Caused by adaptive immune response directed against an antigen expressed within the nervous system.
In paraneoplastic disorders the immune response is directed against neuronal antigens that are ectopically expressed by the tumor.
Post-infectious conditions are mediated by an abnormal immune response to a foreign antigen that results in the elaboration of an immune response targeting a similar appearing self antigen such as the Guillain-Barre syndrome following an infection with Campylobacter jejuni, resulting in production of anti ganglioside antibodies.
In primary autoimmune disorders, the abnormal immune response develops in the absence of any clear inciting trigger, however patients may have a history of autoimmunity, suggesting an underlying inherited predisposition.
To distinguish between primary autoimmune, paraneoplastic, and post infectious etiology is difficult in clinical practice.
Immunologic mechanisms that are implicated in autoimmune disorders of the nevous system can be classified into autoantibody mediated disorders, T-cell mediated disorders, granulomatous inflammation, autoinflammatory pathology, and iatrogenic activation of specific immune processes were targets.
Autoantibodies have a role when targeting surface antigens such as aquaporin-4, NMDAR, and acetylcholine receptor.