Clinical analysis and literature review of anti-contactin-associated protein 2 antibody- associated encephalitis

Abstract

Objective To summarize the clinical characteristics of patients with anti- contactin - associated protein 2 (CASPR2) antibody-associated encephalitis. Methods and Results Total 13 patients diagnosed and treated for anti-CASPR2 antibody-associated encephalitis at The Third Affiliated Hospital, Sun Yat-Sen University from August 2017 to August 2022 were collected. Initial manifestations: 9 patients exhibited limbic system symptoms, 2 patients presented with peripheral nerve symptoms (both with limb pain), one patient had cerebellar ataxia, and one patient had limb weakness. Anti - CASPR2 antibody detection: all the 13 patients underwent serum anti- CASPR2 antibody testing, which was positive in all cases; 10 patients underwent cerebrospinal fluid (CSF) anti-CASPR2 antibody testing, with 5 cases testing positive; 3 patients had other concomitant positive autoimmune antibodies. Head MRI examination: among the 13 patients, 2 patients head T2 - FLAIR showed hyperintensity in the medial temporal lobes either unilaterally or bilaterally; 2 patients had cerebral microbleeds. Treatment: 2 patients were treated only with steroids, 4 patients received only intravenous immunoglobulin (IVIg), 5 patients were treated with steroids and IVIg, one patient received rituximab only, and one patient received a combination of IVIg, steroids, protein A immunoadsorption and rituximab. Follow-up: follow-up ranged from 1-5 years, with 2 patients lost to follow - up; one patient relapsed after self - discontinuation of medication and achieved a modified Rankin Scale (mRS) score of 0 after treatment; of the remaining 10 patients, one patient showed no symptom improvement, one patient had some symptoms preventing normal life, 6 patients had normal life, 2 patients died. Conclusions Anti-CASPR2 antibody-associated encephalitis has complex clinical characteristics, and serum antibody testing is crucial for diagnosis.

Keywords

• encephalitis
• autoimmune diseases
• contactins
• autoantibodies
• immunotherapy