What Is Muscular Dystrophy?

The different types of muscular dystrophy vary in terms of when symptoms start (in infancy, childhood, or adulthood), who they affect (men, women, or both), which muscles they affect, and what their symptoms are. But all forms of muscular dystrophy become increasingly worse or progress — meaning that your muscles get weaker the longer you live with the condition.

As a result, most people with muscular dystrophy eventually lose the ability to walk and must use a wheelchair to get around. Still, some people with the condition have mild cases that progress slowly, while others experience symptoms that quickly become severe and disabling.

At present, there’s no cure for muscular dystrophy, although certain treatments — including physical therapy, speech therapy, assistive orthopedic devices, surgery, and prescription medications — can help to slow progression, control some symptoms, and reduce the risk of complications.

Types of Muscular Dystrophy

Duchenne Muscular Dystrophy

Dystrophin is a protein that helps strengthen muscle fibers and protect them from injury.

Children who have DMD usually experience initial weakness in their upper legs and pelvis. Symptoms include frequent falls, difficulty rising from a lying or sitting position, appearing to waddle when walking, having difficulty running or jumping, and having enlarged calf muscles from scar tissue buildup and replacement of muscle with fat tissue.

Becker Muscular Dystrophy

Some people with Becker may never need to use a wheelchair, while others lose the ability to walk during their teens or later.

Myotonic Dystrophy

Congenital Muscular Dystrophy

Facioscapulohumeral Dystrophy

People with FSHD may have difficulty opening and shutting their eyes or be unable to smile or pucker their lips. Other symptoms may include muscle wasting that causes the shoulders to appear slanted, impaired reflexes in the biceps and triceps, and difficulty swallowing, chewing, or speaking, as well as hearing loss.

The condition may also cause an inward curvature in the spine called lordosis.

Limb-Girdle Muscular Dystrophy

Different subtypes of limb-girdle muscular dystrophy are caused by different gene mutations. They affect both males and females, usually once they reach adolescence or young adulthood.

Emery-Dreifuss Muscular Dystrophy

Distal Muscular Dystrophies

Distal muscular dystrophy tends to be less severe and progresses more slowly than other forms of the condition, but it can spread to other muscles. People with this form of muscular dystrophy may have a hard time using their hands and fingers, and they have trouble walking and climbing stairs. Some forms can lead to breathing problems as the condition progresses.

Oculopharyngeal Muscular Dystrophy

Signs and Symptoms of Muscular Dystrophy

While each person with muscular dystrophy is unique, some of the most common signs and symptoms of the disease include the following:

• Muscle weakness
• Difficulty walking
• Frequent falling
• Difficulty getting up from a lying or sitting position
• Limited movement at certain joints (called contracture)
• Heart problems
• Problems with breathing and swallowing
• Muscle pain or stiffness

Some forms of muscular dystrophy, such as congenital muscular dystrophy and Duchenne muscular dystrophy, are also associated with learning disabilities, intellectual disabilities, and cognitive impairments.

Causes and Risk Factors of Muscular Dystrophy

The most common forms of muscular dystrophy are caused by a variation on the X chromosome influencing production of a protein called dystrophin, while other types of muscular dystrophy have their own set of unique genetic variations, affecting the production of other proteins.

But even within one type of muscular dystrophy, different individuals may have different genetic variations, leading to similar, but not identical, symptoms.

In most cases, the genetic variations that cause muscular dystrophy run in families and are passed from parents to children. For some types of muscular dystrophy, you have to inherit two copies of a nonworking gene, one from each parent, to have the disease; this is called an autosomal recessive inherited disorder.

For other types of muscular dystrophy, you need only inherit one copy of a nonworking gene from one parent to have the disease; this is called a dominant inherited disorder.

A third type of genetic inheritance is called a sex-linked, or X-linked, disorder, in which the genetic variation is carried on the X chromosome. Because males have only one X chromosome, they’re more likely to have X-linked forms of muscular dystrophy than females, who have two X chromosomes. That’s because in females, the normal copy of the X chromosome can usually compensate for the one that has the variation.

Given the complexity of how muscular dystrophy can be inherited, couples who want to have children and who know or suspect they carry gene variations that cause muscular dystrophy are generally advised to meet with a genetic counselor to better understand the risk of passing on the disease and discuss ways of lowering that risk.

How Is Muscular Dystrophy Diagnosed?

Patient History The doctor will ask about symptoms, general health, past illnesses, and any family history of the condition.

Physical Examination The doctor will look for any abnormal curvature in your spine, abnormalities in the way you walk, or evidence of muscle wasting, weakness, or diminished reflexes.

Blood Tests These include measuring your level of creatine kinase, an enzyme that leaks out of damaged muscle. A very high level indicates a muscle disorder such as muscular dystrophy.

Genetic Tests Because muscular dystrophy is a genetic disorder, your doctor will likely recommend you undergo genetic testing to determine whether you have any genetic variations — particularly if your blood tests reveal an elevated creatine kinase level.

Muscle Biopsy A small sample of muscle tissue may be surgically removed and examined under microscope for the presence and appearance of specific proteins. It can also be used to extract DNA for genetic testing.

Neurological Tests These can rule out nervous system disorders that could cause similar symptoms.

Heart Tests Some forms of muscular dystrophy cause heart problems, such as an irregular heartbeat or cardiomyopathy. Tests including an electrocardiogram can measure the rate and frequency of heartbeats.

Imaging Tests Magnetic resonance or ultrasound imaging may be used to examine muscle quality and bulk, as well as the fatty replacement of muscle tissue. This can help spot muscle wasting and other symptoms of muscular dystrophy.

Treatment and Medication Options for Muscular Dystrophy

Medication Options

• Glucocorticoids like prednisone (Deltasone) and deflazacort (Emflaza, Kymbee), which can help increase muscle strength, improve respiratory function, and slow the progression of muscle weakness
• Anticonvulsants, which though typically taken for epilepsy, may help control seizures and some muscle spasms caused by muscular dystrophy
• Immunosuppressants, which may help delay some damage to muscle cells
• Antibiotics, which may be needed to treat respiratory infections, since muscular dystrophy can impact your immune system’s ability to fight them off

• casimersen (Amondys 45)
• eteplirsen (Exondys 51)
• golodirsen (Vyondys 53)
• viltolarsen (Viltepso)
• delandistrogene moxeparvovec-rokl (Elevidys)

Therapies

Physical Therapy Working with a physical therapist can help you keep muscles flexible and strong. A physical therapist may also recommend a combination of light muscle-building and stretching exercises to help you maintain strength and flexibility.

Speech Therapy Some forms of muscular dystrophy cause weakness in the facial and throat muscles, affecting speech or swallowing. Speech therapists can teach people how to work around these problems or, if needed, use special communication equipment.

Occupational Therapy As your physical abilities change, an occupational therapist can teach you techniques to conserve your energy while performing daily tasks or how to find alternative ways of accomplishing what you wish to do. An occupational therapist can also teach you how to use assistive devices such as wheelchairs and utensils, if needed.

Muscular Dystrophy Prognosis

The life expectancy, or life span, for people with muscular dystrophy depends on the type involved, and when it’s diagnosed.

Complications of Muscular Dystrophy

Contractures Contractures are the shortening of muscles or tendons around the joints, and they can limit mobility beyond that caused by muscle weakness. Regular stretching and range-of-motion exercises can delay contractures, but if they become severe, your doctor may recommend surgery, which may restore some joint function and reduce discomfort.

Breathing Difficulties As it progresses, muscular dystrophy may affect the muscles associated with breathing. As a result, an individual with muscular dystrophy may need to use a breathing device (a ventilator), perhaps initially only at night but possibly also during the day. Sleep apnea, in which a person repeatedly stops breathing during sleep, is a common respiratory problem in people with muscular dystrophy.

Coughing Difficulties Weakened respiratory muscles interfere with a person’s ability to cough, and inadequate coughing allows mucus secretions to accumulate in the lungs, raising the risk of infection. Some people with muscular dystrophy need to use a cough assist device or manual assistance to clear secretions.

Swallowing Difficulties Progressive muscle weakness may negatively affect the ability to swallow when eating or drinking. Some of the potential consequences of swallowing difficulties include nutrient deficiencies and a condition called aspiration pneumonia, in which food or mouth secretions can get trapped in the lungs, leading to pneumonia, a lung infection.

In some cases, a speech-language pathologist can help you relearn how to swallow. Alternatively, your doctor may recommend the use of a feeding tube to ensure proper nutrition.

Heart Disease The heart muscles may be affected by muscular dystrophy as the condition progresses. One common heart complication in people with muscular dystrophy is called cardiomyopathy. As the name indicates, cardiomyopathy is a heart muscle disease, and it can cause heart failure. The condition is treatable. Your doctor may recommend blood pressure medications and other drugs to help you maintain adequate heart function.

Scoliosis Spinal complications are common in some forms of muscular dystrophy. The most frequent is scoliosis, or curvature of the spine to one side or the other. It typically occurs in people who can no longer stand or walk and who use a wheelchair full-time.

Osteoporosis Another orthopedic complication linked with muscular dystrophy is osteoporosis, a condition in which the bones become fragile because of a loss of mass. While osteoporosis is normally associated with older age, in people with muscular dystrophy, it may develop as a result of treatment with corticosteroids, particularly in those with DMD.

People with osteoporosis are at increased risk for bone fractures — an important consideration given that weakness in the legs from muscular dystrophy may make a person more prone to falling.