Porphyrias are rare inherited metabolic disorders of heme biosynthesis that lead to pathological accumulation of various porphyrins and their precursors. The inheritance is autosomal dominant. Neurological manifestations of acute intermittent porphyria are varied with involvement of central, peripheral and autonomic nervous systems. The incidence of neurological manifestations in symptomatic patients is very low ( 5-17%). 

PRES is a common imaging abnormality seen in acute intermittent porphyria. PRES presents with sudden onset of headache, seizures, altered mental status and visual disturbances which is most commonly associated with acute hypertension, eclampsia and immunosuppressive agents. Posterior reversible encephalopathy is characterized by reversible vasogenic subcortical edema without infarction. Although typically parieto occipital regions are involved, atypical presentations are not infrequent. 

The etiology of PRES in acute intermittent porphyria is proposed to be due to disruption of blood brain barrier and blood-nerve barrier caused by accumulation of porphyrin precursors.