Hypokalemic periodic paralysis Health Article

Definition

Hypokalemic periodic paralysis is an inherited disorder that causes occasional episodes of muscle weakness.

It is one of a group of genetic disorders that includes hyperkalemic periodic paralysis and thyrotoxic periodic paralysis.

Alternative Names

Periodic paralysis - hypokalemic

Causes, incidence, and risk factors

Hypokalemic periodic paralysis is a condition in which a person has episodes of muscle weakness and sometimes severe paralysis.

The condition is congenital, which means it is present from birth. In most cases, it is passed down through families (inherited) as an autosomal dominant disorder. That means only one parent needs to pass the gene related to this condition onto you in order for you to be affected. Ocassionally, the condition may be the result of a genetic problem that is not inherited.

Unlike other forms of periodic paralysis, persons with this type have normal thyroid function and very low blood levels of potassium during episodes of weakness.

Risks include having other family members with periodic paralysis. The risk is slightly higher in Asian men who also have thyroid disorders.

Disorders that cause intermittent episodes of paralysis as their primary effect are uncommon. Hypokalemic periodic paralysis occurs in approximately 1 out of 100,000 people.

Symptoms

The disorder involves attacks of muscle weakness or loss of muscle movement (paralysis) that come and go. There is normal muscle strength between attacks.

Attacks usually begin in adolescence, but they can occur before age 10. Attacks that do not begin until adulthood are rare and are usually caused by other disorders.

How often the attacks occur varies. Some people have attacks every day, while others have them once a year. Episodes of muscle weakness usually last between a few hours and a day.

The weakness or paralysis:

• Most commonly located at the shoulders and hips
• Involves the arms and legs, but may also affect muscles of the eyes and those that help you breathe and swallow
• Occurs intermittently
• Most commonly occurs on awakening
• Most commonly occurs after sleep or rest
• Is rare during exercise, but may be triggered by rest after exercise
• May be triggered by heavy, high-carbohydrate, high-salt meals or alcohol consumption
• Usually lasts less than 24 hours

Other symptoms may include:

• Positive Babinski's reflex
• Eyelid spasms between episodes

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