Is IgM of diagnostic value in case of delayed intrathecal production of IgG antibodies?

The neurological manifestations of Lyme borreliosis comprise a wide range o f clinical signs. However, these symptoms might have other aetiologies. The refore detection of intrathecal production of specific antibodies is necess ary to confirm the clinical assumption of neuroborreliosis (NB). In case of delayed intrathecal production of specific IgG antibodies, detection of Ig M could play a role in the early diagnosis of NE. To clarify whether IgM is of diagnostic value in such cases, paired CSF serum samples from 176 patie nts with suspected NE admitted to the department of Neurology, Karl Franzen s University, Graz, Austria, were tested. Testing was performed with the ID EA(R) Neuroborreliosis Kit (Dako, Denmark) and Enzygnost Borreliosis(R) (Be hring, Germany) and results of both methods were compared. According to wel l defined criteria 63 of the 176 patients had defined NE and 113 were regar ded as possible NE. Twelve out of 63 patients with defined NE had delayed i ntrathecal IgG production. Only one patient with delayed IgG production had an intrathecal IgM production prior to IgG. In all patients with possible NE no intrathecal production of IgM was detected. At the time of the first lumbar puncture IgG intrathecal production could be detected with the IDEA( R) seven times more often than with the Enzygnost Borreliosis(R). The deter mination of intrathecal production of IgM does not appear to be of diagnost ic value in patients with delayed IgG antibody production. Therefore a cons ecutive lumbar puncture is more likely to confirm clinical assumption if th ere is strong clinical evidence of NE.