Acute obstructive hydrocephalus in posterior reversible encephalopathy syndrome

Posterior reversible encephalopathy syndrome (PRES) is an uncommon, subacute neurological disorder that presents radiologically witha pattern of bilateral parieto-occipital areas of vasogenic oedema. Conditions commonly associated with PRES include autoimmunedisorders, cytotoxic drugs, metabolic abnormalities and, most frequently, hypertensive emergencies. Clinically, headache, visualdisturbances, seizures and an altered level of consciousness are often reported. The outcome is favourable if the underlying cause isaddressed. Posterior fossa involvement resulting in obstructive hydrocephalus is a rare presentation and may be misdiagnosed as a mass lesion or infection, leading to delayed or unnecessary treatment. We describe the clinical presentation, findings on neuroimaging and conservative management of a man with PRES resulting in severe cerebellar oedema and acute obstructive hydrocephalus. This case illustrates that awareness of atypical neuroimaging in PRES is important for the management of these patients and to avoid morbidity and mortality.