Early symptoms and examination methods of myasthenia gravis

Myasthenia gravis is an autoimmune disease that can occur in people of all ages. Clinically, most patients are children, and there are more females than males among adults. Myasthenia gravis is a slowly developing, recurrent disease. If the disease is detected in its early stages and the patient actively seeks medical attention and undergoes professional scientific examinations, effective treatment can be obtained early.

Early symptoms of myasthenia gravis

1. Ptosis: Also known as droopy eyelids. According to our analysis of 3,100 cases of myasthenia gravis, ptosis was the first symptom in 73%. It can occur at any age, but is more common in children. In the early stage, it mostly affects one side, and in the late stage, it mostly affects both sides. In addition, for many patients, when one eyelid bulges, the other eyelid droops, which is a phenomenon of alternating ptosis.

2. Difficulty in swallowing: There is no digestive tract disease and the appetite is good, but you cannot swallow delicious food, even water. When drinking water, it either goes into the trachea and causes coughing, or it flows out of the nostrils. Some patients have to rely on nasogastric tubes to eat due to severe dysphagia.

3. Facial muscle weakness: Due to weakness of the facial expression muscles, patients often cannot close their eyes when sleeping. The expression is usually indifferent and the smile looks unnatural, just like crying, also known as the crying-laughing face. This facial expression makes the person look uncomfortable and the patient appears to be in pain.

4. Speaking with a nasal tone and hoarse voice, just like having a cold. Some patients' voices are fine for the first few minutes when speaking in a meeting or reading a newspaper, but after a while, their voices become hoarse and low, and finally they can no longer make any sound. When he was on the phone, it was fine at the beginning, but after a while, others couldn't hear what he was saying. This is due to weakness of the throat muscles.

What are the examination and identification methods for muscle weakness

1. Neostigmine test

Adults generally use 1-1.5 mg of neostigmine injected intramuscularly. If the symptoms improve 10-15 minutes after injection, reach a peak in 30-60 minutes, and last for 2-3 hours, the neostigmine test is positive.

2. Thymus CT and MRI

Thymic hyperplasia or thymoma may be detected, and enhanced scanning should be performed if necessary to further clarify the diagnosis.

3. Repeated electrical stimulation

Repeated electrical nerve stimulation is a commonly used examination method with diagnostic value. Electrodes are used to stimulate motor nerves and record the amplitude of the muscle's response potential. If the patient's muscle potential gradually declines, it indicates the possibility of a lesion at the neuromuscular junction.

4. Single Fiber Electromyography

Single-fiber electromyography is a more sensitive means of detecting abnormalities in neuromuscular junction conduction than repetitive nerve electrical stimulation. Abnormalities in neuromuscular transmission can be detected by increased "tremors" during repeated electrical nerve stimulation and when clinical symptoms are normal. It has the highest sensitivity of all muscle weakness tests.

5. Detection of acetylcholine receptor antibody titer

The detection of acetylcholine receptor antibody titer is of characteristic significance for the diagnosis of myasthenia gravis. Serum acetylcholine receptor antibodies can be detected in 80% to 90% of systemic myasthenia gravis and 60% of ocular myasthenia gravis. The level of antibody titer is not completely consistent with the severity of clinical symptoms.