What is the Difference Between Spinal Muscular Atrophy and Muscular Dystrophy

The key difference between spinal muscular atrophy and muscular dystrophy is that spinal muscular atrophy is a genetic condition that causes central and peripheral nerve abnormalities together with problems in voluntary muscle movement, while muscular dystrophy is a genetic condition that causes muscle degeneration or weakness without a central or peripheral nerve abnormality.

Spinal muscular atrophy and muscular dystrophy are two genetic disorders that affect muscles and cause muscle weakness. Spinal muscular atrophy causes the shrinking or wasting of muscles, while muscular dystrophy affects the protein that builds and maintains healthy muscles. Moreover, though muscular dystrophy can cause muscle atrophy, both disorders are different, with different causes, symptoms, and treatments.

CONTENTS

1. Overview and Key Difference
2. What is Spinal Muscular Atrophy  
3. What is Muscular Dystrophy
4. Similarities – Spinal Muscular Atrophy and Muscular Dystrophy
5. Spinal Muscular Atrophy vs Muscular Dystrophy in Tabular Form
6. Summary – Spinal Muscular Atrophy vs Muscular Dystrophy

What is Spinal Muscular Atrophy?

Spinal muscular atrophy is a genetic condition that causes central and peripheral nerve abnormalities, together with problems in voluntary muscle movement. Spinal muscular atrophy is a hereditary genetic disorder that progressively destroys motor neurons in the brain stem and spinal cord. The motor neuron usually controls essential skeletal muscle activity such as speaking, walking, breathing, and swallowing. Therefore, spinal muscular atrophy results in problems in speaking, walking, breathing, and swallowing, together with muscle weakness and atrophy. The typical symptoms of spinal muscular atrophy may include floppy arms and legs, movement problems like difficulty sitting, crawling, or walking, twitching muscles, bone and joint problems, and breathing difficulties. However, spinal muscular atrophy does not affect intelligence or learning disabilities. Spinal muscular atrophy is caused due to a mutation in a gene called SMN1 that produces SMN protein.

Moreover, spinal muscular atrophy can generally be diagnosed through blood tests, genetic tests, nerve conduction tests, and muscle biopsy. Furthermore, spinal muscular atrophy is treated through disease-modifying therapy (drugs that stimulate SMN protein like Nusinersen), gene replacement therapy (intravenous (IV) infusion of a drug called onasemnogene that replaces faulty SMN1 gene), physical and occupational therapy, and assistive devices such as braces, crutches, walkers, and wheelchairs.

What is Muscular Dystrophy?

Muscular dystrophy (MD) is a genetic condition that causes muscle degeneration or weakness without a central or peripheral nerve abnormality. Generally, muscular dystrophies are a group of inherited conditions that lead to weakness in muscles and an increased level of disability. There are different types of muscular dystrophies, including Duchene MD, myotonic dystrophy, facioscapulohumeral MD, Becker MD, limb-girdle MD, oculopharyngeal MD, and Emery-Dreifuss MD. The common signs and symptoms of muscular dystrophy may include frequent falls, difficulty rising from a sitting position, trouble running and jumping issues, waddling gait, toes walking, enlargement of calf muscles, muscle pain, and stiffness, learning disabilities, delayed growth, inability relax muscles, muscle weakness particularly beginning in the face, hip, and shoulders. Moreover, muscular dystrophy caused due to mutations in genes like DMD, CAPN3, D4Z4, DMPK E MD, FHL1, LMNA, and PABPN1.

Muscular dystrophy can be diagnosed through enzyme tests (creatine kinase), genetic testing, muscle biopsy, heart monitoring tests (electrocardiography or echocardiography), lung monitoring tests, and electromyography. Furthermore, the treatment options for muscular dystrophy include medications (corticosteroids, eteplirsen, golodirsen ACE inhibitors or beta blockers), therapy (practicing a range of motions and stretching exercises, mobility aid through braces, canes, walkers, wheelchairs, breathing assistance) surgery for contractures or a spinal curvature and pacemakers or cardiac devices for heart function.

What are the Similarities Between Spinal Muscular Atrophy and Muscular Dystrophy?

• Spinal muscular atrophy and muscular dystrophy are two genetic disorders that affect muscles and cause muscle weakness.
• Both disorders are rare inherited conditions.
• Both disorders are due to genetic mutations.
• These disorders can be diagnosed through physical examination and muscle examination.
• They are treated through specific medications and physical therapies.

What is the Difference Between Spinal Muscular Atrophy and Muscular Dystrophy?

Spinal muscular atrophy is a genetic condition that causes central and peripheral nerve abnormalities together with problems in voluntary muscle movement, while muscular dystrophy is a genetic condition that causes muscle degeneration or weakness without a central or peripheral nerve abnormality. Thus, this is the key difference between spinal muscular atrophy and muscular dystrophy. Furthermore, spinal muscular atrophy is a neuromuscular disorder, while muscular dystrophy is a muscle disorder.

The below infographic presents the differences between spinal muscular atrophy and muscular dystrophy in tabular form for side-by-side comparison.

Summary – Spinal Muscular Atrophy vs Muscular Dystrophy

Spinal muscular atrophy and muscular dystrophy are two rare inherited genetic disorders. They predominantly affect muscles and cause muscle weakness. However, spinal muscular atrophy is a genetic condition that causes central and peripheral nerve abnormalities together with problems in voluntary muscle movement, while muscular dystrophy is a genetic condition that causes muscle degeneration or weakness without a central or peripheral nerve abnormality. So, this is the key difference between spinal muscular atrophy and muscular dystrophy.

Reference:

1. “Spinal Muscular Atrophy (SMA) – Diseases.” Muscular Dystrophy Association.
2. “Muscular Dystrophy.” NHS Choices, NHS.

Image Courtesy:

1. “Polio spinal diagram-en” By Cervical vertebra blank.SVG: Fred the OysterPolio spinal diagram.PNG: DO11.10Derived: Angelito7 – Cervical vertebra blank.svgPolio spinal diagram.PNG (CC BY-SA 4.0) via Commons Wikimedia
2. “Emery-Dreifuss muscular dystrophy patient” By Azadeh, A., Javad, J., Abbas, T., Reza, M., Zeinab, F., & Hossein, D. – (2016). Emery-dreifuss muscular dystrophy: A report of a large family with 11 affected individuals. International Journal of Molecular and Cellular Medicine, 5(3), 196-198. (CC BY 3.0) via Commons Wikimedia