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PubMed1994

Reduced sulphoxidation capacity in D-penicillamine induced myasthenia gravis.

Myasthenia gravis may be observed due to treatment with penicillamine (D-PA). The sulphoxidation capacity was measured in nine Swedish patients with rheumatoid arthritis (RA) who had developed myasthenia gravis toward D-PA. The results show that in eight of nine patients tested, this parameter was markedly reduced. A patient with poor sulphoxidation capacity has a twelve-fold greater risk of developing this rare side effect. The significance of this is discussed.

Adult↗
PubMed1993

Acute hemiparesis with hemichorea and crossed hemiparesis; unusual presentation for myasthenia gravis.

Myasthenia gravis is an autoimmune disease mediated by antibodies directed against the acetylcholine receptor. Patients typically present with weakness and fatiguability involving predominantly ocular and bulbar muscles. We describe 2 patients with acute weakness, one with a left hemiparetic pattern and chorea, and the other with crossed left hemiparesis and right facial weakness. More typical features of generalised myasthenia developed with time and both had thymic follicular hyperplasia on thymic histopathology. Clinical improvement occurred in both following thymectomy and immunosuppression. These cases exemplify the fact that markedly asymmetric limb weakness can be an early feature of generalised myasthenia gravis.

Acute Disease↗
PubMed2000

Sevoflurane as a sole anaesthetic for thymectomy in myasthenia gravis.

Myasthenia gravis is a challenging situation for anaesthesiologists due to its neuromuscular involvement. The main concerns are respiratory muscle weakness and side effects due to a heavy dose of anticholinesterases. This limits the use of sedatives, hypnotics and muscle relaxants. Inhalational anaesthetics are best suited. We describe our experience with sevoflurane as a sole anaesthetic in a child having juvenile-type myasthenia gravis with thymoma, who underwent thymectomy by midsternal incision. Very smooth and short duration of induction (35 s) and easy intubation within 60 s without use of muscle relaxant were the remarkable features. Sevoflurane in oxygen and nitrous oxide (MAC=0.5-0.7) was used for maintenance of anaesthesia. Recovery was smooth and fast with no residual respiratory insufficiency. Hence we found sevoflurane to be a highly suitable agent for thymectomy in mysthenia gravis.

Anesthetics, Inhalation↗
PubMedDate not supplied

Anesthetic implications of myasthenia gravis.

Myasthenia gravis is a disease of great significance to the anesthesiologist, because it affects the neuromuscular junction. Many patients with this condition are treated by surgical thymectomy, using techniques developed by Mount Sinai physicians, including Dr. Paul Kirschner, Dr. Alan E. Kark, and the late Dr. Angelos E. Papatestas. The authors review the anesthetic considerations in the management of patients with myasthenia gravis who are undergoing thymectomy and other surgical procedures.

Anesthesia↗
PubMed1998

How subtle differences in MHC class II affect the severity of experimental myasthenia gravis.

Myasthenia gravis is an autoimmune disorder characterized by muscle weakness, due to an antibody-mediated deficit of acetylcholine receptors (AChRs) at neuromuscular junctions. We analyzed the factors that determine the severity of experimental myasthenia gravis (EAMG) induced by immunization with Torpedo AChR, in two congenic strains of mice--B6 mice, which are highly susceptible to EAMG; and bm12 mice, which are relatively resistant, and differ only in a change of three amino acids in MHC Class II. We prepared large numbers of AChR-specific T cell hybridomas from each strain and characterized their epitope specificities and T cell receptor (TCR) gene usage: Half the B6 hybridomas responded to a single AChR peptide (alpha 146-162), and their TCR genes encoded restricted V alpha and V beta chains and CDR3 motifs. bm12 hybridomas had different epitope specificities and different, less restricted TCR genes. APCs were able to present AChR or AChR-derived peptides virtually exclusively to hybridomas of their own strain. Levels of antibodies to Torpedo and autoantibodies to mouse AChR were higher in B6 mice, and were biased toward the IgG2b isotype. We conclude that the "better fit" of MHC II, peptide, and TCR in the B6 mice enhanced cognate interactions of APCs with T cells, and T cells with B cells, resulting in a more abundant and pathogenic AChR antibody response, and thus more severe EAMG.

Animals↗
PubMed1982

Carbamylcholine modulation of E-rosette formation. Effect of plasmapheresis in myasthenia gravis.

Myasthenia gravis may result from a reduction of available acetylcholine receptors at the neuromuscular junction, likely secondary to the presence of anti-acetylcholine receptor antibodies. Since T lymphocytes appear to carry a similar nicotinic acetylcholine receptor, we investigated the capacity of T cells from patients with myasthenia gravis to bind sheep erythrocytes. In addition we determined the effect of carbachol, a cholinergic agonist, on E-rosette formation, and the role of myasthenic serum in modulating these responses. Two groups of patients were identified; one with normal numbers of E-rosettes forming cells (E-RFC) and the other with significantly reduced numbers. The majority of patients with myasthenia had a reduced number of carbachol-sensitive T cells. Incubation of their serum (or the IgG fraction) with normal T cells led to a reduction in numbers of E-RFC, particularly of the carbachol-sensitive subset. These effects were blocked by d-tubocurarine and not by atropine. Following plasmapheresis, normal numbers of E-RFC were detected in the patients and the serum inhibitory activity was no longer detected. The data suggest that in parallel to the achievement of some degree of clinical improvement, plasmapheresis may restore some aspects of lymphocyte function.

Adolescent↗
PubMed2005

Overexpression of IFN-induced protein 10 and its receptor CXCR3 in myasthenia gravis.

Myasthenia gravis (MG) and its animal model, experimental autoimmune MG (EAMG), are autoimmune disorders in which the acetylcholine receptor (AChR) is the major autoantigen. Microarray technology was used to identify new potential drug targets for treatment of myasthenia that would reduce the need for the currently used nonspecific immunosuppression. The chemokine IFN-gamma-inducible protein 10 (IP-10; CXCL10), a CXC chemokine, and its receptor, CXCR3, were found to be overexpressed in lymph node cells of EAMG rats. Quantitative real-time PCR confirmed these findings and revealed up-regulated mRNA levels of another chemoattractant that activates CXCR3, monokine induced by IFN-gamma (Mig; CXCL9). TNF-alpha and IL-1beta, which act synergistically with IFN-gamma to induce IP-10, were also up-regulated. These up-regulations were observed in immune response effector cells, namely, lymph node cells, and in the target organ of the autoimmune attack, the muscle of myasthenic rats, and were significantly reduced after suppression of EAMG by mucosal tolerance induction with an AChR fragment. The relevance of IP-10/CXCR3 signaling in myasthenia was validated by similar observations in MG patients. A significant increase in IP-10 and CXCR3 mRNA levels in both thymus and muscle was observed in myasthenic patients compared with age-matched controls. CXCR3 expression in PBMC of MG patients was markedly increased in CD4(+), but not in CD8(+), T cells or in CD19(+) B cells. Our results demonstrate a positive association of IP-10/CXCR3 signaling with the pathogenesis of EAMG in rats as well as in human MG patients.

Adolescent↗
PubMed1992

Anaesthesia and myasthenia gravis.

Myasthenia gravis is an autoimmune disease, resulting from the production of antibodies against the acetylcholine receptors of the endplate. These antibodies reduce the number of active receptors, brought about either by functional block of the receptors, by increased rate of receptor degradation, or by complement-mediated lysis. In myasthenic muscles, the miniature endplate potential amplitude is decreased, and a large proportion of the endplate potentials are subthreshold. Repetitive nerve stimulation results in a decremental response. The disease is frequently associated with morphological abnormalities of the thymus. In young patients, thymic hyperplasia is common while thymoma is more frequent in elderly patients. Medical treatment of myasthenia gravis aims at improving of neuromuscular transmission by anticholinesterases, suppressing the immune system by corticosteroids and immunosuppressants, or by decreasing the circulating antibodies by plasmapheresis. Adults with generalized myasthenia should have a trans-sternal thymectomy. A balanced technique of general anaesthesia which includes the use of muscle relaxants can be safely used, provided neuromuscular transmission is monitored. Myasthenic patients are sensitive to nondepolarizing relaxants but intermediate-acting nondepolarizing relaxants such as atracurium and vecuronium are eliminated rapidly, and can be titrated to achieve the required neuromuscular block that can be completely reversed at the end of surgery. Postoperatively, ventilatory support may be required in high-risk patients. Also, medical treatment may be maintained, tapered or discontinued depending on the outcome of surgery. Thymectomy benefits nearly 96% of patients, 46% develop complete remission and 50% are asymptomatic or improve on therapy.

Adolescent↗
PubMed1993

Anesthesia and myasthenia gravis.

Myasthenia gravis is an autoimmune disease, resulting from the production of antibodies against the acetylcholine receptors of the endplate. These antibodies reduce the number of active receptors, brought about either by functional block of the receptors, by increased rate of receptor degradation, or by complement-mediated lysis. In myasthenic muscles, the miniature endplate potential amplitude is decreased, and a large proportion of the endplate potentials are subthreshold. Repetitive nerve stimulation results in a decremental response. The disease is frequently associated with morphological abnormalities of the thymus. In young patients, thymic hyperplasia is common while thymoma is more frequent in elderly patients. Medical treatment of myasthenia gravis aims at improving of neuromuscular transmission by anticholinesterases, suppressing the immune system by corticosteroids and immunosuppressents, or by decreasing the circulating antibodies by plasmapheresis. Adults with generalized myasthenia should have a transsternal thymectomy. A balanced technique of general anaesthesia which includes the use of muscle relaxants can be safely used, provided neuromuscular transmission is monitored. Myasthenic patients are sensitive to nondepolarizing relaxants but intermediate-acting nondepolarizing relaxants such as atracurium and vecuronium are eliminated rapidly, and can be titrated to achieve the required neuromuscular block that can be completely reversed at the end of surgery. Postoperatively, ventilatory support may be required in high-risk patients. Also, medical treatment may be maintained, tapered or discontinued depending on the outcome of surgery. Thymectomy benefits nearly 96% of patients, 46% develop complete remission and 50% are asymptomatic or improve on therapy.

Adolescent↗
PubMed1979

The otolaryngologic presentation of myasthenia gravis.

Myasthenia gravis is a neuromuscular disease of insidious onset, characterized by weakness and fatigability of voluntary muscles. Most patients present with symptoms relating to the head and neck and thus may be seen first by the otolaryngologist. Predominant symptoms may be ocular (ptosis or diplopia) or related to fatigue of the oropharyngeal or laryngeal musculature (dysarthria, dysphonia, or dysphagia). Alleviation of muscular weakness and fatigability after administration of anticholinesterase drugs is pathognomonic of myasthenia gravis.

Adolescent↗
PubMed2004

Myasthenia gravis.

Myasthenia gravis is the prototype neuromuscular disease with immunological pathogenesis. The recognition and interpretation of the symptoms should be stressed as the diagnosis is initially achieved on clinical ground. Tests in the areas of immunology, electrophysiology and imaging further help the diagnosis, management and prognosis of the condition. The recent knowledge of immunology seems to point to variations in the immune abnormalities, but it remains to be seen whether the differences have clinical relevance. With the availability of intensive care units, the management of acute events in the myasthenic patients has improved considerably and the morbidity is reduced. Long term remissions are achievable in majority of patients, with supervised use of immunosuppression. In the modern times, the grave connotations of the name myasthenia gravis may be only rarely justified.

Antibodies↗
PubMed1980

The current role of thymectomy for myasthenia gravis.

Myasthenia gravis is an autoimmune disease characterized by muscle weakness and fatigability due to a reduction in available acetylcholine receptors at the neuromuscular junction. Treatment with anticholinesterase drugs and corticosteroids has improved the prognosis for patients with this disease. However, controversy continues concerning the indications for thymectomy. During a 9 year period, 27 patients who underwent thymectomy by median sternotomy were reviewed. Eighty-one percent of these patients benefited from the procedure. Clinical improvement did not correlate with age, sex, duration of symptoms, severity of disease or thymic histology, This suggests that the indications for thymectomy should be liberalized to include most patients with generalized myasthenia who fail to respond readily to conventional medical therapy. The importance of immunosuppression nd plasmapheresis in the therapy of myasthenia gravis awaits further delineation of the immune defect associated with the disease.

Adolescent↗
PubMed2005

Vaccines against myasthenia gravis.

Myasthenia gravis (MG) is an autoimmune disease mediated by antibodies to nicotinic acetylcholine receptor (AChR) interfering with the neuromuscular transmission. Experimental autoimmune MG serves as an excellent animal model to study possible therapeutic modalities for MG. This review will focus on the different ways to turn off the autoimmune response to AChR, which results in suppression of myasthenia. This paper will describe the use of fragments or peptides derived from the AChR, antigen-presenting cells and anti-T cell receptor antibodies, and will discuss the underlying mechanisms of action. Finally, the authors propose new promising therapeutic prospects, including treatment based on the modulation of regulatory T cells, which have recently been found to be functionally defective in MG patients.

Animals↗
PubMed1967

The role of radiation therapy in myasthenia gravis.

Myasthenia gravis is a serious and debilitating disease associated with conduction defects occurring at the myoneural junction. About 15 per cent of the patients have associated tumors of the thymus and 80 per cent of the remaining patients show abnormalities of the thymus. Although a definite relationship between cause and effect has not been proved, thymectomy or radiotherapy of the thymus does seem to influence the disease. Seven cases of myasthenia gravis in which radiation therapy was used at the University of California Medical Center are reported and compared with those described in the literature. It is concluded that patients whose disease is progressing and not well managed medically, and who have no evidence of thymoma, should be treated by irradiation-whether pre-operatively or as definitive treatment, depending on the result of irradiation. Those patients with evidence of thymoma should be irradiated before surgical procedure. Small tumors, or patients in whom surgical risk is increased, may be managed by radiation therapy alone.

Adult↗
PubMed1997

FK506 prevents induction of rat experimental autoimmune myasthenia gravis.

Myasthenia gravis (MG) is an organ-specific autoimmune disease attacking nicotinic acetylcholine receptors (AChR) of the neuromuscular junction. Autoantibody production is regulated by autoimmune helper T cells that are specific to AChR. Therefore the suppression of autoimmune T cell activity could reduce myasthenic symptoms. Amongst immunomodulatory therapies aimed at T cells, we studied the therapeutic effect of FK506 as a T cell-specific immunosuppressive agent. Rats in which experimental autoimmune myasthenia gravis (EAMG) was induced by immunization with synthetic peptide of human AChR alpha-subunit residues 125-147 (H alpha 125-147) were treated daily with FK506 (1 mg/kg). FK506 prevented the reduction in amplitude of miniature endplate potential (MEPP) which was induced by H alpha 125-147 immunization. FK506 also suppressed anti-H alpha 125-147 and anti-rat AChR antibody production accompanied by a decrease in the antigen-specific T cell response against H alpha 125-147. These findings indicate that FK506 prevents induction of rat EAMG evoked by immunizing T cells against H alpha 125-147.

Amino Acid Sequence↗
PubMedDate not supplied

[Thymectomy in myasthenia gravis].

Myasthenia gravis is an autoimmundisease characterized by muscle fatigability due to a reduction in available acetylcholinereceptors at neuromuscular junction. Although the role of the thymus in the pathophysiology remains obscure, the results of thymectomy are out of discussion. However, controversy continues concerning the indications for thymectomy. In a period of six years and a half, 24 patients underwent a thymectomy. 22 of the patients benefited from the procedure. Their was no relation with sex, age, and severity of the disease; but how sooner we operate, how greater the changes for a total remission. With this results we propose thymectomy as essential in the treatment of myasthenia gravis. We found no relationship between anatomopathological results and these of the thymectomy. But we can confirm that a reduction in the acetylcholine antibodies titer is not essential for clinical benefit.

Acetylcholine↗
PubMed1996

A practical guide to the recognition and management of myasthenia gravis.

Myasthenia gravis is an autoimmune disorder of neuromuscular transmission. It is characterised by muscular weakness and fatiguability. Extrinsic ocular muscles are frequently involved at the onset of the disease; in about 15% of cases clinical signs remain confined to these areas, while in the other patients weakness becomes generalised. Diagnosis relies on clinical history and signs, improvement on anticholinesterase injection, electromyographic signs of impaired neuromuscular transmission and serum antiacetylcholine receptor (anti-AChR) antibody titration. Apart from the anti-AChR antibody assay, no single test is specific for myasthenia gravis; it is rather their combined results that can confirm diagnosis. The therapeutic approach varies from patient to patient and, as far as possible, should be adapted to each individual. Symptomatic drugs such as anticholinesterases improve muscle strength but seldom restore it to normal. Immunosuppressive therapy is very effective but entails the risk of severe adverse effects. Thymectomy improves the course of the disease and can increase remission rate; short term treatments are of benefit in the management of myasthenic emergencies.

Adrenal Cortex Hormones↗