What is the Difference Between Motor Neuron Disease and Muscular Dystrophy

The key difference between motor neuron disease and muscular dystrophy is that motor neuron disease is a group of rare disorders that occurs specifically due to problems in the central or peripheral nervous system, while muscular dystrophy is a group of rare disorders that occurs exclusively due to problems in the muscles.

A neuromuscular disease is any disease affecting the peripheral nervous system, the neuromuscular junction, or skeletal muscle. All these components are parts of the motor unit. Motor neuron disease and muscular dystrophy are two types of neuromuscular diseases.

CONTENTS

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

What is Motor Neuron Disease?

Motor neuron disease is a group of rare neurodegenerative disorders that specifically affect motor neurons that control voluntary muscles of the body. This group includes a number of disorders such as amyotrophic lateral sclerosis (ALS), progressive bulbar palsy (PBP), pseudobulbar palsy, progressive muscular atrophy (PMA), primary lateral sclerosis (PLS), spinal muscular atrophy (SMA), monomelic amyotrophy (MMA) and some other rare variants resembling ALS. Motor neuron diseases normally affect both children and adults. Most of these motor neuron diseases are sporadic, and their causes are generally not known. It is believed environmental, toxic, viral, or genetic factors may be involved in these conditions. Some forms of motor neuron disease have inherited genetic bases (e.g. SODI gene).

The sign and symptoms may include a weakening in grip, fatigue, muscle cramp, spasms, twitches, slurred speech, weakness in arms or legs, clumsiness and stumbling, difficulty swallowing, trouble breathing or shortness of breath, inappropriate emotional responses, weight loss, muscle shrinkage, difficulty moving, joint pain, drooling, uncontrollable yawning, changes in personality, and emotional states. This medical condition can be diagnosed through blood and urine tests, MRI brain scans, electromyography (EMG) and nerve conduction study (NCS), lumbar puncture, and muscle biopsy. Furthermore, treatment options for motor neuron diseases may include occupational therapy, physiotherapy, speech and language therapy, advice on dieting and eating, medicines such as riluzole, edaravone, nusinersen, onasemnogene, abeparvovec that slow down the progression of this condition, medicines to reduce muscle stiffness (Botox) and help with saliva problems, pain relievers (ibuprofen), and emotional support.

What is Muscular Dystrophy?

Muscular dystrophy is a genetically and clinically heterogeneous group of neuromuscular diseases that cause progressive weakness and breakdown of skeletal muscle. Muscular dystrophy is also a group of inherited diseases characterized by the wasting away of muscle tissue with or without the breakdown of nerve tissue. Over 30 different disorders are included in muscular dystrophy. Of those, Duchene muscular dystrophy (DMD) accounts for 50% of cases, which affects males beginning around the age of four. Other common muscular dystrophies include Becker muscular dystrophy, facioscapulohumeral muscular dystrophy, myotonic dystrophy, limb-girdle muscular dystrophy, and congenital muscular dystrophy.

The signs and symptoms of muscular dystrophies include progressive muscular wasting, poor balance, scoliosis, progressive inability to walk, waddling gait, calf deformation, limited range of movement, respiratory difficulty, cardiomyopathy, muscle spasms, and Gowers’ sign. Moreover, a majority of muscular dystrophies are inherited (DMD gene, DYSF gene), which follow different inheritance patterns (X-linked, autosomal recessive, autosomal dominant). In some small cases, they may have been caused by a de novo spontaneous mutation.

Muscular dystrophies can be diagnosed through blood tests and genetic testing. Furthermore, treatment options for muscular dystrophies are drugs that address the root cause, including gene therapy (Microdystrophin), antisense drugs (Ataluren, Eteplirsen etc.), using corticosteroids (Deflazacort), and calcium channel blockers (Diltiazem) to slow skeletal and cardiac muscle degeneration, using anticonvulsants to control seizures, using immunosuppressant (Vamorolone) to delay damages to dying muscle cells, physical therapy, corrective surgery, and assisted ventilation.

What are the Similarities Between Motor Neuron Disease and Muscular Dystrophy?

• Motor neuron disease and muscular dystrophy are two types of neuromuscular diseases.
• Both medical conditions include a group of disorders.
• They can affect voluntary muscles.
• The cause of both medical conditions may be sporadic or inherited.
• Children and adults are affected by both medical conditions.
• They are rare, progressive medical conditions.
• They are treated through specific medicines and supportive therapies.

What is the Difference Between Motor Neuron Disease and Muscular Dystrophy?

Motor neuron disease is a group of rare disorders that occurs specifically due to problems in the central or peripheral nervous system, while muscular dystrophy is a group of rare disorders that occurs exclusively due to problems in the muscles. Thus, this is the key difference between motor neuron disease and muscular dystrophy. Furthermore, motor neuron disease is a group comprised of seven different disorders, while muscular dystrophy is a group comprised of thirty different disorders.

The below infographic presents the differences between motor neuron disease and muscular dystrophy in tabular form for side by side comparison.

Summary – Motor Neuron Disease vs Muscular Dystrophy

Motor neuron disease and muscular dystrophy are two types of neuromuscular diseases. Motor neuron disease happens due to problems in the central or peripheral nervous system. Muscular dystrophy happens exclusively due to problems in muscles. So, this summarizes the difference between motor neuron disease and muscular dystrophy.

Reference:

1. “Motor Neuron Disease.” NHS Choices, NHS.
2. “Muscular Dystrophy.” Mayo Clinic, Mayo Foundation for Medical Education and Research.

Image Courtesy:

1. “ALS clinical picture” By Okumiya K, Wada T, Fujisawa M, Ishine M, Garcia Del Saz E, Hirata Y, Kuzuhara S, Kokubo Y, Seguchi H, Sakamoto R, Manuaba I, Watofa P, Rantetampang AL, Matsubayashi K – BMJ Open (2014) –  (CC BY 3.0) via Commons Wikimedia
2. “Facioscapulohumeral muscular dystrophy – Scapular winging” By Shinya Ishizuka, Akinori Kobayakawa, Hideki Hiraiwa, Hiroki Oba, Takefumi Sakaguchi, Masaru Idota, Takahiro Haga, Takafumi Mizuno, Itaru Kawashima, Kanae Kuriyama, Shiro Imagama – :Scapular Winging following Sports-Related Injury in a Rugby Player”, Case Reports in Orthopedics, vol. 2021, Article ID 4511538, 4 pages, 2021. https://doi.org/10.1155/2021/4511538 (CC BY-SA 4.0) via Commons Wikimedia