Overview of Hypokalemic Periodic Paralysis
Hypokalemic periodic paralysis is a muscle disease characterized by periodic episodes of flaccid paralysis of skeletal muscle and a decrease in serum potassium during the episodes. It is inherited as an autosomal dominant disease, with incomplete epistasis, and can be seen in disseminated cases. It can occur at any age, but is more common in 20-40 years old, and is more common in males than females. Clinical manifestations include weakness and paralysis of the limbs, accompanied by numbness and soreness, etc. Drug treatment is the mainstay.
Etiology
Hypokalemic periodic paralysis is an autosomal dominant disease with the causative gene located on chromosome 1. It can be induced by satiation, excessive consumption of carbohydrates, alcoholism, fatigue, strenuous activities, cold, mental stress, trauma, infection, menstruation and application of glucocorticoids and insulin, etc. Sometimes localized flaccid paralysis can be induced by immersion of limbs in cold water.
Symptoms
Hypokalemic periodic paralysis attacks are usually preceded by prodromal symptoms, such as muscle stiffness, fatigue, abnormal limb perception, drowsiness, headache, etc., or excitement, nervousness, apprehension, dyspepsia, irritability and thirst, etc., in the days prior to the attack.
Most of the attacks occur at night when sleeping or waking up early in the morning, or during napping, and when waking up, they find muscle weakness, numbness, soreness and paralysis of the limbs, and in severe cases, there may be paralysis of respiratory muscles and respiratory difficulties. During the attack, tendon reflexes decrease or disappear, but there is no change in perception and consciousness. Each attack lasts as short as 1 to 3 hours and as long as 7 to 9 days, after which it resolves on its own. Muscle paralysis often begins in the lower limbs and progresses gradually upward, with the proximal end heavier than the distal end, symmetrically and with varying degrees of severity. The scope can be several muscle groups or even the whole body. In severe cases, except for facial muscles, eye muscles, muscles related to articulation and speech, diaphragm, sphincter, skeletal muscles of the whole body can be involved, causing speech and respiratory disorders.
Some patients develop oliguria or urinary retention. Cardiac auscultation may reveal signs such as muffled heart sounds, tachycardia, and arrhythmia; in severe cases, there may be a drop in blood pressure, and if treatment is not timely, cardiac arrest or death due to respiratory muscle paralysis may occur.
Tests
1. Serum potassium test
Serum potassium is lowered, usually below 3.5 mmol/L.
2. Electrocardiogram
It shows prolonged PR and QT intervals, U waves, ST-segment drop, and flattened or inverted T waves.
3. Electromyography
Electromyography may show myogenic damage during seizure.
4. Glucose evoked test
Under cardiac monitoring, after taking 50g of glucose orally and injecting 10U of insulin subcutaneously at the same time, observe the changes of muscle strength, blood potassium and ECG every 1 hour.
Diagnosis
1. there is a sudden onset of flaccid paralysis of skeletal muscles during sleep without cerebral nerve damage, sensory deficits and pyramidal signs.
2. Serum potassium was less than 3.5 mmol/L at the time of the attack, and treatment with potassium salts was effective.
3. Secondary hypokalemic paralysis due to other diseases is excluded.
4. The presence of T-wave inversion, ST-segment changes and U-wave on ECG can help the diagnosis.
Treatment
1. Potassium chloride
Potassium chloride can be given nasally or orally during the attack. If the disease is severe and arrhythmia or respiratory muscle paralysis occurs, potassium-containing solution should be dripped into the vein slowly under cardiac monitoring, while paying attention to the urine output. Seizures can also be prevented by taking potassium chloride once a night before bedtime.
2. Acetazolamide
In the presence of a trigger, acetazolamide can prevent the onset of symptoms.
3. Others
Adopt a low-sugar diet, limit sodium intake, and try to avoid triggers, such as cold and excessive exercise, especially at night.
If the patient has dyspnea, artificial respiration and oxygen should be administered promptly.
Prognosis
The disease can recur, in most cases, the prognosis is good, serious cases often die of heart failure or death due to respiratory muscle paralysis and asphyxiation. There is a tendency for the episodes to decrease with age, especially after middle age, but there is also a possibility of developing into a permanent disease.
Prevention
1. Genetic counseling is available if there is a family history of the disease; prenatal diagnosis can be made by genetic testing during pregnancy.
2. Avoiding triggers such as overeating, alcohol abuse, high-sugar diets, fatigue, strenuous activities, stress, and exposure to cold can help prevent attacks.
Nursing care
People living with the patient should pay more attention to the patient’s activities, detect the onset of the disease in time and help the patient to take medication to reduce the patient’s pain.