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PubMed2000

[Neonatal myasthenia gravis].

BACKGROUND: Myasthenia gravis, an autoimmune disease of young women, is due to the dysfunction of neuromuscular transmission. The newborn of a myasthenic mother inconstantly presents a transitory neonatal myasthenic syndrome. Maternal aggravation, or even myasthenic crisis with respiratory failure, can occur in the first three months post-partum. CASE REPORT: Mrs. S., para two without appreciable medical history, delivered normally a boy weighing 4 kg with an Apgar score of 10/10. At 3 h of life the newborn was admitted to the neonatal care unit for grunting and axial hypotonia. Diagnoses of maternal-fetal infection and fetal distress were excluded. The dissociated pattern of neurological disorders (refusal to drink, axial hypotonia, hypomimia, but good contact and normal alertness) led to search for neuromuscular causes or poison. Myasthenia gravis was then considered and confirmed by maternal electromyography, allowing the diagnosis of transient neonatal myasthenia gravis and early diagnosis and treatment of the maternal myasthenic crisis in a specialized care unit. The outcome of both mother and child was favorable under treatment. CONCLUSION: Lack of maternal myasthenia gravis history should not result in excluding the diagnosis of transitory neonatal myasthenia gravis when evocative neonatal neurological signs are present. The symptomatology in the newborn may indeed reveal maternal myasthenia gravis, allowing an early diagnosis in both the mother and the newborn.

Adult↗

PubMed1997

[Importance of neuromuscular "jitter" under stimulation in the diagnosis of myasthenia gravis].

Ninety five patients with global muscular weakness or purely extraocular weakness were included in a retrospective study. Electrical micro stimulation and single fiber electromyography were performed in all, for neuromuscular jitter evaluation in myasthenia gravis diagnosis. In our study, increased jitter was more often present (70% of generalised myasthenia gravis and 57% of ocular myasthenia gravis) than decrement after repetitive nerve stimulations (58% of generalised myasthenia gravis and 14% of ocular myasthenia gravis). Increased jitter was also found in non-myasthenic patients. With the aim of a better sensitivity and specificity of the electrophysiological diagnosis for myasthenia gravis a protocol is described.

Adult↗

PubMed2002

Video-assisted thymectomy for myasthenia gravis: an update of a single institution experience.

OBJECTIVE: Video-assisted thymectomy was introduced in 1992 as a minimally invasive alternative for the treatment of myasthenia gravis. As experience with this technique is limited and follow-up short, we present this expanded and updated experience for purposes of validation of the technique. METHODS: Thirty-eight video-assisted thymectomies for myasthenia gravis were performed in our institution between March 1992 and March 2002. Two patients were lost to follow-up. We analyzed clinical results of 36 patients (14 males and 22 females) with a mean age of 41.2 years. Preoperative clinical staging was assessed by the newly recommended Myasthenia Gravis Foundation of America Clinical Classification. Clinical status at follow-up was assessed by the Myasthenia Gravis Foundation of America Postintervention Status classification. RESULTS: There was no perioperative mortality or long-term morbidity. One of 38 (2.6%) patients required conversion to limited thoracotomy for bleeding. The mean length of hospital stay was 1.64 days (range 0-8 days) with a median stay of 1 day. The mean length of follow-up is 53.24 months (range 4-126 months). Overall clinical improvement at follow-up was observed in 30 of 36 (83.0%) patients, with five of 36 (14.0%) patients in complete stable remission. CONCLUSIONS: Video-assisted thymectomy for myasthenia gravis provides acceptable clinical long-term results by a minimally invasive approach comparable to standard surgical approaches to the disease. The presented data is reported in accordance with the new guidelines by Myasthenia Gravis Foundation of America Task Force for valid comparison with future studies.

Adolescent↗

PubMed1980

Experimental myasthenia gravis. A murine system.

Mice from eight inbred strains were immunized with acetylcholine receptor (AChR) purified from Torpedo californica. All mice developed high concentrations of serum antibodies (10(-6) M) against the immunogen and approximately 80% possessed antibodies reactive with mouse nicotinic AChR. 33% of the mice immunized (n = 236) developed muscular weakness and flaccid paralysis. Behavioral, electrophysiological, and pharmacological similarities were found between the experimentally induced muscular weakness and the disease myasthenia gravis. Susceptibility to experimental myasthenia was found to be strain dependent in that the frequency of paralysis was much greater in some strains than others. The occurrence of muscular weakness and flaccid paralysis did not correlate with the concentration of antibodies reactive with T. californica or mouse AChR. Anti-receptor antibodies which increased the rate of AChR degradation on the mouse muscle cell line, BC3H-1, were found in the serum of both myasthenic and nonmyasthenic mice. 40% of the mice tested possessed antibodies reactive with antigenic determinants present on mouse receptor but not T. californica receptor. The occurrence of antibodies unique to mouse receptor did not correlate with myasthenia. Thus, myasthenia in the mouse does not occur simply as a consequence of the presence of antibodies directed against cell surface antigenic determinants of AChR. If anti-AChR antibodies are both necessary and sufficient for the induction of myasthenia, then these studies suggest that populations of a particular structure and/or specificity are required. It is anticipated that the mouse model of myasthenia gravis will permit the regulation of the anti-receptor immune response to be studied in detail.

Acetylcholine↗

PubMed2000

Preanesthetic train-of-four fade predicts the atracurium requirement of myasthenia gravis patients.

BACKGROUND: The most sensitive diagnostic criterion of myasthenia gravis is a decrement in the muscular response to repetitive stimulation. The authors hypothesized that myasthenia gravis patients who show a train-of-four ratio (T4/T1) < 0.9 in the preanesthetic period will have increased sensitivity to nondepolarizing neuromuscular blocking agents compared with myasthenia gravis patients with preanesthetic T4/T1 > or = 0.9. METHODS: After institutional review board approval was obtained, 20 electrophysiologically documented myasthenia gravis patients were studied. Current pyridostigmine therapy was continued until the morning of surgery. Before induction of anesthesia, neuromuscular transmission was recorded from the hypothenar muscles using electromyography with train-of-four stimulation of the ulnar nerve. According to the T4/T1 ratio, patients were assigned to the "normal" group (T4/T1 > or = 0.9) or the "decrement" group (T4/T1 < 0.9). After induction of intravenous anesthesia, the effective dose to achieve a 95% neuromuscular blockade (ED95) for atracurium was assessed with a cumulative bolus technique. Postoperatively, pyridostigmine was titrated to obtain a T4/T1 > 0.75 and to treat residual myasthenic symptoms. RESULTS: In 14 patients, preanesthetic T4/T1 was > or = 0.9 (normal), whereas 6 patients presented with T4/T1 < 0.9 (decrement). Decrement patients had a lower ED95 of 0.07 +/- 0.03 mg/kg atracurium (mean +/- SD) compared with normal patients with an ED95 of 0.24 +/- 0.11 mg/kg atracurium (P = 0.002). All patients were extubated within 30 min after surgery. Postoperative pyridostigmine infusion did not differ significantly between groups. CONCLUSIONS: The requirement for atracurium is significantly reduced in myasthenia gravis patients with a T4/T1 ratio < 0.9 before anesthesia. This study indicates that routine neuromuscular monitoring in myasthenia gravis patients should be extended into the preinduction period to identify patients who require less atracurium.

Adult↗

PubMed1975

LD antigens associated with HL-A8 and myasthenia gravis.

The finding that the SD antigen HL-A8 is associated with myasthenia gravis has raised the question as to whether or not there is also an association between some specific LD antigen and myasthenia gravis and/or HL-A8. MLC technique was used to study LD antigens in 33 myasthenic patients. The cells of a myasthenic patient who was homozygous for both HL-A and LD products were used in MLC tests as stimulators with HL-A8 bearing cells from 24 myasthenics, their 17 relatives and 16 controls and to non-HL-A8 cells from nine myasthenics and 16 controls. At least three different LD genes were found to be associated with HL-A8. One of them, called LDm' was present in 17 (63 %) of the 27 HL-A8-bearing haplotypes of myasthenics, and in nine (47 %) of the 19 HL-A8-bearing haplotypes of controls. In our study LDm was not found in the 84 haplotypes devoid of HL-A8. LDm is strongly associated with HL-A8 and through this also with myasthenia. Calculated from phenotype frequencies for HL-A8 and its association to LDm' the LDm frequencies are 9 % in the control population, 30 % in myasthenics and 48 % in young females with onset of myasthenia below 35 years. LDm had no indendent correlation with any of the clinical parameters of myasthenia gravis, even though is was found more often in HL-A8+ females with the onset of myasthenia before 35 years than in the whole myasthenic group. LDm appears to be similar to LD8a antigen.

Age Factors↗

PubMed2006

Myasthenia gravis in children: a longitudinal study.

BACKGROUND: Juvenile myasthenia gravis (JMG) is an uncommon disease. Unlike adults, clinical characteristics and outcomes of myasthenia gravis (MG) are not well studied in children. PATIENTS AND METHODS: Case records of 77 patients with MG who were 15 years of age or less at disease onset, evaluated over a period of 34 years at the National Institute of Mental Health and Neurosciences, Bangalore, India, were reviewed. Their clinical characteristics and response to therapy was compared with 290 patients with MG onset after 15 years of age. RESULTS: Median age at onset was 8 years and mean period of follow-up was 6.2 years (range 6 months to 25 years). At presentation, 30% of patients had ocular myasthenia and the rest had generalized disease. Twenty-one patients (27%) had disease confined to ocular muscles throughout the course and three had limb girdle myasthenia. Familial myasthenia was more common than adult onset disease, 10 patients had positive family history. Unlike adults, none of the patients had associated autoimmune disease. Fifty-two patients (67%) received corticosteroids, and azathioprine was added in five patients. Thymectomy was performed in 11 patients, six below the age of 15 years. Thymic histology was normal in one and showed hyperplasia in eight and thymoma in one. Four patients had crisis. At the end of follow-up, 25 patients were asymptomatic, 28 had partial improvement, and nine remained unchanged or worsened and two died. Ten patients achieved complete stable remission. CONCLUSIONS: This study shows some distinctive characteristics of JMG, such as higher frequency of ocular myasthenia, benign course, better long-term outcome and lack of association of thymoma and other autoimmune disorders.

Adolescent↗

PubMed2004

Update on myasthenia gravis.

Myasthenia gravis is an autoimmune disorder caused by autoantibodies against the nicotinic acetylcholine receptor on the postsynaptic membrane at the neuromuscular junction and characterised by weakness and fatigability of the voluntary muscles. It has a bimodal peak of incidence with first peak in the third decade and the second peak in the sixth decade. It is probably underdiagnosed in the very old population. Our understanding of the pathogenesis, immunology, and molecular biology of myasthenia gravis has greatly improved in last three decades. It is almost always possible to establish the diagnosis of myasthenia gravis with the current tests. The modern treatment is highly successful and the mortality of treated myasthenia gravis is practically zero. However, there are still important gaps in our knowledge of the origin of myasthenia gravis, the factors that contribute to chronic disease, and the way to cure the disease. In this article the current knowledge of the various aspects of myasthenia gravis are outlined.

Age of Onset↗

PubMed1983

Thymus irradiation for myasthenia gravis.

Twenty-eight patients with progressive myasthenia gravis without thymoma received treatment of 3000 rads (30 Gy) to the anterior mediastinum, and a followup was conducted for five to 18 years. Twenty-four patients had generalized myasthenia, and four had ocular myasthenia gravis. Twenty patients with generalized myasthenia survived the several month post-treatment period and improved, but four died during that period. The improvement lasted a median of 1.5 years, and older patients had longer remissions than younger patients. The four patients who had ocular myasthenia did not change after treatment. Mediastinal irradiation produces a temporary remission in generalized myasthenia.

Adolescent↗

PubMed2000

Myasthenia gravis and associated autoimmune diseases in children.

Myasthenia gravis has been associated with other autoimmune disorders. We report two children with myasthenia gravis and another autoimmune disease: an 18-month-old boy with ocular myasthenia gravis and Hashimoto's disease and a 14-year-old girl presenting with autoimmune polymyositis, then generalized myasthenia gravis 2 years later. The rare combinations of myasthenia gravis and Hashimoto's disease or polymyositis in children are discussed, and we also briefly review myasthenia gravis and other associated autoimmune diseases in children.

Adolescent↗

PubMed1976

Antibody to acetylcholine receptor in myasthenia gravis. Prevalence, clinical correlates, and diagnostic value.

Elevated amounts of antibodies specific for acetylcholine receptors were detected in 87 percent of sera from 71 patients with myasthenia gravis but not in 175 sera from individuals without myasthenia gravis, including those with other neurologic or autoimmune diseases. Antireceptor antibodies were not directed at the acetylcholine binding site of the receptor. Presence or titer of antibody did not appear to correlate with age, sex, steroid therapy, or duration of symptoms. Myasthenia gravis patients with only ocular symptoms had lower antibody titers, while the majority of titers in myasthenia gravis patients with thymoma exceeded the median titer of the myasthenia gravis group as a whole. Assay of antireceptor antibody should prove a useful test in the diagnosis of myasthenia gravis.

Acetylcholine↗

PubMed2003

CT-guided percutaneous ethanol injection of the thymus for treatment of myasthenia gravis.

OBJECTIVE: This study was designed to validate the therapeutic effectiveness of CT-guided percutaneous ethanol injection of the thymus for the treatment of myasthenia gravis. SUBJECTS AND METHODS: The subjects were 45 patients with myasthenia gravis. The diagnosis was determined by the patients' histories, physical findings, neostigmine tests, and morphologic changes. According to the Osserman classification, the 45 patients with myasthenia gravis were classified as stage I (n = 26), stage III (n = 13), and stage IV (n = 6). A 21- or 22-gauge needle was inserted into the thymus under CT guidance, and then ethanol was injected step by step until it was distributed throughout the whole thymoma, the hyperplasia of the thymus, or the normal thymus. The amount of ethanol injected ranged from 2 to 13 mL, with a mean of 7 mL. RESULTS: CT follow-up at 3-4 weeks showed that the thymus or thymoma was completely or mostly necrotized. CT follow-up at 3 months showed that the vertical, transverse, and anteroposterior dimensions of the thymus in all 45 myasthenia gravis patients decreased by 59.2%, 68.6%, and 73.2%, respectively, compared with those before percutaneous ethanol injection treatment. The therapeutic effect was observable clinically 2 days after treatment in 44 patients, including 36 patients who were able to open their eyes after treatment. A 5-year follow-up study showed that the condition markedly improved in 35 patients, improved in nine patients, and failed to improve in one patient who did not respond to the treatment. After treatment, 37 patients presented with low-grade fever (range, 37.3-37.7 degrees C; mean, 37.5 degrees C), which resolved 3 days later without treatment; all 45 patients complained of mild retrosternal pain after ethanol injection. CONCLUSION: The therapeutic effect of CT-guided percutaneous ethanol injection into the thymus of patients with myasthenia gravis is definite. This procedure is safe and has low morbidity. CT-guided percutaneous ethanol injection is a minimally invasive alternative treatment for myasthenia gravis.

Adolescent↗

PubMedDate not supplied

[Myasthenia in the aged: a case with unusually late onset].

BACKGROUND: Myasthenia is an uncommon autoimmune condition that can occur at any age. Peak frequency is seen around the age of 65 years. We report a case with a particularly late onset and discuss the particular conditions of myasthenia in the elderly subject. CASE REPORT: A 97-year-old patient was hospitalized for dysphonia and dysphagia associated with exercise-induced dyspnea. The general picture suggested generalized myasthenia confirmed by the electromyography exploration and a positive anticholinesterase test. Treatment with acetylcholinesterase inhibitor was effective although cure was incomplete. Further improvement was obtained with immunosuppressor therapy using azathioprine. DISCUSSION: The clinical presentation of very late onset myasthenia differs little from that in younger subjects excepting the very high frequency of brain stem involvement in the initial presentation. Diagnosis may however be more difficult as other conditions are more easily taken to be the causal element. Thus, for the elderly patient, the real problem is to envisage the diagnosis of myasthenia. Positive diagnosis is based on the same criteria as in younger subjects. Clinicians should be aware of the possibility of myasthenia in the geriatric population as specific treatment can improve functional prognosis with satisfactory efficacy.

Age Factors↗

PubMed1998

[Distribution of B-lymphocyte subgroup CD20 and its clinical significance in patients with myasthenia gravis].

OBJECTIVE: To assess the distribution and clinical significance of B-lymphocyte subgroup CD20 in patients with myasthenia gravis. METHOD: B-lymphocyte subset CD20 was studied in patients with thymomas associated with or without myasthenia gravis using immunohistochemistry technique. RESULT: The moderate and obvious aggregation of CD20 positive cells was found in patients with myasthenia gravis, there was a significant difference when compared with those patients without myasthenia gravis (chi(2) = 26.032, P < 0.01). There was negative correlation between the distribution of CD20 positive cells and the staging of thymomas (gamma = 0.07), and no correlation between the distribution and clinical type of myasthenia gravis (gamma < 0.4). CONCLUSION: The results of this study indicated that pathological changes of thymus are more important than those of thymomas itself in the pathogenesis of myasthenia gravis. The degree of B-lymphocyte subgroup aggregation can not truly reflect clinical status because of the heterogeneity of antibody against acetylcholine receptor.

Adult↗

PubMed2002

[Stimulation single fiber electromyography in rats with myasthenia induced by organophosphorus insecticides and their mixtures poisoning].

OBJECTIVE: To study the neuromuscular function and its relation with the occurrence of myasthenia in rats poisoned by dimethoate (D), phoxim (P), methomyl (M), M + D and M + P respectively. METHODS: The stimulation single fiber electromyography(SSFEMG) at different stimulus frequencies(5, 10 and 20 Hz) was used. The whole blood cholinesterase (ChE) activity was measured 1 h before and after poisoning. RESULTS: (1) Myasthenia occurred in 5 out of 9.5 out of 10.5 out of 5, and 8 rats poisoned by D, P, M + D, and M + P, respectively. (2) The average mean consecutive differences(MCD) at 5, 10, and 20 Hz in myasthenic rats were significantly higher than those of poisoned rats without myasthenia and the control ones. (3) SSFEMG changes at 5, 10 and 20 Hz were significantly consistent with the clinical manifestation of myasthenia, especially at 10 Hz and 20 Hz. (4) ChE activity was significantly lower in rats with P or D poisoning while ChE inhibition was of no difference in rats with M, M + D, and M + P poisoning. In the D poisoning and P poisoning groups, there was no significant difference in ChE inhibition between the rats with and without myasthenia. CONCLUSION: Muscle weakness was associated with neuromuscular transmission dysfunction, but not well correlated with ChE inhibition. The SSFEMG with stimulus frequency at 10 Hz or 20 Hz could be used to detect the neuromuscular dysfunction during myasthenia induced by organophosphate insecticides and their mixtures poisoning.

Animals↗

PubMed2005

[The study of phonatory function in myasthenia gravis patients].

OBJECTIVE: To investigate the phonatory function in myasthenia gravis patients and the role of acoustic analysis technique in the diagnosis and the assessment of therapeutic effect on treatment of myasthenia gravis. METHOD: Eighty-three myasthenia gravis patients diagnosed definitely in neurology were divided into two groups, ocular group and generalized group. Each group included male group and female group. Acoustic measures were carried out before and after neostigmine test and treatment. Forty healthy subjects including twenty male and twenty female served as control groups. The basic parameters of the voice using computed voice analysis included F0, shimmer, jitter and NNE. Independent-Samples T Test and Paired-Samples T Test were used. RESULT: The value of F0 and NNE increased in generalized group. The changes of F0 and NNE in generalized group were found to be statistically significant (P < 0.01, 0.05). Neostigmine resulted in an improvement in the parameters of F0 and NNE, the same condition happened after the treatment (P < 0.01). CONCLUSION: Phonatory function of generalized myasthenia gravis patients is abnormal. F0 and NNE increase in generalized myasthenia gravis patients and decrease after the treatment or the intake of neostigmine. Acoustic analysis is a useful method in the diagnosis and assessment of generalized myasthenia gravis patients.

Adolescent↗

PubMedDate not supplied

[Myasthenia gravis in pregnancy].

Twenty-nine patients with myasthenia gravis in pregnancy have been presented. These patients represent a total of 31 deliveries and 33 newborns. Despite that myasthenia gravis is an illness that poses potentially grave complications for both mother and infant, there were no maternal and neonatal deaths. Only two patients experienced significant exacerbation of their disease during pregnancy. Most of patients underwent vaginal delivery. Cesarean section is not indicated unless there are obstetrical reasons. Incidence of cesarean section delivery was 16.1%. Vacuum extractor has been used to shorten the second stage of labor and its incidence was 16.1%. In the seven (22.6%) patients myasthenic signs and symptoms got worse during the postpartal period. Neonatal myasthenia gravis was observed in 13 (39.4%) newborns. Inverse relationship was found between neonatal myasthenia and duration of disease in mothers. Incidence of neonatal myasthenia was higher in newborns born by mothers with short duration of myasthenia gravis.

Adult↗

PubMedDate not supplied

Experimental models of myasthenia gravis: lessons in autoimmunity and progress toward better forms of treatment.

The nicotinic acetylcholine receptor (AChR) is a large membrane protein found in muscle cells. It is involved in the transformation of acetylcholine packets into a membrane depolarization, which thereby leads to a muscle twitch. This large, complex molecule is the target of the autoimmune attack in myasthenia gravis, and much has been learned in the past decade about myasthenia by the induction of autoimmunity to AChR in experimental animals. Experimental autoimmune myasthenia gravis (EAMG) has been produced in a variety of animals by immunization with AChR or AChR-like material, or by the passive transfer of anti-AChR antibodies or lymphocytes from afflicted animals into normal animals. EAMG is a remarkably faithful model of human myasthenia and has provided much information about how the immune response to AChR progresses and how weakness and damage to the neuromuscular junction ensure. EAMG has also allowed the development of a number of revolutionary forms of treatment in which only the abnormal response to AChR is restrained, and other necessary immune functions are left intact. These advances in treatment are not far from being tested in human myasthenia gravis. The experience gained in applying these concepts in EAMG and human myasthenia will be helpful in developing similar forms of treatment for other autoimmune diseases.

Animals↗