Encephalopathy associated with anti-IgLON5 antibody: report of three cases

Abstract

Objective To report the clinical and paraclinical features of a case series with anti-IgLON5 antibody related encephalopathy. Methods One hundred and fifty patients with sleep disorders and subacute or chronic onset of movement disorders, parkinsonism or bulbar palsy were included. The serum and cerebrospinal fluid specimens of these patients were screened for anti-IgLON5 antibody. The clinical and paraclinical features of patients with seropositive anti-IgLON5 antibody were summarized. Results Three patients with seropositive anti-IgLON5 antibody were identified, with one female and two males. The onset age ranged from 61 to 64 years. Case 1 presented with symptoms of involuntary movement, unsteady walk and insomnia; case 2 with symptoms of insomnia, sleep behavioral disorder, psychiatric behavior and dysphagia; case 3 with symptoms of insomnia, sleep behavioral disorder, dysarthria, and tremor. When examined by polysomnography, obstructive sleep apnea syndrome was revealed in cases 1 and 2, serious insomnia was found in cases 2 and 3, and sleep behavioral disorder was revealed in case 2. All three patients were positive for HLA-DQB1*0501, and cases 2 and 3 were positive for HLA-DRB1*1001. All three patients received immunotherapy and only one patient (case 1) responded well to immunotherapy with intravenous immunoglobulin, steroids and mycophenolate mofetil. Conclusions Anti-IgLON5-related encephalopathy is a rare disease with distinct clinical features of both autoimmune disorders and neurodegeneration disorders. These patients may benefit from immunotherapy. Key words: Autoantibodies; Tauopathy; Brain diseases; Sleep disorders; Immunotherapy