An uncommon case of amyotrophic lateral sclerosis with isolation of a virus from the CSF.

An atypical case of amyotrophic lateral sclerosis (ALS) is described, characterized by early manifestation, a long lasting course with asymmetry of the lesions, absence of bulbar symptoms in the presence of an otherwise very advanced symptomatology, and constant signs of an inflammatory reaction in the CSF which was the reason to initiate extensive virological studies, including procedures for virus isolation. A virus belonging to the TbE complex of arbovirus group B (tick-borne flavivures), was finally isolated from the CSF. About 70% of the ALS cases in Hamburg/W. Germany, examined for antibodies, apparently had contact with this virus. The antibody pattern found made it possible to explain this exceptional case.