Myopathy
Myopathy refers to a broad category of muscle disorders characterized by muscle dysfunction, weakness, pain, deformity, and potential muscle wasting. These disorders are typically classified into two main categories: genetic and acquired. Genetic myopathies encompass a variety of inherited conditions such as muscular dystrophies, mitochondrial myopathies, and metabolic myopathies. In contrast, acquired myopathies can arise from factors such as electrolyte imbalances, infections, inflammation, toxins, or injury, and may vary in duration from transient to permanent.
Symptoms of myopathy primarily include muscle weakness, but this can manifest differently depending on the specific condition and affected muscle groups. While myopathy often does not involve the nervous system, some forms can lead to intermittent paralysis and progressive weakness. The complexity of myopathies makes diagnosis challenging, often requiring detailed medical histories and investigations into family backgrounds. Additionally, there is no universal cure for all forms of myopathy, and management may involve medications, therapies, or assistive devices, particularly when muscle weakness affects vital functions like breathing and swallowing. Understanding the nuances of myopathy is essential for effective treatment and support for those affected.
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Myopathy
Myopathy is a general term applied to disorders of muscles. It can include dysfunction, weakness, pain, and deformity as well as wasting. There are two categories used to describe the disorders: genetic and acquired. Of the latter classification, the condition may be transient or permanent, depending on the etiology. Acquired myopathy is most often the result of electrolyte imbalance, hormonal imbalance, infection, inflammation, or toxins. Injury is also commonly responsible. There are divisions of this classification, which include inflammatory, secondary to systemic disorders, and toxic. Genetic myopathies are divided into multiple categories as well: congenital, metabolic, mitochondrial, and muscular dystrophies. Each of the aforementioned categories is further subdivided.
It should be noted that toxic myopathy is inclusive of adverse reactions to common prescriptive drugs as well as alcohol and illicit drugs. Systemic disorders are far reaching and include endocrine, electrolyte imbalance, inflammatory diseases, and neurological injury/illness.
Overview
Aside from injury, the etiology of myopathy is rarely easy to diagnose. It is another of the many dysfunctions that are the result of an underlying anomaly rather than the source of the primary disorder. A thorough history to include that of family members may lead to a quicker determination than shotgun testing. It is important to know if the symptoms, such as weakness, had a delayed or sudden onset, whether the distal or proximal muscles are affected, and most definitely what medications or other chemicals may be present.
Myopathy most often does not involve the nervous system. Some forms of the disorder have periods of paralysis and, in many cases of genetic origins, become progressive. The condition is as diverse as the patients who are affected. The most common symptom among all is weakness; however, where that weakness occurs and the duration of the symptoms vary widely. But, weakness alone does not signal myopathy. Entities such as cerebral palsy, congenital hypomyelinating neuropathies, Eaton-Lambert myasthenic and Guillain-Barré syndromes, myasthenia gravis, and spinal muscular atrophy present with weakness as well. There is no one cause, nor one cure, that will resolve all myopathy.
Topic Today
Neuromuscular disorder research received a boost with the first-ever statistical analysis of three major genetic myopathies by the Muscular Dystrophy Association, results of which were published online July 8, 2013, in the journal Muscle and Nerve. The conservative estimate of annual cost of medical care per patient in the United States was $31,121, $22,533, and $17,451, respectively. However, the total cost to the nation of all three groups amounted to $1.07 to $1.37 billion per year.
If one considers these are but three of many myopathies, the financial impact has to be staggering. Muscular dystrophy is the umbrella name for thirty genetic diseases causing muscle weakness and loss. One estimate of muscular dystrophy incidence has been given at sixty-three per million worldwide. Given the difficulty in gathering statistics for the disease in the United States, the estimate may or may not be accurate for worldwide data.
On another level, there is the personal toll taken by the condition. With some myopathy the inherent weakness, be it intermittent or permanent, can have dangerous consequences. When the disability impacts normal functions, such as breathing and swallowing, assistive devices are available. Other sequelae can be controlled with medication, therapy, and even exercise. There is a big difference between a disease such as muscular dystrophy and other myopathies. Muscular dystrophy often destroys muscles, where myopathy in general is not subject to tissue death. Some hereditary myopathies, such as muscular dystrophy, tend to progress over the course of a patient’s lifetime; while there is no progression in other forms. That does not make it less distressing, just different.
With so many types of myopathies, it is difficult to generalize even within categories of inherent and acquired. There are few statistics available for myopathy morbidity and mortality as a group. Each division presents data for their own type, and that is often given in terms of statistical occurrence within a given population (i.e., 34.5 per 100,000). With little to no supporting studies, it is difficult to assess myopathies that are not as well publicized and studied. In fact, the previously mentioned study started with the three major groups plus spinal muscular atrophy, but the data was insufficient for the latter.
The study itself represents a leap in the effort to demonstrate the financial impact of one component of a group of disabling and devastating illnesses brought on individuals, families, and the nation. The study was done to drive funding by the government as well as become an incentive to pharmaceutical houses. Unfortunately, there is no hard data as yet published for myopathy rates other than those of genetic origin, such as those induced by corticosteroids or endocrine abnormalities.
Bibliography
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