Background: Reversible cerebral vasoconstriction syndrome (RCVS) is an underdiagnosed disease characterized by severe headaches with or without seizures, focal neurological deficits, and constriction of cerebral arteries which resolves spontaneously in 1-3 months. Posterior reversible encephalopathy syndrome (PRES) is typically characterized by headache, altered mental functioning, seizures, and visual loss associated with imaging findings of bilateral subcortical and cortical edema with a predominantly posterior distribution. Case Report: We present 49-year-old and 46-year-old females with thunderclap headache and seizure. MRI shows reversible cortical and subcortical lesions in both fronto-parieto-occipital lobes. And magnetic resonance angiography shows reversible multifocal luminal narrowing of distal cerebral vessels. Conclusion: Primary RCVS may occur as a cause of PRES. We report two cases of non-hypertensive PRES with seizure due to primary RCVS presenting thunderclap headache.ope
