Multiple sclerosis (MS) and muscular dystrophy (MD) have distinct differences. MS affects the protective covering around nerve fibers, while MD affects the muscle fibers.

The causes of MS and MD are also different. MS occurs when the immune system attacks the sheath around nerves, whereas MD occurs due to genetic changes that affect muscle proteins.

Both conditions can be challenging, but MS is rarely fatal. Although ongoing research has improved the outlook for people with MD, the condition still has a significant impact on life expectancy.

This article discusses MS versus MD, including their differences, symptoms, causes, diagnosis, and treatment. It also answers commonly asked questions.

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Multiple sclerosis (MS) and muscular dystrophy (MD) can both affect movement. They also have similar-sounding names. However, they are separate conditions with distinct causes.

MS

MS affects the myelin sheath of nerve fibers in the brain, spinal cord, and optic nerves. Myelin is the substance that makes up the protective coating of all nerves.

The immune system attacks the myelin, sometimes causing areas of scar tissue to form. These areas of damage to the myelin, also called scleroses or plaques, are visible on an MRI scan.

MS also harms nerve cells in the brain and can cause the cerebral cortex to shrink as it progresses. The cerebral cortex is responsible for thinking and memory and plays a role in movement and sensation.

MD

MD is a group of conditions that affect the muscles, not nerves. Each type of MD damages muscle fibers and eventually destroys them, resulting in progressive muscle degeneration and weakness.

In terms of life expectancy, MD is worse than MS.

All types of MD progressively worsen as the muscles weaken. The loss of muscle function can affect breathing and the heart. People with MD typically live into their 20s or 30s.

In contrast, while MS is a long-term and progressive condition, it is rarely fatal. It also affects people in different ways. Some people get milder symptoms.

Additionally, most individuals with MS have relapsing-remitting MS (RRMS). People with RRMS experience flare-ups of symptoms followed by long periods of partial or complete remission. During remissions, people with RRMS may feel relatively well.

People with MD experience symptoms that gradually worsen without periods of improvement.

Both MS and MD cause muscle weakness, which can affect mobility.

This means that people with MS or MD may have difficulty with balance and coordination and experience more frequent falls than people without these conditions. Both conditions can also cause the following:

However, there are also differences in symptoms.

MS symptoms

Early symptoms that occur with MS but not with early MD include dizziness and problems controlling the bladder.

Later, people with MS may experience:

MD symptoms

The symptoms of MD vary depending on the type but could include:

  • low muscle tone
  • difficulty with specific movements, such as getting up from a seated position or climbing stairs
  • contracture, which is tightness and shortening of muscles
  • walking on the toes
  • early hair loss
  • heart complications

As MD progresses, it may cause difficulty swallowing or breathing. Some forms also affect the following:

These conditions also have different causes.

MD causes

In many types of MD, the root cause is a change in genes that affect muscle proteins. A person could inherit these genes from their biological parents.

Less commonly, the genetic changes develop spontaneously. In those with Duchenne MD, around 70% of people inherit the gene, while approximately 30% have a new genetic change not present in their parents.

If a person develops or inherits the genetic change, they could pass it on to their offspring.

MS causes

The causes of MS are more complex and not fully understood.

Genetics play a role, but they do not directly cause the condition in the same way as MD. Instead, certain genes may increase a person’s susceptibility to MS in combination with other factors.

Scientists are still learning what the other factors might be, but they could include:

Diagnosing MS and MD involves taking a medical history and performing a physical examination. If there is a possibility of either condition, a doctor will also perform diagnostic tests to determine the cause.

Tests for MS

Tests for MS focus on looking for evidence of demyelination or lesions in the brain or spinal cord, as well as tests for neurological function. This may include:

MD tests

An MD diagnosis may include genetic testing, as well as:

  • blood and urine tests
  • exercise tests to determine if certain chemicals are elevated during or after exercise
  • medical imaging to examine the muscles
  • electron microscopic examination to detect changes in muscle fibers, such as cell death
  • electromyography, which records electrical activity in muscles
  • immunofluorescence to detect the presence of certain proteins in the muscle fibers
  • nerve conduction velocity, which tests nerve function

For electromyography and immunofluorescence, doctors take a muscle biopsy, or sample, to analyze.

Although no cure currently exists for either MS or MD, treatments can reduce the symptoms and the risk of complications. Treatment can also preserve a person’s independence for as long as possible.

MS

The main treatment of RRMS involves disease-modifying therapies that suppress inflammation. That said, such medications can be less effective for progressive forms of MS.

Other treatment for relapse phases of MS may include:

MD

MD treatment may include:

  • medications for symptom relief
  • medications to delay muscle degeneration, such as steroids to reduce inflammation
  • immunosuppression drugs to slow muscle deterioration
  • regular exercise
  • physical, occupational, and speech therapy
  • deep breathing or coughing exercises for people with breathing difficulties

Below are answers to commonly asked questions about MS and MD.

Can you have MS and MD?

A 2018 case study indicates that it is possible to have both MS and a specific type of MD at the same time, but this rarely happens.

Can doctors mistake MS for MD?

This is unlikely, as the pattern of muscle weakness and the physical examination for each condition is different, even in the early stages. Additionally, MS almost always causes lesions that show up on an MRI scan.

However, in very rare situations, the effects of MS or MD may be very mild and hard to distinguish to begin with. In these cases, as MS or MD progresses, the differences in symptoms and diagnostic testing will become more apparent.

There are many differences between multiple sclerosis (MS) and muscular dystrophy (MD). Both conditions can cause muscle weakness, but MS affects the myelin sheath around nerve cells, while MD affects muscle fibers.

Both conditions cause a wide array of symptoms. However, MD can eventually cause heart complications and difficulty breathing. It also affects life expectancy, whereas most people with MS have a typical lifespan.

Research into treatments to increase survival rates and reduce symptoms in those with MD is ongoing. Current treatments include medications to reduce symptoms and slow disease progression and physical or occupational therapy to maintain independence.