People with spinal muscular atrophy (SMA) may be at a higher risk of other medical conditions, known as comorbidities. More severe types of SMA may lead to more severe complications.

SMA treatments may affect the development of certain comorbidities. Further research will be needed to better understand how SMA treatments affect other health conditions over time.

Disorders of the Muscular and Skeletal Systems

SMA mostly affects muscles. Symptoms such as hypotonia (muscle weakness) lead to complications in the musculoskeletal system.

Scoliosis

One common complication is scoliosis, a curvature of the spine. In people with SMA, the muscles are too weak to hold the spine in the correct alignment, and gravity slowly pulls the curve of the spine into an abnormal alignment. Scoliosis is most common in children with SMA type 2 and it affects people with type 3 (Kugelberg-Welander disease). It can occur in individuals with type 1 (Werdnig-Hoffmann disease) who receive early treatment and live longer.

Research from 2025 found that early treatment for SMA may delay the development of scoliosis or make it less severe.

As many as 90 percent of children with SMA develop scoliosis. In children with SMA, scoliosis develops on average between ages 6 and 8, but onset can be as early as 8 or 9 months of age. Age of onset is later in children who continue to be able to walk. Research from 2025 found that early treatment for SMA may delay the development of scoliosis or make it less severe.

Scoliosis may be treated with bracing, surgery, or an implanted vertical expandable prosthetic titanium rib (VEPTR) device.

Scoliosis can cause or worsen breathing difficulties, affect sitting balance, and impact arm movement. Other spinal deformities can occur, including kyphosis (a forward curve of the upper spine) and lordosis (an inward curve of the spine).

Pelvic Obliquity

Additionally, pelvic obliquity (tilting of the pelvis) affects one-third of people with SMA, leading to hip dislocation in some cases. Hip dislocation happens less often in people with SMA who continue to stand or walk. Hip surgery is sometimes necessary to reduce pain or improve balance.

Joint Contractures

Children with SMA may develop joint contractures, in which joints become stiff due to limited movement. Splints, braces, and physical therapy or occupational therapy may help prevent joint contractures.

SMA treatments may affect the development of certain comorbidities. Further research will be needed to better understand how SMA treatments affect other health conditions over time.

Limited Jaw Movement

Some children with SMA type 2 have limited movement in the jaw (temporomandibular joint), which affects mouth opening. Speech-language therapy can help improve jaw movement and related speech or feeding challenges.

Respiratory Complications

In SMA types 1 and 2, weak intercostal muscles (the muscles between the ribs) combined with a relatively stronger diaphragm may lead to a bell-shaped chest and pectus excavatum (a sunken chest). Scoliosis can also contribute to changes in the chest shape, further complicating breathing. These changes, along with muscle weakness, can cause chronic respiratory failure, which may become life-threatening without intervention.

People with SMA often experience respiratory infections due to weakened respiratory muscles and trouble coughing effectively. These infections, if untreated, can progress rapidly and lead to serious complications like pneumonia.

Treatments for respiratory complications include:

• Noninvasive breathing support, such as bilevel positive airway pressure (BiPAP) or continuous positive airway pressure (CPAP) machines
• Invasive breathing support, such as tracheostomy or mechanical ventilation
• Respiratory therapy
• Devices like a VEPTR to help with chest expansion

Cardiovascular Conditions

Abnormalities of the cardiovascular system (heart and blood vessels) are also among the most frequently reported comorbidities in people with SMA.

Some researchers believe that the genetic mutation (variation) in the SMN1 gene, which causes SMA, might also influence heart function. Individuals with SMA type 1 are more likely to have structural heart abnormalities, such as issues with heart valves or septal walls (the walls separating the heart chambers). Arrhythmias (irregular heart rhythms) can occur in people with SMA types 1, 2, and 3.

Managing Related Conditions To Improve Quality of Life

There are effective ways to manage many complications linked to spinal muscular atrophy. Treating these conditions can help maintain function, improve comfort, and support a better quality of life.

If you or your child starts showing signs of a complication, it’s important to reach out to your healthcare team for guidance and treatment options as early as possible.

Talk With Others Who Understand

On mySMAteam, people share their experiences with spinal muscular atrophy, get advice, and find support from others who understand.

Have you or a loved one developed complications from SMA? Let others know in the comments below.