Acute Motor Axonal Neuropathy (AMAN) Variant of Guillain-Barré Syndrome Following Influenza Vaccination as the Initial Presentation of Systemic Lupus Erythematosus With Lupus Nephritis.

Guillain-Barré syndrome (GBS) is an acute immune-mediated polyradiculoneuropathy that commonly follows infections and, less frequently, vaccination. Although peripheral nervous system involvement may occur in systemic lupus erythematosus (SLE), GBS as the initial manifestation of SLE is uncommon, particularly in adolescents. Herein, we describe the case of a previously healthy 17-year-old Saudi female patient who presented with rapidly progressive bilateral lower-limb weakness, areflexia, bilateral foot drop, and urinary retention occurring approximately two weeks after an upper respiratory tract infection and one week after receiving an influenza vaccine. Nerve conduction studies and electromyography demonstrated a demyelinating-axonal polyneuropathy compatible with the acute motor axonal neuropathy (AMAN) variant of GBS. During hospitalization, she was also found to have inflammatory ascites, pleural effusions, Coombs-positive anemia, proteinuria, positive antinuclear antibodies, markedly elevated anti-double-stranded DNA (anti-dsDNA) antibodies, and hypocomplementemia. Renal biopsy confirmed minimal mesangial lupus nephritis (ISN/RPS Class I). Magnetic resonance imaging of the brain and entire spine was unremarkable. The patient received intravenous immunoglobulin, corticosteroids, hydroxychloroquine, and supportive treatment. Although cyclophosphamide was considered because of concerns regarding neuropsychiatric lupus, it was ultimately withheld. The patient achieved complete neurological recovery without cyclophosphamide. This case highlights the occurrence of AMAN variant GBS shortly after influenza vaccination as the initial presentation leading to the diagnosis of SLE and lupus nephritis.