Spinal muscular atrophy (SMA), a genetic neuromuscular disorder that leads to muscle weakness, is caused by a mutation (variation) in the SMN1 gene. This mutation affects motor neurons (nerve cells) in the spinal cord that control movement. In infants or children with SMA, the resulting muscle weakness can contribute to scoliosis — an abnormal curvature of the spine. Fortunately, several treatment options can help manage scoliosis.

What Is Scoliosis?

Scoliosis associated with neuromuscular conditions like SMA is different from idiopathic scoliosis (scoliosis with no known cause). Neuromuscular scoliosis develops because of underlying muscle weakness from conditions such as SMA. This type of scoliosis progresses as the child grows, often affecting lung capacity and respiratory (breathing) function, which can worsen some symptoms of SMA. The progression may continue even after growth ends.

What Does Scoliosis in SMA Look and Feel Like?

Scoliosis commonly occurs in children with SMA, particularly in SMA types 1, 2, and 3. Research suggests that children with SMA type 2 are most likely to develop scoliosis. Spinal deformities also include kyphosis (a backward or hunchback curve of the spine) or lordosis (an inward curve), according to the SMA Foundation. About 1 in 3 people with scoliosis in SMA also have kyphosis, lordosis, or a pelvic tilt.

Scoliosis in SMA can lead to breathing problems and reduced mobility. As the spine curves, it changes the shape of the back and affects how much room the lungs have to expand. When the lungs can’t expand enough, respiratory distress (reduced oxygen supply to organs) can occur. Mobility is also affected as scoliosis stiffens the hips and creates pelvic obliquity (an uneven pelvis that rotates to one side). Together, these issues make scoliosis a painful and complex complication of SMA.

What Causes Scoliosis in SMA?

Scoliosis in SMA results from muscle weakness around the spine, caused by a mutation (often a deletion) in the SMN1 gene. This gene is responsible for producing survival motor neuron (SMN) protein, which plays a key role in the health of nerves at the base of the brainstem and in the spinal cord. Without enough SMN protein, a person’s nerve cells die and their muscles weaken or atrophy (waste away). When the weakened muscles can’t support the spine, scoliosis can occur.

Treating Scoliosis in SMA

Doctors may offer various options for treating scoliosis in people with SMA. Although bracing is sometimes used, its effectiveness in slowing scoliosis progression is debated. Spinal surgery is the most common treatment, and advances in surgical techniques have helped improve the quality of life for people with scoliosis and SMA. Your child’s medical team for SMA will consider several factors to determine whether to offer surgery, including your child’s severity of scoliosis, respiratory health, and age. Surgical options include spinal fusion surgery and growing rods.

Spinal Fusion Surgery

Spinal fusion joins several vertebrae together to prevent movement and further curvature of the spine. Typically, a piece of bone is inserted into the space, but sometimes plastics or metals are used. One study focused on children who underwent spinal fusion surgery at about age 10, on average. Although these children were still growing, a 10-year follow-up showed that spinal fusion helped control spine curvature progression and pelvic obliquity, providing an effective long-term treatment.

Growing Rods

Growing rods are expandable devices that help manage scoliosis while allowing the spine to continue growing. The rods are anchored at both the top and bottom of the spine, with adjustments made as the child grows. Magnetically controlled growing rods offer a newer, less invasive option — the rods can be adjusted without surgery. Studies indicate that growing rods can be an effective treatment, reducing psychological stress for children and families.

Find Your Team

On mySMAteam, the social network for people with spinal muscular atrophy and their loved ones, more than 2,600 members come together to ask questions, give advice, and share their stories with others who understand life with spinal muscular atrophy.

Have you or a loved one been diagnosed with SMA? Are you experiencing scoliosis with SMA? Share your experience in the comments below, or start a conversation by posting on your Activities page.