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.