Spinal muscular atrophy (SMA) is a rare neuromuscular disorder that causes progressive muscle weakness over time. Depending on SMA type, severity, and age of onset, SMA can interfere with motor function, mobility, chewing and swallowing, and breathing.
The International Standard of Care Committee for Spinal Muscular Atrophy published recommendations supporting physical therapy as part of SMA treatment in 2007. The committee particularly recommended physical therapy for people with SMA who can sit, stand, and walk. Individuals with those abilities generally fall into three of the five primary spinal muscular atrophy types. Ranging from the most to the least severe form, they are type 2, type 3 (Kugelberg-Welander disease), and type 4 (adult onset). Historically, individuals with type 0 or type 1 (Werdnig-Hoffmann disease) have not developed the motor skills or muscle strength to sit independently, stand, or walk. However, with the recent introduction of new treatments for SMA, it is unknown how the prognosis for each SMA type may change.
Physical therapy (also called physiotherapy or PT) is designed to help people manage movement dysfunction, improve functional ability, preserve abilities, or prevent future disability. Physical therapy is often prescribed after an injury or surgery and can also be an important part of treatment for people with physical disabilities resulting from SMA and other kinds of neuromuscular disorders.
In the years between the release of the International Standard of Care Committee for Spinal Muscular Atrophy’s recommendations and today, additional research has emerged to support physical therapy for SMA treatment. More research is ongoing, including a clinical trial of water-based therapy for children with SMA types 2 and 3. Additional research on physical therapy coupled with the advent of new disease-modifying drugs for SMA could change the landscape of SMA treatment options in the coming years.
PT can help address many of the symptoms people with SMA experience, including:
Muscle weakness, also known as hypotonia, is the primary symptom of spinal muscular atrophy. Physical therapy exercises, including water-based therapy and adaptive sports like horseback riding, can help maintain muscle strength and support stamina.
Range of motion exercises can help maintain flexibility and reduce the risk of contractures (the permanent shortening and tightening of joints). Preventing contractures by exercising muscles and joints through their full range of motion can improve mobility and help avoid pain from tight, inflexible joints. Flexibility and range of motion is important for everyone with SMA, regardless of mobility.
Case reports of children with SMA type 2 noted a relationship between achieving assisted walking with orthotics and bracing and a reduced incidence of scoliosis. About half of people with type 3 develop scoliosis, and it affects nearly all children with SMA types 1 and 2.
Physical therapy can help people with SMA who have walking ability maintain their mobility longer and walk more safely. PT to support walking and balance and prevent falls may be most relevant to individuals with type 3 who are beginning to experience greater muscle weakness in their legs.
Nonambulatory people with SMA are at greater risk for osteoporosis and bone fractures, in part because of disuse of limbs. Weight-bearing exercises can help strengthen bones and can also improve breathing and bowel function. People with SMA who cannot stand on their own can use mobility devices called standers to achieve a standing position, which can help strengthen their bones.
There are several types of physical therapy interventions that can be used depending on physical ability. Below are a few types of therapy that might be recommended for people with SMA.
Aquatic therapy, also known as hydrotherapy or water therapy, is among the therapies recommended by the International Standard of Care Committee for Spinal Muscular Atrophy for sitters and walkers. Aquatic therapy is often recommended for people with mobility limitations because the buoyancy of the water makes it possible to perform certain actions in a pool that could not be performed on land.
Pool exercises for SMA vary based on functional ability. For people with type 3, aquatic therapy can include activities designed to support walking, balance, flexibility, strength, and posture. In contrast, a person with type 1 may work on improving respiratory function by blowing pingpong balls in the water.
Occupational therapists focus on helping people participating in daily activities like dressing and grooming, using the computer, or completing work and home tasks. Occupational therapy can help people with SMA relearn how to perform certain activities as they lose muscle strength. This might include learning alternate ways to put on clothing or learning to use assistive devices.
Bracing is a technique used to support weak muscles and help maintain flexibility. Braces can be used to support standing and prevent contractures in people with SMA who can stand but not walk – usually those with SMA type 2. Orthotics for the lower limbs (sometimes called orthoses) can be combined with a walker or other mobility device to support walking for people with sufficient muscle strength.
Ensuring proper positioning for those using a wheelchair is particularly important for supporting the spine and reducing the risk of scoliosis. This can be done by adapting the wheelchair or with braces for the spine.
People with neuromuscular disorders like SMA often unconsciously adapt their gait to cope with muscle weakness. They may slow their speed, shorten their stride, and alter the position of their hips, pelvis, and feet. These modifications can put extra strain on other parts of the body and impact balance and long-term walking ability.
Gait training, a form of physical therapy designed to improve walking ability, can help people with SMA reduce safety risks from poor balance and improve their gait to conserve energy. Gait training can also be used to help people learn to walk with the support of a mobility device.
Identifying the right mobility or adaptive devices and teaching people to use them properly is a critical component of PT for SMA. Depending on a person’s needs, a physical therapist may recommend a walker or wheelchair for daily life. Standers are another mobility option for those who can sit but not walk.
Physical therapy will look different for every person with SMA. No matter your specific needs, here are some tips to help you get the most out of your time in physical therapy.
A physical therapist can be a key player in your multidisciplinary health care team. Working with a physical therapist who understands the needs of a person with SMA can help ensure you get the most out of physical therapy. Neurologic physical therapists are PTs with special training in treating people with conditions like spinal muscular dystrophy, multiple sclerosis (MS), and Parkinson’s disease. Your doctor may be able to recommend a neurologic PT, or you can find one using the American Physical Therapy Association’s provider directory.
Depending on your recommended PT regimen, you may need to attend regular appointments or perform exercises at home. Keeping your appointments and being consistent with home exercises can help you realize the full benefits of physical therapy.
Your physical or occupational therapist is there to help you improve your physical function and improve your quality of life. They want to make adjustments if something isn’t working. Don’t be afraid to speak up if you’re experiencing pain or you’re not able to successfully complete any of the at-home exercises your PT has recommended.
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