Learning point In this case, the child presented with abnormal posture of the right limb, and a brain MRI revealed an abnormal signal in the left basal ganglia region. EEG showed intermittent triphasic waves, particularly in the C3 lead on the left side. Despite extensive clinical examinations and follow-up, the exact nature of the abnormal signal remains undetermined. The child is currently undergoing rehabilitation. This combination of anatomical lesion and EEG findings is clinically rare and has never been reported before.