Sydenham's chorea (SC) is a major manifestation of
rheumatic fever, and the production of anti-basal ganglia
antibodies (ABGA) has been proposed in SC. The pathogenesis is hypothesized as autoimmune targeting of the basal ganglia via molecular mimicry, triggered by
streptococcal infection. The spectrum of diseases in which ABGA may be involved has been broadened to include other extrapyramidal
movement disorders, such as
tics,
dystonia, and
Parkinsonism, as well as other
psychiatric disorders. The autoimmune hypothesis in the presence and absence of ABGA has been suggested in
Tourette's syndrome (TS), early onset
obsessive-compulsive disorders (OCD), and
pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS). Recently, the relationship between ABGA and dopamine neurons in the basal ganglia has been examined, and
autoantibodies against
dopamine receptors were detected in the sera from patients with basal ganglia
encephalitis. In Japan, the occurrence of subacute
encephalitis, where patients suffer from episodes of altered behavior and
involuntary movements, has increased. Immune-modulating treatments are effective, indicating the involvement of an autoimmune mechanism. We aimed to detect the anti-neuronal
autoantibodies in such
encephalitis, using immunohistochemical assessment of patient sera. The sera from patients showing
involuntary movements had immunoreactivity for basal ganglia neurons. Further
epitopes for ABGA will be investigated in
basal ganglia disorders other than SC, TS, OCD, and PANDAS.