What are the symptoms of progressive spinal muscular atrophy

Although progressive spinal muscular atrophy is not common in life, if this disease occurs, it will cause damage to the patient's muscle cells. This disease is a motor neurone disease and the symptoms are very obvious. Common symptoms include muscle atrophy, muscle weakness, muscle relaxation, etc.

1. Infantile spinal muscular atrophy

Also called SMA type I or Werdnig-Hoffmann disease. This type is the most serious of the three types. Some cases develop the disease in utero, with weaker fetal movements. Half of the cases 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 disease progresses rapidly. Active movements decrease, proximal muscles are most seriously affected, and the patient cannot sit alone. Eventually, the hands and feet can still have slight movements.

(2) Muscle relaxation and extremely low tension. When the child lies down, the lower limbs are in a special position with the hips abducted and the knees flexed. Tendon reflexes are reduced or absent.

(3) Muscular atrophy 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) Patients with mild intercostal muscle paralysis may have obvious compensatory abdominal breathing. In severe cases, in addition to severe dyspnea, patients may also experience suprasternal depression when inhaling, i.e., paradoxical thoracic breathing, while diaphragmatic movement remains normal.

(5) The most common motor cranial nerve damage is the hypoglossal nerve, which manifests as tongue muscle atrophy and tremor.

(6) Poor prognosis: The average life expectancy is 18 months and most children die before the age of 2.

2. Intermediate spinal muscular atrophy

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 6-8 months old. 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. This type has a relatively benign course. The survival period is more than 4 years and the patients can survive beyond puberty.

3. Juvenile spinal muscular atrophy

Also known as SMA type III, also known as Kugelberg-Welander disease, Wohlfart-Kugelberg-Welander syndrome or mild SMA. It is the mildest type of SMA. Symptoms of the disease begin in late childhood or adolescence, beginning with abnormal gait and weakness of the proximal muscles of the lower extremities. Slow progress. Gradually affects the distal lower limbs and upper limbs. Can survive into adulthood. It manifests as neuronal proximal muscle atrophy. Children with SMA type III who can walk may have a staggering gait, lumbar lordosis, abdominal protrusion, and may or may not have tendon reflexes. The time to maintain independent walking is closely related to the age of onset of muscle weakness. Those who develop the disease before the age of 2 will be unable to walk at around the age of 15, while those who develop the disease after the age of 2 can maintain the ability to walk until around 50 years old.