From the Guidelines
Myotonic dystrophy patients should receive multidisciplinary care focusing on symptom control and supportive care, as there is no cure, with particular attention to cardiac monitoring, physical therapy, and management of myotonia with medications like mexiletine or phenytoin, as recommended by the American Heart Association 1. The management of myotonic dystrophy involves a comprehensive approach to address the various symptoms and complications associated with the disease.
- Myotonia can be managed with medications such as mexiletine, typically dosed at 150-200mg three times daily, or phenytoin, which can help alleviate the delayed muscle relaxation after contraction.
- Muscle weakness requires physical therapy and possibly the use of mobility aids to maintain independence and prevent further decline.
- Cardiac monitoring is crucial, as patients with myotonic dystrophy, particularly those with type 1 (DM1), are at risk of developing conduction abnormalities that may require pacemaker placement, with approximately 80% of DM1 patients experiencing cardiac manifestations 1.
- Regular eye exams are necessary to detect cataracts, which frequently develop in these patients.
- Respiratory support may be needed, especially during sleep, and patients should be monitored for swallowing difficulties to prevent complications.
- Endocrine issues, such as diabetes and thyroid dysfunction, require appropriate screening and treatment.
- Genetic counseling is important for family planning, given the autosomal dominant inheritance pattern of the disease. The disease's progression and the presence of multiple systemic involvements necessitate a multidisciplinary care approach, involving neurologists, cardiologists, pulmonologists, and other specialists, to provide the best possible outcomes for patients with myotonic dystrophy, as outlined in the American Heart Association's scientific statement on the management of cardiac involvement associated with neuromuscular diseases 1.
From the Research
Myotonic Dystrophy Overview
- Myotonic dystrophy is a progressive multisystem genetic disorder with two main types: type 1 and type 2 2
- Type 1 is the most prevalent muscular dystrophy in adults, with a wide phenotypic spectrum and an average age of death in the fifth decade 2
- Type 2 tends to cause a milder phenotype with later onset of symptoms and is less common than type 1 2
Diagnosis and Management
- Diagnosis of myotonic dystrophy involves genetic testing, which is diagnostic and identifies those at risk for cardiac complications 3
- Management of myotonic dystrophy requires a multidisciplinary approach, including medical, rehabilitative, and social teams 2
- Cardiac management should include surveillance for arrhythmias and left ventricular dysfunction, both of which occur in a progressive manner and contribute to morbidity and mortality 3
Treatment Options
- Mexiletine, a class 1b antiarrhythmic sodium antagonist, has been shown to be effective in reducing myotonia in patients with myotonic dystrophy type 1 4, 5
- Mexiletine is safe and well-tolerated in patients with myotonic dystrophy, but cardiac assessments should be reinforced due to potential proarrhythmic effects 6
- Expert opinion recommends guiding mexiletine treatment in patients with myotonic dystrophy to reduce the risk of severe adverse events and facilitate interactions between specialists 6