Periodic paralysis can be sporadic and familial. Familial periodic paralysis shows an autosomal dominant inheritance pattern and is characterized by episodes of flaccid weakness or paralysis with preserved ventilation. This form is often associated with a decrease in serum potassium levels. This is considered a channelopathy in which there is abnormal, potassium-sensitive, muscle membrane excitability. Mutations have been found in three ion channels for hypokalemic familial periodic paralysis- CACNA1S, SCN4A, and KCNJ2. Several inciting factors have been associated with episodes of familial periodic paralysis including strenuous exercise, hypothermia, and high carbohydrate meals resulting in hyperglycemia. As glucose is transported into the cell, potassium will follow resulting in decreased serum potassium levels.
Patients are counseled to avoid high carbohydrate and salt diets. Avoidance of strenuous exercise is important, however, mild exercise may improve attacks. Symptoms can last several hours to days. Treatment for an acute attack is usually 2-10 g of PO potassium without glucose. Low dose acetazolamide (250-750 mg/day) may prevent attacks.