Leucine-Rich Glioma-Inactivated Protein 1 Antibody-Positive Polyradiculopathy Associated with Epstein-Barr Virus Infection.

Epstein-Barr virus (EBV) has been associated with a plethora of neurological manifestations including polyneuropathy and polyradiculopathy. A 27-year-old man with a recent upper respiratory system infection presented with difficulty in walking. His neurological examination revealed reduced muscle strength in both proximal and distal lower limb muscles without sensory and autonomic signs. Needle electromyography showed abnormal spontaneous activity and reduced recruitment of motor units in muscles innervated by multiple lumbo-sacral roots. Cerebrospinal examination showed increased protein levels with normal cell counts. While spinal MRI was normal, whole-body CT and PET examination showed disseminated lymph node enlargement. Anti-EBV viral capsid antigen and anti-nuclear antigen IgG but not IgM was positive, whereas EBV PCR was negative in blood. Analysis of inguinal lymph node biopsy showed reactive lymphoid hyperplasia and EBV DNA. Leucine-rich glioma-inactivated protein 1 (LGI1) antibody was found in serum but not in CSF. All clinical, imaging, and electrophysiological findings improved following steroid and intravenous immunoglobulin treatment. These findings suggested the acute involvement of lumbo-sacral spinal roots and/or motor neurons. Purely motor polyradiculopathy has been reported in both EBV-positive and LGI1 antibody-positive patients, and EBV infection is known to precede different autoimmune manifestations. Whether EBV infection may trigger LGI1 autoimmunity and cause involvement of spinal motor roots and/or motor neurons needs to be further studied.