AQP4 and acute transverse myelitis: Phase 1b open-label trial in patients with AQP4 + or – NMOSD presenting with acute transverse myelitis or optic neuritis (n = 10). Addition of C1-INH to steroids in acute relapse was associated with decreased EDSS at discharge and 30-day follow-up. Phase 1b open-label trial in patients with AQP4 + or – NMOSD presenting with acute transverse myelitis or optic neuritis (n = 10). Addition of C1-INH to steroids in acute relapse was safe but efficacy data is limited (62).