Case Presentation: 56-year-old woman presented with fluctuating sensorium for 5 days and left side weakness of one day duration. She has past medical history of hypothyroidism and hyperlipidemia. Her home medications included levothyroxine and atorvastatin. She received two doses of mRNA-1273 vaccine, with first dose being around 12 weeks before presentation and second dose 8 weeks before presentation.In the ED, she was found restless, non-communicative and confused with left upper and lower extremity weakness and was intubated in ED, for airway protection. She underwent CT scan of head which showed scattered hemorrhages and infarcts in both right and left cerebral hemispheres. The preliminary differential diagnoses included cerebral metastasis, vasculitis, and cerebral venous sinus thrombosis. She underwent MRI brain with angiogram (MRA) and venogram (MRV) which confirmed infarcts in watershed areas, along with foci of hemorrhages, and dural sinus thrombosis. She was subsequently referred and underwent thrombectomy with successful restoration of venous blood flow. Her mentation and left sided weakness improved, and she was extubated.

Discussion: TTS is a rare but potentially serious side effect of Covid-19 vaccination. It has affected women less than 60 years of age, occurring after a median duration of 14 days after vaccination; however, cases have been reported up to 48 days after vaccination(1). Vaccine associated CVST (VA-VCST) is considered to be due to development of platelet-activating antibodies against platelet factor-4 (PF-4) which mimics heparin induced thrombocytopenia(2). VA-TTS can cause thrombosis in various vascular beds but cerebral veins and dural sinuses have been found to be the most common sites of involvement, for reasons not known presently(1). Diagnosis relies on imaging with CT or MR angiogram with venogram(3,4). Imaging can show infarcts in unusual locations along with hemorrhages, and ‘empty delta sign’ which signifies signal voiding in sagittal sinus due to thrombus(5). Anticoagulation is the cornerstone of therapy in CVST with continuation of treatment up to 3-6 months at least. Once VA-CVST is suspected, it is important to avoid heparin and use of Argatroban, fondaparinux, Apixaban, and Dabigatran is recommended instead(3).In cases with worsening, endovascular intervention can be considered. Overall prognosis remains grim after VA-CVST; with case-fatality rate of 22% reported after ChAdOx1-S/nCov-19 vaccine administration(1). However, timely recognition and intervention can be potentially lifesaving.

Conclusions: VA-CVST should be one of the differentials in patient presenting with mental status changes after Covid-19 vaccine. TTS is reported with Ad26.COV2.S vaccine in United States and ChAdOx1-S/nCov-19 vaccine in Europe and other parts of world, but it has also been reported after mRNA-1273 vaccine administration, although only two cases so far. Majority of cases occurred within 28 days after vaccination, however present case illustrates that delayed presentation may occur. Timely diagnosis of the condition and institution of appropriate intervention can avert adverse outcome.

IMAGE 1: Coronal section of T2 weighted MRI image shows infarct with areas of mosaic hemorrhage in right parietal region

IMAGE 2: MR venogram in coronal section shows absence of opacification of superior sagittal sinus, inferior sagittal sinus, transverse sinus, sigmoid sinus, straight sinus, and great cerebral vein