Herpes Simplex Encephalitis with Rare Complication of Cerebral Venous Sinus Thrombosis (P4.402)

OBJECTIVE: We present a case of Cerebral Venous Sinus Thrombosis (CVST) as a rare complication of Herpes Simplex Virus (HSV) encephalitis. BACKGROUND: There are very limited articles in literature reporting this rare complication of cerebral venous sinus thrombosis with HSV encephalitis. HSV infection occasionally promotes a thrombogenic environment by altering the endothelial cell surface properties, inhibiting natural anticoagulation and activating pro-coagulation. DESIGN/METHODS: We describe a case of a young gentleman with no pertinent past medical history who presented with symptoms of fever, headache, photophobia and one episode of seizure. Examination including fundoscopy was unremarkable except for fever, mild neck rigidity and drowsiness. RESULTS: Initial computed tomography (CT) brain and serum chemistry showed no abnormality with normal white cell count. Cerebrospinal fluid (CSF) analysis showed lymphocyte predominant pleocytosis and CSF polymerase chain reaction (PCR) was positive for HSV. He was treated with acyclovir and showed improvement in symptomatology until day 6 when he acutely developed bilateral upper limb weakness, in-coordination of movements and worsening headache. An urgent magnetic resonance imaging (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 fronto-parietal cortical draining veins. Thrombophilia work up was non revealing. Anti-coagulation was immediately initiated and oral anti-coagulation was continued for one year. He made complete recovery subsequently. CONCLUSIONS: Deterioration after initial improvement in a patient with HSV encephalitis despite appropriate antiviral therapy is unusual. Our case serves as a reminder for the treating clinicians to consider CVST if patients with HSV encephalitis who develops an unexpected new neurological deficits during early phase of appropriate treatment. Early diagnosis and initiation of anticoagulation are important to ensure better neurological outcome. Disclosure: Dr. Lal has nothing to disclose. Dr. Dhamne has nothing to disclose. Dr. Hui has nothing to disclose. Dr. Ahmad has nothing to disclose.