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P34-20 Low MuSK expression in disease susceptible muscles in MuSK+experimental autoimmune myasthenia gravis (EAMG)
29th International Congress of Clinical Neurophysiology
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group, in terms of remission rate. Low dose alternate day steroids and other immunosuppressants were helpful to prevent relapses.
P34-19 Myasthenic crisis after thymectomy in patients with myasthenia gravis
P34-17 The clinical features of myasthenia gravis in a Malaysian population
T.-S. Nam1 , K.-H. Choi2 , S.-M. Choi1 , M.-S. Park1 , B.-C. Kim2 , M.-K. Kim2 , J.-T. Kim2 , K.-H. Cho2 1 Department of Neurology, Chonnam National University Hwasun Hospital, Hwasun, Korea, 2 Department of Neurology, Chonnam National University Medical School, Korea
N. Shahrizaila1 , S.C. Lee1 , K.J. Goh1 Department of Neurology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia 1
Objectives: To describe the clinical features of patients with myasthenia gravis (MG) in a Malaysian population. Methods: A retrospective study of patients with MG presenting to University Malaya Medical Centre (UMMC), Kuala Lumpur was performed. Following review of patients medical records, we describe the demographics, MG classification, treatment response and the presence of other autoimmune diseases in this group of patients. Results: 92 patients were identified. Of this, 60% were female; 59% Chinese, 24% Malays and 17% Indians. The mean age of onset was 50.17 years old (male 52.75 years and female 48.25 years). There were 2 age peaks seen: 20 29 years (predominantly females) and 50 59 years (predominantly males). 40% had ocular MG and 53% generalized MG. In 52 patients, the presence of acetylcholine receptor antibodies was assessed and found positive in 71%. 13% of patients had an associated autoimmune disease. Thymectomy was done in 30 patients and thymic histology showed thymoma in 40% and thymic hyperplasia in 20% Conclusions: In our patient population, the clinical features of MG were similar to that of the Western population in terms of gender and age distribution. However, there appears to be a higher proportion of ocular MG and also a higher incidence of MG in the Chinese population. P34-18 Electrophysiological and immunological tests in myasthenia gravis: Their diagnostic sensitivities and correlation C. Dejthevaporn1 , R. Witoonpanich1 , A. Sriphrapradang2 , T. Pulkes1 Division of Neurology, Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand, 2 Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand 1
Background: Repetitive nerve stimulation (RNS), single-fiber EMG (SFEMG) and acetylcholine receptor antibody (AChRAb) are useful in the diagnosis of myasthenia gravis (MG). This study was to determine the sensitivity of these tests, the abnormalities of these tests in the ocular and generalized MG patients and the correlation between the tests. Methods: RNS, SFEMG and AChRAb were tested in each new MG case. Sensitivity of each test was estimated. The findings of these tests in the ocular and generalized patients were compared. The degrees of abnormalities of SFEMG were studied in seropositive and seronegative patients and were correlated with the level of AChRAb. The association of AChRAb and the chance of ocular MG becoming generalised was also determined. Results: One hundred and twelve MG patients were included. Decremental response to RNS, abnormal SFEMG and AChRAb were detected in 67%, 93% and 38% of ocular and 81%, 99% and 73% of generalized cases, respectively. Generalised patients tended to have higher level of AChRAb than ocular patients. The degrees of abnormalities of SFEMG was more severe in the generalized than the ocular patients. There were no significantly differences in the SFEMG abnormalites between the seropositive and seronegative patients especially the generalized cases and between the patients with higher titers and those with lower titers of AChRAb. None of the seronegative ocular MG patients became generalized whereas twenty five percent of the seropositive cases developed generalized MG. Conclusion: SFEMG is the most sensitive test for the diagnosis of MG. The degrees of abnormalities of SFEMG were more severe in generalized than ocular patients. Generalised patients tended to have higher level of AChRAb. The degrees of SFEMG abnormalities were not significantly different between the seropositive and seronegative generalized patients. Absence of AChRAb seemed to be a good prognostic sign of ocular MG patients.
Objective: To assess the clinical characteristics of myasthenic crisis (MC) after thymectomy in patients with myasthenia gravis (MG) and to identify the predictive factors affecting the occurrence of postoperative MC (POMC). Methods: MG patients who underwent transsternal thymectomy were reviewed retrospectively. POMC was defined as a neuromuscular respiratory failure occurring after operation. The patients were divided into the two groups according to the presence of POMC: group I, those without POMC and group II, those with POMC. Results: Forty-eight MG patients were enrolled. Group I consisted of 36 patients (75.0%) and Group II consisted of 12 (25.0%). In group II, three patients had suffered from early-onset POMC a number of days after thymectomy and the remaining nine experienced late-onset POMC several weeks after thymectomy. The mean time interval from thymectomy to POMC was 41.3±29.9 days (range, 0 to 81 days). Six (50.0%) patients in group II later experienced a 2nd MC. Preoperative bulbar symptoms, history of preoperative MC, and preoperative clinical severity were significantly correlated with the occurrence of POMC (p = 0.001, p = 0.004, p = 0.008, respectively) on univariate analysis. Preoperative bulbar symptoms was significantly correlated with the occurrence of POMC as indicated from a multivariate logistic regression analysis (odds ratio = 12.429, p = 0.001). Conclusions: We found that POMC developed in approximately 25% of the MG patients after thymectomy, particularly within the first 3 months of thymectomy. The recurrence rate of POMC was higher than those of MC in general MG populations. Furthermore, preoperative bulbar symptoms may be the only predictive factor affecting the occurrence of POMC. P34-20 Low MuSK expression in disease susceptible muscles in MuSK+ experimental autoimmune myasthenia gravis (EAMG) A.R. Punga1 , S. Lin2 , M.A. Ruegg2 1 Department of Clinical Neurophysiology, Sweden, 2 Department of Neurobiology/Pharmacology, Biozentrum, University of Basel, Basel, Switzerland Objective: To quantify neuromuscular junction pathology and MuSK and AChR gene expression in individual muscles in mice with MuSK antibody seropositive experimental autoimmune myasthenia gravis (MuSK+EAMG), to determine the cause of the selective muscle involvement in MuSK+MG. Methods: We immunized wild-type C57BL6 mice with recombinant ratMuSK extracellular domain and compared them to healthy control mice. Repetitive nerve stimulation (RNS) was performed. Mice with EAMG were sacrificed and the soleus, EDL, omohyoid and sternomastoid muscles were isolated and stained for acetylcholine receptors (AChRs) and for neurofilament and synaptophysin. Neuromuscular junction derangement was quantified between the muscles and MuSK and AChRa subunit gene expression was measured with RT-PCR. Results: Clinical EAMG features ranged from mild fatigue to severe dysphagia, flaccid paralysis and kyphosis. Obvious decrement on RNS was observed. Fragmentation of AChRs correlated with clinical severity and was significantly increased in the omohyoid, sternomastoid and EDL, whereas it was not significantly changed in the soleus. In the control mice, mRNA levels of MuSK and AChRa were significantly lower in the EDL and omohyoid muscles compared to the soleus muscle (p < 0.05). In the MuSK+EAMG mice, expression of MuSK was significantly reduced in the omohyoid (p < 0.01) and in the EDL (p = 0.05) muscles, compared to the control mice. AChRa mRNA levels were not significantly altered. Conclusions: Our data show that muscles are differentially affected in MuSK+EAMG, supporting the clinical and neurophysiological observations of selective muscle involvement in patients with MuSK+MG. We hereby propose that the selective muscle involvement in MuSK+MG is influenced by the expression levels of MuSK and AChRa subunit.
S309
group, in terms of remission rate. Low dose alternate day steroids and other immunosuppressants were helpful to prevent relapses.
P34-19 Myasthenic crisis after thymectomy in patients with myasthenia gravis
P34-17 The clinical features of myasthenia gravis in a Malaysian population
T.-S. Nam1 , K.-H. Choi2 , S.-M. Choi1 , M.-S. Park1 , B.-C. Kim2 , M.-K. Kim2 , J.-T. Kim2 , K.-H. Cho2 1 Department of Neurology, Chonnam National University Hwasun Hospital, Hwasun, Korea, 2 Department of Neurology, Chonnam National University Medical School, Korea
N. Shahrizaila1 , S.C. Lee1 , K.J. Goh1 Department of Neurology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia 1
Objectives: To describe the clinical features of patients with myasthenia gravis (MG) in a Malaysian population. Methods: A retrospective study of patients with MG presenting to University Malaya Medical Centre (UMMC), Kuala Lumpur was performed. Following review of patients medical records, we describe the demographics, MG classification, treatment response and the presence of other autoimmune diseases in this group of patients. Results: 92 patients were identified. Of this, 60% were female; 59% Chinese, 24% Malays and 17% Indians. The mean age of onset was 50.17 years old (male 52.75 years and female 48.25 years). There were 2 age peaks seen: 20 29 years (predominantly females) and 50 59 years (predominantly males). 40% had ocular MG and 53% generalized MG. In 52 patients, the presence of acetylcholine receptor antibodies was assessed and found positive in 71%. 13% of patients had an associated autoimmune disease. Thymectomy was done in 30 patients and thymic histology showed thymoma in 40% and thymic hyperplasia in 20% Conclusions: In our patient population, the clinical features of MG were similar to that of the Western population in terms of gender and age distribution. However, there appears to be a higher proportion of ocular MG and also a higher incidence of MG in the Chinese population. P34-18 Electrophysiological and immunological tests in myasthenia gravis: Their diagnostic sensitivities and correlation C. Dejthevaporn1 , R. Witoonpanich1 , A. Sriphrapradang2 , T. Pulkes1 Division of Neurology, Department of Medicine, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand, 2 Research Center, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand 1
Background: Repetitive nerve stimulation (RNS), single-fiber EMG (SFEMG) and acetylcholine receptor antibody (AChRAb) are useful in the diagnosis of myasthenia gravis (MG). This study was to determine the sensitivity of these tests, the abnormalities of these tests in the ocular and generalized MG patients and the correlation between the tests. Methods: RNS, SFEMG and AChRAb were tested in each new MG case. Sensitivity of each test was estimated. The findings of these tests in the ocular and generalized patients were compared. The degrees of abnormalities of SFEMG were studied in seropositive and seronegative patients and were correlated with the level of AChRAb. The association of AChRAb and the chance of ocular MG becoming generalised was also determined. Results: One hundred and twelve MG patients were included. Decremental response to RNS, abnormal SFEMG and AChRAb were detected in 67%, 93% and 38% of ocular and 81%, 99% and 73% of generalized cases, respectively. Generalised patients tended to have higher level of AChRAb than ocular patients. The degrees of abnormalities of SFEMG was more severe in the generalized than the ocular patients. There were no significantly differences in the SFEMG abnormalites between the seropositive and seronegative patients especially the generalized cases and between the patients with higher titers and those with lower titers of AChRAb. None of the seronegative ocular MG patients became generalized whereas twenty five percent of the seropositive cases developed generalized MG. Conclusion: SFEMG is the most sensitive test for the diagnosis of MG. The degrees of abnormalities of SFEMG were more severe in generalized than ocular patients. Generalised patients tended to have higher level of AChRAb. The degrees of SFEMG abnormalities were not significantly different between the seropositive and seronegative generalized patients. Absence of AChRAb seemed to be a good prognostic sign of ocular MG patients.
Objective: To assess the clinical characteristics of myasthenic crisis (MC) after thymectomy in patients with myasthenia gravis (MG) and to identify the predictive factors affecting the occurrence of postoperative MC (POMC). Methods: MG patients who underwent transsternal thymectomy were reviewed retrospectively. POMC was defined as a neuromuscular respiratory failure occurring after operation. The patients were divided into the two groups according to the presence of POMC: group I, those without POMC and group II, those with POMC. Results: Forty-eight MG patients were enrolled. Group I consisted of 36 patients (75.0%) and Group II consisted of 12 (25.0%). In group II, three patients had suffered from early-onset POMC a number of days after thymectomy and the remaining nine experienced late-onset POMC several weeks after thymectomy. The mean time interval from thymectomy to POMC was 41.3±29.9 days (range, 0 to 81 days). Six (50.0%) patients in group II later experienced a 2nd MC. Preoperative bulbar symptoms, history of preoperative MC, and preoperative clinical severity were significantly correlated with the occurrence of POMC (p = 0.001, p = 0.004, p = 0.008, respectively) on univariate analysis. Preoperative bulbar symptoms was significantly correlated with the occurrence of POMC as indicated from a multivariate logistic regression analysis (odds ratio = 12.429, p = 0.001). Conclusions: We found that POMC developed in approximately 25% of the MG patients after thymectomy, particularly within the first 3 months of thymectomy. The recurrence rate of POMC was higher than those of MC in general MG populations. Furthermore, preoperative bulbar symptoms may be the only predictive factor affecting the occurrence of POMC. P34-20 Low MuSK expression in disease susceptible muscles in MuSK+ experimental autoimmune myasthenia gravis (EAMG) A.R. Punga1 , S. Lin2 , M.A. Ruegg2 1 Department of Clinical Neurophysiology, Sweden, 2 Department of Neurobiology/Pharmacology, Biozentrum, University of Basel, Basel, Switzerland Objective: To quantify neuromuscular junction pathology and MuSK and AChR gene expression in individual muscles in mice with MuSK antibody seropositive experimental autoimmune myasthenia gravis (MuSK+EAMG), to determine the cause of the selective muscle involvement in MuSK+MG. Methods: We immunized wild-type C57BL6 mice with recombinant ratMuSK extracellular domain and compared them to healthy control mice. Repetitive nerve stimulation (RNS) was performed. Mice with EAMG were sacrificed and the soleus, EDL, omohyoid and sternomastoid muscles were isolated and stained for acetylcholine receptors (AChRs) and for neurofilament and synaptophysin. Neuromuscular junction derangement was quantified between the muscles and MuSK and AChRa subunit gene expression was measured with RT-PCR. Results: Clinical EAMG features ranged from mild fatigue to severe dysphagia, flaccid paralysis and kyphosis. Obvious decrement on RNS was observed. Fragmentation of AChRs correlated with clinical severity and was significantly increased in the omohyoid, sternomastoid and EDL, whereas it was not significantly changed in the soleus. In the control mice, mRNA levels of MuSK and AChRa were significantly lower in the EDL and omohyoid muscles compared to the soleus muscle (p < 0.05). In the MuSK+EAMG mice, expression of MuSK was significantly reduced in the omohyoid (p < 0.01) and in the EDL (p = 0.05) muscles, compared to the control mice. AChRa mRNA levels were not significantly altered. Conclusions: Our data show that muscles are differentially affected in MuSK+EAMG, supporting the clinical and neurophysiological observations of selective muscle involvement in patients with MuSK+MG. We hereby propose that the selective muscle involvement in MuSK+MG is influenced by the expression levels of MuSK and AChRa subunit.