Quiz Page January 2008: Altered Mental Status in a Kidney Transplant Recipient Receiving Tacrolimus

What diagnosis best explains the radiological features present in Fig 1? 

Neuroimaging of this patient shows the typical findings of symmetrical subcortical white matter edema in the posterior cerebral hemispheres, particularly in the parieto-occipital regions in the T2-fluid-attenuated inversion recovery images of the brain (Fig 1). The clinical recovery in addition to near-total resolution of these neuroimaging findings within 2 weeks after discontinuation of immunosuppression (tacrolimus) without any other specific therapy suggest the diagnosis of posterior reversible (leuko) encephalopathy syndrome (PRES or PRLS syndrome; Fig 2).

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Figure 2. Magnetic resonance imaging performed 2 weeks after admission when the patient showed almost complete recovery of mental status.

PRES is a clinicoradiological syndrome of heterogeneous causes with similar neuroimaging findings as described. This descriptive diagnostic term was first used after a case series in 1996.1 This syndrome usually is of insidious onset, with headache, confusion, decreased level of consciousness, visual changes, and seizure disorder associated with the typical neuroimaging findings. This syndrome was described in many medical conditions, including hypertensive encephalopathy, eclampsia, and administration of immunosuppressive or cytotoxic medications. The pathogenesis is unclear, but it appears to be caused by vasogenic edema, mostly in the posterior circulation, secondary to endothelial dysfunction and altered cerebral autoregulation.1, 2 This clinical disorder should be in the differential diagnosis in renal transplant recipients presenting with insidious onset of neurological illness because calcineurin inhibitors are implicated in this condition.3, 4, 5 Early diagnosis in such patients is very important because discontinuation of calcineurin inhibitors may avoid permanent neurological deficits. Our patient recovered completely and was maintained on corticosteroid and rapamycin therapy.