What is Spinal Muscular Atrophy?
Spinal muscular atrophy (SMA) is a genetic disease affecting the central nervous system, peripheral nervous system, and voluntary muscle movement (skeletal muscle). Most of the nerve cells that control muscles are located in the spinal cord, which accounts for the word spinal in the name of the disease. SMA is muscular because its primary effect is on muscles, which don’t receive signals from these nerve cells. Atrophy is the medical term for getting smaller, which is what generally happens to muscles when they’re not stimulated by nerve cells. SMA involves the loss of nerve cells called motor neurons in the spinal cord and is classified as a motor neuron disease.
Signs and symptoms
SMA symptoms cover a broad spectrum, ranging from mild to severe. The muscles closer to the center of the body (proximal muscles) are usually more affected in SMA than are the muscles farther from the center (distal muscles). The muscles closer to the center of the body (proximal muscles) are usually more affected in SMA than are the muscles farther from the center (distal muscles). The primary symptom of chromosome 5-related (SMN-related) SMA is weakness of the voluntary muscles. The muscles most affected are those closest to the center of the body, such as those of the shoulders, hips, thighs, and upper back. The lower limbs seem to be affected more than the upper limbs, and deep tendon reflexes are decreased. Special complications occur if the muscles used for breathing and swallowing are affected, resulting in abnormalities in these functions. If the muscles of the back weaken, spinal curvatures can develop.
Children with spinal muscular atrophy
It is estimated that the disease affects one out of 6,000 to 10,000 children.
Diagnosis of spinal muscular atrophy
The disease can be diagnosed prenatally. However, there isn’t a cure for SMA. Treatments depend upon the type of SMA and symptoms. Many people with SMA receive drug therapy that stimulates production of SMN protein, and/or benefit from physical and occupational therapy and assistive devices, such as orthopaedic braces, crutches, walkers and wheelchairs.