Spinal Muscular Atrophy (SMA) is a genetic disorder causing muscle weakness and atrophy, affecting motor neurons. While often diagnosed in infancy, it can also impact adults, particularly in late-onset cases. Key treatments could include Spinraza and Zolgensma for slowing progression.
Signs of Spinal Muscular Atrophy in Adults
In adults, SMA symptoms can vary widely depending on the age of onset, type of SMA, and how severely motor neurons are affected. SMA in adults is typically classified as Type 3 or Type 4, which are considered milder than the infantile forms.
Key signs of SMA in adults include:
- Muscle Weakness: One of the hallmark signs of SMA in adults is muscle weakness. This typically affects the proximal muscles, or those closer to the center of the body, such as the hips, thighs, and shoulders. Muscle weakness may start subtly but progresses over time.
- Difficulty Walking or Climbing Stairs: Adults with SMA often struggle with activities that require the use of leg muscles, such as walking, climbing stairs, or standing up from a seated position. This can result in frequent falls or the need to use assistive devices like canes or wheelchairs as the disease progresses.
- Fatigue and Muscle Atrophy: Muscle loss or atrophy may become visible in the legs or arms. As the muscles weaken, adults may experience increased fatigue, making everyday tasks more challenging.
- Respiratory Issues: In more advanced stages, SMA can also affect the muscles involved in breathing. Adults may experience shortness of breath, particularly when lying down or during exertion, and in some cases, require respiratory support.
- Tremors or Twitching (Fasciculations): Muscle twitching or tremors, known as fasciculations, are also common in adults with SMA. This occurs due to the deterioration of motor neurons that control muscle movements.
Late-Onset Spinal Muscular Atrophy (Type 4 SMA)
Late-onset SMA, also known as Type 4 SMA, generally manifests after the age of 30. It is the mildest form of SMA, and the progression of the disease is much slower compared to other types. Individuals with late-onset SMA may not notice symptoms until later in life, and in some cases, the disease progresses so slowly that it does not significantly impact their lifespan.
Signs of late-onset SMA are similar to those listed above, but they develop more gradually. These individuals often maintain functional mobility for many years, though they may experience increasing difficulty with motor tasks over time.
Treatment Options for Spinal Muscular Atrophy
Recent advances in gene therapy and treatment have transformed the management of SMA. Two groundbreaking treatments—Spinraza (nusinersen) and Zolgensma (onasemnogene abeparvovec)—are now available and have shown promise in slowing or halting the progression of the disease.
1. Spinraza (Nusinersen):
Spinraza was the first FDA-approved treatment for SMA and is suitable for both children and adults. Spinraza is an antisense oligonucleotide therapy that targets the SMN2 gene, which plays a key role in producing the SMN protein necessary for muscle function. By modifying how the SMN2 gene is spliced, Spinraza helps increase the production of functional SMN protein, thereby improving muscle strength and slowing disease progression.
Spinraza is administered via an intrathecal injection (into the spinal fluid) and is typically given in several doses over the course of a year. Studies have shown that Spinraza can improve motor function in adults with SMA, although the extent of improvement may vary.
2. Zolgensma (Onasemnogene Abeparvovec):
Zolgensma is a gene replacement therapy designed to treat the root cause of SMA. It is most commonly used in infants and young children, but there is ongoing research into its potential benefits for adults. Zolgensma delivers a functional copy of the SMN1 gene, which is missing or mutated in individuals with SMA, through a one-time intravenous infusion.
While Zolgensma has revolutionized SMA treatment for young patients, its application in adults is still being explored. Gene therapy poses unique challenges in adult populations due to the longer duration of disease progression, but ongoing trials offer hope for future applications.
Learn More About Spinal Muscular Atrophy
Spinal Muscular Atrophy in adults, particularly in late-onset cases, can present gradually with symptoms like muscle weakness, difficulty walking, and muscle atrophy. However, treatment options such as Spinraza and Zolgensma provide hope by targeting the underlying genetic causes of the disease. While these therapies have shown significant promise in halting or slowing progression, further research continues to optimize outcomes for adult SMA patients.