Familial periodic paralysis

Alternative names:

hypokalemic periodic paralysis; periodic paralysis - familial; periodic paralysis - hypokalemic

Symptoms:

• weakness or paralysis
  • most commonly located at the shoulders and hips
  • involves the arms and legs
  • occurs intermittently
  • most commonly occurs on awakening
  • may be triggered by rest after exercise
  • may be triggered by heavy, high carbohydrate, high salt meals
  • may last for several days

• spontaneous recovery of normal strength between attacks
• positive Babinski's reflex

Note : The patient's thinking remains alert during attacks.

Signs and tests:

The health care provider may suspect familial periodic paralysis based on a family history of the disorder, the episodic nature of symptoms, demonstration of low-potassium levels during attacks, and elimination of other disorders associated with low-potassium as the cause of symptoms.

Between attacks, the examination is normal. During an attack, reflexes may be decreased or absent. Weakness is flaccid rather than spastic and is greater in the proximal muscle groups (near the body, such as shoulders and hips) than in the distal groups (away from the body, such as the arms and legs). The health care provider may attempt to trigger an attack by reducing potassium levels through administration of insulin and glucose.

Serum potassium is low during attacks but is normal between attacks, confirming the diagnosis of hypokalemic periodic paralysis.

An ECG may be abnormal during attacks. An EMG is normal. A muscle biopsy may occasionally show abnormalities.