A patient is described having Borrelia burgdorferi spirochetal infection clinically affecting central motor neurons selectively and without any sensory impairment. Diagnosis was based on elevated B. burgdorferi IgG antibody titers in cerebrospinal fluid (CSF) and titer normalization at clinical recovery. This occurred promptly and was complete after penicillin treatment despite 14 months of progressive central nervous system (CNS) dysfunction, favouring the hypothesis of the presence of the organism within the CNS. CSF findings characteristic of neuroborreliosis were registered, including parallel occurrence of mononuclear pleocytosis, severe blood-brain barrier damage and marked CSF IgM index elevation of prolonged duration. Some earlier reports of CNS manifestations related to B. burgdorferi are reviewed.