Are high CSF levels of CXCL13 helpful for diagnosis of Lyme neuroborreliosis?

Neuroborreliosis (NB) is a serious complication of infection with the spirochete Borrelia burgdorferi that presents with a variety of clinical manifestations. Identification of Lyme NB and the decision to treat with IV or oral antibiotics are common challenges.^1,2 For persons in endemic areas who present with classic manifestations of Lyme NB and evidence of systemic infection with B burgdorferi, the diagnosis is straightforward. However, for cases with atypical manifestations or ambiguous serology, diagnostic confirmation of Lyme NB can be difficult. The current method of choice for diagnosis of Lyme NB is the demonstration of CSF abnormalities (i.e., increased leukocyte count or elevated albumin CSF/serum ratio, indicating blood–CSF barrier dysfunction) plus the demonstration of intrathecal synthesis of Borrelia-specific antibodies.^2,3 These tests suffer from important limitations. 1) Elevated CSF leukocytes or protein are not specific, and are found in other infectious and noninfectious inflammatory CNS diseases.^3,4 2) Intrathecal production of Borrelia antibodies may be absent at the time of diagnostic lumbar puncture.⁴ 3) Even the demonstration of intrathecal Borrelia-specific antibodies does not necessarily discriminate between active and past infection; specific antibody production persists for years in spite of successful treatment.⁵ In fact, an important problem is the difficulty determining whether …