Nav1.4 channelopathies due to SCN4A mutations can present with episodic attacks of myotonia triggered by fluctuation in the potassium level (potassium-aggravated myotonia). We report a case of potassium-aggravated myotonia due to Nav1.4-M1592V channelopathy with severe and long-lasting focal attacks of myotonia resembling dystonic posturing with diffuse muscle edema in the affected muscles in magnetic resonance imaging and almost constant presence of myotonic discharges in electromyography that can best be described as focal "status myotonicus".

中文翻译：

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Nav1.4-M1592V 通道病中的“肌强直状态”

由于 SCN4A 突变引起的 Nav1.4 通道病可表现为由钾水平波动引发的肌强直发作（钾加重肌强直）。我们报告了一例由 Nav1.4-M1592V 通道病引起的钾加重肌强直病例，肌强直的严重和持久局灶性发作类似于肌张力障碍姿势，磁共振成像显示受影响肌肉中弥漫性肌肉水肿，并且几乎持续存在肌强直放电最好将肌电图描述为局灶性“肌强直状态”。