Periodic Paralysis Syndromes

(Familial Periodic Paralysis; Hyperkalemic Periodic Paralysis; Hypokalemic Periodic Paralysis; Anderson-Tawil Syndrome; Paraneoplastic Periodic Paralysis)


Periodic paralyses (PP) are a rare group of disorders. They result in brief periods of severe muscle weakness.

The most common types are hypokalemic, hyperkalemic, thyrotoxic, and Andersen-Tawil syndrome.


Minerals like sodium and potassium are needed to make muscles contract. With PP, the gateway for these minerals is disturbed and causes problems with the ability of muscles to contract.

PP is caused by problems with genes. Only 1 affected parent is needed to pass the gene to the baby.

Genetic Material

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Risk Factors

Things that may raise the risk of this problem are:

  • Having other people in the family who have PP
  • Thyroid problems


The main problems are brief periods of severe weakness in the arms and legs. Muscle strength returns to normal between attacks. The attacks may be triggered by things like exercise or alcohol.

Depending on the type of PP, a person may also have:

  • Muscle pain or cramps
  • Muscle tingling
  • Weakness in the eyelids and the muscles of the face
  • Abnormal heartbeats
  • Problems breathing or swallowing

Repeat attacks may lead to long-term muscle weakness later in life.

People with some types of PP are at risk for a problem known as malignant hyperthermia. It is a fast and harmful rise in body temperature. It can occur during the use of general anesthesia.


The doctor will ask about your symptoms and health history. You may also be asked about your family health history. A physical exam will be done.

Tests that may be done are:

  • Blood tests to check mineral levels and thyroid hormone levels and to look for problems with genes
  • Electrocardiogram (ECG, EKG) to check the electrical activity of the heart
  • Nerve conduction studies and an electromyography (EMG) to measure the electrical activity of the muscles
  • A biopsy to test muscles

Electromyography (EMG)

Electromyogram EMG
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There is no cure. The goal is to prevent attacks and ease symptoms. Choices are:

  • Lifestyle changes, such as dietary changes and limiting things that trigger attacks
  • Medicines like acetazolamide to manage the type of PP that a person has


There are no known methods to prevent this health problem.


Muscular Dystrophy Association
National Organization for Rare Disorders


Muscular Dystrophy Canada


Andersen-Tawill syndrome. EBSCO DynaMed website. Available at: Accessed October 6, 2020.
Familial periodic paralyses information page. National Institute of Neurological Disorders and Stroke website. Available at: Accessed October 6, 2020.
Hyperkalemic periodic paralysis. EBSCO DynaMed website. Available at: https://www.dyname.... Accessed October 6, 2020.
Sansone V, Meola G, et al. Treatment for periodic paralysis. Cochrane Database Syst Rev. 2008 Jan 23;(1):CD005045.
Last reviewed September 2020 by EBSCO Medical Review Board Rimas Lukas, MD
Last Updated: 5/21/2021

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