SCN4A and congenital myasthenic syndrome: A previous study found that a patient with SCN4A-related CMS, who had normal RNS at 2 Hz, showed a decremental response after a 5-min conditioning stimulation train at 10 Hz, suggesting that prolonged RNS at 10 Hz for 5 min should be performed to search for a defect of neuromuscular transmission in patients with a high index of suspicion for CMS who had normal RNS at 2 Hz (15).