Diagnostic value of CSF findings in antibody-associated limbic and anti-NMDAR-encephalitis
Introduction from Dr Markus Reuber, editor-in-chief of Seizure
Leaving the continuous stream of genetic discoveries on one side, it is about once in a decade that an important novel pathogenic mechanism is discovered, which explains a whole group of previously obscure disorders involving epilepsy. Two decades ago, the importance of mitochondrial cytopathies was recognised. Initially only the tip of the iceberg was visible (in the shape of clearly defined syndromes related to abnormalities of mitochondrial DNA). Gradually the rest of the iceberg has come into view (including atypical presentations of “syndromal” mitochondrial disorders, disorders explained by abnormalities in the nuclear DNA and acquired disorders of mitochondrial function).
The big discovery over the last decade has been the realisation that acquired autoimmune epilepsies are actually quite common (1). Akin to the growth in understanding of mitochondrial epilepsies, the process of discovery has started with some neatly defined syndromes, such as limbic encephalitis (LE) associated antibodies against voltage gated potassium channel (VGKC) or N-methyl-D-aspartate (NMDA) receptors. Now we are seeing a steady stream of publications about the clinical manifestations of autoimmune epilepsies, which will hopefully allow doctors to diagnose these disorders more quickly in the future. The early diagnosis of autoimmune epilepsies is, of course, crucial because genuine antiepileptic drug treatment may be possible (i.e. treatment which would stop the development of epilepsy or cure the disorder rather than merely control seizures).
The paper by Malter, Elger and Surges in this issue of Seizure makes an important contribution to this field. Their finding that oligoclonal bands are usually seen in patients with paraneoplastic LE or LE associated with antibodies against Glutamic Acid Decarboxelase (GAD) or NMDA receptors but less often seen in VGKC-LE should help clinicians diagnose patients more quickly and more securely. What is more, the association of oligoclonal bands with some subtypes of LE suggests that these subtypes are entities, which commonly depend on a primary pathological process within the brain (or, alternatively, that they develop after migration of antibody-producing cells into the CNS).
(1) Vincent, A., Bien, C.G., Irani, S.R. and Waters, P. Autoantibodies associated with diseases of the CNS: new developments and future challenges. Lancet Neurology 2011;10:759-772.
(2) Malter M., Elger, C. E. , Surges, R. Diagnostic value of CSF findings in antibody-associated limbic and anti-NMDAR-encephalitis. Seizure 2013; 22: 136-140.