Tumours of the thyroid gland in relation to some general concepts of neoplasia

History of Myasthenia Gravis Revisited

The first description of myasthenia gravis (MG) was given by Thomas Willis in 1672. MG was the focus of attention after mid-nineteenth century and a great amount of information has been accumulated in a span of 150 years. The aim of this review is to convey this information according to a particular systematic and to briefly relate the experience of Istanbul University. MG history was examined in four periods: 1868-1930, 1930-1960, 1960-1990, and 1990-2020. In the first period (1868-1930), all the clinical characteristics of MG were defined. Physiological/pharmacological studies on the transmission at the neuromuscular junction were initiated, and the concept of repetitive nerve stimulation emerged. A toxic agent was believed to be the cause of MG which appeared to resemble curare intoxication. Association of MG with thymus was noticed. No noteworthy progress was made in its treatment. In the second period (1930-1960), acetylcholine was discovered to be the transmitter at the neuromuscular junction. Repetitive nerve stimulation was used as a diagnostic test. The autoimmune nature of MG was suspected and experiments to this end started to give results. The hallmark of this period was the use of anticholinesterases and thymectomy in the treatment of MG. The third period (1960-1990) can probably be considered a revolutionary era for MG. Important immunological mechanisms (acetylcholine receptor isolation, discovery of anti-acetylcholine receptor antibodies) were clarified and the autoimmune nature of MG was demonstrated. Treatment modalities which completely changed the prognosis of MG, including positive pressure mechanic ventilation and corticosteroids as well as plasma exchange/IVIg and azathioprine, were put to use. In the fourth period (1990-2020), more immunological progress, including the discovery of anti-MuSK antibodies, was achieved. Videothoracoscopic thymectomy reduced the morbidity and mortality rate associated with surgery. New drugs emerged and clinical trials were performed. Valuable guidelines were published. In the last part of the review, the experience in MG of Istanbul University, a pioneer in Turkey, is related.

Myasthenia gravis: Historical achievements and the "golden age" of clinical trials

Since the death of Chief Opechankanough >350 years ago, the myasthenia gravis (MG) community has gained extensive knowledge about MG and how to treat it. This review highlights key milestones in the history of treatment and discusses the current "golden age" of clinical trials. Although originally thought by many clinicians to be a disorder of hysteria and fluctuating weakness without observable cause, MG is one the most understood autoimmune neurologic disorders. However, studying it in clinical trials has been challenging due to the fluctuating nature of the medical condition which impacts MG clinical outcomes. Clinical trials must also account for the possibility of a placebo effect. Because MG is a rare incurable autoimmune disorder, it limits the number of potential patients available to participate in clinical trials. In the last 15 years, however, significant progress has been made with MG randomized clinical trials, resulting in a new drug (eculizumab) for physicians' treatment repertoire and an old technique (thymectomy) confirmed effective for MG. Some of the therapies (eg, thymectomy, corticosteroids, plasma exchange, and intravenous immunoglobulin [IVIg]) have survived the test of time. Others (eg, eculizumab and neonatal Fc receptor inhibitor) are novel and hold promise.

Something in the Blood? A history of the autoimmune hypothesis regarding myasthenia gravis

From the first descriptions of myasthenia gravis (MG) in the late nineteenth century, speculation about the cause of MG has centered on the possibility of some curare-like factor circulating in the blood. The transfer of transient myasthenic symptoms from a myasthenic mother to her newborn reinforced this speculation. However, it was not until 1960, when William Nastuk and coworkers noted that serum complement correlated with the clinical course in MG, and Arthur Strauss and colleagues described antiskeletal muscle antibodies in the sera of some MG patients, that a paradigm shift occurred from prior exclusive focus on the neuromuscular junction to a broader consideration of the relevance of immunological mechanisms in myasthenia. These findings coincided with an even greater scientific revolution pioneered by Macfarlane Burnet towards cell-mediated and away from chemical immunology. The dominant immunological question of the decade 1955-1965, however, was whether human autoimmune diseases actually existed. During the next decade, 1965-1975, various diseases were accepted as being autoimmune in character, and although comparatively rare, MG became prominent among them because of a known antigen, the acetylcholine receptor, and an excellent experimental model.

Mesangial proliferative glomerulonephritis with deposits of anti-nicotinic acetylcholine receptor antibody in a patient with myasthenia gravis

A patient with myasthenia gravis developed nephrotic syndrome 3 years after thymectomy. The kidney biopsy specimen revealed mesangial proliferative glomerulonephritis with immune deposits. The glomerular mesangial cells and tubular epithelial cells were sensitive to alpha-bungarotoxin (alpha-BT), a ligand for nicotinic acetylcholine receptor (nAChR), and the binding was inhibited by native alpha-BT, as well as other nAChR ligands, nicotine and d-tubocurarine. In addition, FITC-alpha-BT-neuromuscular junction complexes could also bind to the mesangial cells, and preincubation with unlabeled nAChR inhibited the binding. These findings are consistent with the notion that both nAChR-like protein and anti-nAChR antibody are present in t he mesangial cells of the patient. Although the pathogenetic role of anti-nAChR antibody on the development of glomerulonephritis is unclear, the present observations provide an important insight into the autoimmune-mediated pathophysiological relationship between myasthenia gravis and mesangial proliferative glomerulonephritis.

Associated disorders in myasthenia gravis: autoimmune diseases and their relation to thymectomy

The prevalence of myasthenia gravis (MG) in the counties of Hordaland and Sogn & Fjordane on January 1, 1984 was 9.6 per 100,000 inhabitants. Other autoimmune diseases were found in 11 out of 48 MG patients. The occurrence of autoimmune thyroiditis (5 patients, 10.4%) and systemic lupus erythematosus (4 patients, 8.3%) in the MG patients was clearly higher than that reported in the general population. Rheumatoid arthritis was found in 2 patients (4.2%). The autoimmune diseases were mainly recorded among the nonthymectomized MG patients. In addition to those with definite diseases of autoimmune nature, 3 other MG patients had thyroid antibodies and 1 had antinuclear factor without clinical evidence of autoimmune disease. Seven MG patients (14.6%) had unspecific arthralgia during active periods of MG. Two MG patients had ankylosing spondylitis.

Myasthenia gravis. Pathogenesis and current concepts in management

Myasthenia gravis is a disorder of autoimmunity in which neuromuscular transmission is impaired by autoantibodies to the acetylcholine receptor (AChR). There is evidence for more than one form of the disorder with differing genetic susceptibilities. The aetiology is unknown, but thymic involvement is suggested by abnormal histology and by the beneficial response of the disorder to thymectomy in more than two-thirds of patients. Thymectomy is indicated in most patients unless the symptoms are minimal or are confined to the extraocular muscles alone, or the patient is elderly. Thymectomy alone results in remission in about one-third of patients, but, in addition, most patients require symptomatic anticholinesterase drugs to prolong the action of acetylcholine at the muscle end-plate. Over-dosage of these drugs can also cause weakness. Immunosuppression with corticosteroids or azathioprine may also improve myasthenia; at present, these drugs are used mainly in patients who do not respond to thymectomy or in those patients considered unsuitable for operation. Plasma exchange can cause a rapid, though temporary, involvement in myasthenia, but it probably has no long term place in its treatment. Future therapy will probably involve specific immunotherapy, such as anti-idiotype antibodies.

Controversies about the treatment of myasthenia gravis

Clinicians treating patients with myasthenia gravis must choose cholinergic drugs, corticosteroids, immunosuppressive drugs, thymectomy, or plasmapheresis. Clinicians must decide the sequence or combination of these therapies and when to deem lack of improvement a sign for a different therapeutic approach. Because controlled trials have not been done to evaluate therapies that may require months or years before benefit is evident, controversy abounds.

Myasthenia gravis: a personal view of pathogenesis and mechanism, part 1

A review of our current knowledge of the etiology and pathogenesis of myasthenia gravis is presented, with particular emphasis on the immunological aspects of the disease. Part 1, published in this issue, deals with the clinical and genetic features of myasthenia gravis which led to the autoimmune theory of the etiology of this disease. Various theories in this field are reviewed, and recent advances in our knowledge of the acetylcholine receptor protein, and its immunology, are examined. Part 2, which will appear in the March/April issue, provides a review of the dysfunction of physiology, pharmacology, and structure of the neuromuscular junction in myasthenia gravis, and the part played by the autoimmune process.

Assessment of cellular and humoral immunity of myasthenics

A close association of autoimmune diseases or autoimmune phenomena in myasthenia gravis is well known. A comprehensive immunological study of 22 patients with myasthenia gravis showed that changes in the immune system mainly involve the thymus-derived lymphocytes (T cells). Anti-thymus antibody was present in 90% of the patients, and it paralleled the frequency of thymic abnormality in myasthenia gravis. It is postulated that in myasthenia gravis the altered T cell functions caused by anti-thymus antibody result in the formation of an array of autoantibodies including the factor which blocks the neuromuscular transmission.

Studies on the nature of autoimmunity in myasthenia gravis. Evidence for an immunodeficiency type

Clinical and laboratory data continue to support the concept of a genetically determined breakdown of immunological tolerance in myasthenia gravis with immunological damage to the motor end plates. The demonstration of impaired function of thymus-derived lymphocytes and of IgA deficiency correlate well with the clinical data in which there is an increase incidence of autoimmune diseases associated with anergy. Whilst the exact pathogenesis of myasthenia gravis is unknown, the available data support the concept of an immune deficiency disorder.

Thymectomy for myasthenia gravis

Thymectomy was performed on 31 patients with myasthenia gravis. Four of them had thymoma, 17 hyperplasia and 9 had normal thymic histology on microscopy. Discontinuation of anticholinergic medication together with tracheostomy, artificial ventilation and intensive observation were essential in the postoperative management. All the patients survived operation and were discharged from hospital. Sixty-eight per cent of the patients were in remission or improved after an average follow-up of 2.5 years. If the patients with thymoma were excluded, 74% were improved and, if only the patients with thymic hyperplasia were included in the series, 89% were improved after thymectomy. The severity of disease and duration of symptoms pre-operatively seemed to be of minor importance for the results of operation, since good results were obtained also in patients with a long history and in clinical classes III and IV. Two patients developed tracheal stenosis as a complication of intubation with a tracheostomy tube. Tracheal resection was performed in one of them and endobronchial removal of granulation tissue producing the stenosis in the other. Both recovered uneventfully. One patient, who was asymptomatic and without medication for myasthenia, died suddenly of acute cerebral bleeding 3 years after thymectomy.