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Background: We have previously reported using two-step cluster analysis to classify myasthenia gravis (MG) patients into the following five subtypes: ocular MG; thymoma-associated MG; MG with thymic hyperplasia; anti-acetylcholine receptor antibody (AChR-Ab)-negative MG; and AChR-Ab-positive MG without thymic abnormalities. The objectives of the present study were to examine the reproducibility of this five-subtype classification using a new data set of MG patients and to identify additional characteristics of these subtypes, particularly in regard to response to treatment. Methods: A total of 923 consecutive MG patients underwent two-step cluster analysis for the classification of subtypes. The variables used for classification were sex, age of onset, disease duration, presence of thymoma or thymic hyperplasia, positivity for AChR-Ab or anti-muscle-specific tyrosine kinase antibody, positivity for other concurrent autoantibodies, and disease condition at worst and current. The period from the start of treatment until the achievement of minimal manifestation status (early-stage response) was determined and then compared between subtypes using Kaplan-Meier analysis and the log-rank test. In addition, between subtypes, the rate of the number of patients who maintained minimal manifestations during the study period/that of patients who only achieved the status once (stability of improved status) was compared. Results: As a result of two-step cluster analysis, 923 MG patients were classified into five subtypes as follows: ocular MG (AChR-Ab-positivity, 77%; histogram of onset age, skewed to older age); thymoma-associated MG (100%; normal distribution); MG with thymic hyperplasia (89%; skewed to younger age); AChR-Ab-negative MG (0%; normal distribution); and AChR-Ab-positive MG without thymic abnormalities (100%, skewed to older age). Furthermore, patients classified as ocular MG showed the best early-stage response to treatment and stability of improved status, followed by those classified as thymoma-associated MG and AChR-Ab-positive MG without thymic abnormalities; by contrast, those classified as AChR-Ab-negative MG showed the worst early-stage response to treatment and stability of improved status. Conclusions: Differences were seen between the five subtypes in demographic characteristics, clinical severity, and therapeutic response. Our five-subtype classification approach would be beneficial not only to elucidate disease subtypes, but also to plan treatment strategies for individual MG patients. [ABSTRACT FROM AUTHOR]

Background: Since there has been no conclusive evidence regarding the treatment of ocular myasthenia, treatment guidelines were recently issued by the European Federation of Neurological Societies/European Neurological Society (EFNS/ENS). However, the therapeutic outcomes concerning the quality-of-life (QOL) of patients with ocular myasthenia are not yet fully understood. Methods: We investigated the therapeutic outcomes of patients with purely ocular myasthenia in a multicenter cross-sectional survey in Japan. To evaluate the severity of ocular symptoms, we used the ocular-quantitative MG (QMG) score advocated by Myasthenia Gravis Foundation of America. We used the Japanese translated version of the MG-QOL15, a self-appraised scoring system. Results: Of 607 myasthenia gravis (MG) patients with an observation-duration of illness ≥ 2 years, the cases of 123 patients (20%) were limited to ocular muscles (purely ocular myasthenia). During the entire clinical course, 81 patients experienced both ptosis and diplopia, 36 had ptosis alone, and six had diplopia alone. Acetyl-cholinesterase inhibitors and prednisolone were used in 98 and 52 patients, respectively. Treatment improved ocular symptoms, with the mean reduction in ocular-QMG score of 2.3 ± 1.8 points. However, 47 patients (38%) failed to gain minimal manifestation or a better status. Patients with unfavorable outcomes also self-reported severe QOL impairment. Multivariate analyses showed that the pretreatment ocular-QMG score was associated with unfavorable outcomes, but not associated with the patient’s QOL. Conclusion: A treatment strategy designed in accord with a patient's ocular presentation must be considered in order to improve ocular symptoms and the patient's QOL. [ABSTRACT FROM AUTHOR]