RESUMO
Objective: Coronavirus disease (COVID-19) vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare but fatal complication observed within 2 weeks of adenovirus-vectored vaccination. Case Report: A 52-year-old male patient, with a family history of autoimmune diseases, presented with a new onset of worsening headache with nausea and vomiting post-vaccination. The patient was diagnosed with VITT based on laboratory findings demonstrating thrombocytopenia, elevated D-dimer, and dural sinus thrombosis identified on neuroimaging. The patient was successfully treated with high-dose immunoglobulin, steroids, and non-heparin anticoagulants, without any neurologic sequelae. Finally, a confirmatory test with anti-platelet factor 4 antibody was strongly positive. Conclusion: Physicians should be vigilant when treating patients presenting with new-onset thunderclap headache, progressive worsening headache, and awakening headache accompanied by nausea or vomiting after vaccination, even if no definite clinical neurological deficits are identified. Emergency laboratory test results for demonstrating elevated D-dimer levels, decreased platelet count, and neuroimaging correlation are integral for diagnosis and must be the standard protocol. Treatment with non-heparin anticoagulants, high-dose intravenous immunoglobulin, and steroids that halt or slow the immune-mediated prothrombotic process should be initiated immediately. Considering the high mortality rate of VITT, treatment should be initiated prior to confirmatory test results.