CSF complements serum for evaluating paraneoplastic antibodies and NMO-IgG

Does this optic neuritis patient have neuromyelitis optica? An approach to optic neuritis in the context of neuromyelitis optica

“…However, plasma cells that secrete AQP4-IgG have been detected in the CSF, and may be a source of AQP4-IgG production [38]. This may in part explain the relatively small proportion of patients with what appears to be NMO with negative serum and positive CSF NMO-IgG [41].…”

A comparison of tissue-based and recombinant protein–based assays for detecting PCA-Tr/DNER-IgG

“…Consistent with prior experience, additional evaluation of CSF improves diagnostic sensitivity for paraneoplastic disorders. 7 Though interassay differences in sensitivity were not statistically significant, clinical importance was retained because PCA-Tr/DNER-IgG is rarely encountered, even in specialized laboratories. Recombinant DNER-IgG assay could serve as reflex confirmatory testing for suspected cases detected by tissue-based immunohistochemical assay (where that is the preferred antibody screening modality) or could be utilized for screening.…”

Confusion

“…-CASPR2 (contactin-associated protein-like 2) antibodies, sometimes associated with polyneuropathy, neuromyotonia, and peripheral nerve hyperexcitability -LGI1 (leucine-rich, glioma-inactivated 1) antibodies (Lai et al 2010 ) • GABA A receptor , which is usually not associated with an underlying neoplasm (Petit-Pedrol et al 2014 ) • GABA B receptor , which is most often associated with small cell lung cancer (Hoftberger et al 2013 ) • AMPA receptor , in patients with carcinoma of the lung, breast, or thymus (Lai et al 2009 ) Both serum and CSF should be tested for these autoantibodies, as they offer complementary information (McKeon et al 2011 ). It is important to recognize that commercial antibody tests are not yet available for all of the causes of limbic encephalitis.…”