Not a Disease of the Past: A Case Report of Heroin-Induced Toxic Leukoencephalopathy Causing Progressive Neurologic Decline.

Toxic leukoencephalopathy is a rare neurological complication associated with various toxins, including inhaled heroin ("chasing the dragon"). We report a case of a 36-year-old female with a history of heroin dependence, in remission for seven years until a recent relapse, who presented with progressive deterioration in speech clarity, swallowing difficulty, and imbalance. Neuroimaging revealed diffuse leukoencephalopathy involving the cerebellar white matter and internal capsules, suggestive of heroin induced leukoencephalopathy. Laboratory evaluation was unremarkable, and infectious, autoimmune, and metabolic causes were considered less likely. This case highlights the importance of recognizing heroin-induced toxic leukoencephalopathy as a cause of subacute progressive neurological decline in patients with recent heroin use, even in the absence of intravenous administration.