Title : Direct and indirect radiological signs of isolated cortical vein thrombosis: a case report
Abstract:
Introduction: Isolated cortical vein thrombosis (ICVT) without major cerebral venous or sinus thrombosis is a rare clinical entity, accounting for less than 1% of all cerebral infarctions1 . ICVT is challenging to diagnose on unenhanced imaging. Direct signs such as the cord sign are less common than indirect findings such as parenchymal oedema and haemorrhagic lesions2,3. We present a case of a young man with polycythaemia and recurrent seizures, diagnosed with ICVT based on direct and indirect signs on plain computed tomography (CT) of the brain and later confirmed with CT venography and magnetic resonance imaging (MRI).
Case: A 35-year-old man was brought to the emergency department (ED) by ambulance following two witnessed seizures, one hour apart. Semiology was described as leti gaze deviation with jerking of all four limbs. Each episode lasted several minutes before aborting spontaneously. On arrival to the ED, a third seizure was witnessed with leti gaze deviation, rigidity of the limbs and rotatory movements of the leti upper limb. This was aborted with intravenous lorazepam. A plain computed tomography (CT) scan of the brain raised suspicion of cortical vein thrombosis with evolving venous infarction based on direct and indirect signs. Indirect signs were loss of grey-white differentiation, parenchymal oedema and punctate haemorrhagic foci in the right superior parietal lobule (Fig. 1a), along with a direct sign of an overlying asymmetrically hyperdense cortical vein (cord sign) (Fig. 1b). Confirmatory CT venography (CTV) showed poor opacification of a cortical vein overlying the right superior parietal lobule, corresponding with the hyperdense appearance on plain CT (Fig. 2). The 3D integral demonstrated asymmetrical venous opacification over the right superior parietal region (Fig. 3). No filling defect was seen in the major cerebral sinuses. Anticoagulation with low molecular weight heparin was commenced, but later stopped in view of thrombocytopenia. Magnetic resonance imaging (MRI) of the brain subsequently showed haemorrhage within the right parietal venous infarct alongside a thrombosed right parasagital cortical vein (Fig. 4). Thrombophilia work-up was negative, but persistent polycythaemia was noted with haemoglobin level ranging from 18-19g/dL. JAK2 mutation screen was negative. The patient subsequently declined further haematological evaluation and was discharged well.
Discussion: ICVT is a rare but important diagnosis with non-specific presenting features. In such patients, awareness of the direct and indirect signs of ICVT on plain CT is crucial for clinicians to maintain a high index of suspicion in order to proceed with appropriate diagnostic modalities (CTV/MRI) and to avoid treatment delay.
