Hyperkalemic periodic paralysis

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Muscular atrophy

Paramyotonia congenita; Periodic paralysis - hyperkalemic

• Weakness/paralysis
  • Most commonly located in the shoulders and hips
  • Arms and legs may also be involved
  • Occurs intermittently
  • May occur on awakening
  • May be triggered by rest after exercise
  • May be triggered by fasting
  • May be triggered by exposure to cold
  • May be triggered by eating small amounts of potassium
  • Usually lasts for less than 2 hours
• Return to normal strength between attacks
• Normal alertness during attacks (no confusion or loss of consciousness)

The health care provider may suspect hyperkalemic periodic paralysis based on a family history of the disorder. Other clues to the disorder are symptoms that come and go and normal or high results of a potassium test. The health care provider will also run tests to rule out other disorders as the cause of intermittent weakness.

Between attacks, examination is normal. During an attack, the following may be observed:

• Reflexes may be decreased or absent
• Weakness is flaccid (loose) rather than spastic (tight)
• Weakness is greater in proximal muscle groups (near the body, such as shoulders and hips) than in distal groups (away from the body, such as arms and legs)

Attacks are not triggered by tests that reduce serum potassium (such as giving insulin and glucose), but may be triggered by giving potassium. Serum potassium is normal or high during attacks and may be normal or high between attacks.

Review Date: 07/25/2006
Reviewed By: David M. Charytan, M.D., M.Sc., Department of Medicine, Division of Nephrology, Brigham and Women's Hospital, Boston, MA. Review provided by VeriMed Healthcare Network.