MDA leads the search for treatments and therapies for myotonic muscular dystrophy (MMD). The Association also provides comprehensive supports and expert clinical care for those living with MMD.
In this section, you’ll find up-to-date information about myotonic muscular dystrophy, as well as many helpful resources. This information has been compiled with input from researchers, physicians and people affected by the disease.
This website contains information about the three known types  of myotonic muscular dystrophy:
As you learn more about MMD, always remember that you’re not alone. MDA is here for you and your family, standing ready to provide help and hope. There is a place for you in the MDA MMD community.
MDA provides support by:
Once you sign up with your local MDA office , you’ll begin receiving MDA’s quarterly Quest  magazine, where you’ll find news about research and health care, helpful products and devices, social and family issues, and more.
In addition, MDA will keep you informed through e-alerts, educational publications and speakers, seminars, videos and newsletters.
Please know that there’s a role for you in the fight against myotonic muscular dystrophy. The MDA community is strong and dedicated, with opportunities for involvement at all levels, such as:
Please know that there’s an important role for every member of the MMD community. We urge you to contact your local MDA office  to learn more.
An MMD diagnosis doesn’t mean an end to your hopes and dreams. Changes, challenges and adaptations lay ahead, but also opportunity, fulfillment, joy and hope for a future free of myotonic muscular dystrophy.
Never forget that MDA is here to help.
|Weakness and wasting (shrinking) of voluntary muscles in the face, neck and lower arms and legs are common in type 1 myotonic muscular dystrophy. Muscles between the ribs and those of the diaphragm, which moves up and down to allow inhalation and exhalation of air, also can be weakened.|
Myotonic muscular dystrophy (MMD) is a form of muscular dystrophy that affects muscles and many other organs in the body.
The word myotonic is the adjective for the word myotonia, an inability to relax muscles at will. The term muscular dystrophy means progressive muscle degeneration, with weakness and shrinkage of the muscle tissue.
Myotonic muscular dystrophy often is abbreviated as “DM” in reference to its Greek name, dystrophia myotonica. Other names for this disorder include simply myotonic dystrophy and, occasionally, Steinert disease, after the German doctor who originally described the disorder in 1909.
(MDA, which covers more than 40 forms of neuromuscular disease, uses the abbreviation “MMD” because “DM” refers to another disease in its program, dermatomyositis .)
MMD is divided into two types.
Type 1 MMD (MMD1) occurs when a gene on chromosome 19 called DMPK contains an abnormally expanded section.
Type 2 MMD (MMD2) is caused by an abnormally expanded section in a gene on chromosome 3 called ZNF9. MMD2 was originally called PROMM, for proximal myotonic myopathy, a term that has remained in use but is somewhat less common than the term MMD2.
The expanded sections of DNA in these two genes appear to have many complex effects on various cellular processes.
MMD causes weakness of the voluntary muscles, although the degree of weakness and the muscles most affected vary greatly according to the type of MMD and the age of the person with the disorder.
Myotonia, the inability to relax muscles at will, is another feature of MMD. For example, it may be difficult for someone with MMD to let go of someone's hand after shaking it.
As the disease progresses, the heart can develop an abnormal rhythm and the heart muscle can weaken. The muscles used for breathing can weaken, causing inadequate breathing, particularly during sleep.
In addition, in type 1 MMD (see Types of MMD ), the involuntary muscles, such as those of the gastrointestinal tract, can be affected. Difficulty swallowing, constipation and gallstones can occur. In females, the muscles of the uterus can behave abnormally, leading to complications in pregnancy and labor.
The development of cataracts (opaque spots in the lenses of the eyes) relatively early in life is another characteristic of MMD, in both type 1 and type 2.
Overall intelligence is usually normal in people with MMD, but learning disabilities and an apathetic demeanor are common in the type 1 form. In congenital MMD1, which affects children from the time of birth, there can be serious impairment of cognitive functioning. These children also may have problems with speech, hearing and vision.
Generally, the earlier MMD1 begins, the more profound the symptoms tend to be. For more, see Signs and Symptoms .
In general, MMD2 has a better overall prognosis than MMD1. The symptoms are often relatively mild and progress slowly. MMD2 rarely occurs during childhood, and there is no known congenital-onset form.
The progression of MMD varies greatly among individuals, but in general, symptoms progress slowly.
The most common type of MMD1 — the "adult-onset" form — begins in adolescence or young adulthood, often with weakness in the muscles of the face, neck, fingers and ankles. The weakness is slowly progressive for these and eventually other muscles.
When MMD1 begins earlier in life than adolescence — the congenital-onset and juvenile-onset forms of the disease — it may be quite different in progression from the adult-onset type. Children with congenital-onset MMD1, once they survive the crucial neonatal period of respiratory muscle weakness with the help of assisted ventilation, usually show improvements in motor and breathing functions over the first year or so. They may have cognitive impairment, delayed speech, difficulty eating and drinking and various other developmental delays. Most will learn to walk. As adolescence approaches, children begin to show symptoms of the adult-onset form of MMD1 and follow its usual progression.
The childhood-onset form of MMD1 — beginning after infancy but before adolescence — is more often characterized by cognitive and behavioral abnormalities than by physical disabilities. Eventually, muscle symptoms develop, to varying degrees.
MMD2 is, in general, a milder disease than type 1. It does not appear to have a congenital-onset form and rarely begins in childhood.
In contrast to type 1 MMD, the muscles affected first in MMD2 are the proximal muscles — those close to the center of the body — particularly those around the hips. However, some finger weakness may be seen early as well. The disorder progresses slowly, but mobility may be impaired early because of weakness of the large, weight-bearing muscles.
MMD2 is quite rare, except in Germany and in people of German descent. Not as much is known about MMD2 as about MMD1.
Identification of the genetic mutations underlying MMD 1 and MMD2, and understanding at least in part how the mutations cause disease, has opened up avenues for therapy development in MMD.
Most of the strategies currently in development aim to block the harmful effects of the expanded DNA in the DMPK gene (type 1) or the ZNF9 gene (type 2). As of 2012, studies in mice are encouraging, and human trials are on the near horizon. For more, see Research  and In Focus: Myotonic Muscular Dystrophy , particularly MMD Research: Seeking to Free Proteins from a ‘Toxic Web’ .
The two major types of myotonic muscular dystrophy (MMD) — MMD1 and MMD2 — are both caused by genetic defects.
MMD1, the most common type, results from an abnormal DNA expansion in the DMPK gene on chromosome 19.
MMD2 arises from an abnormal expansion of DNA in the ZNF9 gene on chromosome 3.
Within MMD1 there are additional subtypes, depending on a person’s age at onset of symptoms. The age of onset is roughly correlated with the size of the DNA expansion, with larger expansions associated with earlier disease onset.
The subtypes of MMD1 are:
MMD2 — sometimes called PROMM (proximal myotonic myopathy) — has not been seen in a congenital-onset form and rarely begins in childhood. Therefore, it is not described in subtypes.
MMD2 tends to involve the proximal muscles (close to the center of the body) rather than the distal muscles (far from the center of the body) that are the first to be affected in MMD1. In general, the disorder is not as severe as MMD1. However, it may affect walking ability earlier than MMD1, because it causes early weakening of the hip muscles. MMD2 is rare compared to MMD1, except in people of German descent.
For more, see Causes/Inheritance .
Below is a general comparison of the major features of MMD1 and MMD2.
|Comparison of MMD1 and MMD2|
|age of onset||birth to adulthood||8 to 60 years|
|earlier onset with each generation||often occurs||doesn't appear to occur|
|neck muscle weakness||common, early||common, early|
|hip and thigh weakness||late||early|
|distal muscle weakness||prominent||mostly hands|
|weakness anywhere||can occur||can occur|
|muscle pain||can occur||often occurs|
|enlargement of calf muscles||does not occur||occurs|
|early cataracts (of the eyes)||occurs||occurs|
|early balding in males||common||common|
|cardiac rhythm abnormalities||common||variable|
|cardiac muscle degeneration||can occur, especially late in disease course||not common|
|excessive daytime sleepiness||common||variable|
|cognitive impairment||occurs often; can be mild to severe||can occur; generally mild|
|respiratory abnormalities||common, particularly sleep-disordered breathing and inadequate breathing||not common|
|gastrointestinal disturbances||difficulty swallowing, constipation, diarrhea, gallstones can occur||not common|
|uterine dysfunction during labor and delivery||can occur||not common|
|high blood sugar because of insulin resistance||can occur||can occur|
Myotonic dystrophy is more than just a muscle disease. Both MMD1 and MMD2 affect several aspects of physical and mental functioning, to varying degrees and with variable scope.
The following sections discuss different problems that can occur, although many people with the disease have only some of them. Most of these symptoms can be lessened with treatment. See Medical Management  for information on current therapies.
Click on the individual subtype to find more information on specific signs and symptoms:
The subjects covered in this section are:
The brain 
Breathing and swallowing muscle weakness 
Head, neck and face muscle weakness 
Heart difficulties 
Insulin resistance 
Internal organs 
Limb and hand muscle weakness 
Myotonia and muscle pain 
Research suggests that, in MMD1, there may be abnormalities in the parts of the brain that determine the rhythm of sleeping and waking, making excessive daytime sleepiness a barrier to full participation in work, school or social life for many adults with the disorder. In some people, there is a kind of overall "apathy" that may be due to changes in the brain related to MMD1.
Although not as much is known about the effects of MMD2 on personality, cognition and sleepiness in MMD2 as in MMD1, it appears that people with MMD2 can have some of the same difficulties in these areas as people with MMD1, but to a lesser degree.
To learn more, read The Brain in MMD  (cognitive and emotional aspects of MMD1) and Excessive Daytime Sleepiness Can Be 'Debilitating' in MMD1 and MMD2  (complex effects of MMD on the brain's sleep-wake cycles and respiratory muscles).
Back to top 
Respiratory muscle weakness does not appear to be a common feature of MMD2.
However, in MMD1, respiratory muscles weakness can affect lung function and deprive the body of needed oxygen. Weakness of the diaphragm and other breathing muscles can lead to problems getting enough oxygen when a person is asleep, even if they don’t have any symptoms of breathing difficulty while awake.
Respiratory problems in MMD1 are further aggravated, many experts believe, by an abnormality in the brain’s breathing control center. This abnormality can lead to a condition known as sleep apnea , in which people stop breathing for several seconds or longer many times a night while asleep.
Swallowing muscles, if weakened, can lead to choking  or “swallowing the wrong way,” (called aspiration) with food or liquid going down the trachea (windpipe) to the lungs instead of down the esophagus to the stomach. Swallowing is partly voluntary and partly involuntary, and both sets of muscles can be affected.
To learn more, read Excessive Daytime Sleepiness Can Be 'Debilitating' in MMD1 and MMD2  (complex effects of MMD on the brain's sleep-wake cycles and respiratory muscles).
Back to top 
Cataracts — cloudy areas of the lens of the eye that eventually can interfere with vision — are extremely common in both MMD1 and MMD2. They generally occur earlier than the common, age-associated cataracts seen in people without MMD.
Cataracts are caused by a chemical change in the lens, which gradually goes from clear to cloudy the way the clear part of an egg changes to white when cooked. Exactly why cataracts occur in MMD isn’t known.
The person with a cataract may notice that things start to look blurry, hazy or dim, and that this worsens gradually over time. It often happens in both eyes, but not necessarily at the same time or at the same rate.
Read Keeping Your Focus: Eye Care , particularly the section called Other vision problems: Not common, sometimes treatable , for additional information about eye care in neuromuscular disorders.
Back to top 
|A long, thin face with hollow temples, drooping eyelids and, in men, balding in the front, is typical in myotonic dystrophy.|
The muscles of the neck, jaw and parts of the head and face may weaken, especially in MMD1. Facial weakness is less common in MMD2.
Weakness and loss of bulk in these muscles leads to a characteristic appearance doctors and experienced family members recognize as MMD.
In men, early balding in the front part of the scalp is very common, adding to the distinct appearance of MMD.
Eyelids may droop (called ptosis; the “p” is silent). The chewing muscles can be affected, which makes the temples appear hollow and the face look thin.
Weak neck muscles, common in both types of MMD, can make it hard to sit up quickly or lift one’s head straight up off a bed or couch. The stronger trunk muscles have to be used for these actions.
Back to top 
The heart  can be affected in MMD1 or MMD2. Oddly, since MMD is mostly a muscle disease, it isn’t the muscle part of the heart (which pumps blood) that’s most affected, but rather the part that sets the rate and rhythm of the heartbeat — the heart’s conduction system.
It’s common in MMD1, especially after many years, to develop a conduction block, which is a block in the electricity-like signal that keeps the heart beating at a safe rate. This appears to occur in MMD2 as well, although there aren’t as many studies in this form of the disease.
Fainting, near fainting or dizzy spells are the usual symptoms of conduction block, and these should never be ignored. Such problems can be fatal.
In both forms of MMD, cardiac muscle impairment also can occur, although it isn’t as common as conduction abnormalities.
To learn more, read Cardiac Care in MMD: Lack of Symptoms May Mask Deadly Problems  and Revising Cardiac Care in Muscular Dystrophies  (covers different types of heart problems that occur in these disorders and how to monitor and treat them).
Back to top 
Fortunately, most people with MMD1 and MMD2 don’t have diabetes, but they may develop a diabetes-like condition that is sometimes referred to as insulin resistance. This means the body makes insulin (a hormone needed for the cells to take up and use sugars), but for some reason, it takes more insulin to do the job because the muscle tissues don’t respond normally to the usual amounts. High blood sugar may result from insulin resistance.
Back to top 
|The digestive tract and uterus (womb) often are affected in type 1 myotonic dystrophy. These organs contain involuntary muscles, which can weaken or develop myotonia (trouble relaxing). Abnormalities in the brain can lead to excessive sleepiness or apathy. The heart (especially the “electrical” part) also can be affected.|
Most of the internal organs in the body are hollow tubes (such as the intestines) or sacs (such as the stomach). The walls of these tubes and sacs contain involuntary muscles that squeeze the organs and move things (food, liquids, a baby during childbirth and so forth) through them.
In MMD1, many of the involuntary muscles that surround the hollow organs can weaken. These include the muscles of the digestive tract, uterus and blood vessels.
Such problems appear to be absent or mild in MMD2.
Abnormal action of the upper digestive tract can impair swallowing. Once food is swallowed, the involuntary muscles of the esophagus should take over and move food into the stomach. However, in MMD1, these muscles can have spasms and weakness, causing a feeling of food getting stuck and sometimes leading to inhaling food into the lungs.
The lower digestive tract — large intestine (colon), rectum and anus — also can be affected by weakness and spasm in MMD1. Crampy pain, constipation and diarrhea can occur.
The gallbladder — a sac under the liver that squeezes bile into the intestines after meals — can weaken in MMD1. People with MMD probably are more likely than the general population to develop gallstones. Symptoms are difficulty digesting fatty foods and pain in the upper right part of the abdomen.
Fortunately, most people do not experience incontinence or urination problems in MMD.
Because of weakness and uncoordinated action of the muscle wall of the uterus, women with MMD1 may experience difficulties in childbirth that can be serious for both mother and baby. These may involve excessive bleeding or ineffective labor. Sometimes a Caesarean operation (C-section) is advised, but surgery also can be a problem in MMD (see Medical Management ).
Blood pressure in MMD1 tends to be low. This is probably due to low tone of the smooth muscles in the blood vessels. It usually poses no problem and may even be one beneficial effect of MMD1.
Back to top 
Weakness of the voluntary muscles usually is the most noticeable symptom for people with adult-onset MMD.
The distal muscles (those farthest from the center of the body) usually are the first — and sometimes the only — limb muscles affected in MMD1. Areas of the limbs affected may include the forearms, hands, lower legs and feet. Over time, these muscles get smaller, so the lower legs and arms may appear thinner than the upper legs and arms.
In MMD2, proximal muscles — those closer to the center of the body — tend to show more weakness than in MMD1. Weakness in the upper part of the leg (thigh) occurs early in MMD2. In MMD1, thigh weakness, if it occurs at all, comes later in the disease.
People with both types of MMD often notice that their grip is weak and that they have trouble using their wrist or hand muscles. The muscles that pick up the foot when walking may weaken, allowing the foot to flop down and cause tripping and falling (foot drop).
Back to top 
Myotonia of voluntary muscles can make it hard for someone with MMD1 or MMD2 to relax their grip, especially in cold temperatures. Door handles, cups, handwriting and using hand tools may pose a problem, although some people never notice it. Myotonia also can affect the muscles of the tongue and jaw, causing difficulty with speech and chewing.
Myotonia can be uncomfortable and even cause pain, although people with MMD1 and MMD2 also can have muscle pain that isn’t connected to the myotonia.
Back to top 
When MMD1 begins in early childhood (but not at birth), the first symptoms tend to be more behavioral and cognitive than physical. Some people with the juvenile-onset form struggle with planning ahead, decision-making and visual-spatial processing. An "avoidant" or apathetic personality can be part of the picture.
As the child matures into adulthood, typical features of adult-onset MMD1 usually emerge.
To learn more about the juveile-onset form of MMD1, be sure to read Juvenile-Onset MMD1 Can Cause Cognitive, Behavior Challenges  (part of Quest's In Focus: Myotonic Muscualr Dystrophy  series).
When MMD symptoms manifest at birth, life-threatening complications ensue. However, once this critical period is past, improvement is likely during early childhood. Later, as a child approaches adolescence, it's likely that the symptoms of adult-onset MMD1 will appear.
Congenital MMD only has been observed in MMD1. To learn more, see Energy, Dedication, Hope Help Parents of Children with Congenital MMD1 , part of Quest's In Focus: Myotonic Muscular Dystrophy  series.
When a child is born with congenital MMD1, it’s almost always found that the mother has adult-onset MMD1 — even though her symptoms may be so mild that she didn’t even know she has the disorder.
Mothers with MMD also can pass on the adult-onset form. A child can inherit the disease from the father, but it’s almost always the adult-onset form. These unusual features aren’t seen in other genetic disorders. For more, see Causes/Inheritance .
Topics covered in this section:
Infants born with congenital MMD often have serious cognitive disabilities, although this isn’t always the case. The condition seems to be related to abnormal development of parts of the brain , presumably caused by genetic abnormalities.
Some experts have suggested that the very high incidence of labor and delivery complications in mothers with MMD also could be a contributing factor to the cognitive problems seen in these babies.
Infants and children with MMD1 symptoms may “outgrow” many of the muscle-related aspects of the disorder as they mature. Although cognitive difficulties don’t improve, they generally do not worsen either, and children can learn when given the right tools, instruction and environment. See Medical Management .
However, despite early gains during childhood, children with congenital MMD will very likely develop the adult form of MMD when they reach adolescence or adulthood.
Back to top 
|A child born with congenital myotonic dystrophy is likely to have facial muscle weakness and an upper lip that looks “tented.” The eye muscles also may be affected.|
The muscles involved in talking often are affected in congenital MMD. Hearing also can be impaired. The eye muscles are affected and can cause the eyes not to work together, a condition called strabismus.
Cataracts, common in adult-onset MMD, aren’t a feature of congenital MMD during early childhood. However, children with congenital MMD are likely to develop them later.
Babies with congenital MMD1 have very weak muscles and a lack of muscle tone (hypotonia). They appear floppy, have trouble breathing, and suck and swallow poorly.
In the past, many infants with congenital MMD didn’t survive. Today, with special care in neonatal intensive care units, such children have a much better chance of survival, although they still will face multiple challenges in childhood.
Children with congenital MMD1 have facial muscle weakness, leading to a bland expression and an upper lip that comes to a point — known as a tented upper lip.
Babies with congenital MMD1 often are born with clubfeet — a curvature of the feet and lower legs. The problem may be due to abnormal muscle development in the lower legs and feet during fetal life.
Infants with MMD1 don’t have myotonia at first but develop it later in life.
Back to top 
Doctors with experience in neuromuscular disorders often find it easy to diagnose type 1 myotonic muscular dystrophy (MMD1). Sometimes, just by looking at a person, asking a few questions and examining him or her, they're well on the way to suspecting MMD1. For instance, teenagers and adults with MMD1 (the most common type) usually have a characteristic long face with hollow temples, and males often have early balding. (See Signs and Symptoms .)
In type 2 myotonic muscular dystrophy (MMD2), these facial features aren't as obvious (also see Signs and Symptoms ).
Many people with MMD1 tell the doctor about recurring abdominal pain, constipation or obstetrical complications. Many also report that their parents had muscle problems.
Sometimes, an eye doctor will notice the particular kind of cataract found in MMD and suspect the disease, referring the patient to a neurologist. Cataracts are common in both MMD1 and MMD2, often occurring by middle age.
Many people may not realize they have any trouble relaxing their grip, while others say they’ve had trouble letting go of a shovel, screwdriver or some other device, especially in cold weather. These symptoms are present in both types of MMD.
The doctor may check for myotonia by lightly tapping the area just under the thumb with a rubber hammer. In most people, there is little or no response. In people with myotonia, there’s a swift contraction of the muscle, which takes several seconds to relax.
The doctor may want to do electrical testing of the muscles and nerves, using an electromyogram, or EMG . In this exam, small needles are inserted into muscles to measure their electrical activity. Myotonia produces a characteristic sound, often described as the noise made by a dive-bombing airplane.
These days, a doctor who suspects MMD1 or MMD2 is likely to move from the history and physical exam to a DNA test (genetic test) to confirm a diagnosis. The DNA test involves only a blood sample and, in almost all cases, can determine whether the family is affected by MMD. For more on getting a definitive genetic diagnosis, see MDA Genetic Counseling Webinar Answers Key Questions  and The Genie's Out of the Bottle: Genetic testing in the 21st century .
Type 1 myotonic dystrophy (MMD1) and type 2 myotonic dystrophy (MMD2) dystrophy are both caused by abnormally expanded stretches of DNA. The expansions occur in two different genes but appear to have similar effects on various cells, particularly the cells of the voluntary and involuntary muscles, including the heart and some nerve cells.
In MMD1, the abnormal DNA expansion is in the DMPK (dystrophia myotonica protein kinase) gene on chromosome 19. The defect was identified as the cause of MMD1 in 1992.
The DNA building blocks cytosine, thymine and guanine (abbreviated as CTG) are repeated many more times than average in this disorder. The normal number of "CTG repeats" in the DMPK gene is three to 37.
In MMD1, there can be hundreds or even thousands of CTG repeats in the DMPK gene. In general, the number of repeats correlates with the age of onset and the severity of the disorder, with the highest numbers correlating with the congenital-onset form, the lower numbers correlating with the adult-onset form, and mid-range numbers correlating with the juvenile-onset form. However, these correlations are by no means perfect and should not be taken as absolute predictors of the course of the disease.
Another unusual feature of the genetic defect that causes MMD1 is that it can change size over time in the same person and when it's being transmitted from parent to child. When the DMPK gene expansion is transmitted from parent to child, it often expands, causing the disease to manifest earlier with each generation in a family.
The congenital-onset form of MMD1 appears to occur only when the DMPK gene flaw comes from the mother. A mother with a small CTG repeat expansion and few or no noticeable symptoms can give birth to a baby with a large CTG expansion and the congenital-onset form of MMD1.
At first, it was believed that the main effects of the expanded DNA in the DMPK gene were that it decreased the amount of available DMPK protein in cells. While this may be a factor in the causation of MMD1, it is now believed that there are widespread effects of the CTG expansions on many cellular processes.
The underlying cause of MMD2 was identified in 2001 as an expanded DNA section in the ZNF9 (zinc finger 9) gene on chromosome 3.
In this disorder, the expansion contains four DNA building blocks — two cytosine molecules followed by a thymine and a guanine (abbreviated CCTG) — repeated far more times than average.
As in MMD1, the effects of the ZNF9 gene abnormality appear to be widespread, affecting many cellular processes.
However, the correlation between repeat length and disease severity or age of onset is not clear in MMD2.
For an in-depth look at MMD research, read MMD Research: Seeking to Free Proteins from a "Toxic Web." 
Both MMD1 and MMD2 are inherited in an autosomal dominant pattern, meaning it takes only one flawed gene (in MMD, one gene carrying the abnormal expansion) to cause symptoms of the disease. If one parent has the disorder, every child of that person has a 50 percent chance of inheriting the gene flaw that causes it.
If either the type 1 (DMPK) or the type 2 (ZNF9) genetic abnormality is passed on, the child will almost certainly develop the disease. MMD1 symptoms very often are milder in the parent than in the child. In MMD2, this increase in severity between generations does not seem to occur, at least most of the time.
Genetic testing for the expanded DNA that leads to either type of MMD can be performed in several laboratories.
For more on genetic testing, read MDA Genetic Counseling Webinar Answers Key Questions  and Facts About Genetics and Neuromuscular Diseases .
As yet, there’s no specific treatment that “gets at the root” of type 1 or type 2 myotonic muscular dystrophy (MMD1 or MMD2). Treatment is aimed at managing symptoms and minimizing disability.
This section first addresses medical management of the many symptoms of adult-onset MMD1/MMD2 and juvenile-onset MMD1. Not everyone will require all these aspects of medical management, and some symptoms may first appear or worsen as a person grows older.
Also, medical management of congenital-onset MMD1 during early childhood is different enough to require its own section.
Click on the individual subtype to find more information on specific strategies for 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 
Cognitive and behavioral abnormalities 
Daytime sleepiness 
Gastrointestinal dysfunction 
Heart abnormalities 
Insulin resistance 
Pregnancy and childbirth 
Skeletal muscle weakness 
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.
Back to top 
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.
Back to top 
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.
Back to top 
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.
Back to top 
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.
Back to top 
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.
Back to top 
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 .
Back to top 
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.
Back to top 
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).
Back to top 
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.)
Back to top 
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.
Back to top 
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.
Back to top 
Babies born with congenital-onset MMD1 have the most complex medical challenges seen in MMD. Although the prognosis for these children has improved, the disease still has profound consequences and can be life-threatening, especially in the early months.
The subjects covered in this section are:
Breathing difficulties 
Cognitive impairment 
Feeding difficulties 
Muscle abnormalities 
The muscles needed for breathing are very weak in congenital-onset MMD1, and a baby born with this disorder is likely to need a ventilator for an uncertain period of time. The breathing muscles do generally become stronger over time.
Back to top 
Cognitive impairment and even mental retardation are common in congenital-onset MMD1, often requiring early intervention during the preschool years and special education later.
Back to top 
The muscles needed for sucking may impair the baby's ability to feed. If the weakness is interfering with nutrition and hydration, a tube can be inserted either down the nose into the stomach (nasogastric tube) or directly into the stomach from outside (gastrostomy tube) until the muscles become strong enough for the child to eat and drink by mouth.
Back to top 
Babies with congenital-onset MMD1 are born "floppy," with weak muscles and poor muscle tone. The medical term for this is hypotonia.
Motor milestones, such as sitting, standing and walking, are likely to be delayed, but ultimately are achieved by most children.
Muscle weakness in the feet may cause them to be fixed in a downward-pointing, inward-turning position. This condition is known as clubfoot or talipes equinovarus. This condition may have to be treated by casting or surgery before a child can walk.
To learn more about congenital MMD1, read:
Back to top 
The major focus in MMD research has been on the molecular underpinnings of the disease. To date, most of the work has been done using animal and cellular models of type 1 MMD. However, many experts believe the findings from the MMD1  experiments will have implications for MMD2  as well.
In both these conditions, the underlying defect is an expansion of DNA. In MMD1, it's the chemical sequence cytosine, thymine, guanine (CTG) in a gene on chromosome 19. In MMD2, it's the chemical sequence CCTG in a gene on chromosome 3. (See Causes/Inheritance .)
During the normal process by which cells transcribe DNA into RNA, the expansion is likewise transcribed, resulting in a long, unruly strand of RNA that stays in the cell nucleus and forms a trap for various cellular proteins. For instance, the protein known as MBNL1, which has a crucial role in ensuring that other proteins are properly formed, is trapped in this toxic "web" of expanded RNA in both forms of the disease.
Most of the strategies aimed at treating the underlying causes of MMD1 and MMD2 aim to either destroy the expanded, toxic RNA in MMD-affected cells, or block the interactions between it and proteins.
Three MMD researchers whose work is particularly promising are using these strategies:
To learn more, read MMD Research: Seeking to Free Proteins from a 'Toxic Web' .
In January 2013, in recognition of the likelihood that clinical trials will soon be conducted in MMD1 and MMD2, MDA established a five-center clinical research network . The researchers in each center will work together to standardize methods of evaluating disease severity and will determine the best ways to assess whether experimental treatments are beneficial.
The new MMD centers are:
A clinical trial is a test in humans of an experimental medication or therapy. Clinical trials are experiments, not treatments, and participation requires careful consideration.
Although it's possible to benefit from participating in a clinical trial, it's also possible that no benefit — or even harm — may occur. Keep your MDA clinic  doctor informed about any clinical trial participation. (Note that MDA has no ability to influence who is chosen to participate in a clinical trial.)
For more about clinical trials in general, see Learn About Clinical Studies , and to learn more about trial participation in neuromuscular disease, read the Quest magazine article Being a Co-Adventurer .
For a more refined list of MMD clinical trials, visit ClinicalTrials.gov , a registry of federally and privately supported clinical trials in the United States and around the world. Select "Search for Clinical Trials," and follow the instructions to narrow down your search results.
Myotonic muscular dystrophy (MMD) has been a part of my family’s life for many years. The symptoms for my siblings and me began in our 30s, and we believe the disease goes back at least two generations before us. Some of my nieces and nephews also are affected.
Like many of you, we were surprised to learn that such a wide range of symptoms — muscle weakness, involuntary clenching of hands and jaw, swallowing problems, eye problems, heart disorders, extreme fatigue and other difficulties — could be caused by a form of muscular dystrophy. With correct information about our disorder, we’re able to monitor and protect our health to a great degree.
This website has been prepared to give you the basic knowledge about MMD that you’ll need to make your life enjoyable and productive. With this information, you or your children can be prepared for changes to come and armed to minimize many effects of the disease.
By understanding how the disease affects me in different ways, I’ve been able to stay active while avoiding more physically demanding activities. I take pains to keep my stress level to a minimum and make sure I get plenty of sleep, because I’ve learned that stress and fatigue will exacerbate my symptoms rapidly. A pacemaker corrects the heart problems caused by my MMD.
I find that, with these precautions and forms of assistance, there’s little I can’t do in my personal life with my husband and extended family.
From this website, you’ll learn some encouraging things about MMD: There are treatments and interventions for most of the symptoms and difficulties that arise with the disease. For instance, I recently had successful surgery for my drooping eyelids. My nieces and nephews showed symptoms in childhood, and they’ve received expert medical guidance from the beginning for symptoms that include learning disabilities.
MDA’s research program is constantly making strides toward better treatments and a cure. It’s good to know that people with disabilities have more opportunities than ever before to develop and use their abilities, as well as legal rights to equal employment opportunity and access to public places. Federal law guarantees children with physical and cognitive disabilities a public education with whatever supports they need.
My family’s greatest ally in living with MMD is MDA. So, as you face the challenges ahead, please remember: You’re not alone.
New Port Richey, Florida