Reversible cerebral vasoconstriction syndrome and posterior reversible encephalopathy syndrome following vaccination: analysis of the VAERS database and systematic review

"Discussion

Our analysis of the VAERS database and systematic review represents the most comprehensive evaluation of RCVS [Reversible cerebral vasoconstriction syndrome] and PRES [posterior reversible encephalopathy syndrome] after vaccination. We included 29 cases (9 RCVS and 20 PRES), most of which were reported in women (72.4%), and those with pre-existing risk factors, including hypertension, renal disease, and immunosuppressive therapy. The COVID-19 mRNA vaccines were most often implicated. Understanding the pathophysiology of RCVS and PRES is essential in understanding how vaccines might contribute to their development. RCVS and PRES are understood as disorders of cerebral autoregulation and vasospasm. In RCVS, there is a transient alteration in the tone of the cerebral arteries, leading to vasoconstriction that can fluctuate and eventually reverses completely. PRES is believed to result from the failure of the cerebral autoregulation mechanism in response to acute changes in blood pressure, resulting in hyperperfusion and endothelial dysfunction, leading to vasogenic edema. The endothelium of cerebral vessels produces several vasoactive substances including nitric oxide and eicosanoids, which help regulate cerebral blood flow. Vaccines, particularly COVID-19 mRNA vaccines, have been proposed to induce a robust immune response that could lead to systemic inflammation and endothelial dysfunction. Thus, disrupting cerebral autoregulation and promoting vasospasm, leading to conditions such as RCVS and PRES. Furthermore, the SARS-CoV-2 spike protein has been suggested to injure endothelial cells directly, and the spike protein produced in response to mRNA vaccines could have similar effects."