Hypokalemic periodic paralysis

Hypokalemic periodic paralysis (hypoKPP) is a rare, autosomal dominant channelopathy characterized by muscle weakness or paralysis with a matching fall in potassium levels in the blood (primarily due to defect in a voltage-gated calcium channel). In individuals with this mutation, attacks often begin in adolescence and most commonly occur on awakening or after sleep or rest following strenuous exercise (attacks during exercise are rare), high carbohydrate meals, meals with high sodium content, sudden changes in temperature, and even excitement, noise, flashing lights and induced by cold temperatures. Weakness may be mild and limited to certain muscle groups, or more severe full body paralysis. Attacks may last for a few hours or persist for several days. Recovery is usually sudden when it occurs, due to release of potassium from swollen muscles as they recover. Some patients may fall into an abortive attack or develop chronic muscle weakness later in life. To differentiate it from Guillian Barre syndrome, deep tendon reflexes are normal and 7th cranial nerve is spared. During an attack reflexes may be decreased or absent.