Bridging the Gap: Baló Concentric Sclerosis-Like Leukoencephalopathy in Chronic Cocaine Use: A 1-Year Clinical and Imaging Follow-Up of 2 Cases.

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.