Background: Pediatric Lyme neuroborreliosis (LNB), caused by Borrelia burgdorferi sensu lato (Bbsl), may rarely present with cerebrovascular involvement, particularly affecting the posterior circulation and causing ischemic or hemorrhagic stroke. In endemic regions, LNB should be considered a potential cause of pediatric stroke.

Case presentation: Case 1: An 8-year-old girl presented with recurrent episodes of impaired awareness, transient right arm flaccidity, and constitutional symptoms. MRI showed leptomeningeal enhancement, and time-of-flight angiography revealed focal narrowing of both posterior cerebral arteries. Cerebrospinal fluid (CSF) demonstrated pleocytosis, elevated protein, and increased Bbsl-specific antibodies and CXCL13. Case 2: A 13-year-old girl presented with acute dizziness, dysarthria, and left-sided weakness. Brain CT was normal, but CT angiography showed irregularities in the posterior circulation, and MRI performed 12 hours later confirmed an acute pontine infarct. CSF showed pleocytosis, elevated protein, increased Bbsl-specific antibodies and CXCL13, and positive Bbsl-PCR.

Intervention: Both patients received intravenous ceftriaxone, patient 1 for two, and patient 2 for three weeks. Case 1 was treated with aspirin, and Case 2 received high-dose methylprednisolone and anticoagulation, later transitioned to aspirin.

Results: Both patients improved rapidly. Case 1 became fully asymptomatic within one month, with near-complete radiologic resolution. Case 2 recovered functional independence and returned to school within weeks, with only mild residual neurological findings at follow-up.

Conclusion: These cases emphasize the varied neurological presentations of LNB and the importance of including Lyme diagnostics in the evaluation of pediatric ischemic events. It is important to recognize LNB as an etiology of pediatric stroke because effective antimicrobial therapy may dramatically change outcome.

Keywords: CXCL13; Cerebral vasculopathy; Cerebrovascular events; Lyme neuroborreliosis; Pediatric stroke; Posterior circulation.