Complication Of Spinal Muscular Atrophy: Pain
People with spinal muscular atrophy (SMA) can experience complications due to progressive muscle weakness. This includes joint and breathing problems. Children with SMA also seem to experience increased pain. We do not yet understand what causes this pain.
Only a few small studies have examined the frequency, severity, and type of pain in SMA. People with SMA have very different pain experiences. Pain management plans should be tailored to each person’s needs.
Do people with SMA experience more pain?
Unlike with other neuromuscular disorders, adults with SMA do not seem to experience more pain than the general population. However, children with SMA do seem to experience more pain. A small study showed that more than 70 percent of children with type 2 and 3 SMA experience persistent or recurring chronic pain. The same study showed that 40 percent of children with muscular dystrophy experience pain.1,2
Most children with SMA report having pain episodes weekly or monthly. The duration of pain usually lasts less than 12 hours. Pain is most commonly felt in the neck, back, and legs. Pain is usually described as mild to moderate.1
We still need larger studies of children and adults with SMA to understand the frequency, severity, and type of pain they experience. There also have not been any studies showing how pain varies between types of SMA.
Why does SMA cause pain?
Some people with SMA experience pain because of other complications. This includes joint contractures and scoliosis, which can lead to joint pain. Spinal surgery and other procedures also lead to pain. About 75 percent of children with SMA and a history of spinal surgery report neck and back pain.1
SMA may also directly increase pain sensation. Motor neurons are the main cells affected in SMA. SMA also causes problems with “sensory neurons.” These are cells that transmit stimuli like taste, smell, and touch to our brain.3,4
Some sensory neurons respond to threats to the body. These are called “pain receptors” or “nociceptors” because their signals lead to sensations of pain. There is some evidence that SMA causes overactive nociceptors, leading to increased feelings of pain.5
Children with type 2 and 3 SMA report that the main triggers of pain are:1
- Too much movement or activity
- Being lifted or transferred
- Getting dressed
People who can walk report that movement, activity, and walking are major triggers of pain. People who cannot walk report sitting and being lifted are the main triggers. However, each person with SMA experiences pain differently and has their own triggers.1
How is pain prevented and treated in SMA?
Increased pain worsens quality of life, mood, mobility, and social functioning in children with SMA. Reducing the burden of pain is an important part of managing SMA.1
Pain management depends on the cause and severity of the pain, as well as other personal factors. For example, pain caused by joint contractures may require surgical management of the contracture. Managing pain during and after surgery is complicated. This is because of the sensitivity to muscle relaxants used in general anesthesia. Doctors will use local anesthesia or spinal anesthesia to reduce pain linked to surgery.6
For pain in general, people with SMA report that the best relief comes from:1
- Changing positions
- Pain medicines
Movement exercises and stretching seem to increase pain in some people but relieve pain in others. In general, people who can walk benefit from more rest, while people who cannot walk benefit from more activity.1
Every person with SMA is unique. Caregivers must take a personalized approach to manage pain. Finding the right balance between activity and rest is one way to relieve pain.1