MRI and clinical studies of facial and bulbar muscle involvement in MUSK antibody-associated myasthenia gravis
MRI and clinical studies of facial and bulbar muscle involvement in MUSK antibody-associated myasthenia gravis
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DOI：
10.1093/brain/awl095
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发表时间：
2006-06-01
期刊：
影响因子：
14.5
通讯作者：
Vincent, Angela
中科院分区：
文献类型：
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作者：
Farrugia, Maria Elena;Robson, Matthew D.;Vincent, Angela
部分没有乙酰胆碱受体 (AChR) 抗体的重症肌无力 (MG) 患者具有肌肉特异性激酶 (MuSK) 抗体。带有 MUSK 抗体的 MG (MuSK-MG) 通常与持续的延髓受累有关，包括明显的面部无力和舌肌萎缩。 MuSK-MG 中肌肉萎缩的程度，以及是否也存在于少数持续延髓受累的乙酰胆碱受体 (AChR-MG) 患者中，尚不清楚。我们研究了 12 名 MuSK-MG 患者，并招募了 14 名 AChR-MG 患者，这些患者的年龄、性别比例、病程以及眼、延髓和面部无力程度大致匹配。我们使用冠状和矢状 T-1 加权 (T1W) 和 T-2 加权 (T2W) 磁共振成像 (MRI) 来评估面部和舌头肌肉的肌肉萎缩。 T1W MRI 上的高信号以及轴向 T1W 序列与 cUTE 序列的比较用于评估舌头中的纤维/脂肪组织。我们将结果与 4 名强直性肌营养不良患者和 12 名健康个体的结果进行了比较。我们将这些变化与临床和治疗史相关联，并建立了新的眼-延髓-面部-呼吸（OBFR）评分。在研究时，两个 MG 组之间的临床指标（包括 OBFR 评分）没有差异。 MRI 显示，与健康对照者相比，MuSK-MG 患者的颊肌、口轮匝肌 (O.oris) 和眼轮匝肌 (O.oculi) 肌肉变薄，而 AChR-MG 患者的这些肌肉变薄并不显着。 MuSK-MG 患者的舌头 T1W 高信号区域增加，MuSK-MG 患者的轴向 T1W 序列信号强度高于对照组。为了寻找影像学和临床结果之间可能的相关性，我们汇总了所有 MG 患者的结果。隔天（AD）> 40 mg 泼尼松龙治疗持续时间与高信号舌头面积百分比呈正相关（P = 0.006），与单个肌肉的 MRI 测量值和平均肌肉尺寸呈负相关（P = 0.001）。新的 OBFR 评分与美国重症肌无力基金会当前的评分以及高信号百分比呈正相关 (P = 0.004)，与平均肌肉尺寸呈负相关 (P < 0.001)。结果表明，MuSK-MG 患者的延髓和面部肌肉无力和萎缩与显着的肌肉萎缩和脂肪替代有关，而在 AChR-MG 患者中未发现这种情况。 MUSK 抗体本身可能导致肌肉变薄，但某些患者在类固醇治疗下难以获得临床缓解，导致较高剂量（> 40 mg AD）治疗时间较长，可能是另一个因素。
A proportion of patients with myasthenia gravis (MG) without acetylcholine receptor (AChR) antibodies have antibodies to muscle-specific kinase (MuSK). MG with MUSK antibodies (MuSK-MG) is often associated with persistent bulbar involvement, including marked facial weakness and tongue muscle wasting. The extent of muscle wasting in MuSK-MG, and whether it is also found in the few acetylcholine receptor (AChR-MG) patients who have persistent bulbar involvement, is not clear. We studied 12 MuSK-MG patients and recruited 14 AChR-MG patients matched broadly for age, sex ratio, duration of disease and degree of ocular, bulbar and facial weakness. We used coronal and sagittal T-1-weighted (T1W)and T-2-Weighted (T2W) magnetic resonance imaging (MRI) to assess muscle wasting in facial and tongue muscles. Hyperintense signal on T1W MRI and comparison of axial T1W sequences with cUTE sequences were used to assess fibrous/fatty tissue in the tongue. We compared the results with those of four patients with myotonic dystrophy and 12 healthy individuals. We correlated the changes with clinical and treatment histories, and established a new ocular-bulbar-facial-respiratory (OBFR) score. At the time of study, none of the clinical measures, including the OBFR score, differed between the two MG groups. MRI demonstrated thinning of the buccinator, orbicularis oris (O.oris) and orbicularis oculi (O.oculi) muscles in MuSK-MG patients compared with healthy controls, whereas thinning of these muscles was not significant in AChR-MG. Tongue areas with T1W high signal were increased in MuSK-MG patients and the intensity of the signal on axial T1W sequences was greater in MuSK-MG than in controls. To look for possible correlations between imaging and clinical findings, we pooled results from all MG patients. The duration of treatment with prednisolone at > 40 mg on alternate days (AD) correlated positively with the percentage of tongue area with high signal (P = 0.006) and negatively with MRI measurements of individual muscles and with the mean muscle dimensions (P = 0.001). The new OBFR score correlated positively with current Myasthenia Gravis Foundation of America grades and with the percentage of high signal (P = 0.004) and negatively with the mean muscle dimensions (P < 0.001). The results show that bulbar and facial muscle weakness and wasting are associated with significant muscle atrophy and fatty replacement in MuSK-MG, which was not found in the AChR-MG patients. MUSK antibodies per se may predispose to muscle thinning, but the difficulties in obtaining clinical remission under steroid therapy in some patients, resulting in long duration of treatment with higher doses (> 40 mg AD), may be an additional factor.