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PubMed1983

HLA antigens and myasthenia gravis in north India.

The HLA antigen distribution was studied in 37 north Indian patients with myasthenia gravis. The control group consisted of 118 normal, healthy individuals of the same ethnic group. The antigens showing the highest frequency were Bw21 (18.9% vs 4.2% p less than 0.005), Bw35 (24.3% vs 6.8%, p less than 0.005) and A9 (51.3% vs 30.5%, p less than 0.025). HLA-B8 was increased nearly two fold in the myasthenia gravis patients (RR = 2.4) and was confined mainly to the young females without thymoma. The possibility that Bw21 and Bw35 might be the markers for susceptibility to autoimmune disorders in India is discussed. The observations also support those of others that HLA-B8 linked susceptibility gene is more frequently found in myasthenia gravis patients with thymic hyperplasia.

Disease Susceptibility↗

PubMed1984

Strong association of HLA BW46 with juvenile onset myasthenia gravis in Hong Kong Chinese.

The HLA antigen distribution and thyroid autoantibody status of 27 Chinese children in Hong Kong with juvenile onset myasthenia gravis have been compared with 110 healthy university students from the same population. Twenty-four of the patients had ocular myasthenia. There was a significantly increased prevalence of HLA BW46 in the patients compared with controls (67% vs 26.4%, p less than 0.005) indicating that BW46 confers a relative risk of 5.6 for juvenile onset myasthenia gravis in Chinese children. The increased prevalence of BW46 was not associated with thyroid autoimmunity in the patients although the antigen is known to be associated with thyrotoxicosis in Chinese. The possibility that BW46 confers protection against the development of acetyl-choline receptor antibodies in Chinese patients is discussed. One patient had the Caucasian antigen B8 and the question whether defective immune response genes were introduced into the Chinese through Caucasian admixture is raised.

Autoantibodies↗

PubMed1985

Thymectomy in myasthenia with pure ocular symptoms.

Eighteen patients with exclusively ocular symptoms of myasthenia were thymectomised. Suspected thymoma, resistance to pyridostigmine therapy or relapse following immunosuppressive therapy were taken as indications for surgery. The mean preoperative observation period before operation was 40 months, and after operation was 26 months. There was no operative or postoperative morbidity or mortality. Histological thymic abnormalities were found in all patients (in one case, thymoma; in four, persistent thymus; in 13, thymic hyperplasia). The histological abnormalities were identical to those found in generalised myasthenia. This included the distribution of T-cell subtypes as identified by use of monoclonal antibodies. The severity of ocular symptoms was rated using a score developed for this purpose. The score progressively declined after surgery to an average of 70% of its initial amount in 80% of patients. Full remission occurred in three cases. No patient developed generalized myasthenia. Antibody titres against acetylcholine receptors if elevated preoperatively also dropped following surgery, with one exception. Clear criteria for the expected therapeutic success of thymectomy could not be identified. Based on our results, and on the assumed significance of the thymus gland for pathogenesis, thymectomy should be considered in patients with pure ocular symptoms.

Adult↗

PubMed1989

Absence of central functional cholinergic deficits in myasthenia gravis.

Sporadic reports have suggested central involvement in myasthenia gravis, a disorder in which there is an antibody-mediated loss of peripheral nicotinic acetylcholine receptors. Five patients with symptomatic myasthenia gravis performed an auditory vigilance test of ability to direct and sustain attention, presumed to reflect central cholinergic function. No deficits were found, either in comparison with the same subject's performance when muscle strength had improved after plasma exchange, or compared with that of healthy controls. The results thus failed to substantiate reports of functionally significant central cholinergic deficits in myasthenia gravis.

Adult↗

PubMed1994

Immunoadsorption therapy for myasthenia gravis.

The results of a multicentre trial were analysed to evaluate the efficacy of immunoadsorption therapy for severe generalised myasthenia gravis. Twenty patients with myasthenia gravis who were concurrently receiving high dose prednisolone and azathioprine therapy were treated with an affinity-type adsorbent, using tryptophan-linked polyvinyl alcohol gel (IM-TR), according to a standardised treatment protocol. The 20 patients received five adsorption treatments within a period of 10 days. In 11, pronounced improvement of myasthenic weakness was seen and long-term remission was maintained. The treatment was especially effective in patients with thymic hyperplasia. Circulating acetylcholine receptor (AChR) antibodies were reduced by about 60% by treating one plasma volume. There was no difference in the rate of removal of the AChR antibodies between patients with thymic hyperplasia and patients with thymoma. No serious complications occurred during 100 procedures. It was concluded that the immunoadsorption therapy with IM-TR is useful in controlling symptoms in patients with severe myasthenia gravis who are otherwise unresponsive.

Adolescent↗

PubMed1995

Familial autoimmune myasthenia gravis: report of four families.

Four families each with two patients with autoimmune myasthenia gravis or related conditions are reported. All clinical forms of myasthenia gravis were represented and different disease types were found within the same family. Either one or two generations could be affected and no association with a single HLA haplotype was found. The frequency of familial autoimmune myasthenia gravis is very low and the genetic factors involved seem to be different from MHC genes.

Adult↗

PubMed1998

Myasthenia gravis: a population based epidemiological study in Cambridgeshire, England.

OBJECTIVES: To perform a comprehensive survey of myasthenia gravis in the county of Cambridgeshire, England, establishing contemporary epidemiological data. METHODS: Cases were ascertained from multiple sources. Prevalent patients were visited and assessed by means of a standardised questionnaire and examination complemented by review of medical case notes. RESULTS: One hundred cases were identified in a population of 684000 (prevalence 15 per 100000 population, 95% confidence intervals (95% CIs) 12-18). Thirty eight new diagnoses were made over a five year period providing an incidence of 1.1/100000 population/year. The sex ratio was 2:1 F:M. After a mean follow up of 11.7 years, symptomatic disease was still restricted to ocular muscles in 25 patients. Thirty four of 100 patients underwent thymectomy a mean of 0.8 years after presentation, and a thymoma was present in 12. Highest remission rates were seen in patients presenting with generalised disease who underwent thymectomy but did not have a thymoma (27%). Cosegregation of an additional autoimmune disease occurred in 27 patients and in 24/49 (49%) women with onset<50 years of age. CONCLUSIONS: This, the second highest reported prevalence for myasthenia, is likely to be the result of optimum case ascertainment, increased disease duration, application of complex diagnostic tests, and the impact of an aging population leading to a relative increase in the prevalence of ocular myasthenia.

Adolescent↗

PubMed2003

A population based epidemiological study on myasthenia gravis in Estonia.

OBJECTIVE: To describe the occurrence of myasthenia gravis in the Baltic area. METHODS: Data were obtained from hospital files recorded during the period 1942 to 1996 from neurologists and the patient organisation. Survival data were checked with the Estonian Citizenship and Migration Board. Prevalence was determined on 1 January 1997. A questionnaire on the course of myasthenia gravis was sent to all the prevalent patients. RESULTS: The size of the population surveyed was 1 462 130. The average annual incidence from 1970 to 1996 was 4.0 per million (women, 5.2; men, 2.6). The point prevalence was 99 per million (women, 133; men 59). The incidence in the younger age group (<50 years) was 3.4 per million (women, 4.8; men, 1.9) and in the older age group (>or=50 years), 5.5 (women, 5.9; men, 4.9). The prevalence ratio was twofold higher in the older age group (p<0.0001)-for men (p = 0.034) as well as for women (p<0.001). CONCLUSIONS: Prevalence and incidence values of myasthenia gravis from Estonia are similar to those reported in most studies from Europe and north America. However, there seems to be a higher frequency in the elderly (>or=50 years) in Estonia.

Adolescent↗

PubMed2003

Repetitive stimulation of the long thoracic nerve in myasthenia gravis: clinical and electrophysiological correlations.

OBJECTIVE: To investigate repetitive stimulation of the long thoracic nerve as a reliable and technically undemanding method for evaluating respiratory muscle function in myasthenia gravis. METHODS: 15 patients with myasthenia gravis and positive single fibre electromyography had repetitive stimulation of the long thoracic nerve together with serratus anterior recordings. There were 20 normal controls. RESULTS: Eight patients with respiratory symptoms all had abnormal results, with an increased response decrement. These patients required intensive monitoring and supplemental oxygen. The remaining seven cases with no respiratory symptoms all had negative studies. CONCLUSIONS: This is a simple well tolerated method that shows good correlation with respiratory symptoms and management requirements in myasthenia gravis. It can alert the physician to serious respiratory complications in this disease.

Adolescent↗

PubMed1990

Concomitant euthyroid Graves' ophthalmopathy and isolated ocular myasthenia gravis.

A 44 year old diabetic woman presented with diplopia and bilateral ptosis and mild exophthalmos. The patient was clinically euthyroid, the baseline thyroid function tests were normal, but the thyroid stimulating hormone response to thyrotrophin releasing hormone was flat. Computed tomographic scan and magnetic resonance imaging of the orbits showed left medial and inferior rectus muscle thickening, more prominent on the left side, consistent with Graves' disease. The tensilon stimulation test resulted in resolution of the ptosis and partial improvement of the ophthalmoplegia. The single fibre electromyography was consistent with a defect in neuromuscular transmission. However, forced duction test was normal and anti-acetylcholine receptor antibodies were undetectable. Significant improvement of the extraocular muscle function and resolution of the right ptosis had resulted from anticholinesterase therapy. These findings and the clinical response to therapy were consistent with concomitant euthyroid Graves' ophthalmopathy and ocular myasthenia gravis. Coexistent isolated ocular myasthenia gravis and Graves' ophthalmopathy is rare and should be considered in patients with findings of ocular myasthenia and extraocular muscle dysfunction.

Adult↗

PubMed1998

Thymectomy for myasthenia gravis.

The pathophysiological role of the thymus in myasthenia gravis, and the mechanism of therapeutic effect of thymectomy, are incompletely understood. Nevertheless, thymectomy is a valuable treatment modality in selected patients with generalised myasthenia gravis. There are several types of thymectomy operation, but no one operative approach is clearly superior to the others. Total removal of the thymus gland is essential. Additional excision of associated mediastinal and cervical tissue, that may harbor ectopic thymic rests, is a controversial surgical issue. Surgeons that advocate thymectomy through small, cosmetically favourable, incisions usually believe that simple removal of the thymus gland is an adequate operation. Surgeons that emphasise the importance of removing extrathymic tissue, in addition to the thymus gland, usually favour greater operative exposure through a median sternotomy. To minimise operative morbidity, surgery for myasthenia gravis requires a multidisciplinary (neurology, surgery, anaesthesia) approach to peri-operative care.

Humans↗

PubMed1996

Surgical treatment of myasthenia gravis in two major Middle East teaching hospitals: factors influencing outcome.

BACKGROUND: The results of thymectomy on patients with generalised myasthenia gravis have been widely reported. However, there is no information on whether the experience of western countries can be generalised to the population of the Middle East. The purpose of this study was to evaluate the safety and efficacy of thymectomy in patients with myasthenia gravis in a Middle East patient population and to identify clinical and histopathological factors associated with improved long term outcome of surgery. METHODS: In a prospective study, sixty three patients (aged 1.5-51 years) were treated in two university teaching hospitals between 1984 and 1991 and followed up for a mean of four years. Close communication was established with neurologists to obtain early referral. Radical anterior mediastinal dissection through a median sternotomy was performed in all patients. The response was evaluated by modified Osserman's classification. RESULTS: Eighteen patients achieved complete remission and a further 39 improved, producing an overall response rate of 90.5%. Patients with milder disease (stage II) had a higher response rate (97%) than those with more advanced disease (78%). Patients operated on with less than three years of symptoms had a better outcome (94%) than those with longer duration of preoperative symptoms, especially in non-thymomatous patients. Age and sex had no effect on the outcome. There was no effect on response rate if patients had hyperplastic or non-specific thymic histological findings, but patients with thymoma fared worse. CONCLUSIONS: These results are comparable with reports from the western world and represent the first prospective study from the Middle East. Thymectomy is indicated for all patients suffering from generalised myasthenia gravis soon after the diagnosis is made, regardless of age, stage, thymic pathology, and preoperative clinical status.

Adolescent↗

PubMed1996

Thymus in myasthenia gravis: comparison of CT and pathologic findings and clinical outcome after thymectomy.

PURPOSE: To correlate computed tomographic (CT) appearance of the thymus with results from histologic examination of thymic tissue and clinical outcome in patients with generalized myasthenia gravis who underwent thymectomy. MATERIALS AND METHODS: Forty-five patients with myasthenia gravis underwent CT of the thorax and thymectomy. Findings at clinical follow-up were available in all patients. RESULTS: Twenty-six patients had normal CT findings, seven had a diffusely enlarged thymus, and 12 had a focal mass. The results of histologic examination showed that 16 of 26 patients with normal CT findings had normal thymic tissue and 10 had lymphoid follicular hyperplasia; all seven patients with an enlarged thymus had lymphoid hyperplasia. Five of 12 patients with a focal mass at CT had lymphoid hyperplasia, and seven had thymoma. Clinical improvement following thymectomy was observed in 27 (93%) of 29 patients with lymphoid hyperplasia or thymoma and 11 (69%) of 16 patients with normal histologic examination (P < .03, chi(2) test). CONCLUSION: The presence of an enlarged thymus or a focal mass in patients with myasthenia gravis indicates lymphoid hyperplasia or thymoma. However, CT is of limited value in distinguishing lymphoid follicular hyperplasia from a normal thymus or thymoma and in predicting clinical outcome.

Adolescent↗

PubMed2004

Adverse effects of myasthenia gravis on rat phrenic diaphragm contractile performance.

Myasthenia gravis has variable effects on the respiratory system, ranging from no abnormalities to life-threatening respiratory failure. Studies characterized diaphragm muscle contractile performance in rat autoimmune myasthenia gravis. Rats received monoclonal antibody that recognizes acetylcholine receptor determinants (or inactive antibody); 3 days later, phrenic nerve and diaphragm were studied in vitro. Myasthenic rats segregated into two groups, those with normal vs. impaired limb muscle function when tested in intact animals ("mild" and "severe" myasthenic). Baseline diaphragm twitch force was reduced for both severe (P < 0.01) and mild (P < 0.05) myasthenic compared with control animals (twitch force: normal 1,352 +/- 140, mild myasthenic 672 +/- 99, severe myasthenic 687 +/- 74 g/cm2). However, only severe myasthenic diaphragm had impaired diaphragm endurance, based on significantly (P < 0.05) accelerated rate of peak force decline during the initial period of stimulation (0.02 + 0.02, 0.03 +/- 0.01, and 0.09 +/- 0.01%/pulse for normal, mild myasthenic, and severe myasthenic, respectively, during continuous stimulation) and intratrain fatigue (up to 30.5 +/- 7.4% intratrain force drop in severe myasthenic vs. none in normal and mild myasthenic, P < 0.01). Furthermore, compared with continuous stimulation, intermittent stimulation had a protective effect on force of severe myasthenic diaphragm (force after 2,000 pulses was 31.4 +/- 2.0% of initial during intermittent stimulation vs. 13.0 +/- 2.1% of initial during continuous stimulation, P < 0.01) but not on normal diaphragm. These data indicate that baseline force and fatigue may be affected to different extents by varying severity of myasthenia gravis and furthermore provide a mechanism by which alterations in breathing pattern may worsen respiratory muscle function in neuromuscular diseases.

Animals↗

PubMed2005

["Seronegative" myasthenia gravis and antiMuSK positive antibodies: description of Spanish series].

BACKGROUND AND OBJECTIVE: Recently, the presence of antibodies to a muscle-specific tyrosine kinase (MuSK) has been reported in some patients with seronegative generalized myasthenia gravis. Our objective was to describe a group of patients who were positive for anti-MuSK antibodies. PATIENTS AND METHOD: Detection of antibodies using a radioimmunoassay was performed in the serum of 26 patients with generalized myasthenia gravis. We identified 9 patients with anti-MuSK antibodies (MuSK+). Clinical and therapeutic data from these patients were reviewed. RESULTS: Eight of nine patients were women aged between 20 and 40 years. Clinically, all of them showed prevalent bulbar signs, initially or during the progression of the disease. 77% of patients showed ocular involvement and 44% had symptoms of fatigability involving limbs. None of them improved upon thymectomy. Response to acetylcholinesterase inhibitors was variable. All of them responded to immunotherapy, although 30% required polytherapy. CONCLUSIONS: The study of anti-MuSK antibodies defines a subgroup of patients, 34,61% in our series, with seronegative generalized myasthenia. This group is characterized by an homogenous clinical presentation with prevalent bulbar symptoms. The knowledge of the immunopathogenic mechanisms of anti-MuSK antibodies will allow a better understanding of both the variable response to acetylcholinesterase inhibitors and the absence of response to thymectomy in these patients.

Adolescent↗

PubMed2002

Respiratory failure due to vocal cord paresis in myasthenia gravis.

This report describes a female patient with myasthenia gravis who developed respiratory failure due to vocal cord paresis. The diagnosis was delayed due to the absence of other myasthenic symptoms (e.g. ptosis, muscle weakness and dysphagia). On direct laryngoscopy, her vocal cords were seen to be in the paramedian position and to move apart after the intravenous injection of edrophonium. The patient initially presented with ocular myasthenia and later returned with isolated respiratory failure. A review of the pertinent literature revealed few reports on myasthenia gravis presenting in this manner.

Aged↗

PubMed1975

Association between myasthenia gravis and malignant lymphoma.

A reticulum cell sarcoma was diagnosed in a myasthenic patient 14 years after the first manifestations of myasthenia gravis. The association of myasthenia and malignancy, especially lymphoreticular, is discussed in view of an increasing number of similar reports in the literature. It is suggested that autoimmune diseases, myasthenia gravis and malignant processes might have a common underlying abnormal immune state related to thymic pathology.

Adult↗

PubMed1989

Association of IgA nephropathy and myasthenia gravis.

Three patients with IgA nephropathy associated with myasthenia gravis are described. In all 3 cases, myasthenia gravis emerged after the discovery of glomerulonephritis. Myasthenic symptoms were improved by thymectomy in 2 cases, but progression of the renal disease was not improved. Some systemic abnormalities, including immunological aberrations, were observed in these two disorders. It is postulated that T cell abnormalities in IgA nephropathy might be independent of the development of myasthenia gravis.

Adult↗