Clinical and electrophysiological characteristics of peripheral neuropathy in autoimmune glial fibrillary acidic protein astrocytopathy: an observational study and literature review

Abstract

Background: The phenotype of peripheral neuropathy (PN) associated with glial fibrillary acidic protein-immunoglobulin G (GFAP-IgG) has not been well described. Objectives: The aim of this study was to report the frequency, clinical, and electrophysiological characteristics of PN in GFAP-IgG-positive patients. Design: This study is a single-center retrospective observational study. Data Sources and methods: GFAP-IgG-positive patients with PN were retrospectively identified from the Huashan Hospital Autoimmune Encephalitis Cohort between 2017 and 2021. Eight patients who presented with PN from other published studies were also included in the analysis. The clinical and electrophysiological characteristics of GFAP-IgG-related PN were described. Results: A total of 21 (31%) patients (7 females, 14 males; M age : 42 ± 16 years) from a cohort of 68 GFAP-IgG-positive patients presented with PN. Twenty of 21 patients had symmetrical weakness. Sensory and autonomic symptoms were present in 16 and 15 patients, respectively. Lower extremities were the most frequently involved regions for both motor (20/21) and sensory (15/21) symptoms. Moreover, 13 patients (4 females, 9 males; M age : 43 ± 13 years) had electrodiagnostic study data, and 12 of 13 patients had abnormal findings. Regarding clinical features, motor nerve fibers were predominantly involved (12/13), and symmetric lower extremities (12/13) were the most commonly affected regions. Axonal neuropathy is the typical underlying pathophysiologic process of PN. All 21 patients responded to immunotherapy. However, four patients with tetraplegia had poor outcomes, and PN was the major determinant of their long-term disability. Most cases (6/8) from the literature presented with similar clinical and electrophysiological features to those from our cohort. Conclusion: Peripheral nerves could be involved in autoimmune GFAP astrocytopathy. Predominant motor axonal neuropathy mainly involving the lower extremities is the most common PN phenotype in this disorder. GFAP-IgG-related PN is responsive to immunotherapy. Registration: Chinese Clinical Trial Registry: ChiCTR2000029115 ( http://www.chictr.org ).