An autosomal dominant familial disorder which presents in infancy or childhood and is characterized by episodes of weakness associated with hyperkalemia. During attacks, muscles of the lower extremities are initially affected, followed by the lower trunk and arms. Episodes last from 15-60 minutes and typically occur after a period of rest following exercise. A defect in skeletal muscle sodium channels has been identified as the cause of this condition. Normokalemic periodic paralysis is a closely related disorder marked by a lack of alterations in potassium levels during attacks of weakness. (Adams et al., Principles of Neurology, 6th ed, p1481)
Also Known As:
Periodic Paralysis, Hyperkalemic; Paralysis, Hyperkalemic Periodic; Adynamia Episodica Hereditaria; Familial Hyperkalemic Periodic Paralysis; Hyperkalemic Periodic Paralysis, Familial; Periodic Paralysis - Hypokalemic; Primary Hyperkalemic Periodic Paralysis; Hyperkalemic Periodic Paralyses; Myotonic Periodic Paralyses; Paralyses, Hyperkalemic Periodic; Paralyses, Myotonic Periodic; Paralysis, Myotonic Periodic; Periodic Paralyses, Hyperkalemic; Periodic Paralyses, Myotonic; Periodic Paralysis, Myotonic; Myotonic Periodic Paralysis; Paralysis, Periodic, Hyperkalemic, Familial