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.