Moaning Phenomenon and Rapidly Progressive Dementia in Anti LGI-1 Associated Progressive Supranuclear Palsy Syndrome

Immunological causes of atypical parkinsonisms linked to neuronal specific antibodies have been recently reported. As these are potentially treatable disorders, it is desirable to identify which clinical features may suggest an autoimmune etiology. A 60-year-old-man with progressive supranuclear palsy associated with anti-LGI-1 antibodies presented with rapidly progressive dementia and moaning. Treatment with steroids and immunoglobulin resulted in temporary clinical improvement and disease stabilization. Anti-LGI-1 antibodies interfere with normal synaptic activity and maturation in the central nervous system. We suggest that an immune-mediated mechanism might be considered in atypical parkinsonisms with unusual features such as rapidly progressive dementia. We present a case of rapidly evolving progressive supranuclear palsy-like parkinsonism associated with anti-LGI-1 antibodies, suggesting that immune-mediated mechanisms might be involved in rapid progression of some atypical parkinsonisms. This case also contributes to the expanding spectrum of moaning-associated disorders.