High-dose intravenous immunoglobulin therapy for myasthenia gravis

The objective of this open, retrospective study was to investigate whether intravenous immunoglobulin (IVIg) could induce a clinically obvious improvement in patients with generalized myasthenia gravis (MG), as judged by MG functional status. Fourteen patients with generalized MG were treated during at least one episode with 0.4 g IVIg per kilogram body weight per day for 5 consecutive days. Patients with confounding variables were excluded; this left 11 patients (16 episodes) to be further analysed. We defined improvement as at least a one-step improvement in MG functional status (according to the University of Virginia’s Modification of Osserman’s classification). Of the treatment episodes, 56% were classified as positive responses. If improvement occurred, onset of improvement started after 3 (1–12) days and peak effect was reached after 7 (4– 30) days (median and range). All four patients who required artificial ventilation could be weaned from it 8.5 (6–11) days after the start of IVIg (median and range). Of the patients treated on two occasions, only one patient had a positive response during both. In MG functional status 5, improvement was observed during five of seven episodes. None of the patients with MG functional status 3 responded. Patients with an acute relapse of MG seemed to respond equally well to IVIg compared with patients with subacute deterioration/ chronic-static state (50% versus 60%). The MG functional status at the start of IVIg and on the day of maximal improvement was compared for all episodes together, and significant improvement was noted (P = 0.0052). We did not see any serious side-effects after IVIg treatment. This retrospective analysis suggests that high-dose IVIg is an effective therapy in some patients with deterioration of generalized MG. If improvement occurs, it starts within a few days of the onset of IVIg and the effect seems to peak within 2 weeks. Received: 4 March 1997 Received in revised form: 28 August 1997 Accepted: 1 September 1997