Lyme neuroborreliosis is a late manifestation of an infection by Borrelia spp., a tick-borne bacterial pathogen that is known for causing Lyme disease and a range of clinical syndromes. The ailment is primarily seen during the summer months and symptoms range from headaches and facial nerve palsy to severe sensory and motor deficits with altered consciousness. The diagnosis mandates a thorough clinical investigation, followed by microbiological studies.
Lyme neuroborreliosis (LN) is one of the many forms of Borrelia spp. infection, a spirochetal bacterial pathogen that is transmitted to the human host after a tick bite, specifically from Ixodes species    . Higher prevalence is encountered in the United States (where Borrelia burgdorferi is the main causative agent, with an incidence rate of 9.1 cases per 100 000 individuals), and in Europe, where B. garinii, B. afzelii and B. burgdorferi sensu stricto are identified as main pathogenic species  . In order for LN to occur, patients first pass through the initial stages of borreliosis (commonly known as Lyme disease) - the appearance of erythema migrans (a sharply-defined circular or "target" lesion that develops in the proximity of the tick bite) within a period of 3-30 days after the bite, and constitutional complaints such as fever, headaches, joint pain, and fever   . LN appears when bacteria are disseminated into the peripheral and central nervous system (CNS) and findings are seen either during early stages of dissemination or after a delayed period of weeks to years as a late manifestation  . LN is frequently described as a complication of Lyme disease in Europe than in the United States (35% vs. <10%, respectively) . Headaches, cranial nerve palsies (mainly of the facial nerve, presenting as either unilateral or bilateral face droop), and papilledema are nonspecific features, which may prolong the time before a correct diagnosis is made, particularly in children where enteroviral meningitis is a common cause of such symptoms  . A more prolonged clinical course and CNS abnormalities, however, are useful distinguishing characteristics . The term Bannwarth's syndrome is used to describe the typical signs of LN (mainly seen in European patients) - lymphocytic meningitis, radiculitis accompanied by sharp pain lasting for weeks or months (with exacerbations during the night), and cranial neuritis    . Apart from the involvement of the peripheral nervous system, Borrelia spp. can reach the CNS and cause significant damage to the brain and the spinal cord, presenting as a variable change in consciousness (from mild confusion to severe and life-threatening encephalitis) .
The diagnosis of LN is a difficult one to make without a proper clinical and microbiological investigation. The physician should first conduct a detailed patient interview during which the incidence of tick bites and typical skin lesions must be assessed, whereas a comprehensive travel history (given the fact that visiting endemic areas is a risk factor) may provide important clues as well  . Tick-borne disease must be considered in all patients with undisclosed cutaneous and constitutional symptoms in the summer months, as the vast majority of such events occur from May to September  . After a detailed physical examination (particularly focused on neurological evaluation), laboratory studies are the cornerstone for confirming the condition. Current recommendations advocate initial serological testing (through enzyme immunoassays or enzyme-linked immunosorbent assays - EIA and ELISA, respectively) of cerebrospinal fluid (CSF) or blood for immunoglobulin (Ig) G and IgM antibodies, followed by more sensitive methods such as Western blot     . CSF examination yields lymphocytic pleocytosis with normal biochemical composition , and the detection of neutrophilic predominance can firmly exclude Lyme disease as the etiology of neurologic infections . Polymerase chain reaction (PCR) testing is a novel technique that allows identification of pathogenic DNA and its implementation is recommended whenever possible  . Imaging studies of the endocranium and the CNS, magnetic resonance imaging (MRI) being the main candidate, reveal nonspecific findings and thus are of limited benefit for discriminating between etiologies of such symptoms  .