What is Periodic Paralysis?
Periodic paralysis is a rare genetic disorder that causes episodes of extreme muscle weakness or paralysis.
Why do these muscle weakness attacks occur? Muscle cells need particles called ions in order to function. These ions, such as potassium, calcium, and sodium, move in and out of the cell through holes called ion channels. Genetic mutations can cause the ion channels to sometimes not open and close properly. When that happens, it’s hard for the muscle to move.
These episodes, or “attacks,” can last for several minutes, a few hours, or even a few days.
There are seven different periodic paralysis types.
Each one has its own characteristics.
Hypokalemic Periodic Paralysis
Hypokalemic Periodic Paralysis (HypoPP or HypoKPP) is the most common form of periodic paralysis,(the potassium never leaves your body, it has just shifted at the cell level)and it is triggered by low blood potassium levels. “Hypo” means low, and “kalemic” refers to potassium. When a person with hypokalemic periodic paralysis does not have enough blood potassium, they might experience muscle weakness or paralysis attack.
Hyperkalemic Periodic Paralysis
Hyperkalemic periodic paralysis (HyperPP or HyperKPP) is characterized by the patient having unusually high potassium levels during attacks. “Hyper” means that there is a high amount of something, which makes it the opposite of “hypokalemic,” even though the two words look almost the same. People who have hyperkalemic periodic paralysis experience muscle weakness and paralysis attacks that usually last anywhere ten minutes to one hour, but sometimes they can last longer.
The Periodic Paralysis Association is here to create awareness and support for those affected by Periodic Paralysis.
Thyrotoxic Periodic Paralysis
When an overactive thyroid gland causes hypokalemic periodic paralysis, the result is a disorder called thyrotoxic periodic paralysis (TPP). Your thyroid gland is located in the base of your neck, and it makes hormones that affect many of your body’s functions. There are some diseases, such as Graves’ disease, that cause the thyroid gland to produce too much of these hormones. When that happens, a variety of problems can take place, such as irregular heartbeat, night sweats, swollen eyes, brittle bones — and muscle weakness attacks.
Normokalemic Periodic Paralysis
Normokalemic periodic paralysis (NormoKPP) is similar to hyperkalemic or hypokalemic periodic paralysis, but it’s not quite the same. People with this type of periodic paralysis have normal blood potassium levels during attacks, unlike the high potassium levels of hyperkalemic periodic paralysis or low levels of potassium as in Hypokalemia Normokalemic attacks can occur at any age, and permanent muscle weakness is possible after many years.
People who have Andersen-Tawil Syndrome (ATS) experience muscle weakness attacks, but they also experience some feelings of muscle weakness between attacks. When it comes to potassium levels, there is a lot of inconsistency. Some attacks cause the patient’s potassium to rise, and other attacks cause it to fall. Some attacks are triggered by eating a high-potassium meal, and other attacks are triggered by the patient not having enough potassium in their meals! Attacks usually begin before age 20.
Potassium Aggravated Myotonia
Myotonia is a condition that causes muscles to not immediately relax after contracting. A person who is experiencing myotonia will have difficulty moving stiff, rigid muscles. If the person tries repeatedly to move those muscles, they will be able to loosen them up. When someone experiences myotonia after they take in too much potassium, they have a potassium aggravated myotonia (PAM). People who have hyperkalemic periodic paralysis often have potassium aggravated myotonia as well.
Paramyotonia congenita (PMC) is a type of periodic paralysis that causes people to have attacks of muscle stiffness (myotonia) when they are active, such as when exercising. Normally, myotonia happens after exercising, not during it. However, if someone has paramyotonia congenita, they will experience myotonia while they are exercising. Because that is the opposite of how myotonia normally works, it’s like a paradox, which is where the “para” in “paramyotonia” comes from. “Congenita” means that this is a condition someone is born with.
Trying to understand a rare disorder that comes in multiple types can be confusing.
Just remember, you are not alone.
Your Next Steps
The PPA is here to help you throughout your periodic paralysis journey. You also have an entire community of people who want to support you. To get more information and resources, visit our Patient Resource center, where you’ll find all of the latest up-to-date science-based knowledge in the field today. You can also join us in taking the Pledge of Advocacy, subscribe to our newsletter, and/or stay connected with us on Facebook and Instagram.