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Myotonic Muscular Dystrophy Type 1

Overview

Myotonic muscular dystrophy (MMD) is a multisystem disorder that affects the brain, skeletal and smooth muscles, eyes, heart, gastrointestinal tract, lungs, and endocrine system. The 2 forms, type 1 and type 2, are caused by different gene mutations. Type 2 does not have a congenital or early childhood form and is not discussed further here. Type 1 can be classified into mild (late onset), classic (adult onset), childhood/juvenile, and congenital forms. The classification describes a continuum ranging from mild to severe disease, which generally correlates with trinucleotide repeat (CTG) length. MMD1 is a progressive condition; repeat expansion and RNA splicing dysregulation increases over time and leads to a gradual worsening in many domains including cognition, muscle strength, and others.
Individuals with mild late adult onset may not develop symptoms until after 50 years old. [Ho: 2015] Classic "adult" onset often occurs after age 10 and involves progressive muscle weakness (often eventually requiring a wheelchair for mobility), cataracts, and cardiac conduction abnormalities. Children with childhood onset (before the age of 10, but after early infancy) often have similar symptoms and disease progression as those with congenital onset. Infants with congenital onset may present at birth with hypotonia, breathing or feeding problems, and drooling and/or swallowing problems. Global developmental delays are often observed in the first few years of life. Distal muscle atrophy and weakness, as well as the hallmark myotonia, may not be noted until school age or later. IQ may be borderline or low, learning disabilities may be present, and attention deficit hyperactivity disorder or characteristics of autism spectrum disorder are common. Management is currently supportive, incorporating regular surveillance and treatment of manifestations.

Other Names & Coding

Congenital myotonic muscular dystrophy DM* Dystrophia myotonica Myotonic dystrophy Steinert disease *Since "DM" could be interpreted as an abbreviation for diabetes mellitus, the abbreviation "MMD" will be used instead for myotonic muscular dystrophy.
ICD-10 coding

G71.11, Myotonic muscular dystrophy

See ICD-10 for Myotonic Muscular Dystrophy (icd10data.com) for further coding details.

Prevalence

MMD is the most common muscular dystrophy. [Norwood: 2009] It affects an average of 1:2000 people in the United States. [Johnson: 2019] In most populations, type 1 appears to be more common than type 2, but prevalence varies in different ethnic populations and the founder effect may increase the prevalence in specific regions. [Theadom: 2014] [Pratte: 2015]

Genetics

MMD results from a trinucleotide repeat (CTG) in the DMPK gene region on chromosome 19. It is one of the many examples of neurologic diseases, such as Huntington disease and fragile X syndrome, that are caused by an excessive number of such repeats (a CTG repeat length of 35 or more is abnormal). Children with congenital MMD often have >1000 repeats, though the congenital form may be seen with fewer repeats. In the case of MMD, these repeats are present in the RNA, but they are not translated into the protein. The disease mechanism for these untranslated repeats is called the “toxic RNA hypothesis.” In this disease model, the excessive CTG repeats bind RNA binding proteins important in splicing (editing) other RNAs besides DMPK. This leads to RNA splicing errors, which have been detected in many different proteins, in the brain (amyloid precursor protein), heart (troponin), muscle (chloride ion channel), and endocrine systems (insulin receptor). This could explain why MMD is a multisystemic disorder. [Wheeler: 2007]
MMD is inherited in an autosomal dominant fashion. The disease-causing allele found in a parent with MMD may lengthen during the process of gametogenesis and the resulting offspring may have more severe disease and earlier onset than seen in the parent. This phenomenon is called anticipation. Anticipation resulting in large expansions (>1000 repeats), and hence congenital MMD, is much more common when the mother is the affected parent; anticipation with smaller or moderate expansions can occur from either parent. [Pratte: 2015] Myotonic Dystrophy Type 1 (GeneReviews) has further details related to genetics. [Bird: 1993]

Prognosis

Age of onset and severity of symptoms is variable. Mild presentation can involve cataracts and mild myotonia. Severe presentation can involve breathing issues, swallowing problems, or cardiac arrhythmias that are life-threatening. While there is no cure or treatment that slows progression of MMD, early intervention can reduce or eliminate some complications.

Practice Guidelines

No authors listed.
A large multicenter study of pediatric myotonic dystrophy type 1 for evidence-based management.
Neurology. 2020;94(9):414. PubMed abstract

Johnson NE, Aldana EZ, Angeard N, Ashizawa T, Berggren KN, Marini-Bettolo C, Duong T, Ekström AB, Sansone V, Tian C, Hellerstein L, Campbell C.
Consensus-based care recommendations for congenital and childhood-onset myotonic dystrophy type 1.
Neurol Clin Pract. 2019;9(5):443-454. PubMed abstract / Full Text

Roles of the Medical Home

At the time of diagnosis, the medical home should advise families regarding areas of uncertainty, such as clinical outcomes and the value of interventions as they pertain to both longevity and quality of life. Clinicians should explain the multisystem implications of this condition and help guide family decisions about monitoring and treating complications. [Kang: 2015]
In addition, the medical home treats acute illness and performs well-child and chronic-care visits where progression of the condition and problems can be proactively managed. The medical home, with input from the family, should be the initiator and coordinator of visits to subspecialists unless a multidisciplinary Neuromuscular Clinic (see Neuromuscular Clinics (see NM providers [1])) is available. The goal is to avoid duplication of services or unnecessary appointments while still seeing the subspecialists needed. All screening and interventions are intended to promote growth and potential development, mitigate cumulative morbidities, optimize function, and limit mortality while maximizing quality of life. [Kang: 2015]

Clinical Assessment

Overview

It is easy to miss the diagnosis of MMD in babies unless the diagnosis is kept in mind when considering a child with respiratory and/or feeding problems, hypotonia, and/or global developmental delays without a family history of the disease. When the newborn or infant presents with these problems, assess the face of the mother (and father) for weakness, ptosis, and hollow temples. To further assess the parents, perform percussion myotonia testing on the tongue and thenar eminences. Have the parent close eyes and fists and hold them tightly for several minutes, then let go suddenly. Individuals with myotonia demonstrate a slow release. An electromyogram in the parent may also demonstrate myotonia associated with MMD if it is not clinically apparent.

Pearls & Alerts for Assessment

MMD may present as global developmental delay

In a child with an uneventful birth, early MMD may present as global developmental delay. The characteristic myotonia is not present until later in childhood and the typical facial features may not be obvious unless the provider is aware of the potential for this underlying diagnosis in a child with developmental delays.

Complications with anesthesia

Individuals with MMD, even those with only mild manifestations of the disease, have a higher rate of complications associated with general anesthesia. Families should be educated about this possibility and reminded of this during well-child visits. [Mangla: 2019].

Incidence of diabetes

Individuals with MMD may have insulin resistance that sometimes develops into diabetes, even in the absence of obesity.

Screening

Of Family Members

Since MMD1 can worsen in successive generations, the diagnosis of an infant with the congenital form may lead to the recognition of milder symptoms in parents and other relatives. It is important to screen at-risk relatives (e.g., siblings and parents) since early diagnosis allows treatment of complications, such as cardiac abnormalities or diabetes.

For Complications

Depending on the individual's age and severity of MMD, screen for cataracts; early-onset cataracts are fairly common (posterior subcapsular/cortical type).
MMD causes electrical problems in the heart, such as arrhythmias, atrial fibrillation, and conduction defects (less commonly cardiac muscle problems). Screen for cardiac problems yearly with an ECG at the minimum.
Screen for sensorineural hearing loss, which is present in more than half of individuals with DMD.
Children should have a sleep study at diagnosis or when new symptoms of daytime sleepiness occur to screen for sleep apnea. Sleep and fatigue are often reported as the most debilitating symptoms of MMD.

Presentations

Mild and classic presentations: Cataracts, cardiac arrhythmias, speech and swallowing problems, fatigue and sleep disorders (including central and obstructive sleep apnea), and early onset of type II diabetes may occur. Less severely affected children may be identified when they fail to meet early developmental milestones.
Congenital/severe presentations: Babies with congenital MMD may be identified at birth with severe hypotonia, positional problems such as clubfeet or hip dysplasia, and breathing or swallowing problems. The latter 2 issues may be severe enough to require ventilation or tube feeding, sometimes for prolonged periods of time. Global developmental delays are often observed in the first few years of life. Distal muscle atrophy and weakness, as well as the hallmark myotonia, may not be noted until school age or later. IQ may be borderline or low, learning disabilities may be present, and attention deficit hyperactivity disorder or characteristics of autism spectrum disorder are common.

Diagnostic Criteria

Diagnosis is made by molecular testing confirming presence of the CTG repeat expansion in the DMPK gene of chromosome 19.

Clinical Classification

For myotonic muscular dystrophy:
  • MMD1, the most common type, results from an abnormal DNA expansion (CTG) in the DMPK gene on chromosome 19 causing mis-splicing of mRNAs, affecting all organs of the body.
  • MMD2 arises from an abnormal expansion of DNA (CCTG) in the first intron of CNBP (cellular nucleic acid binding protein). Note that unlike MMD1, where the number of repeats is roughly correlated with the severity of the disease, there is no correlation between phenotype and repeat length.
Types of Myotonic Dystrophy (MDA) and [Wenninger: 2018] provide further details.

Differential Diagnosis

Differential diagnoses include many less common muscle and nerve diseases, such as distal muscular dystrophies and Dejerine Sottas disease (a type of hereditary motor sensory neuropathy with evidence that would be seen on EMG/NCV testing), and hyperkalemic periodic paralysis (which presents with episodic weakness).
Because of the intellectual disability associated with MMD, diseases of the central nervous system may also be considered. Metabolic testing is normal in myotonic dystrophy. Although brain MRI is usually normal in individuals with MMD, it may show periventricular myelin changes that could be interpreted as evidence of perinatal hypoxic/ischemic injury. [Modoni: 2004] [Peglar: 2019]

Comorbid & Secondary Conditions

Increased rates of autism spectrum disorder, intellectual disability, and attention deficit hyperactivity disorder have been reported in this population. [Ekström: 2008] Diagnosis modules can be found at:

History & Examination

Current & Past Medical History

Ask about a history of speech and swallowing problems, aspiration, frequent drooling, respiratory illnesses, fatigue, cardiac arrhythmia, palpitations, chest pain, dizziness, weakness, behavioral problems, learning delays in school, and diarrhea or constipation.

Family History

Ask about a family history of early heart disease or pacemaker use, severe fatigue, early cataracts (before the age of 50), learning problems, and distal muscle weakness. Remember to examine the mother who may have undiagnosed MMD.

Pregnancy/Perinatal History

Ask about a history of polyhydramnios and decreased fetal movements; prolonged or complicated labor; presence of developmental hip dysplasia and/or clubfeet; breathing and feeding problems near birth, including the inability to breast/bottle feed; difficulties learning to eat as an infant; failure to thrive.

Developmental & Educational Progress

Determine when developmental milestones were achieved. Ask about IQ, learning disabilities, issues with attention, and any educational difficulties. Assess developmental and educational progress.

Social & Family Functioning

Ask about family functioning. Identify resources to help families cope with a new diagnosis of MMD. Ask if the child has access to social and recreational outlets.

Physical Exam

Growth Parameters

Ht | Wt - Children with MMD often have difficulty gaining and maintaining weight. Stature is typically normal in children with MMD.

HEENT/Oral

Children with congenital MMD have facial muscle weakness that can cause a seemingly flattened affect, an upper lip that comes to a point (known as a tented upper lip), and a characteristically long face with hollowing at the temples. Ptosis may be present. Check for drooling, swallowing dysfunction, and cataracts. A high-arched palate may be noted. Adolescent males may have early balding at the temples.

Heart

Check rate and rhythm.

Extremities/Musculoskeletal

Look for clubfeet and examine hips. Monitor for joint contractures and kyphoscoliosis/thoracolumbar scoliosis.

Neurologic Exam

Evaluate for hand myotonia and weakness. Weakness begins in the distal finger flexors and ankle dorsiflexors. Often children will have ptosis and severe oral facial weakness.

Testing

Sensory Testing

Ophthalmologic evaluation should be performed at diagnosis. Although cataracts are unusual in young children, strabismus and ptosis are common. Hearing problems are also common and hearing testing should also be performed at the time of diagnosis.

Laboratory Testing

Children may have thyroid dysfunction and diabetes; consider annual screening with a TSH and HbA1c.

Genetic Testing

Molecular genetic testing is available for diagnosis and is relatively inexpensive; it often obviates biopsy and electromyography.

Other Testing

  • Children with MMD require an ECG yearly to screen for progressive arrhythmias. Any detection of an early arrhythmia, most commonly first-degree heart block requires an urgent evaluation by a cardiologist.
  • Consider a barium swallow study for symptoms of dysphagia or frequent pulmonary infections that may be due to silent aspiration.
  • Perform a complete, age-appropriate, evaluation in all children. Initiate developmental therapies based on delays. Intellectual disability and other psychological symptoms are seen in more than half of children with congenital MMD. A neuropsychological profile may be helpful.

Specialty Collaborations & Other Services

Neuromuscular Clinics (see NM providers [1])

Referral to an MMD clinic for evaluation and genetic testing is recommended.

Pediatric Neurology (see NM providers [5])

If an MMD or other muscle disease clinic is not available, the child should be referred to pediatric neurology and/or genetics, depending on local expertise, for a baseline exam and periodic assessments as needed.

Medical Genetics (see NM providers [2])

A consultation is recommended to help with diagnosis and to help families understand genetic test results so they can make family-planning decisions. [Kang: 2015] If the family has further questions about the genetics of MMD, consider re-evaluation.

Pediatric Physical Medicine & Rehabilitation (see NM providers [3])

Consider a referral to evaluate development and recommend interventions aimed at increasing function.

Treatment & Management

Overview

Although children with myotonic dystrophy often seem to be doing fairly well, a survey performed in the US and Canada revealed that children with MMD are concerned about their problems communicating and with hand/finger problems. Parents were also concerned about their child’s communication but also noted that fatigue was a major problem in functioning on a daily basis. [Johnson: 2015] [Hagerman: 2019]
Knockdown of the toxic repeat expansion may be possible using antisense oligonucleotides. There has been a prior clinical trial (NCT02312011) testing this approach. We would expect others will continue to improve on this approach in the near future. Gene therapy for myotonic dystrophy is likely still years away, but adeno-associated viral vector gene therapy is currently being worked on in the laboratory. [Crudele: 2019]

Pearls & Alerts for Treatment & Management

Complications with vecuronium and general anesthesia

Children and adults with MMD are very slow to regain airway protection reflexes after anesthesia. If surgery is needed in a child with MMD, the anesthesiologist should be made aware of possible anesthetic complications.

Avoid statins

Statins may lead to increasing muscle weakness and pain.

Assess cardiac symptoms immediately

Any symptoms suggestive of cardiac arrhythmia (e.g., chest pain with exertion, light-headedness, or palpitations) should be taken seriously.

Botox may cause worsening in targeted muscle groups

Avoid using neuromuscular blocking agents (e.g., botulinum toxin) in patients with MMD unless the contractures are determined to cause significantly greater impairment than would any potential worsening of weakness in the targeted muscle groups. [Kang: 2015]

Fatigue

Parents of congenitally affected children from the United States and Canada report fatigue as an important problem for their children. Clinically, this is observed as older children who still need naps to function well. When fatigue or daytime sleepiness are present, consider a sleep study for obstructive or central sleep apnea. School accommodations may be necessary for children with fatigue. [Johnson: 2015]

How should common problems be managed differently in children with Myotonic Muscular Dystrophy Type 1?

Bacterial Infections

There is an increased risk for pneumonias in the setting of upper respiratory infections due to weakness of muscles required for optimal respiration.

Prescription Medications

Care needs to be taken to begin any sedating medications at half the typical dose. These patients are sensitive to sedating medications and are at risk for associated respiratory depression. Any medication that prolongs the QT should be evaluated in the context of that patient's current ECG.

Systems

Musculoskeletal

Children with congenital MMD need monitoring for progression of muscle weakness. Contractures of heels, knees, and hips can occur over time, and the medical home clinician should monitor for these or have the child see orthopedics periodically. About 30% of adolescents with MMD demonstrate scoliosis, and in some cases, surgery may be necessary. [Canavese: 2009] If muscle weakness is present, a disability placard for the family car can help to minimize the child's fatigue.

Specialty Collaborations & Other Services

Pediatric Neurology (see NM providers [5])

Depending on local availability, refer for periodic visits to monitor weakness.

Pediatric Orthopedics (see NM providers [7])

Consider a baseline visit with follow-up as necessary.

Neuromuscular Clinics (see NM providers [1])

Neurology follow-up may be available at specialized clinics.

Physical Therapy (see NM providers [12])

Refer for range-of-motion exercises, orthotic devices, heel cord lengthening procedures, or a combination of these interventions for children as needed. [Kang: 2015]

Development (general)

Global developmental delay is almost universal in children with congenital MMD. Begin early intervention when the child is 0 -3 years old. Transition to special education preschool and school as needed. Physical, occupational, feeding, and/or speech therapy may also be necessary.

Specialty Collaborations & Other Services

Early Intervention for Children with Disabilities/Delays (see NM providers [34])

Early intervention programs for children 0 to 3 years of age are available in all states, but the services they offer may differ and supplemental therapies may be necessary.

Preschools (see NM providers [6])

If needed, instruct families to call their local school or school district office for enrollment information. If the child has been in Early Intervention, transition to preschool will be a part of the program.

Occupational Therapy (see NM providers [17])

Refer to enhance daily living activities, such as eating or dressing.

Pediatric Neurology (see NM providers [5])

Depending on local availability, refer for periodic visits to monitor developmental issues.

Mobility/Function/ADLs/Adaptive

Depending on the severity of MMD, mobility may be significantly affected because of global developmental delays and/or muscle weakness. Positional aids may be necessary if the child is not able to sit without assistance. A corner chair, tumble form, or wheelchair may be used to allow the child to be in a seated position for feeding and for optimal hand use during play and activities of daily living. Braces and splints may be used to prevent deformity and to provide support or protection. These may be prescribed for use during the day or night to provide stretching and optimal joint positioning. Standers and/or walkers can allow for standing and help with balance when walking. Weight-bearing activities help prevent osteoporosis, allow full lung expansion, stretch hamstrings, and allow children to be on-level with peers.

Specialty Collaborations & Other Services

Pediatric Physical Medicine & Rehabilitation (see NM providers [3])

Consider referral for children with developmental delays and functional impairments.

Pediatric Orthopedics (see NM providers [7])

Children with joint contractures and/or scoliosis may be managed concurrently with pediatric orthopedics.

Physical Therapy (see NM providers [12])

Refer when help is needed for muscle strengthening, dealing with fatigue, or for a stander, walker, or wheelchair fitting.

Occupational Therapy (see NM providers [17])

Refer to help with functional impairments in carrying out activities of daily living.

Sleep

Fatigue in infants and children with MMD may manifest as a need to take frequent naps past the usual age of napping. In addition to skeletal muscle weakness, respiratory muscles may be weak, adding to fatigue with activity.
Sleep apnea (either central or obstructive), excessive leg movements, and dysregulation of rapid eye movement sleep may also contribute to fatigue in some children. If sleepiness, restless legs, or breathing abnormalities during sleep continue, consider referring to a sleep specialist. In more severe cases, stimulant medication or modafinil (Provigil) may be helpful. In younger children, a behavioral approach may help; the family should control bedtime and wake-up time and plan for scheduled naps. Consider suggesting a disability placard for the family's car to help with conserving the child's energy while out of the house; even if the child is only going to run around at a park, the child should conserve energy to get to the play area.

Specialty Collaborations & Other Services

Sleep Disorders (see NM providers [0])

A consult may be helpful for children with suspected sleep problems including frequent awakening, snoring, and excessive daytime sleepiness. Therapies may include medications, adenoidectomy/tonsillectomy (by ENT), and/or CPAP.

Cardiology

Individuals with MMD may have conduction problems and arrhythmias that can be life-threatening. In one study, the risk of cardiac conduction disorder was 60 times the population risk. [Johnson: 2015] Although it is difficult to predict the age that these complications first occur, children as young as age 10 have demonstrated arrhythmias, particularly during exercise. Visits with a cardiologist and annual EKGs are recommended to detect asymptomatic arrhythmias. [Bassez: 2004] [Groh: 2012]

Specialty Collaborations & Other Services

Pediatric Cardiology (see NM providers [3])

Clinicians should refer children with myotonic dystrophy for a baseline cardiac evaluation. The intervals of further evaluations should depend on the results of the baseline evaluation. [Kang: 2015] Exercise testing should be considered.

Respiratory

Respiratory muscle weakness can be life-threatening in infants with congenital MMD. Although some infants may require mechanical ventilation for a prolonged period, they usually improve with time. Since children with MMD, especially those with swallowing problems, are at an increased risk for pneumonias and other respiratory illnesses, administer influenza, H1N1, and pneumococcal vaccines as appropriate. Remind families to seek oseltamivir phosphate (Tamiflu) during flu season at the onset of flu-like symptoms. As noted above, children are at significantly increased risk of obstructive and central sleep apnea and may benefit from periodic sleep studies. Once children with congenital onset recover from the respiratory failure seen in infancy, they are at minimal risk of experiencing respiratory decline during childhood and do not necessarily need regular pulmonary function tests.

Specialty Collaborations & Other Services

Pediatric Pulmonology (see NM providers [4])

When available, refer to pulmonary or aerodigestive care teams that have experience managing the interface among oropharyngeal function, gastric reflux and dysmotility, nutrition, and respiratory systems and providing anticipatory guidance concerning trajectory, assessment modalities, complications, and potential interventions. [Kang: 2015]

Communication

In children with early-onset MMD, parents and the affected children reported issues involving communication as a frequent and severe problem. [Johnson: 2015] Children may benefit from regular speech therapy, which may improve communication problems.

Specialty Collaborations & Other Services

Speech - Language Pathologists (see NM providers [23])

Consider early referral for language assessment, delay, or augmentive speech methods such as sign language or speech devices.

Gastro-Intestinal & Bowel Function

Reflux: Gastroesophageal reflux is very common, although it might present as arching, irritability, or food refusal rather than vomiting. Treatment can be started empirically with evaluation and/or a referral to gastroenterology if symptoms continue. Treatment is generally initiated with lansoprazole, a proton pump inhibitor. Treatment of reflux can be augmented by the use of a motility agent (metoclopromide or low-dose erythromycin) or H2 blocker, but the clinician must monitor closely for side effects, particularly irritability or dystonia with metoclopromide. If optimal treatment of reflux is not successful, and/or the child remains underweight or has frequent aspiration pneumonias, a Nissen or other type of fundoplication may be necessary. Gastroesophageal Reflux Disease provides management details.
Constipation/diarrhea: Most children with MMD experience constipation alternating with diarrhea. Constipation and diarrhea are easier to treat if caught early; bowel history should be part of every medical home visit. Dietary management with additions of fiber might be all that is necessary, but many children will need daily treatment with laxatives (PEG 3350, MiraLax, or GlycoLax). See the Portal's Constipation for treatment details.
Incontinence: Children may have prolonged urinary and fecal incontinence. A high-fiber diet may be helpful in reducing fecal urgency. If incontinence persists into the teenage years, a trial of anti-myotonia medication may be helpful.

Specialty Collaborations & Other Services

Pediatric Gastroenterology (see NM providers [2])

Consider a referral for constipation, reflux, and/or failure to gain adequate weight.

Nose/Throat/Mouth/Swallowing

Swallowing dysfunction: Swallowing dysfunction may result in drooling, salivary pooling, malnutrition, and/or pulmonary aspiration. A speech therapist (or in some locations an occupational therapist) can evaluate swallowing function and safety, determine if interventions (e.g., speech therapy, special feeding techniques, improved feeding position) might lead to improvements in function, and determine the safest and most efficient textures for eating. In some cases, the therapist may suggest a fluoroscopic video swallow study (also called a modified barium or cookie swallow). If dysphagia is determined to be a problem, diets using pureed foods and thickened liquids may be necessary to prevent aspiration. See Missing issue with id: b51a96d.xml.
Children with significant swallowing problems may need gastrostomy tube placement to allow efficient and safe liquid and/or food delivery. A gastrostomy tube may also be necessary for those children with severe failure to thrive, even if aspiration is not an obvious problem. In some children, placement of a feeding tube might be thought of as a temporary intervention so that the family may focus on the child and the quality of his or her eating without worrying constantly about the number of calories the child has received. In the child with gastroesophageal reflux disease and limited capacity to protect his or her airway, treatment with a Nissen fundoplication may be important. See Feeding Tubes & Gastrostomies in Children and Missing issue with id: 435a721.xml for more information.
Drooling: Many parents choose not to treat drooling due to concerns about the side effects of medication and surgery, but drooling in the socially aware older child can be very embarrassing and can create social barriers. Treatment possibilities include medications to decrease saliva, botulinum toxin treatments (temporary), or surgery to block salivary ducts. No known therapy helps oropharyngeal function. [Morgan: 2012] See Drooling in Children with Special Health Care Needs for resources and information about specific treatments.

Specialty Collaborations & Other Services

Pediatric Gastroenterology (see NM providers [2])

The medical home should order multidisciplinary evaluations with swallow therapists, gastroenterologists, and radiologists if there is evidence of failure to thrive or respiratory symptoms (or both). [Kang: 2015]

Pediatric Otolaryngology (ENT) (see NM providers [11])

Children with drooling, excessive snoring, and/or swallowing problems may benefit from an assessment.

Speech - Language Pathologists (see NM providers [23])

Refer when there are swallowing problems, including drooling. Speech therapists may work with children with eating problems, depending on local expertise.

Nutrition/Growth/Bone

Children with congenital MMD may have a combination of swallowing problems, constipation, and gastroesophageal reflux disease that leads to malnutrition. Careful monitoring of growth and weight gain in children with congenital MMD is critical. Interventions may include optimizing oral feeding, the addition of oral caloric supplements, NG/NJ feeding, and placement of a permanent feeding tube. The medical home should ensure that treatment of dysphagia, gastroesophageal reflux disease, delayed gastric emptying, and constipation is optimized. Intervention should be tailored to the child's needs and family-centered. Missing issue with id: 90b0ad6d.xml and Formulas for information on increasing calories in the child's diet.

Specialty Collaborations & Other Services

Dieticians and Nutritionists (see NM providers [1])

A visit with a nutritionist may be helpful for children with difficulty gaining weight.

Maturation/Sexual/Reproductive

Males with MMD may be hypogonadotropic and may require testosterone supplementation to achieve secondary sexual characteristics. They may also be infertile, but this should not be assumed.
Females with MMD should understand that their child has a 50/50 risk of being born with congenital MMD in a more severe form than the mother exhibits. Pregnancies of mothers with congenital MMD should be managed by a high-risk obstetrician, usually with birth planned for a tertiary care NICU. Labor may be prolonged, with increased risk of retained placenta and hemorrhage. The woman may have polyhydramnios, and she may note that fetal movements are decreased.

Specialty Collaborations & Other Services

Medical Genetics (see NM providers [2])

Genetic consultation is recommended to help with diagnosis and to help families understand genetic test results so they can make family-planning decisions. [Kang: 2015] Genetic counseling for teens with congenital MMD should be offered on a developmentally appropriate basis.

Endocrine/Metabolism

Children with MMD may have a number of endocrine concerns including thyroid problems, diabetes, and delayed puberty. Typically, children with MMD require yearly screening labs including TSH and HbA1c. There are no specific treatment recommendations unique to MMD.

Specialty Collaborations & Other Services

Pediatric Endocrinology (see NM providers [4])

Refer if complications arise.

Mental Health/Behavior

Cognitive behavioral therapy (CBT) is vitally important in the management of POTS-related symptoms. Up to a third of POTS patients have concurrent struggles with anxiety and/or depression and might require counseling or medication management for those problems.

Specialty Collaborations & Other Services

Therapy/Counseling > … (see NM providers [90])

Essential for management with CBT and, if needed, for treatment of depression and/or anxiety.

Developmental - Behavioral Pediatrics (see NM providers [2])

May be helpful if medications are needed for treatment of depression or anxiety.

Recreation & Leisure

Athletic activities enhance psychological health and help counter a drop off in gross motor function, in part due to de-conditioning, as the child grows. Success depends upon the appropriate choice of activities, adapted equipment, adapted rules for the special needs child when appropriate, and support from peers, other parents, and coaches. The medical home can foster participation by including these activities in the management plan. The need for adapted physical education and/or supports or social structuring on the playground should also be included in the child's IEP. There should be active promotion of social integration through leisure to reduce social isolation. The Portal's section on Assistive Technology may be helpful for parents interested in learning more about types of assistive technology.

Specialty Collaborations & Other Services

Physical Therapy (see NM providers [12])

A consultation can help with school and home adaptations (e.g., the child who wants a bike for a present, but the parents don't know what to purchase, or the child is interested in obtaining a sporting wheelchair).

Rec Centers, Parks, Zoos & Museums (see NM providers [10])

Appropriate choice of activities enhances physical benefits and helps reduce risk of social isolation.

Eyes/Vision

Strabismus and ptosis, sometimes requiring surgery, are common in children with congenital MMD. Refer children to an ophthalmologist at diagnosis and then as necessary for re-evaluation. Cataracts don't typically appear until adolescence, but they will need to be monitored for annually.

Specialty Collaborations & Other Services

Pediatric Ophthalmology (see NM providers [6])

Periodic visits starting at diagnosis are recommended.

Dental

Children with MMD have an increased risk of developing caries, plaque, and gingivitis. This may be due to mouth muscle and tongue weakness, decreased jaw opening, salivary pooling, reflux, and behavior problems interfering with oral hygiene. Early preventive care with frequent follow-ups as necessary is recommended. For many children with congenital MMD, sedation or anesthesia may be necessary for cleaning and/or dental work. [Engvall: 2009]

Specialty Collaborations & Other Services

Pediatric Dentistry (see NM providers [6])

Pediatric dentists who have training in dealing with children with special health care needs may be necessary for some children.

General Dentistry (see NM providers [12])

Although they do not have formal training, dentists on this list have expressed an interest in treating children with special health care needs.

Surgery

Patients with neuromuscular diseases are at increased risk of periprocedural complications, including airway problems, suboptimal pain control, pulmonary complications, prolonged recovery times, and complications from bed rest and deconditioning. [Kang: 2015] Before any surgical interventions and general anesthesia, physicians should discuss with families the increased risk of complications with families, especially because these factors may affect consent to certain elective procedures. [Kang: 2015] If surgery is needed, the anesthesiologist should be made aware of possible anesthetic complications and children should be monitored longer than usual in the immediate postoperative period to diagnose and treat respiratory, nutritional, mobility, and gastrointestinal complications. See Anesthesia & Myotonic Dystrophy - Risks & Recommendations (MDF) for a summary of important considerations when administering general anesthesia to children with muscular dystrophy.

Transitions

"Transition" refers to moving from the pediatric health care and educational environment to the adult health care system and occupational environment. Moving children of all abilities toward transition begins with messages of expectation, responsibility, and value. Although children with MMD in special education will be served by the school system until they turn age 22, start planning for transition in early adolescence and include consideration of vocational training and living arrangements (will the individual live alone, in a group home, etc.).
If necessary, apply for guardianship when the child turns 18. The often lengthy process usually includes psychological and medical evaluations and the involvement of a lawyer. At age 18, children in some states may become eligible for Medicaid or may qualify for resources with the Division of Services for People with Disabilities (DSPD) even if they were previously ineligible based on family income. Families may want to read Guardianship/Estate Planning for more information. Also, the Portal's Transition to Adulthood contains resources, checklists, and information about finding adult health care and insurance, guardianship and estate planning, living arrangements, and much more.
No Related Issues were found for this diagnosis.

Ask the Specialist

How would you treat pain in children with MMD?

Often, pain is actually myotonia. Rather than traditional pain medications, consider trying anti-myotonia medications.

Do I need to do anything special before my patient has surgery?

Yes. A number of complications are associated with myotonic dystrophy and surgery. Please see the anesthesia guidelines available at Anesthesia & Myotonic Dystrophy - Risks & Recommendations (MDF).

My patient has significant diarrhea and constipation. What should I do?

The first line of treatment is a high-fiber diet for either diarrhea or constipation. Constipation may be refractory and require other laxatives.

Resources for Clinicians

On the Web

Myotonic Dystrophy Type 1 (GeneReviews)
Detailed information addressing clinical characteristics, diagnosis/testing, management, genetic counseling, and molecular pathogenesis; from the University of Washington and the National Library of Medicine.

Myotonic Dystrophy (OMIM)
Information about clinical features, diagnosis, management, and molecular and population genetics; Online Mendelian Inheritance in Man, authored and edited at the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine

Learning about Myotonic Dystrophy (genome.gov)
Condition-specific information focused on the future of genomics research and genomic medicine; National Human Genome Research Institute.

Myotonic Muscular Dystrophy Type 1 (Orphanet)
Overview of MMD1 (aka Steinert myotonic dystrophy) and links to more information, services, and other resources; from Orphanet, a French-coordinated consortium involving over 40 countries to provide a portal for information about rare diseases and orphan drugs.

Myotonic Muscular Dystrophy Type 2 (Orphanet)
Overview of MMD2 (aka proximal myotonic myopathy) and links to more information, services, and other resources; from Orphanet, a French-coordinated consortium involving over 40 countries to provide a portal for information about rare diseases and orphan drugs.

Helpful Articles

PubMed search for myotonic muscular dystrophy in children and adolescents, last 3 years

Johnson NE.
Myotonic Muscular Dystrophies.
Continuum (Minneap Minn). 2019;25(6):1682-1695. PubMed abstract

Johnson NE, Ekstrom AB, Campbell C, Hung M, Adams HR, Chen W, Luebbe E, Hilbert J, Moxley RT 3rd, Heatwole CR.
Parent-reported multi-national study of the impact of congenital and childhood onset myotonic dystrophy.
Dev Med Child Neurol. 2015. PubMed abstract / Full Text

Johnson NE, Abbott D, Cannon-Albright LA.
Relative risks for comorbidities associated with myotonic dystrophy: A population-based analysis.
Muscle Nerve. 2015;52(4):659-61. PubMed abstract / Full Text

Ho G, Cardamone M, Farrar M.
Congenital and childhood myotonic dystrophy: Current aspects of disease and future directions.
World J Clin Pediatr. 2015;4(4):66-80. PubMed abstract / Full Text

Ho G, Carey KA, Cardamone M, Farrar MA.
Myotonic dystrophy type 1: clinical manifestations in children and adolescents.
Arch Dis Child. 2018. PubMed abstract

Clinical Tools

The Constipation provides clinical assessment tools and patient education about this common co-occurring condition.

Resources for Patients & Families

Myotonic Muscular Dystrophy (FAQ)
Answers to the common questions that parents may have about this condition. Provides links to other relevant high-quality websites.

Information on the Web

Myotonic Dystrophy (MedlinePlus)
Information for families that includes description, frequency, causes, inheritance, other names, and additional resources; from the National Library of Medicine.

Facts about Myotonic Muscular Dystrophy (MDA)
Excellent overview of myotonic muscular dystrophy written for the family and patient; Muscular Dystrophy Association.

National & Local Support

Myotonic Dystrophy Support Group (MDSG)
This support organization offers information about myotonic dystrophy, events, research, and more.

Myotonic Dystrophy Foundation
A non-profit that provides adaptive equipment and emotional support to individuals and families affected by any of the neuromuscular diseases.

Muscular Dystrophy Association
The Muscular Dystrophy Association (MDA) covers many conditions including CMT, Duchenne muscular dystrophy, and spinal muscular atrophy. More information about these conditions, how to register, and clinic locations can be found here.

Studies/Registries

Clinical Trials in Myotonic type 1 (clinicaltrials.gov)
Studies looking at better understanding, diagnosing, and treating this condition; from the National Library of Medicine.

National Registry of Myotonic Dystrophy Patients (University of Rochester)
Accelerates research in myotonic dystrophy and FSH dystrophy by connecting patients with researchers, collecting longitudinal data to track disease progression, and disseminating information to families, researchers, and care providers.

Myotonic Dystrophy Foundation Family Registry (PatientCrossroads)
Connects patients to researchers and allows patients to compare their symptoms with those of other patients.

Services for Patients & Families in New Mexico (NM)

For services not listed above, browse our Services categories or search our database.

* number of provider listings may vary by how states categorize services, whether providers are listed by organization or individual, how services are organized in the state, and other factors; Nationwide (NW) providers are generally limited to web-based services, provider locator services, and organizations that serve children from across the nation.

Authors & Reviewers

Initial publication: February 2016; last update/revision: October 2020
Current Authors and Reviewers:
Author: Lynne M. Kerr, MD, PhD
Reviewer: Nicholas Johnson, MD, MS-CI
Authoring history
2018: update: Lynne M. Kerr, MD, PhDA; Nicholas Johnson, MD, MS-CIA
2016: update: Meghan S Candee, MD, MScR; Nicholas Johnson, MD, MS-CIR
2013: first version: Nicholas Johnson, MD, MS-CIA; Lynne M. Kerr, MD, PhDA
AAuthor; CAContributing Author; SASenior Author; RReviewer

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The myotonic dystrophy experience: a North American cross-sectional study.
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Ho G, Cardamone M, Farrar M.
Congenital and childhood myotonic dystrophy: Current aspects of disease and future directions.
World J Clin Pediatr. 2015;4(4):66-80. PubMed abstract / Full Text

Ho G, Carey KA, Cardamone M, Farrar MA.
Myotonic dystrophy type 1: clinical manifestations in children and adolescents.
Arch Dis Child. 2018. PubMed abstract

Johnson NE.
Myotonic Muscular Dystrophies.
Continuum (Minneap Minn). 2019;25(6):1682-1695. PubMed abstract

Johnson NE, Abbott D, Cannon-Albright LA.
Relative risks for comorbidities associated with myotonic dystrophy: A population-based analysis.
Muscle Nerve. 2015;52(4):659-61. PubMed abstract / Full Text

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Johnson NE, Ekstrom AB, Campbell C, Hung M, Adams HR, Chen W, Luebbe E, Hilbert J, Moxley RT 3rd, Heatwole CR.
Parent-reported multi-national study of the impact of congenital and childhood onset myotonic dystrophy.
Dev Med Child Neurol. 2015. PubMed abstract / Full Text

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Endorsed by the American Academy of Pediatrics in March 2015.

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Theadom A, Rodrigues M, Roxburgh R, Balalla S, Higgins C, Bhattacharjee R, Jones K, Krishnamurthi R, Feigin V.
Prevalence of muscular dystrophies: a systematic literature review.
Neuroepidemiology. 2014;43(3-4):259-68. PubMed abstract / Full Text

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