CD40LG and ischemic stroke: Presentation of IgM antibodies against B. burgdorferi in both serum and CSF and very high titers of IgG antibodies (in the CSF 13,000 times above the norm), strongly positive index of intrathecal synthesis, and an obvious improvement in the child's condition after the introduction of third-generation cephalosporins to the treatment, considering that corticosteroids were not employed at any stage of the patient’s treatment, seem to indicate that neuroborreliosis was the most important factor in the occurrence of ischemic stroke associated with secondary cerebral vasculitis in this child.