Anti-contactin-associated protein-like 2 antibody autoimmune encephalitis with rapidly progressive parkinsonism: a case report and literature review.

objectiveAnti-contactin-associated protein-like 2 (CASPR2) antibody encephalitis is a rare autoimmune encephalitis (AE) that often presents with epilepsy, cognitive dysfunction, peripheral neuropathy, autonomic nerve damage, and ataxia. Parkinsonism is often observed in neurodegenerative diseases but progresses slowly, and rapidly progressive parkinsonism is rare. Given that it is a curable parkinsonism, identifying and providing early immunotherapy is crucial.

methodsWe reported a patient initially presenting with anxiety and depression, whose symptoms were relieved following mood regulation treatment. After discontinuation of the mood-regulating drugs, mood disorders recurred, accompanied by parkinsonism. The onset of parkinsonism was subacute (< 3-month disease course), and progression was rapid. After immunotherapy, all symptoms disappeared completely. We reviewed all relevant literature on anti-CASPR2 antibody encephalitis with parkinsonism.

resultsOur literature review revealed three cases (including our patient): two male and one female, ranging in age from 48 to 72 years. All patients had parkinsonism, generalized tonic-clonic seizures, and hyponatremia. Three patients had anti-CASPR2 antibody positivity in the serum, and one patient had anti-CASPR2 antibody positivity in the CSF. All three patients were treated with anti-epileptic drugs and intravenous steroid pulse therapy, followed by oral steroid therapy, symptoms improved.

conclusionParkinsonism can be easily misdiagnosed as a neurodegenerative disease, especially during the early stages. In patients with parkinsonism, treatable diseases should be considered in addition to neurodegenerative diseases. In clinical practice, anti-CASPR2 antibody encephalitis should be considered if rapidly progressing parkinsonism is encountered after ruling out common etiologies.