Case report: Hemodynamic dynamics in central variant PRES via serial ASL/DTI

Central variant posterior reversible encephalopathy syndrome (PRES) is a rare subtype (4% of cases) affecting brainstem and deep structures, presenting with severe hypertension but minimal neurological deficits, creating diagnostic challenges. A 34-year-old man presented with a two-month history of severe, refractory headache and malignant hypertension (256/150 mmHg). Brain MRI revealed diffuse T2-weighted and FLAIR hyperintensity in the pons and right middle cerebellar peduncle (MCP). Using serial arterial spin labeling (ASL) and diffusion tensor imaging (DTI), we provide the first longitudinal evidence of acute-phase biphasic hemodynamics in central variant PRES: concurrent pontine CBF of 27.1 mL/100 g/min (contralateral reference: 25.2 ± 1.8 mL/100 g/min) and right MCP CBF of 29.3 mL/100 g/min (contralateral reference: 39.1 ± 2.1 mL/100 g/min). This regional perfusion imbalance is consistent with autoregulatory failure and blood-brain barrier (BBB) compromise, leading to vasogenic edema. Critically, the coexistence of these opposing patterns reveals complementary hemodynamic phenotypes of cerebrovascular dysregulation. Post-treatment, pontine CBF was 25.3 mL/100 g/min (contralateral reference: 25.3 ± 1.8 mL/100 g/min) and right MCP CBF was 38.6 mL/100 g/min (contralateral reference: 39.2 ± 2.2 mL/100 g/min), both within the reference range of the contralateral regions, accompanied by progressive increase of fractional anisotropy (FA) on DTI at both the 6-day and 90-day follow-up imaging time points. This case demonstrates biphasic hemodynamic changes in central variant PRES, supporting autoregulatory failure as the mechanism. Serial ASL/DTI provide valuable biomarkers for monitoring recovery in this rare phenotype.