Introduction: Central nervous system manifestations represent 0.54 to 8% of neurological complication in Lyme disease.
Observation: A 78-year-old woman presented a severe meningo-encephalitis with visual disorders (agnosia, alexia) progressing towards coma. Cranial magnetic resonance imaging revealed large areas of hypersignal T2 in the white matter of the lower, parieto-occipital lobes and left temporal lobe. The cerebrospinal fluid (CSF) contained 16 then 293 white corpuscles/mm3 of lympho-monocytes, increased protein level from 2.67 to 5.83 g/l and an increase in IgG index with oligoclonal distribution of IgG. Serological Elisa analysis for Lyme disease was slightly positive in blood (confirmed by western blot) but clearly in the CSF (IgG and IgM). Treatment with ceftriaxone followed by methylprednisolone provided clinical improvement 3 months later.
Discussion: Acute meningo-encephalitis is often benign, protein-like and of good prognosis: the gnosic visual disorders with posterior leukoencephalopathy are unusual. A blood level of specific antibodies slightly positive on Elisa at the early stage of the infection warrants confirmation by Western blot in the blood and by Elisa in the CSF. Additional corticosteroid therapy may be required in the severe forms that evoke acute disseminated encephalomyelitis.