What is Myopathy?

Myopathy refers to the primary structural or functional lesions of the muscle, including secondary muscle weakness caused by the central nervous system (CNS), lower motor neurons, peripheral nerves, and neuromuscular junctions. Based on clinical and laboratory examination characteristics, myopathy can be distinguished from other motor neuron diseases. Clinically, myopathy can be divided into two categories: hereditary and acquired.

Basic Information

English name: myopathy
English alias: myonosus
Visiting department: Neurology

Common causes: Changes in the structure and function of the cell membrane caused by a certain metabolic defect in hereditary muscle cells
Common symptoms: Progressive muscle weakness and muscle atrophy Standing, squatting, standing, walking, climbing, lifting, etc.

Causes of myopathy

Most scholars believe that it is a group of hereditary muscular degenerative diseases. Most are recessive. In addition, there are still other theories of cell membrane autoimmune diagnosis and vasogenic neuron. In recent years, most scholars believe that the disease is caused by a certain metabolic defect in hereditary muscle cells, which changes the structure and function of cell membranes.

Clinical manifestations of myopathy

The disease is mostly a middle-aged male, with slow onset, mainly manifested by progressive muscle weakness and muscle atrophy. The lesions are affected by the size of the hand, the scapular muscle, the scapular muscle, the pelvic muscle, and the gluteal muscle. As a result, the patient experienced difficulties in standing, standing, squatting, walking, landing, and lifting. Vibration of muscle fibers was seen, non-specific myopathic changes in electromyography showed increased creatinine in hematuria. The severity of myopathy is mostly parallel to the severity of hyperthyroidism. After the hyperthyroidism is controlled, myopathy improves. According to the typical genetic form and main clinical manifestations, muscular dystrophy can be divided into the following types:

1. Large scale

It is the most common X-linked recessive genetic disease and can be divided into Duchenne type and Becker according to clinical manifestations.

(1) Duchenne-type malnutrition (DMD) is also called severe pseudohypertrophy. Only seen in boys, if the mother is a carrier of genetic diagnosis and treatment, male offspring will develop the disease. Onset in early childhood, the initial feeling of walking benzene, easy to fall, can not run and climb the stairs, standing forward spinal cord, standing abdomen, two legs aside, walking slowly, swinging in a special "duck step" gait. It is very difficult to get up from a supine position. You must first turn over and prone, then climb your knees with both hands, and gradually support the upright (Gower sign). Due to the weakness and atrophy of the pelvic girdle muscles and the extensor muscles of the hips, knees, and feet, as the disease progresses, the scapular girdle and upper arm muscle groups are involved. Muscles can also be weak. Some affected muscles become enlarged and firm as muscle fibers are replaced by connective tissue and fat. This "pseudohypertrophy" is seen in the gastrocnemius muscle, but also in the proximal muscles of the limbs, quadriceps, and arm muscles. Tendon reflexes are reduced or disappeared without sensory disturbances. In the later stage, tendon contracture and joint stiffness and deformity are often caused by muscle atrophy. Many children are also accompanied by myocardial disease, ECG may have abnormal PR interval, Q wave deepening and other abnormalities. Some children are mentally retarded, and serum CPK is significantly increased. The prognosis of this disease is poor. Most of them cannot walk and stay in bed. They often die of pneumonia, heart failure or chronic wasting disease before the age of 20.

(2) Becker type (BMD) is also called benign pseudomassinodystrophy. The first symptom is weak pelvic girdle and thigh muscles, slow progress, long course of disease, and inability to walk. The prognosis is good. Serum CPK is not significantly higher than Duchenne type. Muscle histochemical staining shows IIB fibers, which is also different from DMD.

2. Facial Shoulder-Brachial Muscular Dystrophy

Is an autosomal dominant inheritance, both men and women can develop the disease. Facial muscle weakness and asymmetry first appear at the time of onset, and teeth, lips, closed eyes, and frowns cannot be displayed. Orbicular orbicularis muscle may have pseudohypertrophy, so that lips become hypertrophic and lips protrude. Some shoulder and humerus muscle groups are affected first, causing the two arms to be lifted into a vertical shoulder. The upper arm muscles atrophy, but the forearm and hand muscles are not violated. The lesions can also affect the tibialis anterior muscles. The pelvic girdle muscles cause weakness and atrophy of the lower limbs, leading to drop feet and lordosis, and the myocardium is not affected. Serum enzymes were normal or slightly increased. The course of the disease progresses very slowly, often with frustration or remission.

3. Limb girdle muscular dystrophy

It is autosomal recessive and occasionally dominant. Often spread, both sexes can develop. The onset of childhood affects the pelvic girdle muscles and psoas major muscles first. It is difficult to walk, unable to board the building, swaying in gait, and often falling. Some only involve the quadriceps, the course of the disease progresses very slowly, and it can invade the scapular muscles in the late stage. Some scapular muscle groups are first affected and become the scapular-fibula muscle type. When malnourished, if it does not belong to the face-shoulder-brachial type, it should be a limb band type.

4. Other types

The quadriceps femoris distal type, progressive extraocular muscle paralysis type, ophthalmo-pharyngeal muscle type (dysphagia dysphagia) are rare.

Myopathy

Serum enzyme assay

(1) Increased serum creatine phosphate kinase (CPK) CPK is an important and sensitive indicator for the diagnosis of this disease, and it has increased before clinical symptoms appear. When the course of the disease is delayed, the vitality gradually decreases, and it can also be used to check genetic immune carriers. When the diagnosis is difficult, the patient's serum CPK can be significantly increased after subcutaneous or intravenous injection of hydrocortisone. The positive rate was 60 to 80%.

(2) Serum myoglobin (MB) is also significantly increased in the early stages of the disease and among carriers of diagnostic genes.

(3) Serum pyruvate (PK) is sensitive. Normal men and women under 20 years old have a serum PK value of 119.00, men over 20 years old are 84.30, women are 77.50. The positive rates of CRK and PK in the above three serum enzymes are higher than Mb. The three comprehensive detection rates were around 70%.

(4) Other enzymes such as aldolase (ADL), lactate dehydrogenase (LDH), aspartate aminotransferase (GOT), alanine aminotransferase (GPT), etc. can also be increased, but they are not specific changes of myopathy and are not sensitive . However, in neurogenic muscle atrophy, there is no false positive phenomenon, so it can complement the measurement of CPK and Mb. In addition, the decrease of cell membrane Na + K + ATPase activity also helps the diagnosis of this disease.

2. Urine test

Urinary creatine excretion increases and creatinine decreases.

3. EMG

When the inserted potential prolonged muscles relax, the self-generating potential appears light; the average amplitude and the average advance limit of the motor unit potential are lower than normal when contracted, and short spikes can also be seen; when the multiphase potential is strongly contracted, pathological interference phases can be seen, and the peak voltage Small, normal motor nerve conduction velocity.

4. Muscle biopsy

It can be seen that the aforementioned pathological changes, when applicable, X-CT or nuclear magnetic resonance examination technology can be used, can find the degree and scope of muscle degeneration, and provide a preferred site for clinical muscle biopsy.

Myopathy diagnosis

In typical cases, based on the slow onset, progressive exacerbations, the special distribution of limb-proximal type with muscular atrophy and weakness, the extremity tendon reflexes are low or disappear, there is no sensory disturbance, and it is not difficult to make a diagnosis. In the recessive hereditary family, after the first case, the subsequent cases can be diagnosed early by the determination of serum CPK, Mb, and PK.

Differential diagnosis of myopathy

Early onset patients need to be distinguished from infantile spinal muscular atrophy and fibula muscular atrophy. Electromyography is of clinical assistance value. Adult onset patients must be treated with subacute or chronic polymyositis and myasthenia Weakness and chronic multiple infectious neuritis are distinguished; for limb girdle muscular dystrophy, it needs to be distinguished from mitochondrial myopathy.

Myopathy

There is no special treatment for this disease. Various therapies such as allopurinol, arrhythmidine, energy mixture, inosine, galantamine, bifendate, gelatin, insulin, glucose therapy, mumps, high-dose vitamin E, and hyperbaric oxygen therapy, etc. It works. Recently, the use of external counterpulsation therapy has certain effects; supportive therapy such as physical therapy and physical therapy, as well as stent surgery and correction of deformities can be used as adjuvant treatment.

Myopathy prevention

Good genetic counseling is an important measure to prevent this disease. If possible, prenatal amniotic fluid cell examination and chromosome examination should be promoted to determine the sex of the fetus. If the fetus is affected, pregnancy should be terminated.

In recent years, immunoblot methods have been established to detect anti-atrophic proteins from muscle biopsy specimens of children with DMD. This method can provide direct specific biochemical indicators for clinical confirmation. Anti-dystrophin detection and natural gene detection can be used for carrier detection, providing reliable information for genetic counseling.