[Isoelectric focusing in neurological diagnosis]

The cerebrospinal fluid (CSF) of 1673 neurological patients in whom conventional agar electrophoresis failed to provide conclusive results was analyzed by isoelectric focusing (IEF). The primary aim of the study was not to analyze the frequency of oligoclonal immunoglobulins in the CSF of patients with inflammatory diseases of the central nervous system (CNS) but to answer the question how often, and in which particular disturbances, gamma-globulin changes typical of inflammatory processes are found in conditions which do not primarily belong to the group of inflammatory CNS diseases. It is shown that oligoclonal IgG bands in these circumstances are not common but did occasionally occur in most diagnostic groups. Results suggest increased frequency in certain groups such as Guillain-Barré polyradiculitis and in various neoplastic disorders. The diagnostic difficulties resulting from these findings and the advantages of IEF over the more generally favoured "Ig-index" are discussed. In addition, we report on the occasional appearance of monoclonal IgG gammopathies either associated with inflammatory CNS reactions or - more frequently - as an isolated and unexplained finding.