Bridging the Gap: Baló Concentric Sclerosis–Like Leukoencephalopathy in Chronic Cocaine Use

Cocaine use is occasionally associated with development of acute leukoencephalopathy but only rarely do the magnetic resonance imaging (MRI) features resemble Baló concentric sclerosis, a demyelinating disorder traditionally considered within the multiple sclerosis spectrum. Here, we report 2 patients with history of cocaine use living in the same geographic area who were referred for acute multifocal leukoencephalopathy with a Baló-like pattern.Patient 1, a 31-year-old woman originally from the Philippines with chronic cocaine use history, presented with 1 week of rapidly worsening nonfluent aphasia, neglect, severe right hemiparesis, and numbness on the same side. Two months later, patient 2, a 25-year-old man originally from Morocco with chronic cocaine use history, presented with acute left leg weakness, confusion, and neglect. In both patients, brain MRI revealed multiple T2-hyperintense rounded lesions in the white matter, characterized by a concentric target-like appearance and gadolinium-enhanced incomplete ring pattern. In patient 1, a stereotactic biopsy confirmed a demyelinating inflammatory process with microcystic degeneration, increased cellularity, and macrophage/CD4+ lymphocyte infiltration. Both patients were treated with high-dose IV corticosteroid, resulting in significant clinical and radiologic improvement sustained at 1-year follow-up. Although corticosteroids yield promising outcomes, long-term prognosis hinges on sustained treatment adherence and abstinence from cocaine.The temporal and geographic proximity of these cases, occurring within 2 months in the same Italian province (covering an area of approximately 70 miles), raises the possibility of a shared toxic exposure which might explain the unique pathology and provide clues to the immune mechanisms that drive Baló-like demyelination.