Myopathies are diseases characterized by primary muscle pathology.1 They can be inherited, acquired, associated with other diseases, or result from toxic exposures. The primary clinical manifestation of a myopathy is weakness, and accompanying symptoms can include (but are not limited to) wasting, cramps, spasms, myoclonus, contractures, and fatigue. Endurance and functional capacity are limited to varying degrees in different classes of myopathies. The pattern of weakness, constellation of associated symptoms, nature of progression, and other organ involvement together can point to a specific diagnosis (see Fig. 75–1).
Pattern of weakness in different disease states. Diagnostic evaluation of persistent weakness. Examination reveals one of seven patterns of weakness. The pattern or weakness in combination with the laboratory evaluation leads to a diagnosis. CK, creatinine kinase; DM, dermatomyositis; FSHD, facioscapulohumeral dystrophy; IBM, inclusion body myositis; MG, myasthenia gravis; OPMD, oculopharyngeal muscular dystrophy; PM, polymyositis. (Reproduced with permission from Amato AA, Brown RH, Jr. Muscular Dystrophies and Other Muscle Diseases. In: Kasper D, Fauci A, Hauser S, Longo D, Jameson J, Loscalzo J, eds. Harrison's Principles of Internal Medicine, 19e New York, NY: McGraw-Hill; 2014.)
An accurate diagnosis is important because it helps the clinician to develop appropriate management strategies.1 In this chapter, we will focus on the myopathies that are most likely to be seen by practicing physiatrists including muscular dystrophies, myotonic dystrophy, inflammatory myopathies, congenital myopathies, and critical illness myopathy. While a detailed description of these and other rare muscle disorders is beyond the scope of this chapter, it is important for physiatrists to be familiar with rehabilitation interventions that can greatly impact the quality of life of these patients.
The physiatrist plays an essential role in helping patients maintain function as much as possible and adapt to changes over time as muscle weakness progresses.2 Physiatrists also coordinate appropriate rehabilitation services as needed and provide guidance about equipment needs and timing. The rehabilitation team also connects patients and families with community support resources and services.
The primary rehabilitation goals for patients with muscle disease include engagement in the most appropriate exercise program, provision of appropriate bracing, mobility equipment, and assistive devices for completing activities of daily living, maintenance of independence to the greatest extent possible, education of patient and family about disease trajectory and expectations, and facilitation of patient autonomy in decision-making.2 Physiatrists can also link patients with clinical studies as appropriate and foster collaboration with multiple medical and rehabilitation specialties to provide a coordinated medical home for patients and families.2
The muscular dystrophies are a group of genetic disorders that cause degeneration of muscle and replacement of muscle with fat and connective tissue.1 The more common muscular dystrophies are Duchenne muscular dystrophy (DMD), Becker muscular dystrophy (BMD), facioscapulohumeral muscular ...