Late presentation of posterior reversible encephalopathy syndrome following liver transplantation in the setting of tacrolimus and cannabis use.

A 45-year-old female presented to hospital with confusion and visual disturbances. She had undergone a liver transplant 3 years prior for cirrhosis secondary to primary biliary cholangitis. Computed tomography and magnetic resonance imaging of the brain showed features consistent with posterior reversible encephalopathy syndrome. Her medications included tacrolimus, sirolimus, and prednisone. She reported smoking 4 grams of cannabis per day. Following cessation of tacrolimus, the patient's encephalopathy and visual disturbances resolved. To our knowledge, this case represents the longest time elapsed from liver transplantation to the development of tacrolimus-associated posterior reversible encephalopathy syndrome in the literature. This case highlights the potential danger of cannabis use in transplant recipients who are on immunosuppressants such as tacrolimus. Clinicians should have a high index of suspicion for posterior reversible encephalopathy syndrome in post-transplant patients presenting with altered mental status, even years after liver transplantation, and be familiar with potential interactions between cannabis and immunosuppressants.