Not only do spinal muscle atrophy (SMA) and paraspinal muscular atrophy sound alike, they also share symptoms such as muscle weakness and limited mobility. Because of these similarities, paraspinal muscular atrophy could potentially be mistaken for adult-onset SMA in an adult. However, there are many differences between these two neurological conditions.

Read on to learn more about key differences in the causes, symptoms, and treatment options of SMA and paraspinal muscular atrophy.

What Is Paraspinal Muscular Atrophy?

The paraspinal muscles are the muscles located on either side of the spinal column, which move the spine or stabilize it. Paraspinal muscular atrophy often occurs after having surgery for a spinal disorder. During spinal surgery, a surgeon might use tools to retract the paraspinal muscles and cut the tendons attaching them to the bone in order to get a closer look at the problem area. Sometimes this process can cause paraspinal muscular atrophy.

Paraspinal muscular atrophy can also be caused by a back injury, a lack of blood supply, a nerve injury, or atrophy (shrinking) from not using your back muscles due to being immobilized or wearing a brace. In paraspinal muscular atrophy, the paraspinal muscles shrink and have fatty infiltrations — an accumulation of fat around the muscle tissue.

How Are SMA and Paraspinal Muscular Atrophy Different?

SMA and paraspinal muscular atrophy are two significantly different conditions. Their causes, many of their symptoms, and their treatment are all different –– even if they share some similarities.

Causes

SMA and paraspinal muscular atrophy are not related conditions. SMA is a rare neuromuscular disease with a genetic basis that is passed from parent to child. The genes involved are survival motor neuron 1 and 2 (SMN1 and SMN2). Motor neurons are nerve cells. If motor neurons are damaged, then the muscles they communicate with can shrink. The SMN genes help make an SMN protein that supports muscle strength and motor function. When copies of these genes are missing or altered, as they are for people with SMA, muscles can grow weaker and continue to shrink.

In contrast to SMA, paraspinal muscular atrophy isn’t a genetic condition. It’s generally associated with spinal surgery. It might be caused by the spinal injury requiring surgery, the surgical procedure itself, or by being immobilized after surgery. Paraspinal muscular atrophy can happen alongside conditions including:

• Degenerative disc disease
• Herniated discs
• Lumbar spinal stenosis
• Scoliosis or other spinal abnormalities

Symptoms

Both SMA and paraspinal muscular atrophy can cause problems with muscle movement and muscle weakness. They can also cause curves in the spine. However, these conditions also have very different symptoms.

Paraspinal muscle atrophy can cause changes in the alignment of the spine, for instance excessive curving of the lower back (lordosis) or excessive rounding of the upper back (kyphosis). It can also cause low back pain. In some cases, it can lead to balance problems, arthritis, and pinched nerves.

Other than gradual muscle weakness and curvature of the spine, the symptoms of SMA are quite different. They also depend on the type of SMA and the age of onset. SMA symptoms can include:

• Poor muscle tone and muscle wasting
• Difficulty with walking or standing
• Challenges with breathing
• Difficulty eating or swallowing

Read more about SMA symptoms, including respiratory infections and sleep problems.

Treatments

Treating paraspinal muscular atrophy often involves physical therapy, either as part of the rehabilitation process after spinal surgery or in response to an injury or general back pain. This can help strengthen the core muscles and regain mobility.

In contrast, SMA is treated very differently, since it’s a genetic condition. There’s no way to reverse motor neuron degeneration, so SMA treatment is mainly focused on improving mobility and quality of life. Two medications — nusinersen (Spinraza) and risdiplam (Evrysdi) — are approved by the US Food and Drug Administration (FDA), and clinical trials for newer medications are ongoing. The FDA has also approved onasemnogene abeparvovec-xioi (Zolgensma), a gene therapy treatment for SMA in children younger than 2 years of age.

If you’re an adult concerned about muscle weakness, there are many things that might be causing it. You may need to ask for a referral to a neurologist for screening. If you’ve had a spinal condition or a spine surgery in the past, there’s a chance the weakness could be due to paraspinal muscular atrophy. Seeking medical advice early on and taking action can make a big difference in how the symptoms are addressed, the condition is managed, and ultimately, in improving your quality of life.

Talk With Others Who Understand

On mySMAteam, the social network for people with SMA and their loved ones, more than 2,000 members come together to ask questions, give advice, and share their stories with others who understand life with SMA.

Are you living with muscle weakness or back pain? Have you been diagnosed with paraspinal muscular atrophy or SMA? Share your experience in the comments below, or start a conversation by posting on your Activities page.