Myasthenia gravis is a common clinical symptom in neurology. The reason why the human body has all kinds of movements, expressions and even sounds is the result of coordinated movements of various muscles, and normal muscle movements depend on the integrity of the muscles themselves and the function of the nervous system that governs the coordination of muscle movements.
I. Etiology
From the brain to the spinal cord to the peripheral nerves and finally to the muscles, it is similar to the basic combat unit in the army from the general headquarters to the group army to the divisions and regiments and finally to the company, the whole system must be closely linked and coordinated. The mechanism varies.
Second, the clinical manifestations
1. Myasthenia gravis caused by brain lesions
Brain lesions can cause monoplegia in one limb, hemiplegia in one limb, and quadriplegia. For example, a small localized lesion (tumor) in the brain often causes uniparesis in one limb, cerebral hemorrhage, cerebral infarction, craniocerebral trauma, etc. often cause hemiparesis on the opposite side of the lesion, while extensive bilateral lesions in the brain, such as encephalitis and anoxic encephalopathy, can cause quadriplegia. Of course, in addition to the paralysis of the limbs, these lesions also have other characteristics of brain lesions, such as headache, vomiting, confusion, and mental abnormalities.
2.Weakness caused by spinal cord lesions
Spinal cord lesions such as inflammation, tumors, trauma, vascular disease, and herniated discs in the spine also often cause paralysis of the limbs, and the weakness caused by spinal cord lesions is characterized by significant sensory impairment of the limbs and effort, inability to relieve or control urination and defecation in addition to paralysis of the limbs. With one exception, poliomyelitis (commonly known as poliomyelitis) manifests only paralysis of the limbs, with neither sensory nor bowel and urinary disturbances. It is worth mentioning that spinal cord lesions, especially those of the cervical spinal cord (such as the spinal cord type in cervical spondylosis and tumors of the cervical spinal cord) are often misdiagnosed or missed in the early stages of clinical practice and should be taken seriously.
3. Muscle weakness caused by peripheral neuropathy
This is another important group of diseases that cause muscle weakness. Fractures can cause damage to the ulnar nerve, radial nerve, median nerve of the upper limb and the femoral nerve, sciatic nerve, tibial nerve, peroneal nerve or gluteal nerve of the lower limb, thus causing weakness or even complete paralysis of the corresponding muscles innervated by the nerve. In addition, cervical spondylosis and lumbar spine osteophytes are also common causes of muscle weakness in the upper and lower extremities. Peripheral neuritis often affects the distal extremities, while the proximal extremities are not affected, manifesting as muscle weakness in the distal extremities, along with numbness, pain, or loss of sensation in the distal extremities.
Green-Barre syndrome (polyneuritis) is a specific condition that causes muscle weakness. The first symptom of the disease is often symmetrical weakness of the extremities, which worsens progressively and in severe cases can involve the intercostal muscles and diaphragm, which are responsible for breathing and can be life-threatening. It is important to note that as long as the disease is diagnosed correctly and the treatment measures are effective, the patient can recover completely after the acute phase.
4.Muscle weakness caused by muscle lesions
This group of diseases includes myotonic dystrophy, myasthenia gravis, polymyositis, periodic paralysis, drug myopathy, endocrine myopathy, cancer myopathy, infantile myopathy, etc. The above diseases, which usually affect the proximal extremities, are mostly (or roughly) symmetrical on both sides and are heavier in the lower extremities (upper extremities) than in the upper extremities (lower extremities) at a certain period of the disease. The onset and course of the disease vary: there are those with insidious onset and slow progression, such as myotonic dystrophy, chronic polymyositis, certain drug myopathies and endocrine myopathies; there are those with rapid onset and possible remission-relapse, such as polymyositis; there are periodic attacks, i.e., limb paralysis during attacks, and limb movement as normal during the inter-episode period, such as hypokalemic periodic paralysis; there are also fluctuating conditions or even There are also fluctuations in the condition, such as myasthenia gravis, which is often lighter in the morning and heavier in the afternoon.
Diagnosis
There are three main problems to be solved in diagnosis, one is whether the patient is a true myasthenia gravis, the second is where the lesion is located if it is a true myasthenia gravis, and the third is what is the nature of the lesion causing the myasthenia gravis, that is, whether it is inflammation, tumor or vascular disease.
To solve the first problem, it should be distinguished from the random motion disorder and hysterical paralysis caused by bone and joint lesions. In the case of bone and joint lesions, the random movement of the limbs may be limited, but it is not true paralysis. The causes are mostly local pain and limited movement due to local swelling, fracture dislocation, joint dislocation, etc. Hysterical paresis occurs in young women and has a rapid onset, often with pre-morbid psychological factors, different types of paresis, varying degrees of paresis, and variable time frames. However, the diagnosis must be made with caution and care must be taken to exclude organic causes.
The second and third questions that need to be addressed in the diagnosis are the location and nature of the lesion if it is a true myasthenia gravis. These two problems are mainly neurological and need to be solved by a neurologist, based on the medical history and examination of each patient, on the one hand, and the necessary specialized tests, such as cranial CT, electroencephalogram, cerebrospinal fluid, evoked potentials, electromyography, etc., often according to the patient’s specific situation.
IV. Treatment
This is a highly specialized issue, and different sites and lesions of different nature often have their own targeted treatment. It mainly includes etiological treatment, symptomatic treatment, rehabilitation treatment and other aspects. Among the common diseases that cause muscle weakness, stroke (cerebral infarction, cerebral hemorrhage, etc.) should be treated by improving cerebral blood supply and protecting brain tissues, while strengthening rehabilitation therapy, in addition to eliminating risk factors that cause stroke and preventing recurrence of stroke are equally important. In the case of myasthenia gravis caused by acute myelitis, the main concern is the correct application of adrenocorticotropic hormones and correct rehabilitation exercises. Myasthenia gravis is a chronic disease with prolonged symptoms, and the main treatment is a long course of standardized adrenocorticotropic hormone therapy, together with the necessary anticholinesterase drugs (neostigmine, pyridostigmine bromide, methotrexate, etc.). Tumors. In severe cases of Guillain-D-Barre syndrome (polyneuritis), the patient’s life can be endangered, so great attention should be paid to this disease, because there is no specific drug treatment, the key is timely symptomatic comprehensive treatment and care, keep the respiratory tract open, prevent secondary infection is the key to treatment, the patient through the acute phase, the patient can mostly fully recover.
In addition, patients with muscle weakness caused by peripheral nerve or muscle diseases, such as myasthenia gravis, polyneuritis, etc., should prohibit drugs that can aggravate the nerve junction transmission or inhibit the effect of respiratory muscle, such as kanamycin, quinine, streptomycin, etc., otherwise the condition is often significantly aggravated, and even life-threatening.
In conclusion, the treatment of muscle weakness cannot be generalized, and the above mentioned is limited to a few common cases. Regular and systematic treatment is the guarantee of recovery, and should be carried out under the guidance of a professional physician, do not use drugs hastily, and do not blindly believe in the doctor under the urgency of the disease, resulting in the loss of property, but also miss the time of treatment, and even endanger life.