Expanding clinical spectrum of Caspr2 antibody-associated disease: warning on brainstem involvement and respiratory failure.

We report the case of a 68-year-old man who presented with ataxia, insomnia, rapidly developing cognitive decline, seizures and small vessel vasculitis. Both serum and cerebro-spinal fluid samples showed positive titre of anti-CASPR2 antibodies. Limbic encephalitis was diagnosed and immunomodulatory therapy was started with benefit. After one-year follow-up, the patient relapsed with a difficult-to-treat respiratory failure, brainstem involvement, neuropathic pain and severe dysautonomia with esophageal dysfunction. We discuss here the occurrence of life-threating complication such as respiratory dysfunction in CASPR2 limbic encephalitis. Furthermore, we showed different phenotype and treatment response during disease onset compared to relapse. This case expands the clinical spectrum of anti-CASPR2 associated disease, underlying the need for respiratory and sleep evaluation.