What is the cause of muscle weakness in the limbs

There are many causes of muscle weakness, and any lesion in the pathway from the muscles to the brain center can cause muscle weakness, generally speaking, the lesions of the muscles themselves or the lesions of the muscle-nerve junctions

Myasthenia gravis is an autoimmune disease that, like other autoimmune diseases, is caused by a disorder of the body's immune system that disrupts the body's normal "order". Myasthenia gravis is the attack of acetylcholine receptors in the postsynaptic membrane of the neuromuscular junction by autoantibodies, and when the function of this important receptor is abnormal, it will directly affect the normal conduction and action of neuromuscles.

Disorders of the body's immune system are generally related to environmental factors, infection factors, drug factors, etc., but the specific causes of myasthenia gravis are not clear. Patients with myasthenia gravis often have other autoimmune diseases such as hyperthyroidism, thyroiditis, systemic lupus erythematosus, rheumatoid arthritis, and pemphigus.

The common ** of muscle weakness is listed as follows: first, myasthenia gravis, which is an autoimmune neuromuscular junction disease, with fluctuating symptoms, light morning and twilight, skeletal muscle pathological fatigue, which can affect eye muscles, limb muscles, and respiratory muscles. Second, periodic paralysis is divided into hypokalemia, hyperkalemia, and normal blood potassium type, of which the hypokalemic type is the most common, and the main manifestation is proximal muscle weakness of the limbs during the attack, accompanied by hypokalemia, which often appears after overeating, and generally does not involve respiratory muscles.

Third, muscular dystrophy, manifested by progressive weakness of the limbs or facial muscles with muscle atrophy, often gastrocnemius pain, markedly elevated muscle enzyme profile, and electromyography suggestive of myogenic damage. Fourth, polymyositis, an acute onset of muscle inflammation characterized by muscle pain, weakness, and elevated muscle enzyme profile. Fifth, peripheral nerve damage can be peripheral nerve damage alone, or neuritis involving nerve roots, or simultaneous damage to upper and lower motor neurons, representing multiple peripheral neuropathy, Guillain-Barré syndrome, and motor neuron disease.

Sixth, some other, less common diseases, such as paraneoplastic syndromes.

What are the most common symptoms of muscle weakness:

1. Skeletal muscle abnormality, easy to fatigue, often in the morning when the muscle strength is better, to the afternoon or evening symptoms aggravate, most patients involve the extraocular muscles, to the levator palpebrae muscle is the most likely to be involved, with the development of the disease can involve more extraocular muscles, out of diplopia, and finally the eyeball can be fixed, the intraocular muscles are generally not affected.

2. Ptosis of the upper eyelids: asymmetrical, mostly bilateral. It can also start on one side or progress from one side to the other.

The main manifestations are abnormal posture when seeing, decreased ocular clefts, amblyopia, and diplopia. Symptoms are mild in the morning and severe in the evening and may be relieved by rest or sleep. A positive fatigue test may aid in diagnosis.

3. Weakness of limbs: Feeling weakness of limbs, difficulty in standing up, going upstairs, holding objects, or raising arms over the head.

4. Low voice: When you speak too much or too long, your voice is gradually low and nasal. Difficulty chewing and swallowing.

5. Muscle weakness of the trunk and limbs: less common in children. The main manifestations are weakness and fatigue.

6. The medullary innervation muscles, neck muscles, shoulder girdle muscles, trunk muscles and upper and lower limb muscles can be involved, and if you speak for too long, your voice will gradually be low, and your voice will be unclear and nasal, and due to the weakness of the jaw, soft jaw and swallowing muscles, intercostal muscles, etc., it can affect the chewing and swallowing function and even dyspnea.

Myasthenia is a chronic disease caused by neuromuscular transmission disorders. The clinical feature is that the affected bony muscles are highly fatigued and partially recovered with rest and anticholinesterase drugs**. The occurrence of this disease has a certain relationship with genetic factors, and it can occur at any age, but it is most common at the age of 10 to 35 years, and there are also middle-aged and older patients.

The clinical manifestations are that all skeletal muscles can be affected, but extraocular muscles are the most common. The specific manifestations are drooping eyelids, diplopia, etc., or the muscles of the whole body are affected at the same time, aggravated after fatigue, and partially recovered after rest. The extent and extent of the affected muscles vary widely.

Laboratory tests show elevated serum immunoglobulins in 2 3 patients. Most patients have elevated serum antibodies to acetylcholine receptor (ACHR). Chest x-ray and thymus x-ray often show thymic hyperplasia or thymic tumor.

Electromyography (EMG) shows decreased amplitude of muscle action potential, and single-fiber EMG shows delayed or blocked interfiber excitatory transmission.

Western medicine for muscle weakness is mainly the use of anticholinesterase drugs and immunosuppressants. Anticholinesterase drugs include neostigmine, pyridine stalinmine, enzyme inhibition or mestigmine, and the side effects of these drugs include miosis, drooling, sweating, abdominal pain, diarrhea, etc., and atropine can be taken at the same time to fight. Immunosuppressants mainly include corticosteroids and cyclophosphamide.

Surgery** is suitable for patients with thymoma.

If muscle weakness involves the bulbar muscles and respiratory muscles, so that the body can not maintain normal ventilation function, and enters a dangerous state, called myasthenic crisis, the most important measures at this time are to keep the airway open, and should be done as soon as possible for tracheotomy or nasal intubation, nasogastric catheter and breathing assistance, in addition to preventing lung infection and gastrointestinal bleeding.