ABSTRACT NUMBER: ESOC2026A788 ASYMPTOMATIC CEREBRAL VENOUS SINUS THROMBOSIS IN A WOMAN RECEIVING HORMONE REPLACEMENT THERAPY: AN INCIDENTAL DIAGNOSIS

Abstract Background and aims Cerebral venous sinus thrombosis (CVST) is a rare cerebrovascular disorder. Asymptomatic CVST is exceptionally rare and can easily go undetected, delaying treatment and increasing complication risk. Hormone replacement therapy (HRT) is a recognized prothrombotic factor, but reports of incidentally diagnosed, asymptomatic CVST in HRT users are scarce. Methods A 59-year-old woman on HRT (Femoston) since age 55 presented with mild, nonspecific occipital and cervical headaches. Initial brain MRI suggested possible venous sinus involvement, prompting repeat MRI venography, which confirmed thrombosis of the right transverse sinus, right sigmoid sinus, and proximal right internal jugular vein. Neurological examination was unremarkable. Laboratory studies excluded inherited or acquired thrombophilia, infection, inflammatory disease, and malignancy. HRT was identified as the principal reversible risk factor. Results HRT was discontinued and anticoagulation therapy initiated per current guidelines. The patient remained clinically asymptomatic during follow-up. Imaging demonstrated partial to complete recanalization of affected venous structures, without hemorrhagic complication. Conclusions This case emphasizes that CVST may remain silent even with extensive venous involvement. Clinicians should maintain a low threshold for neuroimaging in patients with hormon-related risk factors. Reporting such cases highlights the clinical importance of recognizing asymptomatic CVST, guiding timely anticoagulation and informed decisions regarding continuation of hormone therapy. Conflict of interest Ieva Ozolina: nothing to disclose