Cerebral venous thrombosis without thrombocytopenia after a single dose of COVID-19 (Ad26.COV2.S) vaccine injection: a case report.

BACKGROUND: The coronavirus pandemic became the hard challenge for the modern global health system. To date, vaccination is the best strategy against Sars-Cov-2-related illness. About 3 billions of people received at least one of the approved vaccines. The related adverse events were reported during the various experimental phases, but newer and less common side effects are emerging post-marketing. Vaccine-induced thrombocytopenia with thrombosis (VITT) is one of these insidious adverse reactions and it is considered responsible of venous thrombosis, in both the splanchnic and the cerebral circulation. Although its mechanism has been presumably established, resembling that observed in heparin-induced thrombocytopenia, some venous thromboses seem not to recognize this etiology and their pathogenesis remains unknown. Here we described a case of cerebral venous thrombosis after administration of the Ad26.COV2.S, presenting without thrombocytopenia, paving the way for possible novel causes of this vaccine-induced pathological condition. CASE PRESENTATION: A 45-year-old woman came to our observation for bilateral periorbital headache associated with retro-orbital pain started 8 days after administration of COVID vaccine Jannsen. Ophthalmologic exam showing a bilateral papilledema raised the suspicion of intracranial hypertension. Cerebral magnetic resonance imaging revealed signal alteration with T1-positive contrast enhancement in the right temporal and insular lobes suggestive of cerebral venous thrombosis. The absence of thrombocytopenia and platelet factor 4 (PF-4) antibodies led the clinicians to rule out VITT. The patient was treated successfully with warfarin. CONCLUSION: Venous thrombosis occurring after COVID-19 vaccination represents an adverse event of special interest. Patients with thrombosis and thrombocytopenia appear to be affected by a general thrombophilic state, sustained by an autoimmune mechanism, and show a higher mortality. Thrombosis without thrombocytopenia's pathogenesis has not yet been clarified, but laboratory data and good response to vitamin K antagonists help clinicians in the differential diagnosis with VITT. Future research will allow us to discover other possible mechanisms and maybe identify a subgroup of patients with a higher risk of developing this medical complication.