Periodic paralysis - hyperkalemic
The disorder involves attacks of muscle weakness or loss of muscle movement (paralysis) that come and go. There is normal muscle strength between attacks.
Attacks usually begin in childhood. How often the attacks occur varies. Some people have several attacks a day. Attacks typically last only 1 to 2 hours, but can sometimes last as long as a day. They are usually not severe enough to need therapy. Some people have associated myotonia, in which they cannot immediately relax their muscles after use.
The weakness or paralysis:
Triggers may include:
The health care provider may suspect hyperkalemic periodic paralysis based on a family history of the disorder. Other clues to the disorder are muscle weakness symptoms that come and go with normal or high results of a potassium test.
Between attacks, a physical examination shows nothing abnormal. During an attack, muscle reflexes are decreased or absent, and muscles go limp rather than staying stiff. The muscle groups near the body, such as shoulders and hips, are involved more often than the arms and legs.
The health care provider may run additional tests to rule out other causes.
Barohn RJ. Muscle diseases. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 447.
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