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Early Aggressive Therapy for Myasthenia Gravis
Abstract & Commentary
By Michael Rubin, MD, Professor of Clinical Neurology, Weill Cornell Medical College. Dr. Rubin reports no financial relationships relevant to this field of study.
Synopsis: Early plasmapheresis and high-dose intravenous corticosteroids may be as effective as conventional oral corticosteroid therapy in the treatment of myasthenia gravis.
Source: Nagane Y, Suzuki S, Suzuki N, Utsugisawa K. Early aggressive treatment strategy against myasthenia gravis. Europ Neurol 2011;65:16–22 DOI: 10.1159/000322497.
Can early aggressive therapy (EAT) improve the long-term outcome of newly diagnosed myasthenia gravis (MG)? EAT was defined as a single plasma exchange, followed by 1 g intravenous methylprednisolone, immediately, and on the two subsequent mornings, followed by low-dose oral corticosteroids to maintain clinical improvement. To assess the efficacy of EAT, a retrospective analysis of patients with new-onset, generalized MG, was undertaken, and patients treated with the EAT protocol were compared to new-onset MG patients treated with high-dose oral prednisone alone, administered in a conventional fashion (10-20 mg per day and slowly increasing the dose on a weekly basis by 5-10 mg per day, to a maximum of 1 mg/kg per day). Patients were maintained on this dose until maximum improvement was appreciated. Prednisone then was tapered, on a monthly basis, by 20% of the previous daily dose. Pyridostigmine bromide was given as needed. Inclusion criteria required having received treatment for at least 1 year with continued follow-up, and availability of complete medical records, including clinical severity scores, comprising the quantitative MG (QMG) score or the quantified MG strength (QMGS) score. Exclusion criteria for EAT included having received plasma exchange, intravenous immunoglobulin, or high-dose methylprednisolone in the absence of myasthenic crisis; not having received maximum prednisone dosage due to side effects; or having received oral prednisone for uncontrolled symptoms. Statistical analysis was provided using the Mann-Whitney U test for continuous variables, the X2 test for categorical variables, and the Wilcoxon signed-ranks test, with P < 0.05 considered statistically significant.
a.ong 410 new-onset MG patients seen at Hanamaki General Hospital and Keio University Hospital in Tokyo, Japan, between April 1995 and November 2009, 281 were diagnosed with generalized MG, of which 76 received EAT and 81 received high-dose oral prednisolone therapy. Of these, 49 EAT patients and 22 high-dose oral prednisolone patients satisfied entry criteria and served as the basis for this retrospective study. EAT patients demonstrated marked early improvement with lower subsequent oral prednisone dosage requirements compared to the high-dose prednisolone group, and minimal manifestations of disease were seen in the EAT group at 1 year and at final observation at 4.1 years. Both new-onset diabetes and moon facies were less frequent in the EAT group but additional short-term hospitalizations were required in this group for additional EAT to maintain remission. EAT may have some advantages over high-dose oral prednisone but these may be outweighed by the disadvantages of requiring repeated hospitalizations. As a retrospective study, the above findings need to be replicated in a prospective, randomized treatment trial comparing the two regimens.
Patients with generalized myasthenia also benefit from thymectomy, regardless of whether a hyperplastic or atrophic thymus is present.1 Among 175 myasthenia patients who underwent trans-sternal thymectomy between 1990 and 2004, 128 had hyperplastic and 47 had atrophic thymus glands. Median time to remission was similar in both groups (4.8 vs. 4.9 years) but median time to clinical improvement was 1 year longer (P = 0.005) in the atrophic thymus group, which also demonstrated more ectopic thymus in the anterior mediastinum. Both hyperplastic and atrophic thymus tissue exhibited increased B-cell activating factor receptor, CD19, and CD21. Thymectomy is warranted for MG patients even in the presence of an atrophic thymus.
1. Chen Z, Luo H, Peng Y, et al. Comparative clinical features and immune responses after extended thymectomy for myasthenia gravis in patients with atrophic versus hyperplastic thymus. Ann Thorac Surg 2011;91:212-218.