Myotonic Dystrophy Foundation

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Physical Therapy Assessment

During an initial evaluation a physical therapist will obtain a detailed history of the symptoms and/or problems, how they have changed over time, factors that make them better or worse and how they affect the daily activities and lives of the affected individual. Information regarding the person’s occupation, lifestyle, leisure activities, and their role in the family unit is essential to the evaluation process.

As stated before, myotonic dystrophy is a systemic condition. It is therefore important for the physical therapist to perform a systems review, according to the Guide to Physical Therapy,4 including cognition/communication, the musculoskeletal system, the neuromuscular system, the cardiovascular/pulmonary system, and the integumentary/skin system.

People with myotonic dystrophy can have difficulties in both cognition and communication. Up to a third of individuals with DM1 may have symptoms related to central nervous system involvement.2 The symptoms include somnolence, apathy, specific personality traits, depression and fatigue. More recently Meola 5and Gaul6have documented executive function deficits. These cognitive deficits may impact a person’s ability to comply with recommendations and are important to take into consideration when establishing a plan of care or management program. Communication difficulties can arise as a result of weakness of the facial muscles as well as the presence of myotonia in the jaw and tongue2. This not only impacts proper communication between patients and care providers, but also has an effect on social communication leading to some of the psychosocial issues mentioned previously.

The neuromuscular and musculoskeletal systems are often the focus of the examination, as weakness and resulting functional difficulties are often the most disabling features of the disorder. The most common pattern of muscle involvement in DM1 includes the facial (masseter and temporalis) muscles, neck muscles (sternocleidomastoids), long finger flexors of the hand and ankle dorsiflexors, 2 muscle involvement usually begins in the teens, twenties or thirties and is slowly progressive. The weakness progresses from the distal to proximal muscles. Muscular weakness in congenital myotonic dystrophy presents during the neonate period with generalized hypotonia. In DM2 the muscular involvement is predominantly proximal and also slowly progressive, beginning in the ‘mid-adult’ life. Currently, there are no reports of a childhood or congenital form of DM2.2It is critical that physical therapists are knowledgeable in manual muscle testing for all muscles, as the pattern of weakness can be predictive of both the disease itself as well as mobility concerns that may arise. Strength can also be measured more objectively by hand-held dynamometers as well as expensive systems such as a Quantitative Muscle Assessment (QMA) system. QMA systems are often utilized in the research setting. Normative data for both of these methods have been established in the pediatric as well as adult populations. 7-10

Myotonia is the other musculoskeletal manifestation of myotonic dystrophy. Myotonia is the inability to relax a muscle after a forceful contraction.11, 12 Individuals with myotonia affecting the hand musculature often report difficulty releasing their grip after a vigorous handshake which creates an embarrassing social situation. Complaints of myotonia are also reported in the jaw and tongue leading to difficulties with speech, swallowing and chewing. Myotonia in the leg muscles may lead to difficulty with movements like climbing stairs, running etc. Symptoms of myotonia may also be present in other parts of the body. Often patients will report that their myotonia symptoms are worse in cooler temperatures.2 Myotonia has been managed by anti-myotonic medications such as Mexiletine.12.

Myotonic dystrophy is a slowly progressive disease and as strength decreases, individuals may become adept in substituting less affected muscles to perform movement. Hence it is important to assess simple functional activities, including the ability to get up from a chair, ambulate, and climb stairs. These functional tasks can also be timed and used as outcome measures to document benefits of interventions or to monitor the progression of the disease. Assessment of hand function, including grip strength, is also important in this population. Detailed information related to hand function testing and treatment is provided in the section on occupational therapy.

The cardiovascular system can be compromised by the presence of cardiac arrhythmias and conduction defects as well as involvement of the cardiac muscle itself. Insufficiency of the respiratory system may be a result of both myotonia and weakness in the muscles that control respiration.3 This often leads to a reduced vital capacity later in the disease. Individuals with myotonic dystrophy who have reduced respiratory function are often at more risk for pulmonary complications such as pneumonia.3 When making exercise recommendations for a home program, it is essential to educate individuals about how to monitor the cardio respiratory responses with simple tools like pulse monitors, Borg scale, etc. It is essential that individuals report their responses to the exercises to the person overseeing and/or monitoring the home program. It is also important to explain to the individual the need to continue normal air exchange during strength training as val salva maneuvers, or breath holds may affect the heart rhythm.13 Depending on the progression of their disease, individuals with myotonic dystrophy may have limited exercise tolerance and will need to be monitored carefully.13

The integumentary system is not usually involved as the sensory system is spared in myotonic dystrophy. However, if poor mobility is demonstrated and bony prominences are exposed secondary to muscle wasting, the integumentary system may require attention.

Pain is a common complaint among individuals with DM1 and DM2. 14-16 In a study by Jensen et al., complaints of pain were reported most commonly in the low back and legs. Pain has been reported to be more severe in individuals who have mobility limitations and use assistive devices than those who have mobility limitations and do not use assistive devices.16 Individuals with myotonic dystrophy experience pain for many years and pain interferes with daily activities. Therefore, pain should be assessed and addressed in the treatment plan as necessary.

Lastly, it should also be mentioned that many of these individuals have gastrointestinal manifestations that may be present anywhere along the digestive tract. Symptoms reported span the spectrum of dysphasia and heartburn to abdominal pain and changes in bowel function.17, 18 It is important to note that the involvement of the GI system may be very disabling to the person and again, may impact the person’s ability to participate in exercise programs.

 Next: Physical Therapy Management