[The diagnosis of Lyme borreliosis. Apropos of a neurological case].

The clinical diagnosis of Lyme borreliosis is easily established in the initial phase of the illness. Erythema chronicum migrans is pathognomonic of this infection. However, during further complications (neurological, cardiac or articular) the diagnosis is chiefly based on laboratory results. The detection of specific antibodies to B. burgdorferi is one of the effective means of confirming the diagnosis. Culture or isolation of this bacteria is not routinely performed due to its very low yield. In this article a case of serologically proved neuro-borreliosis is described and the methods of diagnosis are discussed. Intrathecal synthesis of antibodies observed in the cerebrospinal fluid of this patient and the specificity of serologic tests confirmed by Western-blot provide the diagnosis. However, the absence of locally synthesized antibodies in the cerebrospinal fluid is not sufficient to rule out neuro-borreliosis.