High-dose intravenous penicillin G does not prevent further progression in early neurological manifestation of Lyme borreliosis.

We report two cases of Lyme borreliosis (LB) with erythema migrans (EM) and simultaneous meningopolyneuritis with radicular pain and lymphocytic pleocytosis in the cerebrospinal fluid (CSF). EM and pain disappeared completely under high-dose penicillin G therapy within few a days. Pathological findings in CSF improved. Nevertheless, during and after therapy, neurological signs of LB developed: cranial nerve palsies as well as paresis of extremity muscles with radicular distribution.