Neurological Manifestations in a Kidney Transplant Recipient: An Unexpected Case of Manganese Toxicity.

Manganese (Mn) toxicity is a relatively uncommon neurotoxic condition characterized by neuropsychiatric symptoms and parkinsonism. We describe a 46-year-old woman with end-stage renal disease due to congenital obstructive uropathy, status post deceased-donor kidney transplantation (2021), who presented with one month of worsening tremors, gait instability, intermittent aphasia, and altered awareness. Brain magnetic resonance imaging demonstrated persistent but improved T1 hyperintensity of the globus pallidus compared to prior imaging, consistent with Mn deposition. Serum Mn was markedly elevated at 14.9 µg/L (reference range 0.5-1.2 µg/L). Chelation therapy with calcium disodium ethylenediaminetetraacetic acid was initiated but discontinued early due to decline in renal function. Despite early cessation, treatment resulted in biochemical improvement and partial clinical recovery. Kidney allograft biopsy, performed due to a rise in creatinine during the hospital course, demonstrated severe chronic changes without evidence of acute rejection. Thorough history taking and evaluation of environmental factors did not identify a clear source of Mn exposure. The patient's history was notable for Budd-Chiari syndrome with portal hypertension status post transjugular intrahepatic portosystemic shunt, which likely contributed to impaired Mn clearance. To our knowledge, Mn toxicity occurring in a functioning kidney transplant recipient has not previously been reported. This case underscores the diagnostic and therapeutic challenges of Mn toxicity.