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Periodic Paralysis Syndromes


Periodic paralysis is a rare groups of conditions that is usually inherited. It causes occasional episodes of severe muscle weakness. The most common types of periodic paralysis are hypokalemic, hyperkalemic and Andersen-Tawil syndrome. Less common forms include paramyotonia congenita von Eulenburg, thyrotoxic, distal renal tubular acidosis, X-linked episodic muscle weakness syndrome and congenital myasthenic syndromes.


Periodic paralysis is a condition that is present from birth. Periodic paralysis is caused by abnormalities of the electrolyte channels in muscles that are part of normal contraction.

Familial periodic paralysis is inherited, but may occur without a known family history. With the inherited form of the disorder, only 1 affected parent is needed to transmit the gene to the baby. Rarely, the condition occurs as a result of a noninherited genetic defect.

Genetic Material
Chromosome DNA
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Risk Factors

Factors that increase your chance of developing periodic paralysis include:

  • Family history of periodic paralysis
  • Thyroid disorder—high thyroid hormone levels, particularly in Asian males


Episodes of severe weakness in the arms and legs are the major symptom. The person remains alert and aware during attacks. There is no loss of sensation. Typically, these episodes occur during sleep, early morning, or after strenuous activity. Cold, stress, and alcohol may also produce attacks. Other, less common, symptoms may include:

  • Weakness in the eyelids and face muscles
  • Muscle pain
  • Irregular heartbeats (especially with Andersen-Tawil syndrome)
  • Difficulty breathing or swallowing—This requires emergency care

Although muscle strength returns to normal between attacks, repeated episodes of weakness may lead to chronic muscle weakness later in life.

Some features are specific to the type of periodic paralysis.

  • Hypokalemic:
    • Potassium levels are low during attacks
    • Frequency of attacks varies from daily to yearly
    • Attacks usually last between 4-24 hours, but can last for several days
    • Attacks usually begin in adolescence, but they can occur before age 10
  • Hyperkalemic:
    • Potassium levels are high or normal during attacks
    • Attacks are usually shorter, more frequent , and less severe than the hypokalemic form; breathing and swallowing difficulties are extremely rare
    • Between attacks, patients often experience muscle spasms or difficulty relaxing their muscles, a condition is known as myotonia
    • Attacks usually begin in early childhood
  • Andersen-Tawil
    • Potassium levels can be low, hig, or normal during attacks
    • Attacks may last 1 hour to several days and weakness may persist after attacks
    • Attacks can begin at any point during childhood
    • Associated with some abnormal facial features

Persons with some types of periodic paralysis are at risk for a condition known as malignant hyperthermia. This can occur during the use of general anesthesia. Anyone with a family history of periodic paralysis needs to notify the anesthesiologist of this history prior to any surgery.


Because this primarily is an inherited condition, the most important part of diagnosis is obtaining a family history. You will be asked about your symptoms and your medical history. A physical exam will be done.

Your doctor may want to bring on an attack during an office visit. This should only be done under careful monitoring by an experienced neurologist. If an attack is triggered, several tests may be done, including:

Your muscle tissue may need to be tested. This can be done with a biopsy.

Electromyography (EMG)
Electromyogram EMG
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Since there is no cure for periodic paralysis, lifelong treatment is usually required. Treatment focuses on preventing attacks and relieving symptoms.

Lifestyle Changes

There are a few behaviors you can adopt to reduce the frequency and severity of attacks:

  • Hypokalemic:
    • Eat a low carbohydrate, low sodium, high potassium diet.
    • Avoid strenuous exercise.
  • Hyperkalemic:


The type of medications prescribed depend on the type of periodic paralysis.

  • Medications for hypokalemic, hyperkalemic, and Andersen Tawil syndrome include:
    • Acetazolamide—may prevent an attack by reducing the flow of potassium from the bloodstream into the cells of the body.
    • Diuretics (water pills)
    • Drugs to control abnormal heart beats
  • Hypokalemic:
    • Potassium may stop an attack; intravenous potassium may be prescribed for severe weakness.
    • Avoiding certain commonly prescribed medications may help reduce the onset of attacks.
    • If you have a thyroid condition, be sure to get treatment for it.
  • Hyperkalemic:
    • Thiazide diuretics, or water pills, may be prescribed to prevent an attack.
    • Glucose and insulin, or calcium carbonate may be prescribed to slow or stop an attack.


Familial periodic paralysis cannot be prevented. Because it can be inherited, genetic counseling may be advised for couples at risk of passing on the disorder.

For the hypokalemic type, attacks may be reduced by:

  • Avoiding corticosteroids and glucose infusions
  • Following a diet low in carbohydrates and sodium and rich in potassium

For the hyperkalemic type, attacks may be reduced by:

  • Avoiding high potassium foods, fasting, and drugs known to increase potassium levels
  • Engaging in regular, mild exercise

Revision Information

  • Muscular Dystrophy Association

  • National Organization for Rare Disorders

  • Health Canada

  • Muscular Dystrophy Canada

  • Hyperkalemic periodic paralysis. EBSCO DynaMed website. Available at: Updated April 30, 2013. Accessed May 11, 2016.

    Hypokalemic periodic paralysis. EBSCO DynaMed website. Available at: Updated March 19, 2012. Accessed May 11, 2016.

    Andersen-Tawill syndrome. EBSCO DynaMed website. Available at: Updated August 3, 2012. Accessed May 11, 2016.

  • Jurkat-Ratt K, Lehmann-Horn F. Paroxysmal muscle weakness-the periodic paralyses. J Neurol. 2006;253:1391-1398.

  • Finsterer J. Primary periodic paralyses. Acta Neurol Scand. 2008 Mar;117(3):145-58.

    NINDS familial periodic paralyses information page. National Institute of Neurological Disorders and Stroke website. Available at: Updated August 10, 2015. Accessed May 11, 2016.

  • Patient page: attacks of immobility caused by diet or exercise? The mystery of periodic paralyses. Neurology. 2004;63:E17-E18.