Comparison of diagnosis value for new onset myasthenia gravis by many clinical auxiliary examinations

BACKGROUND： The clinical values of neostigmine test, clinical electrophysiologic study and acetylcholine receptor antibody detection in diagnosing myasthenia gravis （MG） found newly are unclear in China.OBJECTIVE： To investigate the reference value of common clinical diagnosis parameters in correctly diagnosing untreated MG found newly.DESIGN： Retrospective case analysis.SETTING： Department of Neurology, Beijing Hospital, Ministry of Health.PARTICIPANTS： Totally 156 outpatients with MG admitted to Department of Neurology, Beijing Hospital,Ministry of Health between January 1999 and December 2002. The involved patients, 72 males and 84 females, were aged 2 - 79 years. They were classified according to Osserman＇s criteria： ⅡA 72, ⅡB 76, Ⅲ3 and Ⅳ 5. They were all subjected to being inquired of disease history, neostigmine test, and acetylcholine receptor antibody detection, met the diagnosis criteria of Neuroimmunology Committee of China, and confirmed by clinical electrophysiologic detections; Informed consents were obtained from all the involved subjects.METHODS： ①After admission, every patient was intramuscularly injected with 1.5 mg neostigmine; If the patient was a child, the injection dose was decreased according to his/her age. If his/her score of any observation index after injection was improved ≥ 50% as compared with before injection , his positive index was Set as positive. Positive neostigmine test was set if there was one positive index. ②Repetitive nerve stimulation and single fiber electromyography were performed with Dantec Keypoint electromyogram （EMG） apparatus. ③Acetylcholine receptor antibody was detected by ELISA method.MAIN OUTCOME MEASURES： Clinical absolute and relative scores of MG, acetylcholine receptor antibody level, and repetitive nerve stimulation and single fiber electromyography examination results.RESULTS： The positive rates of neostigmine test, repetitive nerve stimulation and single fiber electromyography examination for MG were 86.5%, 82.6%, and 69.2%, respectively, and the positive rate of acetylcholine receptor antibody was 78.8%.CONCLUSION： Standardized neostigmine test has the highest sensitivity to diagnose MG.

Clinical significance of detection of antibodies to fetal and adult acetylcholine receptors in myasthenia gravis

Objective To evaluate the frequency, distribution and clinical significance of the antibodies to the fetal and/or adult acetylcholine receptor （AChR） in patients with myasthenia gravis （MG）. Methods AChR antibodies were detected by cell-based assay in the serum of ocular MG （OMG） （n = 90） and generalized MG （GMG） patients （n = 110）. The fetal-type （2α： β： γ： δ） and adult-type （2α： β： ε： δ） AChR were used as antigens, and their relevance to disease presentation was assessed. Results The overall frequencies of anti-adult and anti-fetal AChR antibodies were similar in all 200 patients examined, with 14 having serum specific to the AChR-γ subunit, and 22 to the AChR-ε subunit. The overall sensitivity when using the fetal and adult AChR antibodies was higher than that when using the fetal AChR antibody only （P = 0.015）. Compared with OMG patients, the mean age at disease onset and the positive ratio of antibodies to both isoforms of the AChR were significantly higher in patients who subsequently progressed to GMG. Older patients and patients with both anti-fetal and anti-adult AChR antibodies had a greater risk for developing generalized disease [odds ratio （OR）, 1.03; 95% confidence interval （CI）, 1.01–1.06 and OR, 5.09; 95% CI, 2.23–11.62]. Conclusion Using both fetal-and adult-type AChRs as the antigens may be more sensitive than using either subtype. Patients with serum specific to both isoforms are at a greater risk of progressing to GMG. Patients with disease onset at an advanced age appear to have a higher frequency of GMG conversion.