Studies in Myasthenia Gravis

-We evaluated the epidemiological, clinical, laboratory and therapeutical aspects of 41 patients with thymomatous myasthenia gravis. Thirty five patients (85.36%) were submitted to thymectomy. Follow-up ranged from two to 18 years. Diagnosis of thymoma was based upon clinical investigations and CT scan of the anterior mediastinum and in 11 patients supported by immunological tests of anti-striated muscle antibodies with a positive result in more than 80% of cases. Histopathologic examination of all thymomectomized patients confirmed the diagnosis of thymoma. There was a significant predominance of benign over malignant thymoma. Occurred higher prevalence of male patients and of patients over 40 years of age. The therapeutical strategy to control myasthenic clinical findings was the same as that for non-thymomatous myasthenia gravis. The corticosteroids associated to cytotoxic drugs were less often used. Radiotherapy of the anterior mediastinum was more often used in patients having invasive tumors submitted to surgery or not. With regard to survival and control of myasthenia gravis, especially in younger patients and in those submitted to early surgery, results of treatment were surprisingly favorable.KEY WORDS: myasthenia gravis, thymoma, thymectomy.Miastenia grave e timoma: avaliação de 41 pacientes RESUMO -Avaliamos 41 pacientes com miastenia grave timomatosa sob os aspectos epidemiológico, clínico e terapêutico. Trinta e cinco pacientes (85,36%) foram timectomizados. O seguimento clínico variou de dois meses até 18 anos. O diagnóstico do timoma foi fundamentado no estudo de imagem do mediastino (tomografia axial computadorizada) e, em 11 pacientes, complementado com a determinação sérica de anticorpos para músculo estriado com resultado positivo em mais de 80% dos casos e confirmado pelo exame anátomo-patológico do timo realizado em todos os pacientes operados. Ocorreu predomínio significante de timomas benignos sobre timomas malignos, forma clínica generalizada severa, frequente envolvimento do sexo masculino e, em pacientes com mais de 40 anos de idade. A estratégia terapêutica para o controle dos sintomas miastênicos foi a mesma que para os pacientes não timomatosos. O emprego de imunossupressão medicamentosa esteróide associada a drogas citotóxicas foi menos frequente. A radioterapia foi usada com mais frequência nos pacientes portadores de tumores invasivos operados ou não. PALAVRAS-CHAVE: miastenia grave, timoma, timectomia.Acquired myasthenia gravis (MG) is an immunological disease with antibody activity against the acetylcholine nicotine receptor (antiAChR) of the neuromuscular junction, with fluctuant weakness of the skeletal muscle which improves with the administration of cholinergic drugs (CD). These antibodies are produced by B lymphocytes activated by helper T lymphocytes antigen-specific (CD4) 1,2 in the thymus and peripheral blood of patients with MG 3,4 .

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“…In this series the association of MG and thymoma (TMG) is of 11% which agrees with references found in literature 2,[4][5][6][7] .…”

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confidence: 91%

Myasthenia gravis and thymoma: evaluation of 41 patients

Assis

Zambon²,

Souza³

et al. 1999

Arq. Neuro-Psiquiatr.

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“…Eight patients were receiving prednisone (with doses varying from 15 mg every other day to daily dosing of 50 mg), two azathioprine (one in combination with prednisone), and one cyclosporin (in combination with prednisone). The patients' functional status was classified according to the OSSERMAN [13] grade (table 1). None of the patients had a prior history of respiratory disease.…”

Section: Patientsmentioning

confidence: 99%

Ventilatory muscle strength and endurance in myasthenia gravis

Keenan¹,

Alexander²,

Jd³

et al. 1995

Eur Respir J

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V Ve en nt ti il la at to or ry y m mu us sc cl le e s st tr re en ng gt th h a an nd d e en nd du ur ra an nc ce e i in n m my ya as st th he en ni ia a g gr ra av vi is s We studied 17 patients with myasthenia gravis (four with ocular involvement alone and 13 with varying degrees of generalized myasthenia gravis). Spirometry, ventilatory muscle strength (maximum inspiratory and expiratory pressures (MIP and MEP)) and endurance (2 min incremental threshold loading test) were measured before and 20 min after i.m. neostigmine. We compared the results with those of 10 normal controls. We found no difference between patients with isolated ocular involvement and controls. Ocular myasthenia gravis patients did not improve after neostigmine. The patients with generalized myasthenia gravis had reduced baseline ventilatory muscle strength (MIP 67 cmH 2 O (70% of predicted), MEP 86 cmH 2 O (50% of pred) and endurance (mean maximal load achieved = 246 g, mean pressure at highest load (P) = 19.4 cmH 2 O) compared with controls. After neostigmine, there was a significant increase in MIP in patients with generalized myasthenia gravis and a trend towards an increased MEP. As a group, the patients with generalized myasthenia gravis did not demonstrate a change in their ventilatory muscle endurance after neostigmine; however, there was considerable interpatient variability in response.We conclude that patients with isolated ocular MG have normal ventilatory muscle strength when tested conventionally. The measurement of ventilatory muscle endurance by incremental threshold loading does not provide additional information to the measurement of ventilatory muscle strength in patients with generalized myasthenia gravis.

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“…Because of reported associations with MG outcomes, we also extracted the following study population characteristics: proportion of patients younger than 50 years at the time of diagnosis of MG, proportion of female patients, proportion of patients with more severe MG at the time of diagnosis (defined by Osserman's grade 2b, 3, or 4 8 ), and the proportion of patients with strictly ocular myasthenia at the time of diagnosis.…”

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confidence: 99%

Practice parameter: Thymectomy for autoimmune myasthenia gravis (an evidence-based review) [RETIRED]

2000

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The Quality Standards Subcommittee of the American Academy of Neurology is charged with developing practice parameters for neurologists for diagnostic procedures, treatment modalities, and clinical disorders. The selection of topics for which practice parameters are used is based on prevalence, frequency of use, economic impact, membership involvement, controversy, urgency, external constraints, and resources required. This paper addresses the role of thymectomy in the treatment of nonthymomatous autoimmune MG.In 1939, Blalock et al. 1 reported the remission of generalized MG in a 21-year-old woman after removal of a cystic thymic tumor. Subsequently, Blalock et al.2,3 performed thymectomy on MG patients without thymoma, found hyperplasia in the thymus glands, and reported improvement in at least half of their patients. Since these reports, thymectomy, with or without the presence of thymoma, has gained widespread acceptance as a form of treatment for MG.Because a definitive study of the effectiveness of thymectomy has never been done, 4,5 the role of thymectomy in the management of MG remains uncertain. Nevertheless, physicians have to advise their patients regarding the benefits of thymectomy based on the existing literature. Our goal is to develop evidence-based recommendations for clinicians considering thymectomy for patients with nonthymomatous autoimmune MG by performing a systematic review and analysis of the literature. Process. Identification and selection of studies.We searched the National Library of Medicine's Medline database from 1966 to February 1998 using the medical subject headings "myasthenia gravis" (restricted to the surgery subheading) and "thymectomy." To identify articles published before 1966, or missed by our original search strategy, we reviewed the references of the identified articles.We classified the resulting articles into the following categories: Class II, controlled but nonrandomized studies describing outcomes in MG patients with and without thymectomy; and Class III, uncontrolled case series describing outcomes in patients with or without thymectomy.Within a given controlled (Class II) study, we planned to describe the therapeutic effect of thymectomy by comparing the rate MG patients receiving thymectomy achieved desirable outcomes with the rate MG patients not receiving thymectomy achieved desirable outcomes. The nonrandomized nature of Class II studies often introduces differences in the baseline characteristics of the thymectomy and nonthymectomy patient groups that can effect MG outcomes independent of thymectomy. To the extent possible, we planned to adjust for these confounding differences in baseline prognostic characteristics. In the absence of randomized controlled trials, such adjustments are critical for estimating the actual therapeutic effect, if any, of thymectomy. 6Between uncontrolled (Class III) studies, comparisons of outcome rates in thymectomy and nonthymectomy MG patients introduce additional confounding baseline differences.6 These additional confounde...

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Studies in Myasthenia Gravis

Cited by 111 publications

References 14 publications

Myasthenia gravis and thymoma: evaluation of 41 patients

Myasthenia gravis and thymoma: evaluation of 41 patients

Ventilatory muscle strength and endurance in myasthenia gravis

Practice parameter: Thymectomy for autoimmune myasthenia gravis (an evidence-based review) [RETIRED]

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