[A case of muscle sodium channelopathy with markedly high value of serum creatine kinase and mild eyelid myotonia].

We report on a Japanese 13-year-old male without a family history of muscle disease admitted to our hospital due to an elevated serum creatine kinase. From the age of 3 he was complaining of muscle stiffness during and after exercise. At the age of 7 he experienced muscle stiffness and weakness during long-distance running, which would continue till the next day, disappearing only after resting for a day. Upon examination, we noted that repeated eyelid contractions induced myotonia that increased in the cold. Electromyography revealed myotonic discharge in the tongue muscle. Genetic analysis revealed a mutation of Nav1.4, M1592V. Although this mutation had originally been reported in families with Hyperkalemic periodic paralysis (Hyper PP), we diagnosed as paramyotonia congenita due to the symptoms of exercise and cold-induced myotonia without an attack of generalized weakness. This case suggest that sodium channelopathy is very rare, but should be considered in the differential diagnosis of an elevation of serum creatine kinase even if coexisting myotonia is only mild.

Lacunar syndrome associated with paradoxical brain embolism.

We report a patient who developed lacunar syndrome due to left upper pons infarction after performing leg exercises associated with paradoxical brain embolism. A 32-year-old man developed right arm weakness and moderate dysarthria following leg exercise. Brain MRI showed a paramedian pontine infarction of the left upper pons, and contrast transesophageal echocardiographic examination indicated that the patent foramen ovale was the embolic source. Simultaneous RI venography examination of the lower limbs identified deep venous thrombosis in the right leg as a paradoxical emboligenic source. We concluded that the presence of lacunar syndrome suggests that this mechanism was responsible for the paradoxical brain embolism.