RESUMEN
A case of acute and reversible bilateral basal ganglia with thalami involvement associated with serological evidence of Mycoplasma pneumoniae infection is reported. Increased titers of immunoglobulin M antibodies against GM1 ganglioside components were found during an acute phase of neurological illness. Brain magnetic resonance imaging (MRI) showed bilateral involvement of the basal ganglia and thalamus, which disappeared 1 month later. The child recovered fully after corticosteroid and immunoglobulin therapy, and antiganglioside antibodies returned to within the normal range. The authors speculate on the diagnostic hypothesis regarding selective basal ganglia and thalamic involvement and the relationship with anti-GM1 ganglioside immunoglobulin M antibodies.