Factors influencing outcome of prednisone dose reduction in myasthenia gravis

Effect of Initial Prednisone Dosing on Ocular Myasthenia Gravis Control

BACKGROUND

Ocular myasthenia is an autoimmune condition that results in double vision or ptosis. It often requires treatment with prednisone for immunosuppression, but there have been no prospective trials to help clinicians determine ideal dosing.

METHODS

This was a retrospective study comparing myasthenia symptom control at 1 month between patients treated with a maximum daily equivalent dose of prednisone less than 20 mg (low-dose group) vs 20 mg or more (medium-dose group).

RESULTS

Thirty-nine patients were identified: 19 patients in the low-dose group with mean maximum daily dose of 10 mg and 20 patients in the medium-dose group with a mean maximum daily dose of 29 mg. The low-dose group had 75% controlled or significantly improved at 1 month, and the medium-dose group had 74% controlled or significantly improved at 1 month, P = 0.94. The overall seropositivity rate was 64%, with 84% of the antibody-positive group being controlled or significantly improved at 1 month and 57% of the antibody-negative group being controlled or significantly improved at 1 month, P = 0.07, and no difference in prednisone dosing between the 2 groups.

CONCLUSION

Based on the results of this small retrospective study, it seems initial treatment for ocular myasthenia gravis with a mean maximum daily prednisone dose of 10 mg is similarly effective compared with mean maximum daily dose of 29 mg for control at 1 month.

Maintenance immunosuppression in myasthenia gravis, an update

Therapies for myasthenia gravis (MG) include symptomatic and immunosuppressive/immunomodulatory treatment. Options for immunosuppression include corticosteroids, azathioprine, mycophenolate mofetil, cyclosporine, tacrolimus, methotrexate, rituximab, cyclophosphamide, eculizumab, intravenous immunoglobulin, subcutaneous immunoglobulin, plasmapheresis, and thymectomy. The practical aspects of long-term immunosuppressive therapy in MG are critically reviewed in this article. Application of one or more of these specific therapies is guided based on known efficacy, adverse effect profile, particular disease subtype and severity, and patient co-morbidities.

Intravenous immunoglobulin as monotherapy for myasthenia gravis during pregnancy

INTRODUCTION

Pregnant women with myasthenia gravis (MG) are at increased risk of complications and adverse outcomes, including the teratogenic effects of many drugs used to treat MG women of childbearing age. The effectiveness of intravenous immunoglobulins (IVIg) on other autoimmune mediated diseases has been extensively reported in recent years, although little is known about the role of IVIg in the treatment of MG during pregnancy. We designed this study to determine the effectiveness of IVIg as monotherapy during pregnancy for women with MG.

MATERIAL AND METHODS

Five pregnant MG patients (mean age at delivery 36.4years, SD 5.8, range 29.4-45.2) were studied in 2013-14. Their treatment was switched to monthly IVIg cycles 2months before the pregnancy. Follow-up included monthly neurological QMG throughout the pregnancy and postpartum, obstetrical monitoring during monthly visits in the first two trimesters of the pregnancy, fortnightly visits between week 32 and week 36, and weekly visits after 36weeks, and neonatal follow-up after delivery.

RESULTS

We observed no exacerbations during pregnancy, delivery or post-partum. The mean QMG score at baseline (before pregnancy) was 7.4 points in five women with generalized forms of MG. The maximum mean value reached during pregnancy was 8.6 points. The mean pregnancy duration was 38 w+5 d. No infant with transient neonatal myasthenia gravis.

CONCLUSIONS

These results suggest that monotherapy with IVIg during pregnancy in MG patients could be promising, although confirmation is required in studies with larger populations.

Benefits of Comprehensive Rehabilitation Therapy in Thymectomy for Myasthenia Gravis: A Propensity Score Matching Analysis

OBJECTIVE

To demonstrate the effectiveness of a comprehensive program of rehabilitation therapy in patients undergoing thymectomy for myasthenia gravis (MG).

DESIGN

From 2005 to 2010, 46 consecutive patients affected by MG underwent a rehabilitation program both before and after thymectomy. We matched each patient with a "control patient" who underwent thymectomy within the period 1999 to 2004 with no preoperative rehabilitation, who had the closest propensity score matching.

RESULTS

All patients but 2 were able to complete the intended program. Eighteen patients (41%) experienced mild fatigue (>25 at MG quantitative score). Propensity score selected a group of 17 patients for the matching process. The group of patients who underwent the rehabilitation program showed significant preoperative improvement associated with a reduced operative risk, a decreased early postoperative morbidity, a lower rate of postoperative intensive care unit needed (12% vs 35%; P = 0.01) and a shorter hospital stay (3 vs 5 days; P = 0.04). After the expected perioperative decline, all major myasthenic outcomes demonstrated a significant faster recovery at 3 months. Complete stable remission did not reveal significant differences.

CONCLUSIONS

Exercise is not necessarily a contraindication in MG, and rehabilitation can be safely performed before and after thymectomy, reducing operative risks and decreasing recovery time.

TO CLAIM CME CREDITS

Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCMECME OBJECTIVES: Upon completion of this article, the reader should be able to do the following: (1) appreciate the benefits of physical therapy in individuals with myasthenia gravis; (2) describe the benefits of physical therapy on postoperative morbidity in myasthenia gravis patients who undergo thymectomy; and (3) incorporate appropriate rehabilitation into the treatment plan of patient with myasthenia gravis.

LEVEL

AdvancedACCREDITATION: The Association of Academic Physiatrists is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.The Association of Academic Physiatrists designates this activity for a maximum of 1.5 AMA PRA Category 1 Credit(s)™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

Glucocorticoids in myasthenia gravis - if, when, how, and how much?

Glucocorticoids (GC) are the most commonly used immune-directed therapy in myasthenia gravis (MG). However, to date, GC have not proven their effectiveness in the setting of a randomized clinical trial that complies with currently accepted standards. The rationale for the use of GC in MG is the autoimmune nature of the disease, which is supported by consistent positive results from retrospective studies. Well-defined recommendations for treatment of MG with GC are lacking and further hampered by inter- and intra-individual differences in the disease course and responses to GC treatment. Uncertainties concerning GC treatment in MG encompass the indication for treatment initiation, exact dosage, dose adjustment in specific conditions (e.g., pregnancy, thymectomy), mode of tapering, and surveillance of adverse events (AE). This review illustrates the mode of action of GC in the treatment for MG, presents the currently available data on GC treatment in MG, and attempts to translate the currently available information into clinical recommendations.

Extended transsternal thymectomy for the treatment of ocular myasthenia gravis

BACKGROUND

The optimal treatment for ocular myasthenia gravis (OMG) remains controversial. We conducted a review of the long-term clinical outcomes of Chinese patients with OMG after extended transsternal thymectomy (ETT) to determine the efficacy of this procedure as a treatment for OMG.

METHODS

We reviewed the cases of 115 consecutive patients with OMG who underwent ETT at our Myasthenia Gravis Research Center between January 2006 and December 2008. Extended transsternal thymectomy was done in patients who had thymoma, resistance to pyridostigmine therapy, or relapse after immunosuppressive therapy. The patients' postoperative responses were defined as strict complete remission (SCR), consisting of an asymptomatic status without medication for more than 12 months; general complete remission (GCR), consisting of an asymptomatic status with low-dose single-drug therapy or without medication for more than 12 months; or improvement, consisting of fewer symptoms or less of a need for medication than before surgery.

RESULTS

The overall complication rate was 7.8%. None of the patients experienced a myasthenic crisis, progression to generalized myasthenia gravis, or mortality. Hyperplasia of the thymus was present in 106 of the 115 patients (92.2%). Among 110 patients on whom follow-up was done postoperatively, 29 (26.4%) were in SCR, 64 (58.2%) showed improvement, 7 (6.4%) remained unchanged, and 10 (9.1%) had a worsening of their conditions. Kaplan-Meier analysis revealed rates of GCR of 41.8% at 24 months and 47.3% at 48 months after surgery, and rates of SCR of 24.5% at 24 months and 26.4% at 48 months. Both univariate analysis and multivariate Cox regression analysis revealed that only preoperative duration of illness was positively associated with GCR (p < 0.001).

CONCLUSIONS

The results of the review indicate that ETT is a safe and effective treatment for OMG, especially in patients with illness of shorter duration.

Extended transcervical thymectomy: the ultimate minimally invasive approach

The ideal operative technique for thymectomy in myasthenia gravis remains controversial. Most surgeons perform thymectomy through median sternotomy; more recently, thoracoscopic and robotic approaches have been described. "Extended transcervical thymectomy" is an out-patient procedure that appears less morbid and costly than other approaches. It allows a complete extracapsular thymic resection. Kaplan-Meier complete stable remission rates after transcervical thymectomy are 33% and 35% at 3 and 6 years (higher including patients remaining on single-drug immunosuppression). The major surgical complication rate is 0.7%. We believe that this less morbid and less costly operation is a very reasonable choice in the surgical treatment of myasthenia gravis.

Extended transcervical thymectomy in the treatment of myasthenia gravis

The ideal operative technique for thymectomy in myasthenia gravis remains controversial. Most surgeons perform thymectomy via median sternotomy, some supplementing this with an even more extensive mediastinal and cervical dissection designed to remove all areas of possible ectopic thymic tissue. We and others have advocated a transcervical approach that is less morbid and costly than sternotomy approaches. The transcervical approach allows a complete extracapsular thymic resection, but it does not address all areas of potential ectopic thymic tissue. We have published our experience with 151 extended transcervical thymectomies (TCT). At mean follow-up of 53 months (complete follow-up in 97%), Kaplan-Meier estimates of complete stable remission were 33% and 35% at 3 and 6 years. If one includes patients who became asymptomatic but remained on low dose, single-drug immunosuppression as complete remissions (CRs), then the CR rates were 43% and 45% at 3 and 6 years. Longer term (mean 83 months) follow-up of the earliest 84 patients in the series showed preserved CR rates. On multivariate analysis, only preoperative Osserman Class (group mean 2.3) was significantly associated with improved CR rate. These results were obtained with a major operative complication rate of 0.7% and minor complication rate of 6.6%, and nearly every operation was performed without the need for overnight hospital admission. We believe that these response rates following TCT are sufficiently similar to those following transsternal techniques of thymectomy to allow us to recommend this less morbid and less costly operation as an eminently reasonable choice in the surgical treatment of myasthenia gravis.

Outcomes after 151 extended transcervical thymectomies for myasthenia gravis

BACKGROUND

The ideal operative technique for thymectomy in myasthenia gravis (MG) remains controversial. We present the largest series of extended transcervical thymectomy to provide outcomes data to compare with transsternal procedures.

METHODS

A retrospective chart review/interview was made of 164 patients operated upon from 1992 to 2004. Complete remission (CR) was defined as asymptomatic off medication for 6 months or asymptomatic on low-dose single-drug therapy (< or = 10 mg/d prednisone or < or = 150 mg/d azathioprine). A modified Osserman classification based upon the Myasthenia Gravis Foundation of America quantitative disease severity score was employed.

RESULTS

The overall complication rate was 7.3%, and nearly all procedures were outpatient. Mean age at surgery was 43 years, and mean preoperative Osserman class was 2.3 (21% class 1; 39% class 2; 28% class 3; 12% class 4). Mean length of follow-up was 53 months. Mean postoperative Osserman class was 1.0. Nineteen percent of patients failed to improve. The crude cumulative CR rate was 37% (n = 58). Kaplan-Meier estimates of CR were 43% and 45% at 3 and 6 years, respectively. On multivariate analysis, only preoperative disease severity was significantly (inversely) associated with Kaplan-Meier CR rates. Longer-term follow-up (83 months) of only the earlier patients shows preserved CR rates (46%).

CONCLUSIONS

This largest series of extended transcervical thymectomy for MG confirms that the 5-year Kaplan-Meier CR rate is comparable with that obtained after transsternal procedures. Patients with less severe disease have higher CR rates. Complete responses are durable, as the CR rate remains stable with extended follow-up.

Treatment review and update for myasthenia gravis

Myasthenia gravis (MG) is the best understood autoimmune disease, with well-characterized humoral and cellular effector mechanisms. It is not surprising, therefore, that immunotherapies play a key role in the management of MG. Significant progress has been made over the last few decades in the treatment of patients with MG, and the number of effective avenues of therapy continue to increase. In this review, we provide an update on management options in MG, highlighting recent literature on both traditional and more novel approaches.

Clinical evaluation and management of myasthenia gravis

Myasthenia gravis (MG) is a syndrome of fluctuating skeletal muscle weakness that worsens with use and improves with rest. Eye, facial, oropharyngeal, axial, and limb muscles may be involved in varying combinations and degrees of severity. Its etiology is heterogeneous, divided initially between those rare congenital myasthenic syndromes, which are genetic, and the bulk of MG, which is acquired and autoimmune. The autoimmune conditions are divided in turn between those that possess measurable serum acetylcholine receptor (AChR) antibodies and a smaller group that does not. The latter group includes those MG patients who have serum antibodies to muscle-specific tyrosine kinase (MuSK). Therapeutic considerations differ for early-onset MG, late-onset MG, and MG associated with the presence of a thymoma. Most MG patients can be treated effectively, but there is still a need for more specific immunological approaches.

Myasthenia gravis and Lambert-Eaton syndrome

Myasthenia gravis is a common autoimmune disorder characterized by the presence of pathogenic antibodies directed against the acetylcholine receptor. Patients present with variable degrees and distribution of fluctuating weakness at times life threatening. Clinical manifestations, establishment of diagnosis, the natural history of myasthenia gravis, and therapeutic options are herein reviewed. Far less common is Lambert-Eaton syndrome (the myasthenic syndrome), another autoimmune disorder due to the presence of antibodies directed against the PQ-type voltage-gated calcium channels. Clinical features and treatment options are summarized.

Myasthenia gravis

BACKGROUND

In myasthenia gravis (MG), the prototypic autoimmune disease, antibodies against acetylcholine receptors impair neuromuscular transmission and produce weakness. Although recognized for several hundred years, it has only been over the last three decades that effective treatments have become available for MG.

REVIEW SUMMARY

This review summarizes the principles of normal neuromuscular transmission, the clinical features of MG, and the tests available for its diagnosis. The current treatments for MG are discussed, including possible mechanisms of action and a discussion of potential adverse effects. When available, evidence-based justification for individual treatment options is given, and areas of controversy identified.

CONCLUSIONS

Significant improvements in the diagnosis and management of MG have been made over the last several decades. The available treatments either improve neuromuscular transmission directly, or suppress or modulate the pathogenic immune response in MG. Treatment is highly individualized and must take into account the severity of disease, the presence of other diseases, and the kinetics of response for the available treatments. This requires detailed knowledge of the mechanisms of action and possible adverse effects for each treatment. However, despite an optimistic outlook with modern treatment, the management of MG continues to be plagued by lack of efficacy in some, and significant adverse effects in most MG patients.

Immunosuppressive treatment of ocular myasthenia gravis

Myasthenia gravis (MG) is caused by autoantibodies against proteins at the neuromuscular junction. This autoimmune process leads to abnormal fatiguability and weakness of striated muscle. Ptosis and diplopia are among the most common manifestations of MG. The term "ocular MG" (OMG) as opposed to "generalised MG" (GMG) is used to define the clinical subtype of MG with isolated eye muscle weakness. Although OMG may appear to cause only moderate disability, it can significantly impair the patient's activities of daily living and progress to generalised myasthenia. Therefore, a clear management plan should be installed early in these patients. Since prospective treatment trials have not been performed, basic management strategies for OMG have to be deduced from retrospective studies, trials in GMG, and generally accepted clinical experience. Cholinesterase inhibitors are used in all types of MG, but are often less helpful in OMG. In the absence of thymoma, thymectomy is usually not considered in OMG, although a few studies have described histological abnormalities in thymuses from patients with OMG. Corticosteroids are of great short term benefit in most patients with OMG but potential adverse effects limit their long term use. Azathioprine is needed to reduce long term corticosteroid adverse effects, but this agent requires about 6 months to be effective. In summary, OMG has a good prognosis in most patients, with corticosteroids and azathioprine being the major treatment options. The challenges for the clinician are to recognise the condition despite the large number of differential diagnoses, to minimise the patient's symptoms using the therapies available and to carefully limit potentially hazardous therapeutic efforts, especially in mild or even uncertain cases.

Randomized trial of azathioprine or prednisone for initial immunosuppressive treatment of myasthenia gravis

Ten patients with myasthenia gravis were randomized to azathioprine or prednisone as the initial immunomodulating drug and followed for over one year. Of five patients randomized to azathioprine, two had idiosyncratic reactions and were immediately crossed over to prednisone. Two patients completed one year on azathioprine with little or no change in level of function and were crossed over to prednisone and showed greater improvement. The fifth patient on azathioprine had a satisfactory improvement and continued on it during the second year. All patients initially randomized to prednisone improved, but the degree varied among patients. The side effects of azathioprine were idiosyncratic reactions. The side effects of prednisone were manageable.

Ocular myasthenia gravis: response to long-term immunosuppressive treatment

OBJECTIVE

Ocular myasthenia gravis is a subtype of myasthenia gravis that causes relatively mild disability, but may convert into severe generalised muscle weakness. A universal management plan for ocular myasthenia gravis has not been established. This study was performed to determine the outcome of ocular myasthenia gravis with the currently available therapeutic options.

METHODS

Retrospective analysis of 78 patients with ocular myasthenia gravis with a mean disease duration of 8.3 (range 0.5-58.3) years.

RESULTS

In 54 patients (69%) symptoms and signs remained confined to the extraocular muscles during the observation period. The remaining 24 patients (31%) developed symptoms of generalised myasthenia gravis; 50% of them within two years, 75% within four years after onset. A somewhat reduced risk of generalisation was found in those with mild symptoms, normal repetitive nerve stimulation test, and low or absent antiacetylcholine receptor (AChR) antibodies at the time of diagnosis. Patients receiving immunosuppressive treatment (corticosteroids and/or azathioprine) rarely developed generalised myasthenia gravis (six of 50, 12%). Those without such treatment, usually due to uncertain diagnosis and late referral, converted into generalised myasthenia gravis significantly more often (18 of 28, 64%).

CONCLUSIONS

The prognosis of ocular myasthenia gravis is good. A conventional scheme with short-term corticosteroids and long-term azathioprine seems adequate to achieve remission in most patients. The proportion of patients developing generalised myasthenia gravis was smaller in this population compared with previously published groups (usually 50%-70%). Early immunosuppressive treatment is at least partially responsible for this finding. Thymectomy (performed here in 12 patients with an abnormal chest CT) also correlated with a good outcome, but had no apparent advantage over medical treatment alone.

Ocular myasthenia: a protean disorder

Ocular myasthenia is a localized form of myasthenia clinically involving only the extraocular, levator palpebrae superioris, and/or orbicularis oculi muscles. Ocular manifestations can masquerade as a variety of ocular motility disorders, including cranial nerve and gaze palsies. A history of variable and fatiguable muscle weakness suggests this diagnosis, which may be confirmed by the edrophonium (Tensilon) test and acetylcholine receptor antibody titer. Anticholinesterases, corticosteroids and other immunosuppressive agents, and other therapeutic modalities, including thymectomy and plasmapheresis, are used in treatment. As the pathophysiology of myasthenia has been elucidated in recent years, newer treatment strategies have evolved, resulting in a much more favorable prognosis than several decades ago. This review provides historical background, pathophysiology, immuno-genetics, diagnostic testing, and treatment options for ocular myasthenia, as well as a discussion of drug-induced myasthenic syndromes.

Ocular myasthenia gravis. A critical review of clinical and pathophysiological aspects

Myasthenia gravis (MG) is probably the best studied autoimmune disease caused by autoantibodies against the acetylcholine receptor (AChR) at the neuromuscular junction, subsequently leading to abnormal fatigability and weakness of skeletal muscle. Extraocular muscle weakness with droopy eyelids and double vision is present in about 90% of MG patients, being the initial complaint in about 50%. In approximately 20% of the patients the disease will always be confined to the extraocular muscles. The single most important diagnostic test is the detection of serum antibodies against AChR which is positive in 90% of patients with generalized MG, but only in 65% with purely ocular MG. Electromyographic studies and the Tensilon test are of diagnostic value in clear-cut cases, but may be equivocal in purely ocular myasthenia, especially the latter not rarely producing false-positive results. Treatment response to corticosteroids and anti-cholinesterase agents is satisfactory in many patients with ocular MG, however other immunosuppressive drugs may also be needed. Pathogenetically relevant steps of the underlying autoimmune process have been elucidated during the last few years; nevertheless a number of questions remain open, especially what starts off the autoimmune process, and why are eye muscles so frequently involved in MG?

Azathioprine in myasthenia gravis: observations in 41 patients and a review of literature

We report azathioprine treatment of 41 patients with myasthenia gravis, with a follow-up of more than 3 yr. The data show that azathioprine is effective in controlling the disease, both as a single drug as well as in combination with prednisone. In addition it may be steroid sparing. Older patients derived more benefit from the medicament. Side-effects could be managed fairly well, except for one patient who developed a non-Hodgkin lymphoma. Data from this study do not support the supposition that the therapeutic effect of azathioprine is dependent on macrocytosis. Fluctuations of serum levels of antibodies to the acetylcholine receptor were simultaneous with clinical changes and thus were not of predictive volume for the clinical course.