A Novel Limited-Dose C5 Inhibitor Add-On as Rescue Therapy for Refractory NMOSD Attacks: A Practical Alternative to Conventional Multi-Dose Regimens

This study evaluated the efficacy and safety of limited-dose eculizumab as rescue therapy for acute neuromyelitis optica spectrum disorder (NMOSD) attacks refractory to first-line treatment. Eight patients (six aquaporin-4 antibody seropositive and two seronegative) with incomplete responses to intravenous methylprednisolone with or without plasma exchange received one to four weekly doses of eculizumab (900 mg). Six patients with severe attacks (median nadir Expanded Disability Status Scale/Visual Outcome Scale: 9.0/11.5) showed only minimal improvement after conventional therapy. The remaining two, although not meeting severe criteria, also responded poorly. Add-on limited-dose eculizumab produced substantial neurological recovery: in myelitis, median Expanded Disability Status Scale improved from 8.5 to 3.5 at three months; in optic neuritis, median Visual Outcome Scale improved from 8.5 to 5.0. The proportion achieving marked-to-moderate improvement rose from 14.3% at one month to 85.7% at three months. Both seronegative patients responded favorably. Treatment was well tolerated, with no serious adverse events. These findings indicate that limited-dose eculizumab is an effective and safe option for accelerating recovery in refractory acute NMOSD attacks and may serve as a practical bridging strategy to long-term immunosuppression.