Periodic Paralyses

Periodic paralyses are disorders of involuntary, intermittent muscle weakness. During attacks affected muscles become:

  • Slack.

  • Weak.

  • Unable to contract.

Between attacks affected muscles usually work normally. The two most common types of periodic paralyses are:


Hypokalemic periodic paralysis is characterized by a fall in potassium levels in the blood. It is also called familial. Attacks are usually triggered by:

  • Exercising too strenuously.

  • Eating too many carbohydrates.

  • Taking drugs such as insulin.

Attacks begin in adolescence. Attacks may last for a few hours or persist for several days. Some patients may develop a fixed muscle weakness later in life.


  • A rise in potassium levels in the blood during may accompany attacks. Attacks are frequent and last 1 to 2 hours. They are usually triggered by:

  • Strenuous exercise.

  • Stress.

  • Eating certain foods.

  • Taking potassium.

Some attacks may be accompanied by the inability to immediately relax a contracted muscle (myotonia). Attacks often begin at an early age (infancy to early childhood). Heart beat problems may also develop during these attacks.


Treatment of the periodic paralyses focuses on:

  • Preventing further attacks.

  • Relieving acute symptoms.

There are medicines used to prevent or decrease the frequency of attacks.Some attacks are often so brief that treatment is unnecessary. Potassium may be given during attacks in an effort to stop the attack.