Muscular Dystrophy vs. Multiple Sclerosis

Although multiple sclerosis (MS) and muscular dystrophy (MD) are both debilitating diseases that may seem similar, they are quite different in their cause, the way they affect the body, and how they are treated.

Multiple sclerosis is an immune-mediated disease (an autoimmune disease) that affects the central nervous system (CNS)—the brain, spinal cord, and optic nerves. The immune system causes inflammation that damages myelin (a fatty substance that covers the nerves) and the nerves themselves.

When this damage occurs, scar tissue develops, interrupting the flow of information from the nerves and the brain. This interruption causes a variety of neurological symptoms, from pins and needles sensations to the inability to walk.

Muscular dystrophy (MD) is a group of genetic diseases that causes muscles used during voluntary movement to weaken and degenerate.

While each type of MD varies in severity and how it affects the body, all forms of muscular dystrophy will grow worse over time as muscles progressively degenerate and weaken. Many people with MD eventually lose the ability to walk.

Neither MS nor MD has a cure, but treatments can slow progression and improve quality of life.

Causes

There are distinct differences in the causes of MS and MD. MS is caused by an autoimmune response to the central nervous system. MD is caused by a gene mutation that affects muscle proteins.

Muscular Dystrophy Causes

All types of muscular dystrophy are inherited. The genes inherited involve the proteins that are critical to muscle function and growth. There are three ways in which MD is inherited.

Autosomal Dominant Inheritance

In this case, MD occurs when one parent passes the defective gene on to the child and the other passes on a normal gene.

Autosomal means the mutation can occur on any of the 22 non-sex chromosomes, and dominant refers to the fact that only one parent needs to pass along the defective gene for the child to inherit the disorder. There is a 50% chance that a child born to parents where one parent has the defective gene will have MD.  

Autosomal Recessive Inheritance

Parents in this scenario both have one defective gene but are not affected by the disorder. Children have a 25% chance of inheriting both copies of the defective gene and being born with MD and a 50% chance of inheriting one copy of the gene and becoming a carrier that could affect their future children.

X-Linked (or Sex-Linked) Recessive Inheritance

In this case, the defective gene is passed along through the mother, who carries the affected gene on one or both of her X chromosomes and passes it along to her son.

Sons of carrier mothers have a 50% chance of inheriting the disorder. Daughters of carrier mothers have a 50% chance of inheriting the gene but are usually not affected because their father's normal X chromosome can offset the effects of the mother’s faulty one.

Fathers who carry the defective gene cannot pass it to their sons, but their daughters will be carriers. Occasionally, daughters who are carriers can experience milder symptoms of MD.   

Multiple Sclerosis Causes

While the exact cause of MS is unknown, ongoing studies are being done in several different areas—immunology, environmental, genetic, and infectious factors.

Immunology

The abnormal immune response that occurs in MS causes inflammation and damage to the central nervous system. Studies have been done on the T and B cells in people with MS (two types of lymphocyte white blood cells).

T cells that come from the lymph system enter the CNS in MS. Once in the CNS, they release chemicals that cause inflammation. This inflammation damages myelin and nerve fibers.

In people without MS, T regulatory cells normally turn off inflammation. However, in MS, these T regulatory cells don’t function properly and can't turn off the inflammation. B cells become activated with the help of T cells and produce antibodies that cause damage in the CNS.

Environmental

While there is no single environmental risk factor that has been shown to cause MS, there are several that are thought to contribute to the overall risk:

• Low vitamin D: There is growing evidence that low vitamin D levels can contribute to the development of MS. Vitamin D levels are increased by exposure to direct sunlight, and people who live farther from the equator (and therefore have less access to sunlight) have a higher risk for MS.
• Smoking: Evidence is growing that smoking puts you more at risk for developing MS and is associated with more rapid disease progression and severe disease.
• Obesity in childhood and adolescence: Especially in girls, childhood obesity has also been shown to increase the risk for developing MS later in life. 

Genetic Associations

MS is not an inherited disease; however, the risk for people developing MS who have biological relatives with MS is higher.

Infectious Factors

Many viruses and bacteria have been studied to see if they increase the risk of developing MS. More evidence is mounting that previous infection with the Epstein-Barr virus (the virus that causes mononucleosis) contributes to the risk of developing MS.

Types

To aid in diagnosis and treatment, MD and MS are categorized into different types. Muscular dystrophy has nine types based on which genes are affected. Multiple sclerosis is categorized into four types based on the course of the disease.

Muscular Dystrophy Types

There are nine main types of muscular dystrophy that vary by symptoms, age of onset, rate of progression and prognosis. Severity varies between all nine, but all types of MD cause progressive skeletal muscle deterioration.

Duchenne MD is the most common childhood form of the disease and usually appears during the toddler years. It is marked by an absence of the muscle protein dystrophin. Most children with Duchenne MD are unable to run or jump.

Without aggressive care and treatment, life expectancy ranges from the teens to early 20s. However, as improvements in care have been made, many children with Duchenne MD can now live into their 30s or 40s.

Becker MD is less severe than Duchenne and usually appears around age 11 but can appear as late as 25. Muscle weakness and atrophy varies greatly, but many people are able to walk until their mid-30s or later. Those with Becker MD have partial but insufficient function of the protein dystrophin.

Congenital MD is present at birth or evident before the age of 2. Most children are diagnosed when they fail to meet landmarks in motor function and muscle control. They often cannot sit or stand without assistance.

The prognosis with congenital MD varies as some children may die when very young, where others may live into adulthood with little disability.

Distal MD usually appears between the ages of 40 and 60. The course of the disease is typically less severe and progresses slowly. In Distal MD, the muscles of the hands, forearms, lower legs, and feet are affected, causing difficulty in extending the fingers and performing small tasks.

When muscles of the legs and feet are affected, walking and climbing stairs become difficult. Distal MD can also affect the heart and breathing muscles, and people who are affected may eventually need a ventilator.

Emery-Dreifuss MD mainly affects boys and is usually evident by the age of 10, but symptoms can appear as late as the mid-20s. Upper arm and lower leg weakness and wasting is slow, and contractures in the spine, ankles, and knees often come first.

Most people with Emery-Dreifuss MD will have some form of a heart problem by the age of 30. Those with this type of MD often die in mid-adulthood from cardiac or pulmonary failure.

Facioscapulohumeral MD usually appears in the teen years but can occur in childhood or as late as age 40. Initially it affects the muscles of the face, shoulders, and upper arms. Disease progression is typically slow, and most people will experience a normal life span.

Limb-girdle MD has two forms based on genetic mutations. When limb-girdle MD is caused by the recessive gene form, symptoms usually start in childhood or the teenage years. When caused by the dominant form, onset usually occurs during adulthood.

People with limb-girdle MD will experience muscle weakness that begins at the hips and then spreads to the shoulders, legs, and neck. Intelligence remains normal in most cases. Generally, prognosis is based on time of onset. The earlier signs appear, the more progressive the disease is in leading to disability.

Myotonic dystrophy usually appears between the ages of 20 and 30. Muscles in the face and neck are affected. Most people with myotonic dystrophy will live to a normal life expectancy. Progress towards disability will be slow.

Oculpharyngeal MD most often appears in one’s 40s or 50s and is marked by drooping eyelids followed by weakness in the facial muscles and throat. Vision and swallowing problems may follow. Muscle weakness and wasting in the shoulders and neck is also common.

Multiple Sclerosis Types

Though MS is highly unpredictable and varied, most people will initially experience episodes of flares, or exacerbations, followed by remission. However, this too can vary, which is why neurologists have established four types of MS based on the course of the disease:

• Relapsing-remitting MS: This is the most common form of MS. It is characterized by flares of symptoms followed by periods of remission, when symptoms lessen or disappear.
• Secondary progressive MS: Some people may progress from relapsing-remitting MS to this state where the disease continues to worsen with or without periods of remission.
• Primary progressive MS: Ten percent of people with MS will experience symptoms that continue to worsen gradually from the onset of the disease. There may be plateaus, but there are no relapses or remissions.
• Progressive-relapsing MS: Fewer than 5% of people with MS will experience progressive-relapsing MS, where the disease is progressive from the start, with flares of worsening symptoms along the way and no periods of remission. 

Symptoms

The symptoms for both diseases vary based on how the disease affects the body. MD symptoms mainly involve the muscles. MS symptoms are mainly neurological.

Muscular Dystrophy Symptoms

The symptoms of muscular dystrophy vary based on the type of MD; however, all involve the muscles. In MD, the muscles become weak and begin to waste, causing a variety of symptoms depending on which muscles are affected.

MD is a progressive disease that gets worse and more debilitating over time. Symptoms of MD include but are not limited to:

• Delayed motor development—taking longer to sit, stand, or walk
• Enlarged calf muscles
• Muscle weakness that worsens
• Walking on the toes or waddling
• Using the hands to get up off the floor
• Enlargement of the heart that gets worse over time
• Difficulty walking
• Frequent falls
• Muscle aches
• Joint stiffening

Multiple Sclerosis Symptoms

MS symptoms are highly unpredictable and can fluctuate over time. No two individuals with MS will experience the same symptoms.

Some people may experience one or two of the following symptoms, while others may experience all of them. With relapsing-remitting MS, you may experience symptoms that come and go or enter remission and disappear.

MS Symptoms include but are not limited to:

• Fatigue
• Numbness or tingling
• Weakness
• Walking problems
• Spasticity
• Vision problems
• Dizziness and vertigo
• Bladder problems
• Sexual problems
• Bowel problems
• Pain and itching
• Cognitive changes
• Emotional changes
• Depression
• Difficulty swallowing 

Treatment

Treatment varies with both diseases. There are few medications specifically designed for MD, but there are treatment options to relieve symptoms.

There are many medical options to slow disease progression for MS, as well as treatment options to relieve symptoms.

Muscular Dystrophy Treatments

While there is no cure for muscular dystrophy, there are treatment options that can help relieve symptoms, improve quality of life, and slow progression.

If you have MD your treatment may include physical therapy, respiratory therapy, speech therapy, orthopedic devices for support, and corrective orthopedic surgery.

The Food and Drug Administration (FDA) has approved several drugs specifically for Duchenne MD to help slow its progression. Depending on your gene mutation. you may be prescribed Vyondys 53 (golodirsen), Viltepso (viltolarsen), or Amondys 45 (casimersen).

Depending on how MD affects you, you may receive other types of drugs such as corticosteroids to slow muscle degeneration, immunosuppressants to delay damage to muscle cells, antibiotics to fight respiratory infections, or anticonvulsants to control seizures and muscle activity.

Multiple Sclerosis Treatments

The goal of treatment for multiple sclerosis is not to cure but to relieve symptoms and slow disease progression.

For symptom relief, you may be prescribed muscle relaxants and tranquilizers such as baclofen and diazepam to help with spasticity (muscle stiffening or tightening that prevents fluid movement). Steroids may be given to treat acute symptoms of a flare or increased inflammation. For fatigue, you may be prescribed Provigil (modafinil) or Adderall (dextroamphetamine and amphetamine).

Physical therapy and exercise can also help with fatigue and mobility. Mobility aids such as foot braces, canes, or walkers can help you remain independent and mobile as well.

To help with disease progression, the FDA has approved a variety of disease-modifying drugs that have been shown in clinical trials to reduce the number of relapses, limit new disease activity as seen on an MRI (magnetic resonance imaging), and delay progression of disability.

These drugs include but are not limited to:

• Avonex or Rebif (interferon beta-1a)
• Betaseron (interferon beta-1b)
• Copaxone (glatiramer acetate)
• Gilenya (fingolimod)
• Tecfidera (dimethyl fumarate)
• Lemtrada (alemtuzumab)
• Ocrevus (ocrelizumab)
• Tysabri (natalizumab)i

A Word From Verywell

Muscular dystrophy and multiple sclerosis may have similar symptoms, yet they are two distinctly different diseases in the way they affect the body. MS affects the central nervous system, causing neurological symptoms, whereas MD affects the muscles causing symptoms that affect movement.

While neither has a cure and both can be debilitating, there are treatment options that can slow disease progression and help with quality of life.