sinus. MATERIALS AND METHODS A clinical and radiological database of patients with final diagnosis of CVT was compiled from the inpatient hospital information service of a tertiary neurological hospital over 5 years. CT and MRI studies in 22 patients were retrospectively examined for direct signs of venous sinus thrombosis and for complications of CVT. The diagnosis of CVT before and after CT and MRI was reviewed. RESULTS Clinical diagnosis of possible CVT was suspected in only 1 patient. When the diagnosis was not suspected, CT diagnosis was difficult and there was a high false negative rate of 52.6%. MRI fared better, but the false negative rate was still 11%. Directs signs of venous sinus thrombosis such as the triangle sign, empty delta sign on CT and loss of the normal flow voids on MRI, could be retrospectively detected in 57.9%, 100% and 100% of patients respectively. Although 4 patients presented with subarachnoid haemorrhage, these direct signs were present in 3 patients. CONCLUSION Clinical diagnosis of CVT is rarely suspected before CT and MRI, and although subtle positive signs are often present, these may not be appreciated unless there is a high index of suspicion or image review at multidisciplinary team meetings.