Chasing the Dragon Syndrome: A Case of Toxic Leukoencephalopathy and Response to Intravenous Immunoglobulin

Heroin inhalational leukoencephalopathy (HLE), also known as "chasing the dragon" syndrome, is a rare but severe neurological disorder associated with inhaling heroin vapors. It is characterized by progressive white matter damage and distinctive magnetic resonance imaging (MRI) findings, with no definitive treatment and a generally poor prognosis. We report the case of a 43-year-old man with a history of polysubstance abuse who presented with acute altered mental status. Initial investigations revealed aspiration pneumonia and a positive urine drug screen for cocaine and opioids. Magnetic resonance imaging (MRI) of the brain demonstrated diffuse, symmetrical T2-weighted fluid-attenuated inversion recovery (T2/FLAIR) hyperintensities in the white matter, sparing the deep gray nuclei, brainstem, and cerebellum, findings consistent with toxic leukoencephalopathy. Despite treatment with antibiotics, steroids, supportive care, and psychiatric management, his neurological condition deteriorated, requiring intensive care unit (ICU) admission and mechanical ventilation. Administration of intravenous immunoglobulin (IVIG) at a total dose of 2 g/kg over three days resulted in improvement in awareness and motor function. He was eventually discharged to a subacute rehabilitation facility. This case highlights the diagnostic complexity of HLE in the setting of multi-substance use, where imaging findings may overlap with other toxic encephalopathies. The observed clinical improvement following IVIG raises the possibility of a therapeutic role, warranting further investigation. Early recognition of (heroin inhalational leukoencephalopathy) HLE and its imaging findings is essential to initiate supportive interventions and explore emerging therapies.