Periodic paralysis

Introduction to periodicity Periodic paralysis is a group of diseases characterized by transient recurrent skeletal muscle transient flaccid paralysis. According to the serum potassium concentration and symptoms at the time of onset, it can be divided into hypokalemia type, hyperkalemia type and normal blood potassium type, among which hypokalemia type is the most common. The etiology and pathogenesis of this disease have not yet been elucidated. In addition to thyroid, adrenal gland and other endocrine dysfunction can be the cause of this disease, many of the effects on glucose metabolism, water and electrolyte balance can also cause similar periodic paralysis. Potassium salts are not only related to electrolyte balance and intermediate metabolic processes of sugar, but also to normal nerve conduction and stress at neuromuscular junction points. The occurrence of muscle spasm seems to be closely related to the change of serum potassium ion concentration in patients, but there is no clear relationship with the severity. In short, potassium and glucose metabolism disorders are the main aspects of the pathogenesis of this disease; there is also a complex relationship between endocrine dysfunction and myasthenia gravis. basic knowledge The proportion of illness: 0.0003% Susceptible people: no specific population Mode of infection: non-infectious Complications: sudden death, difficulty swallowing

Periodic cause

Low potassium periodic paralysis (30%):

Most of them are sporadic in China, and European and American countries are more common in hereditary or familial origin, and sporadic only accounts for 20%. Therefore, it is called familial periodic paralysis, which is autosomal dominant, and the gene is located at 1q31~32, with dihydropyridine. Receptor genes are linked and may be caused by genetic mutations.

Hereditary paroxysmal myasthenia (30%):

Ankylosing periodic paralysis is an autosomal dominant myopathy. In recent years, it has been found that there are mismatch mutations, high potassium and positive potassium in the skeletal muscle sodium channel subunit gene (SCN4A) located at 17q23.1~25.3. Periodic paralysis is associated with this genetic mutation and is considered a skeletal muscle sodium channel disease.

Potassium metabolism disorder (40%):

The imbalance of potassium balance inside and outside the muscle cells is the main cause of seizures. It is also related to the distribution of other ions inside and outside the membrane and the functional changes of ion channels on the cell membrane, while the glucose metabolism process and endocrine hormones such as insulin, adrenaline and adrenocortical hormone are potassium. The metabolism also has a wide range of effects.

Periodic prevention

1. Usually should avoid overwork, over-saturation and cold and other incentives.

2. Adrenalin, insulin, hormone drugs should be used with caution or disabled.

3. Frequent seizures should limit salt intake, and can take potassium chloride or spiral lactone to prevent seizures.

Periodic paralysis Complications, sudden death, difficulty swallowing

Patients with periodic paralysis may have persistent muscle weakness and even muscle atrophy in patients with frequent episodes. Individual patients may still have arrhythmia during intermittent periods, often sudden death due to ventricular tachycardia, and a few severe cases of hypokalemia. In addition to the above symptoms, chest tightness, palpitations, difficulty breathing, slow heartbeat, irregular heartbeat, dysuria, chewing weakness, eating cough, difficulty swallowing, unclear speech, etc. may occur due to paralysis of the diaphragm, respiratory muscles, and myocardium. .

Frequent sputum symptoms Common symptoms Fatigue limb symmetry soft palate dysphoria palsy overeating gluttony inability to drunk nervous kidney interstitial damage dyspnea

Periodic paralysis can be divided into three categories: hypokalemia, hyperkalemia and normal potassium.

First, hypokalemia periodic paralysis: the most common, young adults are more common, may have a family history, often induced by cold, full meal, fatigue, etc.; often in the middle of the night, early morning or after a nap acute onset, manifested as the lower extremity The beginning of the sputum gradually affects the upper limbs; the limbs are symmetrical, the proximal end is heavier than the distal end, and reaches a peak within a few hours. Very few can accumulate the muscles of the cervical, phrenic and cranial nerves. Hours to several days, then gradually recover, early thirst, sweating, sore limbs, abnormal feelings and other symptoms, sputum reflexes during the attack, sputum muscle electrical stimulation no excitatory reaction, feeling normal.

Second, high blood potassium periodic paralysis: very rare, the disease often occurs in children before the age of 10, more men, rest after hunger and vigorous exercise, cold and cold environment or take potassium salt, spiral lactone can Induced, clinical manifestations are similar to hypokalemic periodic paralysis, each episode lasting from a few minutes to tens of minutes, rarely more than 1 hour, often accompanied by eyelid rigidity.

Third, normal blood potassium peripheral paralysis: also known as sodium reactive periodic paralysis, rare, onset before the age of 10, halophilic patients often induced after reducing the amount of salt, clinical manifestations with hypokalemia periodic paralysis, continued The time can be as long as 10 days or more.

Periodic inspection

1, serum potassium hypokalemia cycle paralysis serum potassium is low, can be as low as 1.5mmol / L, but the reduction level can be inconsistent with clinical signs of muscle weakness, urinary potassium reduction, large potassium excretion during recovery, hyperkalemia cycle paralysis At the time of onset, serum potassium and urinary potassium were elevated, and serum potassium increased by 7-8 mmol/L. Normal potassium potassium cycle was normal.

2, serum creatine kinase subunit B (S-CKB) activity increased, serum myosin content increased, seen in hypokalemia periodic paralysis.

3, ECG changes

(1). Low potassium type electrocardiogram showed low potassium changes, showing PR interval, QT interval prolonged, QRS wave widened, ST segment moved down, high towering u wave appeared, and there were different degrees of atrioventricular block in heavy weight, ventricular Premature beats or other heart rhythm disorders, EMG examination showed severe muscle excitability in patients with severe symptoms, decreased motor unit potential, decreased amplitude, and no induced action potential in electrical stimulation.

(2). The high potassium type electrocardiogram showed a hyperkalemia change, and the T wave was elevated and pointed.

Periodic diagnosis

Diagnostic criteria

Paroxysmal flaccid paralysis, loss of sputum reflexes, and loss of electrical excitability, as the interictal period is normal, the induction test is more helpful for the diagnosis.

First, medical history and symptoms:

Young adults are more common, may have a family history, often induced by cold, full meal, fatigue; often in the middle of the night, early morning or after a nap acute onset, and recurrent episodes of soft limbs as the main performance.

Second, physical examination found:

1. The degree of limbs is not flaccid, often starting from the lower extremities, the proximal end is heavier, severe respiratory muscle involvement, muscle pain, no sensory disturbances, most of the recovery to a few hours to a day or two, up to a week.

2. When the myocardium is involved, there may be bradycardia, premature ventricular contractions, and elevated blood pressure.

3. Hypokalemia caused by rickets, Guillain-Barré syndrome and hyperthyroidism, hyperaldosteronism, gossypol poisoning, renal tubular acidosis, etc. should be excluded.

Third, auxiliary inspection:

The blood potassium level decreased during the attack, and the electrocardiogram showed a low potassium change. The response of the muscles to DC stimulation is diminished.

Differential diagnosis

Other diseases that can cause similar paralysis should be identified. The most impressive clinical practice is the identification of GBS and cerebrovascular accidents, especially ischemic cerebrovascular disease and transient cerebral insufficiency.

1. Primary aldosteronism often has recurrent limb weakness and hypokalemia, but the initial onset is older, the duration of each episode can last for several months, the symptoms are slower and often difficult to recover. Normal; in addition, there are still high blood pressure, nocturia and so on.

2. Acute infectious polyneuritis Most patients have a history of upper respiratory tract or digestive tract infection from a few days to several weeks before the onset of symptoms. The symptoms gradually increase after onset, reaching a peak within 1 to 2 weeks, after the condition is stable 2 to 4 Weekly recovery, cerebrospinal fluid examination can be found in the phenomenon of protein cell separation; and periodic sputum episodes peak or recovery time is shorter, accompanied by a decrease or increase in serum potassium, generally without obvious sensory loss.

3. Myasthenia gravis is characterized by partial or all skeletal muscle susceptibility to fatigue. It is aggravated during activities, improved after rest, and is effective against cholinesterase inhibitors. 90% of patients have AchR-Ab positive in blood.

4. Acute sputum poisoning may have quadriplegia, drooping eyelids, pronunciation and difficulty in swallowing, as well as gastrointestinal tremors, nausea and vomiting, diarrhea and other gastrointestinal symptoms, as well as eating salt or drug history with excessive bismuth.

5. The onset of polymyositis is slow, with fever, muscle pain, Raynaud's phenomenon, increased blood CPK, and duration is rarely shorter than weeks or months.

6. Hypokalemia is mostly caused in the cotton-producing area and the history of eating cottonseed oil. In addition to the weakness of the paroxysmal limbs, it is often accompanied by gastrointestinal symptoms and is effective for the treatment of potassium chloride.

7. Hyperthyroidism combined with low-potassium periodic cookware, hyperthyroidism, clinical manifestations, T3, T4 increased, periodic sputum cessation after normal thyroid function.

Other hypokalemia

(1) renal tubular acidosis: the distal defects of the distal convoluted tubule can not be acid and potassium, low potassium and high chlorine, urine pH increased.

(2) hypokalemia caused by diuretics, vomiting and diarrhea.

8. The rickets are stimulated by mental factors, and there are more episodes during the day. There are no obvious features of the distal and distal tendons of the limbs. The tendon reflex is not weakened, and the myoelectric stimulation response is normal.

9. Hypokalemia and periodic paralysis should be differentiated from Guillain-Barré syndrome. The disease starts faster and recovers faster. The limbs are delayed, no respiratory muscle paralysis and cranial nerve damage, no feeling. Obstacles and nerves and irritations, cerebrospinal fluid examination is normal, blood potassium is low, potassium supplementation is effective, and there is a history of recurrent attacks; while Guillain-Barré syndrome has a history of pre-infection and autoimmune response, acute or subacute Disease, progress no more than 4 weeks, may have different degrees of respiratory muscle paralysis and cranial nerve damage, cerebrospinal fluid examination showed protein-cell separation, electrophysiological examination early F wave or H reflection delay, blood potassium test results are normal, no previous recurrent Medical history.

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