Posterior reversible encephalopathy syndrome complicating hyperosmolar hyperglycemic syndrome.

Hyperosmolar hyperglycemic syndrome is a life-threatening diabetic emergency that manifests as altered mental status. An otherwise healthy 40-year-old man presented to our emergency department with headache and severe hypertension. Brain magnetic resonance imaging showed evidence of posterior reversible encephalopathy syndrome, a usually reversible neurological syndrome characterized by subcortical vasogenic oedema. This first reported case details posterior reversible encephalopathy syndrome concurrent with hyperosmolar hyperglycemic syndrome. Prompt diagnosis and management were essential to avoid non-reversible consequences.