Suspected Lyme-associated peripheral facial palsy in an adolescent with pre-existing sensorineural hearing loss: A diagnostic challenge

Introduction. Lyme neuroborreliosis (LNB) represents a neurological manifestation of infection caused by Borrelia burgdorferi sensu lato. According to established European diagnostic criteria, confirmed LNB requires cerebrospinal fluid pleocytosis and evidence of intrathecal antibody synthesis; however, these criteria are not always fulfilled in clinical practice, which may lead to diagnostic uncertainty. Case report. A 15-year-old girl presented with acute right-sided peripheral facial palsy. Serological testing demonstrated positive IgM and IgG antibodies to Borrelia burgdorferi sensu lato. Cerebrospinal fluid analysis was not performed, precluding confirmation of neuroborreliosis. Brain MRI excluded central causes of facial palsy. The patient received empirical antibiotic therapy in combination with corticosteroids, followed by partial clinical recovery over time. Pre-existing sensorineural hearing loss and incidental MRI findings were considered unrelated to the acute presentation. Conclusion. This case highlights the limitations of attributing peripheral facial palsy to Lyme disease based solely on serological findings. In the absence of cerebrospinal fluid analysis, diagnostic uncertainty remains, emphasizing the need for cautious interpretation of laboratory results and thorough consideration of alternative etiologies.