When muscles waste away...

Thinning of muscle mass due to disuse or neurogenic conditions can cause muscle atrophy. Watch out for signs of numbness, weakness and tingling in your limbs, writes Dr Jayaram Chundru

The most prevalent neuromuscular disorder with infantile-onset is Spinal Muscular Atrophy (SMA) which is a group of hereditary disorders in which a person loses muscle control due to nerve cell loss in the spinal cord and brain stem. It is a form of motor neuron disease and a neurological condition.

In contrast to India, where the SMA carrier frequency was one in 38, the West has an SMA carrier frequency of one in 50. A person with SMA will inherit two copies of a missing or mutated survival motor neuron 1 (SMN1) gene. One mutated gene is inherited from the mother, while the other is inherited from the father. Without being aware of it, an adult can carry a single copy of the SMA-causing gene mutation.

Cause of SMA

SMA patients either lack a portion of the SMN1 gene or have a mutant version of the gene. A functional SMN1 gene generates SMN protein. This protein is necessary for the survival and efficient operation of motor neurons. Motor neurons shrink and die in SMA patients because they don’t produce enough SMN protein. Because of this, the brain is unable to regulate voluntary motions, particularly those involving the head, neck, arms, and legs. A limited quantity of SMN protein is produced by the SMN2 genes found in some people. An SMN2 gene can occur in as many as eight copies per individual. The extra genes compensate for the absence of the SMN1 protein, so people with multiple copies of the SMN2 gene often experience less severe SMA symptoms. SMA is rarely brought on by non-SMN gene mutations (non-chromosome 5).

Ways to manage SMA

A few ways to manage spinal muscular atrophy are:

Medication: Three drugs — nusinersen (Spinraza), onasemnogene abeparvovec-xioi (Zolgensma), and risdiplam (Evrysdi) — have received FDA approval to treat SMA. Risdiplam is the first and only approved treatment in India for Spinal Muscular Atrophy (SMA) patients that has received DGCI approval. These are disease-modifying therapies that affect the SMA-related genes. The body receives instructions from the SMN1 and SMN2 genes to create a protein that aids in regulating muscle action.

Breathing: Weak muscles prevent air from passing readily into and out of the lungs in SMA, particularly types 1 and 2. The child might require a unique mask or mouthpiece if this occurs. In severe cases, a breathing machine may be required.

Movement: Exercises and regular daily activities like physical and occupational therapy can assist in safeguarding the child’s joints and maintaining muscle strength. Leg braces, a walker, or an electric wheelchair may be recommended by a therapist. Specialised devices can operate computers, phones, and aid in writing and drawing.

Nutrition & swallowing: Babies and kids with SMA may struggle with sucking and swallowing when their mouth and throat muscles are weak. The child might not receive a healthy diet in such a situation and might struggle to grow. Some infants could require a feeding tube. Consulting a dietitian is recommended in such cases.

Spinal problems: Children who develop SMA at a young age may develop a curve in their spine. In order to protect the developing spine of your child, a doctor may advise that they wear a back brace. They may require surgery to correct the issue once they have stopped growing.

SMA can have a negative impact on health and lifespan. It is a chronic condition that progressively becomes worse. The presence of symptoms at birth (type 1), during infancy (types 2 or 3), or in adulthood are all possible (type 4). Newer gene replacement and disease-modifying medicines show promise. If spinal muscular atrophy runs in your family, talking to your doctor about prevention strategies to lower the chance that your unborn child may have the condition can be beneficial.

(The author is an expert in neurological diseases.)