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Myasthenia gravis in pregnancy is rare, and its occurence in conjunction with preeclampsia has not been previously described. A case report of preeclampsia in a myasthenic patient is described with recommendations for management. The authors conclude that magnesium is a contraindicated pharmacologic agent in a myasthenic patient.
INTRODUCTION: Myasthenia gravis is an autoimmune disorder characterized by fluctuating muscle weakness and fatigue of different muscle groups. Myasthenia gravis may affect persons of all ages, but especially women aged 20 to 40 years. DEVELOPMENT AND CONCLUSIONS: The ocular, facial and bulbar muscles are most often involved in this disease. The muscle weakness of patients with myasthenia gravis becomes worse with intercurrent episodes of infection, fever and physical or emotional exhaustion. Respiratory infection (bacterial or viral) is the most frequent trigger factor. The presence of antibodies to acetylcholine receptors in a patient with the clinical features of myasthenia gravis, confirms the diagnosis. Treatment is controversial. Each patient therefore has to be treated individually, as no single treatment is suitable for all patients. Treatment may include anticholinesterase drugs, corticosteroids, plasmapheresis, immunoglobulin, immunosuppressive drugs and thymectomy.
Myasthenia gravis in a woman was followed by the development of severe erosive lichen planus and thymoma. Lichen planus is not ordinarily associated with other cutaneous or systemic disorders. The reported immunologic findings in some patients with lichen planus and especially the occasional association of lichen planus with certain disorders linked with immunologic disturbances suggest an autoimmune pathogenesis for this disorder.
Myasthenia gravis is a chronic autoimmune disease that results in progressive weakness of the striated muscles. Autoantibodies destroy acetylcholine receptor sites, preventing adequate nerve impulse conduction to the muscles. Medical treatment is directed at increasing the amount of available acetylcholine or at reducing the levels of circulating antibodies. Nursing care is complex and involves patient education about drug therapy and treatment options as well as caring for the numerous problems that arise from varying degrees of muscle weakness. Skilled nursing assessment and intervention can help protect the myasthenic patient from the life-threatening complications of respiratory compromise.
BACKGROUND: Myasthenia gravis is a potentially serious but treatable muscle disease caused by autoantibodies directed at the acetylcholine receptor (AChR) on the postsynaptic membrane of the neuromuscular junction. There is anecdotal evidence that the diagnosis is sometimes missed in older patients. OBJECTIVE: To examine the incidence and age distribution of positive AChR antibodies in samples referred to diagnostic laboratories in the UK, and the prevalence of positive AChR antibodies in samples from a cohort of older individuals. METHODS: Positive AChR antibody tests were identified from all UK centres registered for the assay with the European quality assurance scheme (EQAS) during 1997-99, and the age and sex specific incidence was calculated, based on the UK population. The prevalence of AChR antibodies in sera from a sample of 2000 individuals aged > or =60 years was determined. RESULTS: 3183 individuals had positive AChR antibody tests on routine screening during the years 1997 to 1999 in the UK, giving an annual incidence of 1.8/100 000. In both sexes, the age specific incidence rose steeply between the ages of 45 and 74, reaching 9.9/100 000 in men, and then fell, with a sharp decline above the age of 80. In the prevalence study, whereas only one serum from individuals aged 60-74 years was positive for AChR antibodies (0.12%), sera from eight individuals aged > or =75 years were positive (0.7%). Only one had a previous clinical diagnosis of myasthenia gravis but four others had histories of stroke or transient ischaemic attacks. CONCLUSIONS: The sharp fall in the incidence of clinically recognised myasthenia gravis in people over 80 years of age in our national AChR antibody incidence study, and the high prevalence of previously unrecognised positive AChR antibodies in those > or =75 years old, suggest that myasthenia gravis may be substantially underdiagnosed in older people.
Patients with myasthenia gravis (MG) represent a significant management problem for the anesthesiologist. Anesthetic concerns center on the MG patient's unpredictable response to muscle relaxants and increased susceptibility to postoperative respiratory failure, resulting in prolonged dependence on mechanical ventilation. We describe the first reported use of total intravenous anesthesia with propofol to provide satisfactory surgical conditions in two patients with MG undergoing trans-sternal thymectomy. Propofol is a suitable drug for intubation and continuous infusion anesthesia, allowing fine control of anesthetic depth, good operating conditions, and a recovery profile suitable for MG patients undergoing surgery.
In a myasthenia gravis patient with profound ophthalmoplegia who was given edrophonium during forward fixation or horizontal/vertical saccades, horizontal macrosaccadic oscillations occurred that were conjugate, 2 to 3 Hz, and of peak-to-peak amplitude up to 50 degrees. The intersaccadic interval averaged 129.5 msec as measured by electro-oculography. Eye closure or the use of Frenzel goggles markedly reduced the amplitude and frequency of the macrosaccadic oscillations. This short latency is similar to that of a corrective saccade, and suggests that edrophonium induces macrosaccadic oscillations through a non-visually guided reflex saccade by temporarily unmasking the adaptively increased saccadic gain to overcome myasthenic ocular paresis.
Myasthenia gravis is a motor neuron disease caused by the presence of antibodies against acetylcholine receptors that interfere with proper functioning of the neuromuscular junction. Twenty percent of patients show bulbar involvement as the first indication of disease, with symptoms such as rhinolalia, dysphagia or phonasthenia. We report the cases of five patients for which our intervention was requested. We were involved in capacities ranging from the interpretation of the first symptom of disease to assessment of surgical possibilities for the treatment of chronic aspiration and severe respiratory symptoms in patients with major dysphagia. We review the scant bibliography published in the last five years.
A myasthenia gravis (MG) patient who seems to have recovered can later have recurrence of myasthenic signs. Clearly clinical remission does not always correspond to the normalization of all the factors involved in the pathogenesis of the disease. In ten patients who had apparently recovered from MG, electromyographic tests of repetitive supramaximal stimulation were performed and the anti-acetylcholine receptor (anti-AChR) antibody was assessed. In two of the ten patients all these tests were normal, thus showing lack of electromyographic myasthenic fatigability and the absence of circulating anti-AChR antibodies. Our hypothesis is that for these two subjects the risk of a recurrence of MG is lower than for the others.
Experimental autoimmune myasthenia gravis (EAMG) is a T cell-dependent antibody-mediated neuromuscular autoimmune disease induced in susceptible rats by a single immunisation with torpedo acetylcholine receptor (AChR). Here, we report that subcutaneous administration of a novel immunosuppressant, LF 15-0195, is effective in inhibiting the induction and the progression of rat EAMG-suggesting that this drug may be used for preventive and curative treatment. The beneficial effect of LF 15-0195 is accompanied by decreased production of pathogenic autoantibodies and inhibition of the differentiation of antigen specific T cells into effector lymphocytes. These finding suggest that LF 15-0195 is a promising therapeutic for this autoimmune disease.
Chinese Singaporean myasthenia gravis (MG) patients are associated with three HLA haplotypes: Cw1 B46 DRB1*0901 DQB1*0303 DQA1*03, DRB1*14 DRB3*0202 DQB1*0503 DQA1*0101 and DRB1*1202 DRB3*0301 DQB1*0301 DQA1*0601. The B46 haplotype was associated with the total group of MG patients but in particular with those with younger onset, low antiacetylcholine receptor (anti-AchR) titres, with only ocular lesions and with normal thymuses. The DRB1*14 haplotype was associated with thymic hyperplasia, younger onset patients, with high anti-AchR titres and with generalised MG. The DRB1*1202 haplotype was associated with thymoma, older onset patients, ocular lesions, and mid to high anti-AchR titres.
Sera from myasthenia gravis (MG) patients with thymoma were examined in Western blot for the presence of antibodies to proteins in the sarcoplasmic reticulum (SR) of cardiac muscle. Fourteen of 30 MG thymoma sera had IgG antibodies to a protein with the same electrophoretic mobility as cardiac muscle ryanodine receptor (RyR). Anti-cardiac RyR antibodies were not detected in any of the 45 sera from MG patients without thymoma. The same 14 MG thymoma sera, but none of the others, bound to RyR from skeletal muscle as well. Neutralization experiments showed that the anti-RyR antibodies in MG patient cross-reacted with cardiac and skeletal muscle RyR. Since skeletal and cardiac muscle RyRs are antigenically different, our findings may indicate that autoantibodies to RyR in MG originate by sensitization to a peptide shared by cardiac and skeletal muscle RyR, rather than to the complete native RyR.
Myasthenia gravis (MG) is an autoimmune disease characterized by production of antibodies to acetylcholine receptor at the motor end-plate responsible for impairment of neuromuscular transmission. There is general agreement about the involvement of the thymus in the pathogenesis of MG, and thymic pathological changes are commonly found in MG patients. Genetic factors seem to play an important role in susceptibility to MG. As with other autoimmune diseases, genetic predisposition to MG probably involves multiple genes. Ample evidence suggests that genes within the major histocompatibility complex (MHC) are involved in susceptibility to autoimmune diseases. Both data from the literature and our findings indicate that different genes within the MHC could predispose to various forms of MG, and that particularly the tumour necrosis factor genes may play a role in the association between the different thymic disorders and MG.
Patients with myasthenia gravis (MG) may develop heart disease. Our data on 108 MG patients were examined to assess the type and frequency of this. 17 of 108 patients (16%) showed signs of heart disease which could be regarded as MG-related. 11 of these, of whom 5 died suddenly, had clinical symptoms, mainly arrhythmias. Signs of heart disease were most frequent in thymoma patients (5 of 10), and all 3 microscopically examined hearts from these patients showed a focal myocarditis. 44 spinal muscular atrophy patients serving as controls showed a 16% frequency of signs of heart disease of unknown etiology. However, only 1 of 44 spinal muscular atrophy patients (2%) had clinical symptoms as compared to 11 of 108 MG patients (10%). Together with the characteristic focal nature of the myocarditis and the microscopic similarities between lesions of heart and skeletal muscle, this indicates that the heart disease is specifically related to MG.
Experimental autoimmune myasthenia gravis (EAGM) was induced in female AO rats, by a single immunization with Torpedo acetylcholine receptor (AChR). Animals injected with saline served as controls. The study showed substantial changes in EAMG rats in the thymopoiesis, causing an increase in the relative proportion of mature CD8+ and, particularly, CD4+ (possibly autoreactive) single positive (SP) cells expressing TCRalphabeta at high level (TCRalphabeta(high)), as well as in that of mature double negative (DN) TCRalphabeta(high) cells, which are believed to be the immunoregulatory cells that augment autoantibody (autoAb) production. These results indicate that an augmented production of autoreactive CD4+ cells, on one side, and an increase of the immunoregulatory T cells that augment autoAb production, on the other side (reflecting, most likely, an increased entry of activated autoreactive CD4+ T cells from the periphery into the thymus), may have a significant role in the sustention of immune response in EAMG, and may suggest a putative mechanism underlying the sustention of autoimmune response in acquired MG.
Experimental autoimmune myasthenia gravis (EAMG) in rats can be produced as the result of immunization with purified acetylcholine receptor (AChR). However, antibodies produced against an irreversibly denatured AChR were not capable of producing detectable AChR-dependent neuromuscular impairment such as that seen following immunization with AChR of intact conformation. This immunopathological difference was observed despite the fact that both immunizations resulted in the production of clonotypically heterogeneous antibodies with similar titers, isotype distribution, and relative binding avidities for conformationally intact AChR. Although they had no apparent disease-causing potential of their own, antibodies produced against denatured AChR could, however, bind AChR at the neuromuscular junction and mediate in vivo AChR-dependent neuromuscular impairment if a second anti-antibody was provided. Finally, immunization against denatured AChR, or administration to naive rats of antibodies obtained by immunization against denatured AChR, resulted in the recipient rats becoming resistant to the usual pathological effects of antibodies produced against intact AChR (either induced by active immunization or following passive antibody transfer). These observations suggest that disease severity in this system may be influenced by relationships between disease-causing and disease-abrogating antibodies.
Patients with myasthenia gravis (MG) face major pulmonary problems as a part of the disease process. In this descriptive study, changes in selected pulmonary functions (respiratory rate, negative inspiratory force, tidal volume and forced vital capacity) in 14 patients diagnosed with mild or moderate MG were measured every two hours from 8:00 a.m. to 8:00 p.m. Females comprised 64% of the sample while 36% were males. All subjects received anticholinesterase medication, and some subjects received additional treatment modalities. Most of the subjects were nonsmokers or previous smokers, but two subjects continued to smoke. Ninety-three percent of the sample had forced vital capacities less than 60% of their predicted values. Myasthenic forced vital capacities were significantly lower (p = .0000) than those predicted for normal subjects. The inspiratory force for the sample was low at 8:00 a.m. as well as in females over 55 years of age. There was a wide variation in tidal volume. The comparison of myasthenic values for respiratory rate, inspiratory force and tidal volume to normal values derived from random tables and prediction equations was not significant. The major implications from this study are the need to assess pulmonary function in the hospitalized myasthenic every two hours, and the need for a program of coughing, deep breathing and sighing after medication administration when muscles are strongest.
Myasthenia gravis (MG) is strongly associated with antibodies to acetylcholine receptor (AChR), whereas the extent of T cell involvement is not settled. The number of cells secreting interferon-gamma (IFN-gamma) in response to AChR during 48 h culture of blood mononuclear cells (PBL) may reflect AChR-reactive T cells. Using an immunospot assay, we detected such cells in 23 of 30 patients with MG at a mean number of 1 per 33.333 PBL. AChR-reactive T cells were also found in patients with other neurological diseases (OND) and in healthy subjects but at lower frequencies and numbers. The T cell response to purified protein derivative and to PHA, and also to two major myelin proteins (basic protein and proteolipid protein) did not differ between MG and the two control groups, underlining the specificity of an augmented T cell reactivity to AChR in MG. Evaluation of the B cell response by enumerating anti-AChR IgG antibody secreting cells revealed such cells in 27 of 28 patients with MG at a mean value of 1 per 14,085 PBL. Cells secreting anti-AChR antibodies of the IgA and IgM isotypes were also detected in MG, but less frequently, at lower numbers, and only in conjunction with IgG antibody secreting cells. Anti-AChR antibody secreting cells were also found among patient with OND and in healthy controls, but at lower frequencies and numbers. These data confirm that AChR is a major target for autoimmune response in MG.