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Hyperkalemic periodic paralysis
Periodic paralysis - hyperkalemic; Familial hyperkalemic periodic paralysis; HyperKPP; HyperPP; Gamstorp disease
Hyperkalemic periodic paralysis (hyperPP) is a disorder that causes occasional episodes of muscle weakness and sometimes a higher than normal level of potassium in the blood. The medical name for high potassium level is hyperkalemia .
Muscle weakness
Weakness is reduced strength in one or more muscles.
Hyperkalemia
High potassium level is a problem in which the amount of potassium in the blood is higher than normal. The medical name of this condition is hyperka...
HyperPP is one of a group of genetic disorders that includes hypokalemic periodic paralysis and thyrotoxic periodic paralysis .
Hypokalemic periodic paralysis
Hypokalemic periodic paralysis (hypoPP) is a disorder that causes occasional episodes of muscle weakness and sometimes a lower than normal level of p...
Thyrotoxic periodic paralysis
Thyrotoxic periodic paralysis is a condition in which there are episodes of muscle weakness. It occurs in people who have high levels of thyroid hor...
Causes
HyperPP is congenital. This means it is present at birth. In most cases, it is passed down through families (inherited) as an autosomal dominant disorder. In other words, only one parent needs to pass the gene related to this condition on to their child in order for the child to be affected.
Occasionally, the condition may be the result of a genetic problem that is not inherited.
It is believed that the disorder is related to problems with the way the body controls sodium and potassium levels in cells.
Risk factors include having other family members with periodic paralysis. It affects men more often than women.
Symptoms
Symptoms include attacks of muscle weakness or loss of muscle movement ( paralysis ) that come and go. There is normal muscle strength between attacks.
Paralysis
Muscle function loss is when a muscle does not work or move normally. The medical term for complete loss of muscle function is paralysis.
Attacks usually begin in childhood. How often the attacks occur varies. Some people have several attacks a day. They are usually not severe enough to need therapy. Some people have associated myotonia, in which they cannot immediately relax their muscles after use.
The weakness or paralysis:
- Most commonly occurs at the shoulders and hips
- May also involve the arms and legs, but does not affect muscles of the eyes and muscles that help with breathing and swallowing
- Most commonly occurs while resting after activity or exercise
- May occur on awakening
- Occurs on and off
- Usually lasts 1 to 2 hours, but may last up to an entire day
Triggers may include:
- Eating a high carbohydrate meal
- Exercise
- Exposure to cold
- Eating potassium-rich foods or taking medicines that contain potassium
Exams and Tests
The health care provider may suspect hyperPP based on a family history of the disorder. Other clues to the disorder are muscle weakness symptoms that come and go with normal or high results of a potassium test .
Potassium test
This test measures the amount of potassium in the fluid portion (serum) of the blood. Potassium (K+) helps nerves and muscles communicate. It also ...
Between attacks, a physical examination shows nothing abnormal. During and between attacks, potassium blood level can be normal or high.
During an attack, muscle reflexes are decreased or absent. And muscles go limp rather than staying stiff. Muscle groups near the body, such as the shoulders and hips, are involved more often than the arms and legs.
Tests that may be done include:
-
Electrocardiogram
(ECG)
, which may be abnormal during attacks
(ECG)
An electrocardiogram (ECG) is a test that records the electrical activity of the heart.
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Electromyography
(EMG)
, which is usually normal between attacks and abnormal during attacks
(EMG)
Electromyography (EMG) is a test that checks the health of the muscles and the nerves that control the muscles.
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Muscle biopsy
, which may show abnormalities
Muscle biopsy
A muscle biopsy is the removal of a small piece of muscle tissue for examination.
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Other tests may be ordered to rule out other causes.
Treatment
The goal of treatment is to relieve symptoms and prevent further attacks.
Attacks are seldom severe enough to require emergency treatment. But irregular heartbeats ( heart arrhythmias ) may also occur during attacks, for which emergency treatment is needed. Muscle weakness can become worse with repeated attacks, so treatment to prevent the attacks should occur as soon as possible.
Heart arrhythmias
An arrhythmia is a disorder of the heart rate (pulse) or heart rhythm. The heart can beat too fast (tachycardia), too slow (bradycardia), or irregul...
Glucose or other carbohydrates (sugars) given during an attack may reduce the severity of the symptoms. Calcium or diuretics (water pills) may need to be given through a vein to stop sudden attacks.
Outlook (Prognosis)
Sometimes, attacks disappear later in life on their own. But repeated attacks may lead to permanent muscle weakness.
HyperPP responds well to treatment. Treatment may prevent, and may even reverse, progressive muscle weakness.
Possible Complications
Health problems that may be due to hyperPP include:
-
Kidney stones
(a side effect of medicine used to treat the condition)
Kidney stones
A kidney stone is a solid mass made up of tiny crystals. One or more stones can be in the kidney or ureter at the same time.
ImageRead Article Now Book Mark Article - Irregular heartbeat
- Difficulty breathing, speaking, or swallowing during attacks (rare)
- Muscle weakness that slowly continues to get worse
When to Contact a Medical Professional
Call your provider if you have muscle weakness that comes and goes, especially you have family members who have periodic paralysis.
Go to the emergency room or call the local emergency number (such as 911) if you faint or have difficulty breathing, speaking, or swallowing.
Prevention
A medicine called acetazolamide prevents attacks in many cases. Other medicines may also be prescribed. A low potassium, high carbohydrate diet may help prevent attacks. Avoiding fasting, strenuous activity, or cold temperatures also may help.
References
Jurkat-Rott K, Rudel R, Lehmann-Horn F. Muscle channelopathies: myotonias and periodic paralyses. In: Darras BT, Jones R, Ryan MM, De Vivo DC, eds. Neuromuscular Disorders of Infancy, Childhood, and Adolescence . 2nd ed. Philadelphia, PA: Elsevier; 2015:chap 38.
Kerchner GA, Ptacek LJ. Channelopathies: episodic and electrical disorders of nervous system. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SK, eds. Bradley's Neurology in Clinical Practice . 7th ed. Philadelphia, PA: Elsevier; 2016:chap 99.
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Muscular atrophy - illustration
Muscular atrophy is the decrease in size and wasting of muscle tissue. Muscles that lose their nerve supply can atrophy and simply waste away.
Muscular atrophy
illustration
Review Date: 10/13/2015
Reviewed By: Walead Latif DO, nephrologist, Medical Director of Fresenius Vascular Care, and Clinical Assistant Professor of Rutgers Medical School, Newark, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
