Abstract：
The periodic paralyses are muscle channelopathies: hypokalemic periodic paralysis (CACNA1S and SCN4A variants), hyperkalemic periodic paralysis (SCN4A variants), and Andersen-Tawil syndrome (KCNJ2). Both episodic weakness and disabling fixed weakness can occur. Little literature exists on magnetic resonance imaging (MRI) in muscle channelopathies. We undertake muscle MRI across all subsets of periodic paralysis and correlate with clinical features.
A total of 45 participants and eight healthy controls were enrolled and underwent T1-weighted and short-tau-inversion-recovery (STIR) MRI imaging of leg muscles. Muscles were scored using the modified Mercuri Scale.
A total of 17 patients had CACNA1S variants, 16 SCN4A, and 12 KCNJ2. Thirty-one (69%) had weakness, and 9 (20%) required a gait-aid/wheelchair. A total of 78% of patients had intramuscular fat accumulation on MRI. Patients with SCN4A variants were most severely affected. In SCN4A, the anterior thigh and posterior calf were more affected, in contrast to the posterior thigh and posterior calf in KCNJ2. We identified a pattern of peri-tendinous STIR hyperintensity in nine patients. There were moderate correlations between Mercuri, STIR scores, and age. Intramuscular fat accumulation was seen in seven patients with no fixed weakness.
We demonstrate a significant burden of disease in patients with periodic paralyses. MRI intramuscular fat accumulation may be helpful in detecting early muscle involvement, particularly in those without fixed weakness. Longitudinal studies are needed to assess the role of muscle MRI in quantifying disease progression over time and as a potential biomarker in clinical trials.
A total of 45 participants and eight healthy controls were enrolled and underwent T1-weighted and short-tau-inversion-recovery (STIR) MRI imaging of leg muscles. Muscles were scored using the modified Mercuri Scale.
A total of 17 patients had CACNA1S variants, 16 SCN4A, and 12 KCNJ2. Thirty-one (69%) had weakness, and 9 (20%) required a gait-aid/wheelchair. A total of 78% of patients had intramuscular fat accumulation on MRI. Patients with SCN4A variants were most severely affected. In SCN4A, the anterior thigh and posterior calf were more affected, in contrast to the posterior thigh and posterior calf in KCNJ2. We identified a pattern of peri-tendinous STIR hyperintensity in nine patients. There were moderate correlations between Mercuri, STIR scores, and age. Intramuscular fat accumulation was seen in seven patients with no fixed weakness.
We demonstrate a significant burden of disease in patients with periodic paralyses. MRI intramuscular fat accumulation may be helpful in detecting early muscle involvement, particularly in those without fixed weakness. Longitudinal studies are needed to assess the role of muscle MRI in quantifying disease progression over time and as a potential biomarker in clinical trials.
摘要：
目的：周期性麻痹是肌信道病：低钾性周期性麻痹（CACNA1S和SCN4A变体），高钾血症性周期性麻痹（SCN4A变种），和Andersen-Tawil综合征（KCNJ2）。发作性无力和致残性固定无力均可发生。关于肌信道病的磁共振成像（MRI）的文献很少。我们对周期性麻痹的所有子集进行肌肉MRI，并与临床特征相关。
方法：共纳入45名参与者和8名健康对照，并对腿部肌肉进行T1加权和短tau倒置恢复（STIR）MRI成像。使用改良的Mercuri量表对肌肉进行评分。
结果：共有17例患者有CACNA1S变异，16SCN4A,12KCNJ231人(69%)有弱点，和9（20％）需要步态辅助/轮椅。共有78％的患者在MRI上有肌内脂肪堆积。SCN4A变异的患者受影响最严重。在SCN4A中，大腿前部和小腿后部受影响更大，与KCNJ2中的大腿后和小腿后相反。我们确定了9例患者的肌腱周围STIR高强度模式。Mercuri之间存在中等相关性，STIR得分,和年龄。7例无固定无力的患者出现肌内脂肪堆积。
结论：我们证明了周期性瘫痪患者的疾病负担很大。MRI肌肉内脂肪积累可能有助于检测早期肌肉受累，尤其是那些没有固定弱点的人。需要纵向研究来评估肌肉MRI在随时间量化疾病进展中的作用，并作为临床试验中的潜在生物标志物。
方法：共纳入45名参与者和8名健康对照，并对腿部肌肉进行T1加权和短tau倒置恢复（STIR）MRI成像。使用改良的Mercuri量表对肌肉进行评分。
结果：共有17例患者有CACNA1S变异，16SCN4A,12KCNJ231人(69%)有弱点，和9（20％）需要步态辅助/轮椅。共有78％的患者在MRI上有肌内脂肪堆积。SCN4A变异的患者受影响最严重。在SCN4A中，大腿前部和小腿后部受影响更大，与KCNJ2中的大腿后和小腿后相反。我们确定了9例患者的肌腱周围STIR高强度模式。Mercuri之间存在中等相关性，STIR得分,和年龄。7例无固定无力的患者出现肌内脂肪堆积。
结论：我们证明了周期性瘫痪患者的疾病负担很大。MRI肌肉内脂肪积累可能有助于检测早期肌肉受累，尤其是那些没有固定弱点的人。需要纵向研究来评估肌肉MRI在随时间量化疾病进展中的作用，并作为临床试验中的潜在生物标志物。
