Cerebral venous thrombosis post BNT162b2 mRNA SARS‐CoV‐2 vaccination: A black swan event

Singapore, 26 June 2021, Fan et al, American Journal of Haematology


We present three cases of CVT post BNT162b2 mRNA SARS‐CoV‐2 vaccination.

Patient 1: A healthy 54‐year‐old Chinese male with well controlled hyperlipidaemia, developed severe headache and vomiting 24 h after his second dose of BNT162b2 mRNA vaccine, and acute left hemiparesis 2 days later. A CT Brain revealed a large right temporo‐parietal lobe intraparenchymal hemorrhage with associated midline shift and uncal herniation, necessitating a decompressive craniectomy. A CT angiogram excluded underlying vascular malformations, and CT venogram confirmed dural venous sinus thrombosis (transverse and sigmoid sinus). Full blood count, coagulation profile and thrombophilia screen were unremarkable. Tests for anti‐platelet factor 4 (anti‐PF4) antibodies and heparin induced platelet aggregation (HIPA) were negative. Bilateral lower limb deep vein thrombosis ultrasound scans were negative. Whole body CT did not reveal any other thrombosis or malignancy. He was anticoagulated on unfractionated heparin (UFH) and subsequently converted to low molecular weight heparin (LMWH) and is currently undergoing rehabilitation.

Patient 2: A healthy 62‐year‐old Chinese female with a history of well‐controlled hypertension presented with headache and vomiting 9 days after her second dose of BNT162b2 mRNA Covid‐19 vaccine. Her full blood count and coagulation panel were unremarkable. Both CT Brain and CT venogram on admission confirmed acute right cerebral bleed involving occipital and temporal lobes associated with subarachnoid hemorrhage due to thrombosed right transverse and sigmoid sinus veins. Unfractionated heparin was started with close therapeutic monitoring. On day 4 of admission there was a drop in her Glasgow Coma Scale from 14 to 9, with repeat CT showed increasing size of haemorrhagic right cerebral venous infarcts with worsening of mass effect and development of early hydrocephalus, requiring decompressive craniectomy. This was later complicated by intracranial empyema requiring drainage. Post operatively, UFH infusion was resumed and later converted to LMWH. Thrombophilia workup was negative. Bilateral lower limb deep vein thrombosis scan was negative for thrombosis. Whole body CT performed 3 weeks into admission was negative for malignancy, however, right upper lobe segmental artery pulmonary embolism, left internal iliac artery and right common iliac vein thrombi were detected, likely from immobility in ICU and perioperative discontinuation of anticoagulation. Incidentally, a left iliopsoas haematoma was detected. Despite her haematoma, UFH was resumed due the increased thrombotic burden and later converted to LMWH, with bridging to warfarin a week later.

Patient 3: A 60‐year‐old Chinese female with family history of thrombosis (her son had unprovoked pulmonary embolism) and medical history of diabetes mellitus, hypertension and hyperlipidaemia, presented 8 days after her second dose of BNT162b2 mRNA Covid‐19 vaccine for right ataxic hemiparesis. Both CT brain and venogram confirmed extensive dural venous thrombosis and venous infarct in bilateral perirolandic gyri. This was complicated by acute right occipital lobe intraparenchymal hematoma and bilateral subarachnoid hemorrhage. Her CVT was treated with LMWH, followed by bridging to warfarin. Thrombophilia workup apart from a low anti thrombin III (AT) level of 55% (reference range 80%–130%), was unremarkable. She had no previous history of deep vein thrombosis. Her low levels of AT III during acute illness could possibly be attributed to acute and extensive thrombosis which can lower levels transiently, hence plans were made to recheck AT III levels when the patient is asymptomatic. Whole body CT scan performed did not reveal any malignancy. She made an uneventful recovery and was discharged.

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