What are the symptoms of progressive muscular atrophy of the spinal cord

We must take diseases like progressive spinal atrophy seriously, because their occurrence will have varying degrees of impact on the patient's body, with the possibility of paralysis and muscle atrophy. The symptoms of progressive muscular atrophy of the spinal cord can also be detected in a timely manner.

1. Infant Spinal Muscular Atrophy

Also called SMA type I or Werdnig-Hoffmann disease. This type is the most serious of the three types. According to foreign reports, the incidence rate is 1/20,000 live births. About one-third of cases develop the disease in utero, with weakened fetal movements; half develop the disease at birth or in the first few months after birth, and almost all develop the disease within 5 months. It is rare for the infants to survive for a year. These infants already have symptoms during the fetal period, with reduced fetal movements, and obvious limb weakness, feeding difficulties and breathing difficulties after birth.

Clinical features:

(1) Symmetrical muscle weakness: The lower limbs are affected first, and the condition progresses rapidly. Active movement decreases, with proximal muscles being most seriously affected. The patient cannot sit alone, and eventually develops into mild movement of the hands and feet.

(2) Muscle relaxation and extremely low tension: When the child is lying, the lower limbs are in the frog-leg position (Figure 1), with the hips abducted and the knees flexed. Tendon reflexes are reduced or absent.

(3) Muscular atrophy: It can affect the muscles of the limbs, neck, trunk and chest. Because infants have a lot of subcutaneous fat, muscular atrophy is not easy to detect.

(4) Intercostal muscle paralysis: In mild cases, there may be obvious compensatory abdominal breathing. In severe cases, in addition to severe dyspnea, suprasternal depression can be seen when inhaling, that is, paradoxical thoracic breathing, and the diaphragm movement is always normal.

(5) Damage to motor cranial nerves: The most common symptom is the hypoglossal nerve, which manifests as tongue muscle atrophy and tremor.

(6) The prognosis is poor, with an average life expectancy of 18 months and most children die before the age of 2.

2. Juvenile SMA

It is also called SMA-II, intermediate SMA or chronic SMA. It develops slightly later than type I, usually within 1 year of age, and progresses slowly. Children grow and develop normally at 6 to 8 months of age. Most cases show severe proximal muscle weakness, which is more severe in the lower limbs than in the upper limbs. Many type II children can sit alone, and a few can even stand or walk with the help of others, but cannot walk alone. Multiple micromyoclonus is the main manifestation. The respiratory and swallowing muscles are not affected, the facial muscles are not affected, and the sphincter function is normal.