Clinical trial of plasma exchange and high-dose intravenous immunoglobulin in myasthenia gravis. Myasthenia Gravis Clinical Study Group. Immunoglobulin treatment versus plasma exchange in patients with chronic moderate to severe myasthenia gravis. [Long-term effects of plasma exchange in myasthenia. Results of a randomized study].
We have conducted a trial to randomly assess the efficacy and tolerance of intravenous immunoglobulin (i.v.Ig) or plasma exchange (PE) in myasthenia gravis (MG) exacerbation and to compare two doses of i.v.Ig. Eighty-seven patients with MG exacerbation were randomized to receive either three PE (n = 41), or i.v.Ig (n = 46) 0.4 gm/kg daily further allocated to 3 (n = 23) or 5 days (n = 23). The main end point was the variation of a myasthenic muscular score (MSS) between randomization and day 15. The MSS variation was similar in both groups (median value, +18 in the PE group and +15.5 in the i.v.Ig group, p = 0.65). Similar efficacy, although slightly reduced in the 5-day group was observed with both i.v.Ig schedules. The tolerance of i.v.Ig was better than that of PE with a total of 14 side effects observed in 9 patients, 8 in the PE group and 1 in the i.v.Ig group (p = 0.01). Although our trial failed to show a pronounced difference in the efficacy of both treatments, it exhibited a very limited risk for i.v.Ig. i.v.Ig is an alternative for the treatment of myasthenic crisis. The small sample sizes in our trial, however, could explain why a difference in efficacy was not observed. Further studies are needed to compare PE with i.v.Ig and to determine the optimal dosage of i.v.Ig. The purpose of this study was to compare the efficacy of high-dose intravenous immunoglobulin (IVIG) treatment with plasma exchange in patients suffering from moderate to severe myasthenia gravis (MG) in a stable phase. There are no controlled studies comparing IVIG with plasma exchange in patients who despite immunosuppressive treatment have persistent incapacitating MG symptoms. This was a controlled crossover study. Twelve patients with generalized moderate to severe MG on immunosuppressive treatment for at least 12 months were included. The patients were evaluated clinically using a quantified MG clinical score (QMGS) before and at follow-up visits after each treatment. One week after the treatments, the patients who received plasma exchange treatment showed a significant improvement in QMGS compared to baseline but although some improvement was seen after IVIG this did not reach statistical significance. Four weeks after both plasma exchange and IVIG treatments, there was a significant improvement in QMGS compared to baseline. One week and 4 weeks after treatment, no significant difference between the 2 treatments was found. Both treatments have a clinically significant effect 4 weeks out in patients with chronic MG, but the improvement has a more rapid onset after plasma exchange than after IVIG. A randomized study was carried out in 14 myasthenia patients to compare the long-term effects of two therapeutic regimens. Group I patients received prednisone 1 mg/kg/24 h for one month, then in decreasing dosage; in case of failure at the end of the first month, cyclophosphamide 2 mg/kg/24 h was added to the prednisone treatment. Group II patients received the same treatment associated with 3 plasma exchanges over a 10-day period; these were continued, if required, at the rate of once a week. The minimum follow up was one year. The results (greater improvement in muscular strength and vital capacity) were better after one month in group I and thereafter similar in both groups. However, the mean daily dose of prednisone was higher in Group I. The number of exacerbations of myasthenia was greater in group II (11 versus 2 in group I over a 24-months period). The mean fall in anti-R Ach ab was about the same in both groups. This study confirms the rapid effectiveness of plasma exchanges and their value in severe myasthenia. The higher incidence of exacerbations in Group II was probably due to a rebound phenomenon and points to the need for combined immuno-suppressive treatment.
No adequate RCTs have been performed to determine whether plasma exchange improves the short- or long-term outcome for chronic myasthenia gravis or myasthenia gravis exacerbation. However, many studies with case series report short-term benefit from plasma exchange in myasthenia gravis, especially in myasthenic crisis. In severe exacerbations of myasthenia gravis one RCT did not show a significant difference between plasma exchange and intravenous immunoglobulin. Further research is need to compare plasma exchange with alternative short-term treatments for myasthenic crisis or before thymectomy and to determine the value of long-term plasma exchange for treating myasthenia gravis.