Cerebrospinal Fluid Profiles Across Clinical Manifestations of Early European Lyme Neuroborreliosis.

Background: Early European lyme neuroborreliosis (LNB) presents with distinct clinical manifestations, but comparative data on cerebrospinal fluid (CSF) findings across these forms are limited. Methods: We conducted a retrospective study of 405 patients with confirmed early LNB treated at a single center between 2005 and 2025. Thirteen routine CSF parameters were analyzed across three main clinical manifestations-meningoradiculoneuritis (Bannwarth syndrome), cranial neuritis, and erythema migrans (EM)-associated meningitis-and in relation to the duration of neurological symptoms. Multivariate regression was used to assess independent associations. Results: Of 405 patients, 274 (68%) had Bannwarth syndrome, 82 (20%) cranial neuritis, and 49 (12%) EM-meningitis. CSF abnormalities differed significantly among groups and were most pronounced in Bannwarth syndrome and least marked in EM-meningitis. Patients with Bannwarth syndrome more frequently had positive borrelial serology and intrathecal antibody synthesis. CSF leukocyte counts, protein, and albumin increased during the first 4 weeks of disease and then stabilized, whereas immunoglobulin levels peaked around week 6. Longer duration of neurological symptoms was associated with higher lymphocyte proportion, increased protein levels, and elevated IgM and IgG concentrations. Multivariate analysis confirmed that clinical manifestation, symptom duration, age, and sex independently influenced CSF parameters. Conclusions: The three principal manifestations of early European LNB differ in the magnitude of CSF inflammation and blood-brain barrier dysfunction. Bannwarth syndrome is associated with the most pronounced intrathecal inflammatory response, whereas EM-associated meningitis represents a milder phenotype. CSF abnormalities evolve over time, underscoring the importance of early diagnostic evaluation.