Adult-Onset MMD1/MMD2 and Juvenile-Onset MMD1

Medical Management

This section addresses medical management of the many symptoms of adult-onset MMD1 and MMD2, as well as juvenile-onset MMD1. These three forms of MMD share similar medical management strategies.

The subjects covered are:

Anesthesia warning
Breathing and coughing muscle weakness
Cataracts
Cognitive and behavioral abnormalities
Daytime sleepiness
Gastrointestinal dysfunction
Heart abnormalities
Insulin resistance
Myotonia
Pain
Pregnancy and childbirth
Skeletal muscle weakness

Anesthesia warning

An unusually high rate of complications and even deaths associated with general anesthesia given during surgery have been reported in people with MMD1. This can occur even if the MMD is mild. In fact, mild cases can be particularly dangerous because the surgeon, anesthesiologist and patient may be less likely to pay attention to the MMD when planning surgery.

Surgery usually can be safely undertaken with careful monitoring of cardiac and respiratory functions before, during and after the procedure. Be sure to tell the entire medical team, especially those responsible for the anesthesia, that you or your family member has MMD. If at all possible, have the anesthesiologist and the neurologist communicate long before the surgery.

Adverse reactions to anesthesia do not seem as serious in MMD2. However, caution is advised.

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Breathing and coughing muscle weakness

In MMD1, breathing muscle weakness can be an important factor in the disease course. It does not seem common in MMD2.

A good way to treat respiratory muscle weakness is to pump air into the lungs during the night with a small, portable “breathing booster” known as a bilevel positive airway pressure device (BiPAP is the trademarked name of the device made by Philips Respironics). It’s usually used with a face mask that can be easily put on and taken off. This kind of breathing assistance also can be used during the day, although usually that’s not necessary.

(Devices that use continuous positive airway pressure — brand name CPAP — often are not appropriate for people whose respiratory problems are caused by weak breathing muscles. For more, see Not Enough ZZZzzzs.)

Cough assistance machines (CoughAssist is a brand name) and assisted cough techniques can help people clear out secretions, especially when a person with MMD1 has a cold or chest infection. The MDA clinic doctor, respiratory therapist or pulmonologist can advise about these techniques and machines, and how to use them.

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Cataracts

Cataracts — opaque spots on the lens of the eye — are common in both MMD1 and MMD2. If they interfere with vision, they can be removed surgically. Caution with anesthesia and pain medication is necessary, and the surgical team should be aware of and familiar with the patient's MMD.

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Cognitive and behavioral abnormalities

Cognitive and behavioral abnormalities can exist at any point in MMD1 or MMD2, although they're more common in MMD1 and particularly when MMD1 begins in childhood.

In general, these abnormalities manifest as an "avoidant" or apathetic personality, and difficulties with planning ahead, making decisions and processing visual and spatial information.

An evaluation by a neuropsychologist, special education strategies and counseling can be helpful, as can medications that increase alertness and attention (for example, modafinil), depending on the person and the details of his or her individual situation.

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Daytime sleepiness

Daytime sleepiness, which is more common in MMD1 but also occurs in MMD2, can sometimes be helped with medication. One drug that can be used is methylphenidate (Ritalin). Newer drugs are modafinil (Provigil) and armodafinil (Nuvigil). These drugs may work on the brain’s sleep-wake cycle. Treating excessive sleepiness can make life more enjoyable for the person with MMD and his or her family.

Another approach that can be tried is to coax the body into a better rhythm of sleeping and waking by going to bed and getting up at the same time every day. Consult with a respiratory specialist familiar with muscular dystrophy to determine if breathing is compromised during sleep.

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Gastrointestinal dysfunction

Dysfunction of the muscles of the throat or esophagus can occur in MMD1, impairing swallowing.

It’s important to watch for swallowing problems, such as a tendency to choke on food or drinks, and be sure to mention them to the doctor. A swallowing specialist can help people learn to swallow more safely and, if necessary, how to change the consistencies of foods and liquids so they can be swallowed more easily.

Vomiting can be very dangerous for a person with MMD whose swallowing muscles are weak. A head-down position is crucial to prevent inhaling the vomit — a possibly fatal event.

Read Sorting Out Speech Services for more information about speech and swallowing specialists.

Difficulty swallowing does not seem to be a common feature of MMD2.

In MMD1, the intestines may not move digested food along as well as they should, so constipation can be a chronic problem. A doctor can help set up a more effective bowel schedule and, if necessary, recommend laxatives, suppositories or enemas to help manage this condition.

Constipation does not seem to be a common factor in MMD2.

The gallbladder, a hollow sac on the right side of the upper abdomen, likewise can be sluggish in MMD1, leading to the formation of gallstones. These may cause persistent pain in the upper abdomen. Surgery to remove the gallbladder can be performed if necessary.

Gallbladder dysfunction does not seem to be a feature of MMD2.

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Heart abnormalities

Not everyone with MMD needs treatment for heart problems, but everyone should be checked for them on a regular basis. The problem seems more common in MMD1 than in MMD2, although both types of MMD can affect the heart.

The most common type of heart problem in MMD is an abnormal heart rhythm (arrhythmia) called a conduction disturbance. When a conduction disturbance is present, signals do not move through the heart in the normal way. This can be very serious, even causing sudden death. Therefore, it's imperative that people with MMD have regular electrocardiograms (EKGs, also known as ECGs).

Some people with MMD develop an abnormal heart rhythm known as atrial fibrillation, in which the top part of the heart beats extremely fast, causing turbulent blood flow that can lead to clots and strokes.

Various electronic devices — pacemakers and implantable defibrillators — can be used to treat abnormal heart rhythms. Sometimes, medications also are prescribed. These include such drugs as beta blockers and anti-arrhythmic drugs.

Sometimes, especially late in the disease course, the heart muscle itself can weaken, causing a type of disorder known as cardiomyopathy. Medications can be prescribed to lessen the stress on the heart in this disorder. These are known as beta blockers and ACE inhibitors.

For more information, read Cardiac Care in MMD: Lack of Symptoms May Mask Deadly Problems and Revising Cardiac Care in Muscular Dystrophies.

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Insulin resistance

A phenomenon known as insulin resistance — meaning the insulin produced by the body isn't utilized as well as it should be — can cause high blood sugar and sometimes even diabetes. Insulin resistance is common in people with MMD1 and is thought to affect approximately 20 percent of those with MMD2. The phenomenon often doesn't cause any trouble but should be monitored by a physician. If it does become problematic, insulin or other medications that lower blood sugar can be prescribed.

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Myotonia

Myotonia — inability to relax muscles at will — occurs in both MMD1 and MMD2. Grip myotonia — not being able to release one's grip after, for example, shaking hands or holding a steering wheel — can be the main thing people notice. If myotonia is bothersome, it can be treated by drugs, such as mexiletine (Mexitil).

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Pain

Pain in the skeletal muscles is a common feature of MMD2 and is less common in MMD1. The pain does not appear to be related to myotonia or to exercise. However, cold temperatures make it worse. Painful stiffness can occur, particularly in the legs.

A doctor may suggest an over-the-counter pain remedy or even a prescription pain medication in some circumstances. Some people find warm baths, heating pads or massage to be helpful.

Pain in the involuntary muscles — for instance, of the gastrointestinal tract or uterus — may be more common in MMD1. The underlying cause of the pain, such as constipation, should be identified and treated where possible.

Some pain in the involuntary muscles may respond to heat or massage, and some may require pain medication, under a doctor's supervision.

A doctor should always be told that MMD is present, as this may make a difference in how the pain should be treated. (For instance, in MMD1, it's important to avoid pain medications that affect breathing.)

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Pregnancy and childbirth

In both MMD1 and MMD2, pregnancy can be complicated by a mother's heart abnormalities, requiring special care and attention, particularly during labor and delivery.

In MMD1, uterine and vaginal muscles may be weak, posing additional problems for pregnancy and delivery and making a surgical delivery more likely.

Reactions to anesthesia and pain medications can be unpredictable and need the attention of someone familiar with these disorders.

In addition, a mother who has mild MMD1 may give birth to a child with congenital-onset MMD1 who will need a neonatal intensive care unit and specialists familiar with this condition.

For more information on myotonic dystrophy and pregnancy, read Caution, Preparation and Teamwork Lead to the
Best Pregnancy Outcomes in Women wtih Neuromuscular Diseases
in the multipart series called Great Expectations: Pregnancy and Childbirth with Neuromuscular Disease. Also be sure to read Baby Born with Challenges in the same series.

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Skeletal muscle weakness

In MMD1, weakness of the skeletal muscles is concentrated in the face, tongue, neck, forearms, hands and feet, especially at the beginning. Later on, other muscles can be affected, such as those of the thighs, and the breathing muscles.

Some people can compensate for weak foot muscles by picking up the foot from the knee and walking with a “marching” step. Eventually, though, many people with MMD1 find that a cane or walker is helpful to compensate for foot and leg weakness.

A lower leg brace, called an ankle-foot orthosis, or AFO, may be needed. Some people with MMD1 use a wheelchair or a power scooter for convenience when covering long distances. For more, read Putting Your Best Foot Forward.

Various devices that hold the hand in a good position for using a keyboard or writing or drawing can help compensate for weak wrist and hand muscles.

In MMD2, by contrast, the weakness begins in the large muscles close to the center of the body. Early in the disease course, there is weakness of the hips and thighs. The upper arms and shoulders are often involved early, and the forearms and fingers can be affected early as well.

The facial muscles usually remain strong, weakening in only a small percentage of people with MMD2. The lower legs and feet tend to remain strong as well, although the calf muscles can become enlarged.

Walking aids, such as walkers, canes, and even scooters and wheelchairs, can be helpful.

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Disease: