No cure is currently known for muscular dystrophy, but physical therapy may help patients retain muscle function and strength (NIH 2012). A multidisciplinary approach involving neurologists, psychiatrists, physical and occupational therapists, speech and respiratory therapists, dietitians, psychologists, and genetic counselors is ideal. These professionals have to work together to meet the needs of each individual patient (Amato 2011).
Physical and Speech Therapy
Physical therapy is recommended as a general principle to prevent deformities and promote walking (Rocha 2010; NINDS 2011). Some scientists recommend active and/or passive stretching 4–6 days a week for specific joints or muscle groups to prevent or decrease the extent of contractures (Bushby 2010B). However, others have pointed out that stretching programs can often be painful and ineffective. Furthermore, in animal models, some forms of exercise were shown to cause a more rapid deterioration of muscle function; professional guidance is ultimately recommended when considering exercise programs (Morrison 2011).
Speech therapy is particularly useful for patients with weakened facial and throat muscles. Special communication devices, such as voice synthesizers, are also sometimes required (NINDS 2011).
Pharmacologic treatments for dystrophinopathies were deemed ineffective until 1974, when corticosteroids were demonstrated to provide a short-term increase in muscle strength (Griggs 2011; Morrison 2011). Some additional interventions have been developed since then that have improved muscular dystrophy treatment outcomes.
Corticosteroids have been shown to prolong the time that DMD patients can walk (by 2 years) and to prevent scoliosis (curvature of the spine). They are the only therapeutic strategy that has been consistently shown to be effective for the treatment of DMD (Malik 2012). Moreover, corticosteroids are the preferred therapy to increase muscle strength (Beytía 2012). While effective, researchers still are not sure exactly how corticosteroids work (Strober 2006; NINDS 2011). Based on experience, corticosteroid therapy should be initiated in boys with DMD who are able to walk before they experience a plateau in their physical performance, and well before they lose their ability to walk (Bushby 2005).
Weakening and enlargement of the heart occurs in over 90% of DMD patients over 18 (Manzur 2009). A historical cohort study of DMD cases undergoing repeated cardiac evaluations from 1998–2002 revealed that, if started before evidence of heart failure, corticosteroids can delay the development of heart rhythm abnormalities (Markham 2008).
Adverse effects of corticosteroid treatment include short stature, acne, fluid retention, weight gain, growth retardation, asymptomatic cataracts, glucose intolerance, osteopenia (lower bone density), and fractures (NINDS 2011). These side effects sometimes limit the long-term use of corticosteroids (Walter 2007; Morrison 2011). Growth failure is of particular concern in boys with DMD receiving high-dose glucocorticoids. In 2012, the first study was performed that examined the effects of growth hormone in boys with DMD who had glucocorticoid-induced growth failure. The study found that after 1 year, growth hormone helped improve growth and did not cause adverse cardiopulmonary or neuromuscular effects (Rutter 2012).
- Angiotensin-converting enzyme (ACE) inhibitors are used to treat congestive heart failure and hypertension. In an animal model that develops symptoms similar to DMD, ACE inhibitors help to protect against deterioration of the heart muscle (Politano 2012). Furthermore, human clinical evidence revealed that a >60-month treatment with perindopril (Coversyl®), a long-acting ACE inhibitor, delayed the onset of left ventricular dysfunction in children with DMD, although some have questioned the methodological rigor of the study (Politano 2012; Domingo 2011).
- Tumor necrosis factor-alpha (TNF-α) inhibitors. Drugs that bind to and inhibit the inflammatory cytokine TNF-α, such as etanercept (Enbrel®), help reduce local muscle inflammation and delay the damage to muscle cells (Wang 2009).
- Drugs that block muscle spasms, such as dantrolene (Dantrium®) and mexiletine (Mexitil®), have also been used to prevent DM-associated muscle spasms and weakness (NINDS 2011).
- Antiepileptics. The frequency of epilepsy is higher in people with DMD than the general population (Pane 2013). In these cases, antiepileptic drugs such as carbamazepine (Tegretol®, Carbatrol®), phenytoin (Dilantin®), clonazepam (Klonopin®), and felbamate (Felbatol®), are used to control seizures (NINDS 2011).
- Antibiotics are important for treating respiratory infections (NINDS 2011).
Supportive care has to be tailored to every patient’s particular circumstance and condition. Examples of this type of therapy include:
- Assisted ventilation is often needed in the later stages of muscular dystrophy to compensate for weakness in respiratory muscles (NINDS 2011). Daytime assisted ventilation is usually required in boys with DMD when their vital capacity, which is the maximum amount of air that can be exhaled after a forced breath, drops to 60% or below.
- Orthopedic devices, such as ankle-foot orthoses (orthopedic appliances that support deformed joints and/or bones), help prevent contractures and are often worn for life (NINDS 2011). Standing devices, such as knee-ankle-foot orthoses, have to be considered on an individual basis. They are usually offered to boys at the point when they can take only a few steps without help, and were shown to prolong walking for an average of 1.5–2 years (Kinali 2007; Guglieri 2011).
- Cardiac pacemaker implantation may be advised for some muscular dystrophy patients, as heart rhythm abnormalities may occur in some types of muscular dystrophy (Boriani 2003).
- Vaccination is important to prevent death from infectious diseases (eg, influenza) in patients with many types of dystrophy, who are especially prone to infection after respiratory failure (Amato 2011; Bushby 2010B; Guglieri 2011).
- Assistance with eating. Patients with DMD often have difficulty chewing and swallowing. Continued episodes of choking may lead to fear of eating and can prolong the length of mealtimes. Feeding difficulties were reported in 30% of DMD patients under age 25 (Aloysius 2008). A clinical assessment of swallowing is indicated when there is a 10% unintentional weight loss or a decline in the expected weight gain based on age (Bushby 2010B). Due to their swallowing difficulties, patients with oculopharyngeal muscular dystrophy could become socially withdrawn, and they should be advised about the possibility to eat before or after social gatherings, if they deem it necessary (Brais 2011).
- Pain management is a complex task in muscular dystrophies. Depending on the cause, pain management can range from physical therapy to drugs and, more rarely, orthopedic interventions (Bushby 2010B).
- Psychosocial management is an important intervention, particularly for more severe forms of muscular dystrophy. Treatment should be guided by prevention and early intervention. The increased rate of depression among DMD patients underscores the need to offer supportive interventions to patients and their families (Bushby 2010A).
Scoliosis represents a major problem in patients with muscular dystrophy, particularly when children lose the ability to walk (Strober 2006). In addition, when left untreated, scoliosis can further affect respiratory function (Finsterer 2006). Patients with DMD who are not treated with glucocorticoids have a 90% chance of developing significant scoliosis. Scoliosis is generally progressive and can cause vertebral compression fractures (a collapse of the vertebrae after being weakened by osteoporosis) and affect respiratory function. However, while daily glucocorticoid administration reduces the risk of scoliosis and/or delays its onset, it also increases the risk of vertebral fractures (Bushby 2010B).
Alternatively, surgery can be used to correct scoliosis. The best timing for surgery is generally when the patient’s lung function is still satisfactory and before symptomatic heart problems start (Finsterer 2006). For lower limb contractures, no unanimous recommendations exist with regard to the timing of surgery. The type of intervention depends on individual circumstances and whether they are performed during the patient’s ambulatory (mobile) or non-ambulatory period (Bushby 2010B). Spinal stabilization through surgery is usually recommended before the curve of the spine reaches 30 degrees, because at more advanced stages, cardiopulmonary weakness makes surgery more risky (Strober 2006). Spinal fusion prevents further deformation of the spine, straightens the spine, eliminates pain, and slows respiratory decline (Bushby 2010B). Surgery can also be used to correct eyelid ptosis (drooping eyelid) and can be performed in patients with OPMD. Finally, in patients with a moderate to severe impairment of swallowing, surgery can be used to improve swallowing (Brais 2011).