Isolated Cortical Venous Thrombosis as a Mimic for Cortical Subarachnoid Hemorrhage.

Isolated cortical venous thrombosis is very rare and poorly understood. The clinical presentation is also not well described in the literature. We report here a case of isolated cortical venous thrombosis that mimicked cortical subarachnoid hemorrhage (SAH). A 62-year-old man with a history of chronic subdural hemorrhage visited our hospital with headache. Brain computed tomography (CT) revealed a linear hyperdense area in the right central sulcus (cord sign), suggestive of isolated cortical SAH. Magnetic resonance imaging (MRI) revealed susceptibility in the corresponding area. CT angiography revealed no specific finding. However, transfemoral cerebral angiography (TFCA) identified filling defects in the right cortical veins. Under isolated cortical venous thrombosis, anticoagulation therapy was used to prevent the propagation of thrombosis. The patient had no recurrence of symptoms. If a cord sign is present on noncontrast CT images, further studies (MRI/magnetic resonance venography or TFCA) should be performed in a step-wise manner. Such considerations could prevent a fatal outcome and poor prognosis.