Lymphocytic meningitis, cranial neuritis or radiculoneuritis occur in up to 15% of patients with untreated Borrelia burgdorferi infection. Presentations of multifocal PNS involvement can range from painful monoradiculitis to confluent mononeuropathy multiplex. Serologic testing is highly accurate after 4 to 6 weeks of infection. In CNS infection, production of anti-Bburgdorferi antibody is often demonstrable in CSF. Oral antimicrobials are microbiologically curative in virtually all patients, including acute European neuroborreliosis. Severe cases may require parenteral treatment. The fatigue and cognitive symptoms seen in some patients with extra-neurological disease are neither evidence of CNS infection nor specific to Lyme disease.