Posterior reversible encephalopathy syndrome (PRES) associated with liquorice consumption

Posterior reversible encephalopathy syndrome (PRES) is a medical emergency but prompt recognition, early institution of supportive care and identifying and removing potential triggers are associated with a good clinical outcome. We report an unusual case of PRES associated with liquorice consumption.

A 56-year-old lady presented with thunderclap headache, visual disturbance and a generalised tonic-clonic seizure. Blood pressure on admission was markedly elevated but improved within 24 h. Cranial CT and lumbar puncture were normal (no xanthochromia). She had hypokalaemia. Cranial MRI revealed abnormalities in the occipital lobes consistent with PRES. There was no evidence of restricted diffusion or vasoconstriction. Follow-up MRI 3 weeks later demonstrated complete resolution. On direct questioning she revealed in recent months she had habitually eaten liquorice sweets each day; they were "on special offer" in her local shop.

Liquorice contains a biologically active compound glycyrrhizic acid which inhibits 11β hydroxysteroid dehydrogenase. Excessive liquorice consumption can cause mineralocorticoid excess and has been recently reported to cause PRES. We propose that in the absence of other triggers, frequent liquorice consumption precipitated the development of PRES in our patient and should be considered as a possible cause of this condition.