Basal Ganglia Autoimmune Encephalitis Following Leptospirosis

Basal ganglia encephalitis is a part of the spectrum of autoimmune basal ganglia disorders. We are reporting a child who had a fever with focal seizures followed by behavioral problems, rigidity, bradykinesia, and dystonia. His parkinsonism-like features were increasing day by day up to the level that the child was non-ambulatory. His initial Magnetic Resonance Imaging (MRI) of the brain showed asymmetrical T2 hyperintensities involving both the caudate nuclei and putamina. Later, with progressive symptoms, repeat MRI revealed a swelling and symmetrical signal change in both the caudate nuclei and putamina in the form of T2 and Fluid-attenuated inversion recovery (FLAIR) hyperintensities. In addition, there was T2 hyperintensity involving bilateral substantia nigra. Serum basal ganglia antibody, Leptospira Immunoglobulin M (IgM) antibody was positive, and Cerebrospinal Fluid (CSF) oligoclonal band was positive. So, the child was diagnosed with post-leptospirosis autoimmune basal ganglia encephalitis. He was managed with immunomodulatory agents and significant improvement in the symptoms with mild residual extrapyramidal symptoms were noted.