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PubMed1980

Clinical electrophysiology in myasthenia gravis.

Effective diagnostic methods are of great importance in order to recognise myasthenic patients among those with muscle fatigability. Intracellular recordings are useful for research work within the field and for detailed description of the motor end-plate's physiology in the individual case. The method is not used for the routine diagnosis of myasthenia gravis. The decrement of the electrical muscle response with nerve stimulation is the most commonly used method. The diagnostic yield is higher in proximal muscles, in warmed muscles, after exercise, and after ischaemia. A significant number of patients may be undiagnosed with this technique. The mechanical response with nerve stimulation shows the same type of decrement but also an abnormal response to long stimulation. The diagnostic value of this is under dispute. Single fibre ENG needs more patient cooperation than do these tests. The diagnostic yield is significantly higher. Some patients considered to have myasthenia gravis do not show any abnormalities with this technique, particularly those with the pure ocular form. Conventional EMG is not useful for the diagnosis of myasthenia, but may be indicated in these patients when concurrent nerve or muscle disease is in question. Tests for eye movement fatique have not proved useful. Stapedius reflex fatigability is demonstrated in about the same proportion of patients as have positive SFEMG findings. The technique is not uncomfortable for the patient and requires minimal cooperation. The general usefulness must be assessed by further routine use. Even with the advent of immunological tests, neurophysiological investigations are indispensable in helping establish the diagnosis of myasthenia gravis. Discrepancies between the results comparing electrophysiological and immunological tests may indicate that myasthenia gravis is a heterogenous entity within which subgroups may be identified.

Computers↗

PubMed1986

HLA antigens and acetylcholine receptor antibody in the subclassification of myasthenia gravis in Hong Kong Chinese.

Thirty seven Chinese adults and 23 children in Hong Kong with myasthenia gravis were tested for HLA-A and -B antigens and acetylcholine receptor (AChR) antibody. HLA BW46 had a significantly increased prevalence in patients with juvenile onset ocular myasthenia gravis. Only one third of the juvenile ocular patients had AChR antibodies and the titres were generally low. In the adult patients taken as a whole there was a non-significant increase in the prevalence of HLA B5 and HLA B15. HLA BW46 was more prevalent in adult patients without AChR antibody and less prevalent in patients with AChR antibody but the findings were not statistically significant. It is suggested that ocular myasthenia gravis is determined by a pathological mechanism for which susceptibility is determined by HLA BW46. There was a strong correlation between ocular myasthenia gravis and Graves' disease in the adult patients. The possibility that ocular myasthenia gravis is accentuated by a BW46-associated predisposition to ocular Graves' disease is considered.

Adolescent↗

PubMed1987

Surgical treatment for myasthenia gravis.

A new surgical technique for thymectomy is presented. Three hundred and seventeen patients with myasthenia gravis and 20 with thymomas who had myasthenic symptoms were operated on. The new surgical approach--a small transverse sternotomy--was used in 257 cases (in 240 patients with myasthenia gravis and 17 with thymomas) and conventional median sternotomy in 80. In myasthenic patients small transverse sternotomy enabled radical thymectomy to be performed with an uneventful postoperative course and very good cosmetic results. There were no hospital deaths among patients with myasthenia gravis after thymectomy. The long term results, assessed after 18-24 months, were good: the total remission rate was 39.5%, and there was a great improvement in 48.5% and an improvement in 9%. After thymectomy about 30% of patients received supplementary treatment with prednisone. A correlation between the duration of symptoms and the result of thymectomy was established: the shorter the duration of myasthenia gravis the better the results. In the small group of 20 patients with thymomas two died in hospital. In 12 patients with encapsulated thymic tumours the long term results were similar to those in patients with myasthenia gravis, whereas in patients with infiltrating thymic tumours the results were unsatisfactory.

Adult↗

PubMed1995

Comparative effects of plasma exchange and pyridostigmine on respiratory muscle strength and breathing pattern in patients with myasthenia gravis.

BACKGROUND: Pyridostigmine, an acetylcholinesterase antagonist, is useful in improving respiratory function in patients with myasthenia gravis. More recently, plasma exchange has been employed in myasthenia gravis because it acts presumably by removal of circulating antibodies against acetylcholine receptors. Surprisingly, comparative data on the effects of pyridostigmine and plasma exchange on lung volumes, respiratory muscle strength, and ventilatory control system in patients with myasthenia gravis are lacking. METHODS: Nine consecutive patients with grade IIb myasthenia gravis were studied under control conditions and after a therapeutic dose of pyridostigmine. In a second study the patients were re-evaluated a few days after a cycle of plasma exchange, before taking pyridostigmine. In each subject pulmonary volumes, inspiratory (MIP) and expiratory (MEP) muscle force, and respiratory muscle strength, calculated as average MIP and MEP as percentages of their predicted values, were measured. The ventilatory control system was evaluated in terms of volume (tidal volume, VT) and time (inspiratory time, TI, and total time, TTOT) components of the respiratory cycle. Mean inspiratory flow (VT/TI)--that is, the "driving"--and TI/TTOT: that is, the "timing"--components of ventilation were also measured. RESULTS: In each patient treatment relieved weakness and tiredness, and dyspnoea grade was reduced with plasma exchange. Following treatment, vital capacity (VC) increased on average by 9.7% with pyridostigmine and by 14% with plasma exchange, and MIP increased by 18% and 26%, respectively. In addition, with plasma exchange but not with pyridostigmine forced expiratory volume in one second (FEV1) increased by 16% and MEP increased by 24.5%, while functional residual capacity (FRC) decreased a little (6.8%). The change in respiratory muscle strength was related to change in VC (r2 = 0.48). With plasma exchange, VT increased by 18.6% and VT/TI increased by 13.5%, while neither TI nor TI/TTOT changed. CONCLUSIONS: Plasma exchange can be used in patients with myasthenia gravis when symptoms are not adequately controlled by anticholinesterase agents. Plasma exchange increases respiratory muscle force and tidal volume due to changes in "driving" but not "timing" of the respiratory cycle.

Adult↗

PubMed1996

3,4-diaminopyridine in childhood myasthenia: double-blind, placebo-controlled trial.

Eleven patients with congenital and five with juvenile myasthenia gravis, aged 5 to 24 years, were given 3,4-diaminopyridine in a double-blind, placebo-controlled, crossover study. Clinical improvement was observed in 5 of 11 congenital myasthenia patients, and placebo effect, in 3 of 11. Juvenile myasthenia patients did not respond. Single-fiber electromyographic studies did not reveal any changes correlating with the clinical status of the patient. This study demonstrates the importance of double-blind and placebo-controlled studies to determine the effect of 3,4-diaminopyridine in congenital myasthenia. This drug may have different effects on various presynaptic and postsynaptic defects of neuromuscular transmission resulting in congenital myasthenia syndromes.

4-Aminopyridine↗

PubMed2003

Myasthenia gravis (MG): epidemiological data and prognostic factors.

Data from 756 myasthenic patients were analyzed for diagnostic criteria, clinical aspects, and therapeutic approaches. The patients were followed up at our institution from 1981 to 2001. Clinical evaluation was performed according to the myasthenia gravis score adopted at our clinic. Clinical features of each patient (comprising demographic, clinical, neurophysiological, immunological, radiological, and surgical data, as well as serial myasthenia gravis scores) were filed in a relational database containing more than 7000 records. Clinical efficacy and variables influencing outcome were assessed by life-table methods and Cox proportional hazards regression analysis. Complete stable remission, as defined by the Task Force of the Medical Scientific Advisory Board of the Myasthenia Gravis Foundation of America, was the end point for good prognosis. Four hundred and ninety-nine patients (66%) were female and 257 (34%) were male. Mean follow-up was 55.1 +/- 48.1 months. Onset of symptoms peaked in the third decade in females, whereas the male distribution was bimodal with peaks in the third and sixth decades. Modality of myasthenia gravis presentation was as follows: ocular, 39.3%; generalized, 28.5%; bulbar, 31.3%; and respiratory, 0.8%. Thymectomy was carried out on 63.7% of our patients by different approaches: (1) transcervical; (2) transsternal; (3) video-thoracoscopic mini-invasive surgery. The last approach has been preferentially used in more recent years and accounted for 62.4% of the thymectomized myasthenia gravis population. Univariate analysis and Kaplan-Meier analysis showed that variables such as sex (female), age at onset (below 40 years), thymectomy, and histological diagnosis of thymic hyperplasia were significantly associated with complete stable remission, whereas on multivariate analysis only age at onset below 40 years and thymectomy were confirmed.

Age Factors↗

PubMed1976

Electrophysiologic diagnosis of myasthenia gravis and the regional curare test.

Two hundred and fifty consecutive patients were evaluated for myasthenia gravis with repetitive supramaximal stimulation of peripheral nerves and regional curare administration when necessary. Among patients with definite generalized myasthenia gravis, 72 percent had abnormal responses to repetitive supramaximal stimulation alone and another 17 percent had abnormal responses after regional curare administration. Among those with possible generalized myasthenia gravis, 15 percent had abnormal responses to repetitive supramaximal stimulation and another 12 percent had abnormal responses after regional curare administration. Of those with only ocular symptoms, 46 percent had abnormal responses to repetitive supramaximal stimulation before or after regional curare administration, suggesting generalized involvement. Myasthenia gravis has not developed subsequently in any of the equivocal patients with negative electric tests. We have found these electric procedures to be simple, safe, and at least as effective as other methods in diagnosing myasthenia gravis.

Curare↗

PubMed1990

New treatment approaches to myasthenia gravis.

Myasthenia gravis is an autoimmune disorder in which neuromuscular transmission is impaired by autoantibodies to the acetylcholine receptor (AChR). There are 3 varieties of generalised myasthenia with differing genetic susceptibilities. There is also a purely ocular form in which the weakness is confined to the extraocular muscles, and a neonatal variety which occurs in 20% of babies born to myasthenic mothers due to transplacental passage of the acetylcholine receptor antibody. Another variety of myasthenia occurs several months after treatment with D-penicillamine. The role of the thymus is suggested by abnormal histology in patients with myasthenia and by the beneficial effects of thymectomy in more than two-thirds of patients. Thymectomy is indicated in most patients unless the symptoms are minimal or the weakness is confined to the extraocular muscles. Most patients require treatment with anticholinesterase drugs to prolong the action of acetylcholine at the muscle end-plate. Overdosage of these drugs can provoke a cholinergic weakness. Remissions can be achieved with corticosteroids in 80% of patients. Immunosuppression with azathioprine is used mainly in patients who do not respond to thymectomy or in those patients who are considered unsuitable for operation. Plasma exchange can cause a rapid but temporary improvement in myasthenia, and has no long term place in its treatment.

Female↗

PubMed2001

Incidence and characteristics of Myasthenia gravis in Dar Es Salaam, Tanzania.

OBJECTIVE: To ascertain the annual incidence and characterise the clinical features of Myasthenia gravis in Dar es Salaam, Tanzania during a ten-year period from 1st January 1988 to 31 December 1998. DESIGN: Prospective cumulative registration at a major urban hospital of all patients with newly diagnosed Myasthenia gravis who were resident in Dar es salaam. SETTING: Muhimbili Medical Centre Teaching Hospital, Dar es Salaam, Tanzania. SUBJECTS: Forty seven patients, twenty males, twenty seven females satisfied the criteria for the diagnosis of Myasthenia gravis (MG). RESULTS: The annual incidence of MG of both sexes was 3 per 1,000,000 population of all age groups (95% CI 2.0 to 3.6). The incidence per 1,000,000 population was lowest in those aged below ten years 2.2 (95% CI 1.4 to 3.4) which was statistically significant. The incidence per 1,000,000 per year was higher in females but this was not statistically significant. The clinical presentation of MG in Tanzania was localised disease accounting for 47% ocular type and 53% was mild to moderately severe generalised type MG. Twenty per cent of patients with generalised MG presented with bulbar features. Single fibre electromyography was the most sensitive test. CONCLUSION: Myasthenia gravis is fairly rare in Tanzania as is in other sub-Saharan countries and presents in similar way to European in terms of age, sex, and clinical features. Ocular Myasthenia gravis was more prevalent in Tanzania than in Europe.

Adolescent↗

PubMed1999

Inherited predisposition to myasthenia gravis in Newfoundlands.

Acquired myasthenia gravis was diagnosed in 6 Newfoundlands from 2 distinct lineages. Three dogs, including 1 pair of littermates, from each lineage were affected. History and clinical signs did not differ from that reported for other dogs with acquired myasthenia gravis. Although a genetic predisposition for development of certain autoimmune diseases in several species has been identified, the immunopathogenesis of myasthenia gravis is multifactorial and includes hormonal, environmental, and infectious disease factors. The high incidence of myasthenia gravis in these 2 distinct lineages of Newfoundlands, a breed with a low relative risk for development of this disease, suggests an underlying genetic mechanism. However, mode of inheritance could not be determined from this small number of dogs. Regardless, breeders should be alerted to this disorder, and they should consider removing Newfoundlands with acquired myasthenia gravis from breeding programs.

Animals↗

PubMed1999

[Myasthenia and pregnancy].

The myasthenia is a neurological autoimmune disease affecting women in reproductive age. The combination of myasthenia and gravidity has two important aspects; reflection of gravidity on the neurological illness and the influence of the myasthenia on the course of the gravidity and the delivery. The authors present one case of myasthenia and gravidity and offer some practical advises: 1. narrow collaboration between the patient and the different specialists. 2. good information about the myasthenia evolution during the gravidity. 3. adequate therapeutic approach to the given case.

Adult↗

PubMed1999

[Measurement of acetylcholine receptor antibodies in serum of patients with myasthenia gravis].

The aim of this study is the evaluation of the level of antiacetylcholine receptor antibodies in patients with different types of myasthenia (according to Osserman's classification) and establishing of correlation between the level of such antibodies and the clinical state of the patients. 63 patients with diagnosed myasthenia and 30 healthy controls without immunological diseases were evaluated. In all of them standard neurological examination was performed and the levels of antiacetylcholine receptor antibodies were measured. In 45 patients electrophysiological investigations were carried out. In 43 cases elevated levels of antiacetylcholine receptor antibodies were noted. In 20 patients the levels were within normal range. The level of antibodies showed correlation with the clinical type of myasthenia according to Osserman (the more severe was myasthenia, the higher was the level of antibodies). But the clinical state of the patient at the moment of examination did not show any clear correlation with the level of antibodies. Acetylcholine receptor antibodies measurement has significant diagnostic value in myasthenia. Nevertheless it should be interpreted with other diagnostic techniques.

Adult↗

PubMed2001

[A case of post-thymomectomy myasthenia gravis after extrapleural pneumonectomy for invasive thymoma which necessistated long-term mechanical ventilation].

The patient was a 58-year-old male with invasive thymoma which had disseminated in the left thorax and was histologically a polygonal cell type lesion. While the serum value of anti-acetylcholine receptor antibody was high before surgery, there were signs of myasthenia gravis. After preoperative chemotherapy, a thymectomy and left panpleuropneumonectomy were conducted. Forty days after surgery, the patients suffered post-thymomectomy myasthenia gravis, which necessitated mechanical ventilation for 6 months. Despite steroid therapy and 17 plasmapheresis procedures the tidal volume increased by little more than 200-250 ml during that time. The causes of ventilatory failure, therefore, were probably decreased pulmonary function due to extrapleural pneumonectomy and the myasthenia gravis. According to the literature, polygonal cell type thymomas with high serum levels of anti-acethycholine receptor antibody have higher incidences of post-thymomectomy myasthenia gragvis than other ones. Therefore, the risk of post-thymomectomy myasthenia gravis should be kept in mind when extrapleural pneumonectomy for invasive thymoma is being considered, especially in the cases of this type.

Autoantibodies↗

PubMed1975

Transcervical thymectomy in myasthenia gravis.

Since 1967, transcervical thymectomy has been the procedure of choice for all patients with nonthymomatous myasthenia gravis and a selected group of patients with thymomatous myasthenia gravis operated upon at the Mount Sinai Hospital. A total of 180 transcervical thymectomies have been performed. In 12 patients, a pre-existing tracheostomy was present. Morbidity was minimal, limited to three instances of bleeding, five of pneumothorax, one of self-limited chylothorax, and one wound infection. One postoperative death from an unrelated cause occurred in 1967. The postoperative course has been smoother and the management of the myasthenia gravis considerably easier than those following transthoracic approaches. Consequently, routine elective tracheostomy at the time of thymectomy has been abandoned. The average period of hospitalization does not exceed one week. As a result of the minimal risk involved, indications for thymectomy now include all patients with generalized myasthenia gravis, and the procedure is performed earlier in the course of disease. Postoperative electromyographic findings show immediate improvement in the majority of patients operated upon during the first year in which symptoms occur. Transcervical thymectomy arrests the progress of the disease, decreases the mortality rate, and has long term results equal to those of transthoracic approaches. Earlier remissions, fewer germinal centers, and a smaller number of thymomas were noted in patients operated upon early in the course of the disease. A decrease in neoplasms outside the thymus gland and in neonatal myasthenia gravis was also noted following thymectomy.

Breast Neoplasms↗

PubMed2002

Major review: the clinical spectrum of pediatric myasthenia gravis: blepharoptosis, ophthalmoplegia and strabismus. A report of 14 cases.

BACKGROUND: Myasthenia gravis is infrequently encountered in pediatric ophthalmology practice. The purpose of this study is to evaluate the clinical spectrum of this condition in children and to identify factors that may aid the clinician in its diagnosis and management. SUBJECTS AND METHODS: A retrospective chart review was performed on all pediatric patients presenting with myasthenia gravis to the Departments of Pediatric Ophthalmology and Neuro- ophthalmology at the Texas Children's Hospital from 1989-1999. Information regarding mode of presentation, myasthenic classification, ocular and systemic involvement, diagnostic investigations, therapy and outcome was collected and evaluated. RESULTS: Fourteen patients were included in the study whose ages ranged from 1-17 years at presentation. One patient had congenital myasthenia gravis and 13 had juvenile myasthenia gravis. Thirteen of 14 (93%) patients presented with ocular findings; two of whom had associated systemic disease at presentation. Six of 14 (43%) patients had systemic involvement during the course of their illness, of whom three (21%) had respiratory compromise requiring assisted ventilation. Thirteen of 14 (93%) patients received pyridostigmine as first line treatment. Ten of 14 (71%) patients had a favorable response. A favorable response was defined as improvement in the extraocular motility to within 10 prism diopters of orthotropia with resolution of the blepharoptosis. Three of 14 patients (21%) received a combination of pyridostigmine and steroids, all of whom had a favorable response. Seven of 14 patients (50%) underwent thymectomy; all had a favorable response. Two of 14 patients (14%) required both blepharoptosis and strabismus surgery. CONCLUSION: Pediatric myasthenia gravis may present initially to the ophthalmologist and should be considered in any pediatric patients with blepharoptosis and an ocular motility disturbance. Prompt diagnosis may be associated with significant reduction in morbidity. A favorable response to medical and surgery therapy was noted in most of our patients.

Adolescent↗

PubMed2002

[Demographic and clinical characteristics of patients with myasthenia gravis].

THE AIM OF THE STUDY: To evaluate demographic and clinical features of the patients with myasthenia gravis. MATERIAL AND METHODS: Retrospective analysis of medical data on 82 patients with myasthenia gravis, referred to the University Hospital of Kaunas during 1992 to 2001. RESULTS AND CONCLUSIONS: More than a half of all patients with myasthenia gravis were female, and almost four fifths fell ill before the age of 50 years. The most common first sign of myasthenia gravis was unilateral or bilateral ptosis and diplopia. The Osserman-Genkins grade at onset was I in 34.1%, IIA in 35.4% and IIB in 30.5% of cases. Among thymectomised patients, the percentage of thymomas in late-onset group (> or = 50 years) was higher than in the early-onset group (< 50 years). Mortality rate was 7.3%. Myasthenic crisis was the main cause of death in all cases. Overall, 99% of patients were treated with acethylcholinesterase inhibitors and 92% with prednisolone at some time. Pharmacological remission was observed in more than 40% of patients. Prospective design of the study is recommended for the research of chronic noncommunicable diseases since it allows to evaluate the course and progression of the disease, effectiveness and side-effects of the treatment in more precise way. We used retrospective data in this study, therefore the results should be considered keeping in mind the possibility of bias and as the basis of prospective autoimmune myasthenia gravis studies in future.

Adult↗

PubMed2004

Clinical manifestations of myasthenia gravis - review of cases seen at the Lagos University Teaching Hospital.

OBJECTIVE: to review cases of myasthenia gravis at the Lagos University Teaching Hospital. METHODS: features of 27 cases of myasthenia gravis seen at the Neurology outpatient clinic of the Lagos University Teaching Hospital between January 1995 and December 2000 were reviewed using a uniform protocol. RESULTS: peak age incidence was in the third decade, and the male to female ratio 1.7 to 1. The commonest presentation was ptosis (85.1% ), followed by diplopia (37% ) and limb weakness (37% ). Other features such as dysphonia, dysphagia and dysarthria, were relatively uncommon. Ocular myasthenia gravis was diagnosed in half of the patients and generalised myasthenia in the other half. All the patients except four responded satisfactorily to prednisolone and/or anti-cholinesterase. Azathioprine was added to the treatment of those that did not respond well, and replaced prednisolone in a patient who developed steroid-induced diabetes mellitus. One patient developed myasthenic crisis and required artificial ventilator support. One patient had thymectomy. CONCLUSION: cases of myasthenia gravis present infrequently at the neurology clinic of the Lagos University Teaching Hospital. Clinical presentation and response to treatment are similar to those described elsewhere.

Adolescent↗

PubMed2004

Myasthenia gravis in childhood.

INTRODUCTION: Pathologic alterations in neuromuscular transmission, known as Myasthenia Gravis (MG), comprise combinations (forms) of pre- and post-synaptic changes whose age at onset and clinical manifestations are dissimilar. Some forms have autoimmune features, while others have a defect due to functional or structural plaque alternations. The purpose of this work is to describe the clinical forms of MG seen in childhood, to facilitate proper diagnosis and treatment. MATERIAL AND METHODS: Retrospective data from 87 patients studied at the Ricardo Gutierrez Children's Hospital from 1990 to 2002 are presented. They were evaluated by clinical, pharmacological, electrophysiological, laboratory and radiological exams. RESULTS: Three distinct groups of patients were found: Group 1, Transient Neonatal Myasthenia Gravis (TNMG) represented 6.8% 9 (n=6) of the total number of patients. None of these six patients had ocular involvement. Group 2, Congenital Myasthenia (CMG) represented 17.2% of cases 9 (n=15). These patients had an onset of symptoms from 1 to 12 months of age. Eight cases were sporadic and the remainder familial. The most frequent symptom in this group was bilateral blepharoptosis in 13 patients. Group 3, Juvenile Myasthenia (JMG) comprised 76% of the patients (n=66). The onset of symptoms in this group ranged from 13 months to 14 years (mean 3.6 years). Thirty-nine of these children presented purely with ocular symptoms. CONCLUSIONS: Children with myasthenia gravis may present to the ophthalmologist first, with symptoms such as unilateral or bilateral blepharoptosis, diplopia, strabismus or ophthalmoplegia. Therefore, it is essential that the ophthalmologist be aware of the varied features of this disorder in children in order to diagnosis it correctly and make appropriate treatment referrals.

Adult↗