Acute onset of anti-IgLON5 disease with meningeal enhancement: a case report.

Background: Anti-IgLON5 disease is a relatively rare autoimmune disease of the nervous system. The clinical course of this disease is generally chronic and progressive, exhibiting heterogeneity in clinical presentation and the lack of specific imaging features. We now report a case of a Anti-IgLON5 antibody-positive patient demonstrated two distinctive features. Firstly, the onset was marked by acute encephalopathy symptoms, including fever, with consciousness disturbance as the initial manifestation. Secondly, imaging studies revealed multiple lesions within the meninges and intracranial regions, characterized by extensive thickening and enhancement of the dura mater.

Case Presentation: A previously healthy 78-year-old male patient presented with impaired consciousness and was admitted to the hospital. Brain MRI demonstrated abnormal signal located in the bilateral basal ganglia, frontal and parietal lobes. Post-contrast enhancement demonstrated thickening and enhancement of the dura mater in the bilateral frontal regions, along with mild enhancementin the cortical areas of the bilateral temporal lobes. Cerebrospinal fluid (CSF) analysis indicated the presence of oligoclonal bands in both serum and CSF, with a higher count in the CSF compared to serum. IgG antibodies against IgLON5 were detected in serum and CSF at a titer of 1:100. CSF concentrations of total Tau protein (t-Tau) and phosphorylated Tau protein (p-Tau) were normal. In conjunction with a positive serum and CSF IgLON5 antibody and exclusion of other diseases, diagnosis of anti-IgLON5 disease was made. Symptoms resolved completely after intravenous methylprednisolone and immunoglobulin therapy were administered. At 3-week follow-up the small patchy abnormal signal in the bilateral basal ganglia, frontal and parietal lobes have resolved. Additionally, post-contrast imaging reveals the absence of the previously noted abnormal dural enhancement. and there was no recurrence 18 months after the onset of the disease.

Conclusions: Anti-IgLON5 disease is a heterogeneous disorder characterized by a wide spectrum of clinical manifestations. IgLON5 encephalopathy characterized mainly by symptoms of acute neurological symptoms and MRI evidence of meningeal enhancement has not been reported previously. The appropriate diagnostic strategy should encompass a thorough clinical evaluation, testing for anti-IgLON5 antibodies in both CSF and serum, as well as HLA genotyping. Timely diagnosis and early Intravenous methylprednisolone and/or IVIG therapy are beneficial in improving prognosis and preventing recurrence.