Emiko Tsuda

Health-related quality-of-life and treatment targets in myasthenia gravis.

Introduction: The aim of this study was to determine factors affecting health‐related quality of life (HRQOL) and to propose appropriate treatment targets for patients with myasthenia gravis (MG). Methods: We evaluated 640 consecutive patients with MG seen at 11 neurological centers. Two‐year follow‐up data were obtained for 282 patients. Correlations between detailed clinical factors and the Japanese version of the 15‐item MG‐specific QOL scale score were analyzed. Results: In a cross‐sectional analysis of 640 MG patients, multivariate regression revealed that disease severity, as evaluated by the MG Composite (P < 0.0001), total dose of oral prednisolone during the last year (P = 0.002), and Cushingoid appearance index (P = 0.0004), showed significant negative effects on HRQOL, but the quantitative MG score and current prednisolone dose did not. Conclusions: Achieving minimal manifestations (MM) status or better with prednisolone ≤5 mg/day was found to exert a major positive impact on HRQOL in both the cross‐sectional and 2‐year follow‐up patient samples and can be recommended as a treatment target. Muscle Nerve 50: 493–500, 2014

Reference values for voluntary and stimulated single-fibre EMG using concentric needle electrodes: A multicentre prospective study

OBJECTIVE The aim of this study is to establish reference values for single-fibre electromyography (SFEMG) using concentric needles in a prospective, multicentre study. METHODS Voluntary or stimulated SFEMG at the extensor digitorum communis (EDC) or frontalis (FRO) muscles was conducted in 56-63 of a total of 69 normal subjects below the age of 60years at six Japanese institutes. The cut-off values for mean consecutive difference (MCD) of individual potentials were calculated using +2.5 SD or 95% prediction limit (one-tail) of the upper 10th percentile MCD value for individual subjects. RESULTS The cut-off values for individual MCD (+2.5 SD) were 56.8μs for EDC-V (voluntary SFEMG for EDC), 58.8μs for EDC-S (stimulated SFEMG for EDC), 56.8μs for FRO-V (voluntary SFEMG for FRO) and 51.0μs for FRO-S (stimulated SFEMG for FRO). The false positive rates using these cut-off values were around 2%. CONCLUSIONS The +2.5 SD and 95% prediction limit might be two optimal cut-off values, depending on the clinical question. The obtained reference values were larger than those reported previously using concentric needles, but might better coincide with conventional values. SIGNIFICANCE This is the first multicentre study reporting reference values for SFEMG using concentric needles. The way to determine cut-off values and the statistically correct definition of the percentile were discussed.

Oral corticosteroid therapy and present disease status in myasthenia gravis

Introduction: The aim of this study was to elucidate the effectiveness of oral prednisolone (PSL) according to dosing regimen in 472 patients with myasthenia gravis (MG). Methods: We compared the clinical characteristics and PSL treatment between 226 patients who achieved minimal manifestations (MM) or better and 246 patients who remained improved (I) or worsened, according to the MG Foundation of America postintervention status. Results: Achievement of MM or better at peak PSL dose (odds ratio 12.25, P < 0.0001) and combined use of plasma exchange/plasmapheresis (PE/PP) and/or intravenous immunoglobulin (IVIg) (odds ratio 1.92, P = 0.04) were associated positively, and total PSL dose during the past year (odds ratio 0.17, P = 0.03) was associated negatively with present MM or better status. Conclusions: Higher PSL dose and longer PSL treatment do not ensure better outcome. In the absence of a good response, the PSL dose should be decreased by combining with modalities such as PE/PP or IVIg. Muscle Nerve 51:692–696, 2015

Quality of life in purely ocular myasthenia in Japan

BackgroundSince 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.MethodsWe 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.ResultsOf 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.ConclusionA treatment strategy designed in accord with a patients ocular presentation must be considered in order to improve ocular symptoms and the patients QOL.

Correlation of bite force with excitation–contraction coupling time of the masseter in myasthenia gravis

OBJECTIVE The aim of this study was to elucidate the relationship between the impairment of excitation-contraction (E-C) coupling of masseter and the bite force in patients with myasthenia gravis (MG). METHODS In 20 patients with MG, masseteric compound muscle action potential (CMAP) and mandibular movement-related potentials (MRP) were recorded simultaneously after stimulating the trigeminal motor nerve with a needle electrode. The E-C coupling time (ECCT) was calculated by the latency difference between CMAP and MRP. Bite force was measured using a pressure-sensitive sheet. Serial assessments of % decrement in masseteric repetitive nerve stimulation (RNS), ECCT, and bite force were performed before and after corticosteroid therapy alone or in various combinations with FK506, cyclosporin A, intravenous immunoglobulin and immunoabsorption. RESULTS Percent amplitude decrement in RNS and ECCT decreased significantly accompanying an increase in bite force after treatment. Simple regression analysis demonstrated a linear correlation among % decrement, ECCT and bite force. However, ECCT shortening accompanying bite force recovery without reduction in % decrement was observed in 4 patients. CONCLUSIONS Masseteric E-C coupling is impaired in some MG patients, and functional recovery of E-C coupling contributes at least in part to the increase in bite force after treatment. SIGNIFICANCE Impaired E-C coupling contributes to muscle weakness in patients with MG.

Contribution of anti-ryanodine receptor antibody to impairment of excitation-contraction coupling in myasthenia gravis.

OBJECTIVE The aim of this study was to elucidate the relationship between the impairment of excitation-contraction (E-C) coupling and anti-ryanodine receptor (RyR) antibody in patients with myasthenia gravis (MG). METHODS Masseteric compound muscle action potential (CMAP) and mandibular movement-related potentials (MRPs) were recorded simultaneously after stimulating the trigeminal motor nerve with a needle electrode. The E-C coupling time (ECCT) was calculated as the latency difference between CMAP and MRP. For each patient, we selected a representative data set when there was no abnormal decrement in response to repetitive nerve stimulation. The 26 data sets were divided into an anti-RyR-positive group (n=12) and an anti-RyR-negative group (n=14). RESULTS Masseteric ECCT was significantly longer (p=0.017) in anti-RyR-positive group (median, mean, range; 3.6, 3.8, 3.0-5.9 ms) than in anti-RyR-negative group (3.1, 3.1, 2.7-4.0) although there were no significant differences in masseteric CMAP amplitude and % decrement between the two groups. The bite force was significantly lower in anti-RyR-positive group than in normal controls. CONCLUSIONS Presence of anti-RyR antibodies is associated with significantly prolonged masseteric ECCT compared to absence of the antibodies in MG. SIGNIFICANCE Anti-RyR antibody contributes to E-C coupling impairment in the masseter muscle in patients with MG.

Early effect of tacrolimus in improving excitation–contraction coupling in myasthenia gravis

OBJECTIVES Tacrolimus (FK506) is a macrolide T-cell immunomodulator used to treat myasthenia gravis (MG). Besides immunosuppression, tacrolimus has been reported to have the potential to increase muscle strength by enhancing ryanodine receptor (RyR) function. However, few attempts have been made to demonstrate the early effect of tacrolimus as an RyR enhancer in clinical investigation. METHODS In 20 MG patients, masseteric compound muscle action potential (CMAP) and mandibular movement-related potentials (MRPs) were recorded simultaneously after stimulating the trigeminal motor nerve with a needle electrode. The excitation-contraction (E-C) coupling time (ECCT) was calculated by the latency difference between CMAP and MRP. Bite force was measured using a pressure-sensitive sheet. Serial assessments of % decrement in masseteric repetitive nerve stimulation (RNS), ECCT and bite force were performed before and within 4 weeks of tacrolimus (3 mg day(-1)) treatment. The median (mean, range) interval of assessment was 2 (2.4, 1-4) weeks. We also measured serum antibodies against RyR, acetylcholine receptor and muscle-specific receptor tyrosine kinase. RESULTS Bite force increased after tacrolimus treatment accompanying clinical improvement assessed by Myasthenia Gravis Foundation of America classification, but the bite force difference did not reach statistical significance. Wilcoxon matched-pairs signed-ranks test detected a significant ECCT shortening in 12 patients assessed after 1-2 weeks of tacrolimus treatment as well as in eight patients assessed after 3-4 weeks. In contrast, masseteric CMAP and % decrement showed no significant changes after short-term tacrolimus treatment. CONCLUSIONS Tacrolimus induces ECCT shortening accompanying clinical improvement despite no improvement in % decrement within 2 weeks. SIGNIFICANCE This early effect of tacrolimus may imply a pharmacological enhancement of RyR function to improve E-C coupling in MG.

Is surgical intervention safe and effective in the treatment of myasthenic blepharoptosis? A multicenter survey in Japan

neurological centers constituting the Japan MG Registry Study Group. All of the patients were interviewed about the clinical features of their MG and whether they had undergone blepharoptosis surgery. A total of 19 patients (2.8%; 7 men, 12 women; mean age: 65.7 years) had undergone blepharoptosis surgery, and were further evaluated by using a questionnaire. Questions regarding the timing of the surgery (relative to MG onset), the ease of eyelid opening [over both the short term ( ≤ 1 year) and long term (>1 year), postoperatively], aesthetic outcome (scarring), overall satisfaction with the surgery, and any noted complications. Three-point Likert scales were used to assess the ease of eyelid opening (much easier, easier, worse), scarring (very minimal, minimal, visible), and overall satisfaction with the surgery (very satisfied, satisfied, dissatisfied). To evaluate scarring, the patients answered the questionnaires with their attending neurologists in the out-patient clinics. The actual surgeons were not present to help in obtaining unbiased opinions from the patients. All clinical information was collected after the patients had provided written Dear Sir, Myasthenia gravis (MG) is an antibodymediated, neuromuscular transmission disorder. Its clinical manifestations range from ocular myasthenia, which can be visually disabling, to myasthenic crisis, with patients experiencing life-threatening respiratory insufficiencies [1] . Several effective medical treatments are available for the ocular symptoms of MG [2–6] ; however, physicians often struggle to treat patients with longstanding blepharoptosis [7–9] . Moreover, although blepharoptosis surgery is occasionally applied in such cases [10, 11] , the indications and clinical effectiveness of blepharoptosis surgery for MG patients remains unclear. In the present study, we retrospectively investigated the clinical features of blepharoptosis surgery by interviewing 19 Japanese patients with MG.

Association between Glucocorticoid-Induced Osteoporosis and Myasthenia Gravis: A Cross-Sectional Study.

Purpose To investigate the association between glucocorticoid-induced osteoporosis and myasthenia gravis (MG) using a cross-sectional survey in Japan. Methods We studied 363 patients with MG (female 68%; mean age, 57 ± 16 years) who were followed at six Japanese centers between April and July 2012. We evaluated the clinical information of MG and fractures, bone markers, and radiological assessment. Quality of life was measured using an MG-specific battery, MG-QOL15. Results Glucocorticoids were administered in 283 (78%) of 363 MG patients. Eighteen (6%) of 283 MG patients treated with prednisolone had a history of osteoporotic fractures. The duration of glucocorticoid therapy, but not the dose of prednisolone, was associated with the osteoporotic fractures in MG patients. Bone mineral density was significantly decreased in the MG patients with fractures. The multivariate analyses showed that the total quantitative MG score was the only independent factor associated with osteoporotic fractures (OR = 1.30, 95% CI 1.02–1.67, p = 0.03). MG patients who had experienced fractures reported more severe difficulties in activities of daily living. Conclusion Glucocorticoid-induced osteoporosis aggravates quality of life in patients with MG.

Response to treatment of myasthenia gravis according to clinical subtype.

BackgroundWe 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.MethodsA 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.ResultsAs 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.ConclusionsDifferences 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.