Summary

We present a case of cerebral venous sinus thrombosis (CVST) as a rare complication of herpes simplex virus (HSV) encephalitis. A young man with no pertinent medical history was diagnosed with HSV encephalitis. After initial treatment, he showed improvement in symptomatology until day 6 when he acutely developed new neurological deficits. An urgent MRI brain showed changes in left temporal lobe consistent with HSV encephalitis and lack of flow void in superior sagittal sinus. Subsequent magnetic resonance venography confirmed the diagnosis of superior sagittal sinus thrombosis along with thrombosis of bilateral frontoparietal cortical draining veins. Anticoagulation was immediately initiated and oral anticoagulation was continued for 1 year. He made complete recovery subsequently. Our case serves as a reminder for the treating clinicians to consider CVST in patients with HSV encephalitis who develop an unexpected new neurological deficits during early phase of appropriate treatment.