• central pontine myelinolysis
• posterior reversible encephalopathy syndrome
• diffusion weighted imaging

I read with interest the article by Sugimoto et al.¹ The authors report the case of a 31 year old man with an eating disorder and hypokalaemia who was noted to have asymptomatic increased T2 signal in the central pons on brain magnetic resonance imaging (MRI), in the setting of intensive intravenous fluid rehydration. He was thought to have asymptomatic central pontine myelinolysis (CPM). Six months later, a repeat brain MRI revealed that the pontine lesion had disappeared. The authors refer to other reports in the literature of asymptomatic and reversible CPM.

However, I argue that a far more plausible diagnosis for this patient is posterior reversible encephalopathy syndrome (PRES), which was originally described by Hinchey et al in 1996.² This condition is characterised by vasogenic oedema in the posterior circulation territories of the brain, and is classically completely reversible. PRES involving just the pons has been reported by several groups³ and, although usually …