Family periodic paralysis

Family periodic paralysis is a rare autosomal condition characterized by episodes of flaccid paralysis with loss of deep tendon reflexes and a lack of muscle response to electrical stimulation. There are 3 forms: hyperkalemic, hypokalemic and normokaliemic. The diagnosis indicates an anamnesis, confirm the diagnosis, provoking the episode (the introduction of glucose with insulin to cause hypokalemia, or potassium chloride, to cause hyperkalemia). Treatment of family periodic paralysis depends on the form.

[1], [2], [3], [4], [5], [6], [7], [8],

What causes family periodic paralysis?

The hypokalemic form of familial periodic paralysis develops as a result of a mutation in the calcium channel gene associated with the dihydropyridine receptor. The hyperkalemic form is a consequence of mutations of the gene encoding the alpha subunit of sodium channels in the skeletal muscle (SCN4A). The cause of the normokaliemic form remains unclear; in some circumstances, it may be a consequence of the mutation of the gene that codes for the sodium channels.

Symptoms of family periodic paralysis

With hypokalemic form, episodes usually appear before the age of 16. The day after active exercise, the patient often wakes up with weakness, which can be light and limited to certain muscle groups or can cover all 4 limbs. Episodes are provoked by food rich in carbohydrates. The oculomotor muscles, innervated by the bulbar group of the cranial nerves, and the respiratory muscles are squeezed. Consciousness does not suffer. The level of potassium in the blood and urine is reduced. Weakness persists up to 24 hours.

With hyperkalemic form, episodes often begin to appear at an earlier age and are usually shorter, more frequent and less severe. Episodes are provoked by physical exercises after eating or starving. Myotonia is often noted (later onset of relaxation after muscle contraction). Myotonia of the eyelids may be the only symptom.

With normokaliemic form, affected patients are sensitive to potassium intake with food, and they have episodes of mild muscle weakness at a normal serum potassium level.

Diagnosis of family periodic paralysis

The best diagnostic indicator is an anamnesis - typical episodes. When measured during an episode, the potassium level in the serum can be changed. Family periodic paralysis can sometimes be provoked by the administration of glucose and insulin (hypokalemic form) or potassium chloride (hyperkalemic form), but only experienced physicians should perform these procedures, as with an induced episode, paralysis of the respiratory muscle or intracardiac conduction disorder may develop.

[9], [10], [11], [12], [13]

Treatment of family periodic paralysis

Episodes of hypokalemic paralysis are treated with the appointment of potassium chloride 2-10 g in a solution for oral administration (without the addition of sugar) or intravenous administration of potassium. A diet low in carbohydrates and sodium is shown; Exclusion of activities requiring muscle tension, as well as alcohol after periods of rest; taking acetazolamide 250-2000 mg orally once a day can help prevent the development of hypokalemic episodes.

The beginning mild episode of hyperkalemic paralysis can be interrupted by mild physical exercise or carbohydrate intake at a rate of 2 g / kg. A developing episode requires thiazides, acetazolamide, or inhaled beta-agonists. Severe attacks require intravenous calcium gluconate or glucose with insulin. Regular intake of carbohydrates, low potassium in food and avoiding starvation and activities that require muscle tension, after eating, as well as being in the cold, help prevent hypokalemic episodes.

With normokaliemic form, large doses of sodium improve the condition and reduce weakness. The introduction of glucose is ineffective. Family periodic paralysis can be prevented by avoiding rest after physical exertion, excessive intake of alcohol and being in the cold.