Proportion of confirmed Lyme neuroborreliosis cases among adult patients with suspected early European Lyme neuroborreliosis.

Purpose: To determine the frequency of confirmed Lyme neuroborreliosis (LNB) cases in adult patients with three different clinical presentations consistent with early LNB.

Methods: Data were obtained through routine health care at the UMC Ljubljana, Slovenia from 2005 to 2022, using clinical pathways. The patients were classified into three groups: (i) radicular pain of new onset (N = 332); or (ii) involvement of cranial nerve(s) but without radicular pain (N = 997); or (iii) erythema migrans (EM) skin lesion(s) in conjunction with symptoms suggestive of nervous system involvement but without either cranial nerve palsy or radicular pain (N = 240). The diagnosis of LNB considered the following variables: the presence of: (1) neurologic symptoms consistent with LNB (with no other obvious explanation); (2) cerebrospinal fluid (CSF) pleocytosis (> 5 × 10⁶ leukocytes/L); and (3) demonstration of intrathecal synthesis of borrelial antibodies, and/or cultivation of borrelia from CSF, and/or the presence of EM. Patients fulfilling only the first two criteria were interpreted as having possible LNB, while those who satisfied all three criteria were regarded as having confirmed LNB.

Results: Of 1569 adult patients, 348 (22.2%) had confirmed LNB and 70 (4.5%) others had possible LNB. The proportion of confirmed LNB cases was the highest for patients with radicular pain (217/332, 65.4%), followed by the group with EM and neurologic symptoms (47/240, 19.6%), and those with cranial neuritis (84/997, 8.4%).

Conclusion: Only 22% of patients evaluated had confirmed LNB. The proportion of confirmed LNB cases correlated with clinical presentation and was highest among patients with recent onset of radicular pain.