Myopathies are muscle diseases. In most cases, the striated skeletal muscles are affected. For example, muscular dystrophies or myotonic syndromes belong to the group of myopathies.
What are myopathies?
The term myopathy comes from Greek and means muscle disease. Accordingly, myopathies are diseases of the muscles. They usually affect the striated muscles of the skeleton. However, diseases of the heart muscle, known as cardiomyopathies, also belong to the group of myopathies. Myopathies must be distinguished from other diseases that are also associated with a weakness of the musculature. For example, amyotrophic lateral sclerosis or spinal muscular atrophy are not myopathies. They belong to the motor neuron diseases. Myopathies can be divided into primary and secondary myopathies.
Causes
Primary myopathies are based primarily on diseases of the musculature. Thus, no other disease underlies them. Muscular dystrophies are among the degenerative primary myopathies. These include:
- Limb-girdle dystrophy,
- The facioscapulohumeral muscular dystrophy.
- The congenital muscular dystrophy.
Most muscular dystrophies are genetic. Myotonic syndromes such as myotonic dystrophy type 1, myotonic dystrophy type 2, paramyotonia congenita Eulenburg or myotonia congenita Thomsen are also inherited. Congenital myopathies already show up in newborns. Disease patterns such as nemaline myopathy, central core myopathy or myopathy with congenital fiber type disproportion are also caused by genetic defects. The same is true for mitochondrial myopathies. Due to a [[ mutation]] in the DNA of the mitochondria, the mitochondria are diminished or altered. This results in a disruption of energy metabolism within the cell organelles. Myopathies also occur in the context of other underlying diseases. These muscle diseases are also referred to as secondary myopathies. Secondary myopathies are often the result of diseases of the endocrine system. They occur in hyperthyroidism or hypothyroidism, Cushing’s disease, and parathyroid disorders (hypo- or hyperparathyroidism). Metabolic diseases can also be manifested by myopathies. Muscles require a lot of energy. Therefore, disorders of energy metabolism in particular manifest themselves in the muscles. Important diseases here are lipid storage disease or glycogen storage disease. Myopathies can also be the result of nutrient deficiency. For example, muscle diseases occur with vitamin D deficiency or with selenium deficiency. Inflammatory myopathies occur in autoimmune diseases or infectious diseases. Trichinosis is an infectious disease that commonly causes myopathies. Autoimmune diseases with myopathies include polymyositis and inclusion body myositis.Myopathies can also be triggered by drugs, alcohol abuse, or other exogenous toxins.
Symptoms, complaints, and signs
The characteristic symptom of all myopathies is muscle weakness. In the muscular dystrophies, muscle degeneration occurs in addition to progressive muscle weakness. Congenital myopathies begin immediately after birth or in the first months of life. The muscles develop too slowly or incompletely. The children cannot operate their muscles against gravity. Myotonic syndromes are characterized by a pathologically prolonged phase of muscle tension. An inflammatory process underlies the inflammatory myopathies. In addition to muscle weakness, there is redness and overheating of the muscles. Pain is also possible. If the heart muscle is affected by myopathy, conduction is impaired. The result is cardiac arrhythmias. As a result of mitochondrial myopathy, brain function may be impaired. Symptoms similar to stroke may occur. These phenomena are also referred to as MELAS syndrome. Mitochondrial myopathy is a multisystemic disease. The eyes or inner ear may also be affected. Damage to the retina and optic nerve can lead to blindness. The development of diabetes mellitus is also favored by mitochondrial myopathy.
Diagnosis and disease progression
Initial evidence of myopathy is provided by muscle weakness as a characteristic syndrome.In a detailed medical history, the physician clarifies possible risk factors or causes. If a muscle disease is suspected, a blood laboratory can be performed. In muscular dystrophy, the creatine kinase (CK) in the blood serum is elevated. This increases when skeletal muscle fibers are lost. The elevation of creatine kinase in the blood is called hypercreatinemia. Aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), and lactate dehydrogenase (LDH) are also elevated, but they are not as sensitive or specific as serum creatine kinase. The level of creatine kinase differs quite markedly between muscular dystrophies. The value can therefore also be used for differential diagnosis. To confirm the diagnosis, a muscle biopsy is performed in most myopathies. Depending on the type of disease, different typical structures show up in the histologic examination.
Complications
Myopathy primarily causes severe muscle weakness. The resilience of the affected person decreases significantly and there are severe limitations in everyday life. The affected persons appear tired and weary due to the disease and can thereby no longer perform ordinary activities of daily living. It is not uncommon for myopathy to also lead to complaints of the heart, so that disturbances of the heart rhythm can occur. In the worst case, the affected person can also die of sudden cardiac death as a result of this complaint. The discomfort at the heart continues to have a negative effect on the conduction of stimuli. In some cases, myopathy causes paralysis and further limits sensitivity. Motor function may also be negatively affected by this disease. It is still not uncommon for those affected to suffer from diabetes. Treatment of myopathy can take place with the help of medication and through therapies and exercises. This can limit and reduce many symptoms. However, it is usually impossible to predict whether a complete cure will occur. Complications can occur if a tumor has also developed. Due to this, the patient’s life expectancy may be reduced.
When should you see a doctor?
A persistent general feeling of illness as well as internal weakness should be clarified by a physician. If there are disturbances of the metabolism or irregularities of the heart rhythm, a visit to the doctor should be made to clarify the cause. Sleep disturbances, a lack of concentration and attention as well as a decrease in general performance should be examined and treated. If there is an increased need for energy, rapid fatigue or reduced ability to work under pressure, there is a health impairment that should be clarified. If there is general dysfunction, loss of vision or hearing, a physician is needed. Internal irritability, sensory disturbances, numbness of the skin and hypersensitivity to temperature or touch, should be discussed with a physician. Inflammation of the muscles, an internal heat development, an increased need for fluids as well as headaches are signs of the organism for a present illness. If there are interruptions of consciousness, muscle weakness or malaise, it is necessary to consult a doctor. Discoloration of the skin is considered a warning sign and should be presented to a physician. Heart palpitations, sleep disturbances, restlessness, and emotional abnormalities should also be discussed with a physician. With changes in behavior, a depressive demeanor or mood swings, sequelae can occur that must be considered when making a diagnosis. They may indirectly worsen an existing disorder or trigger further disorders that should be treated.
Treatment and therapy
Primary myopathies usually cannot be treated causally because they are based on a genetic defect. Depending on the myopathy, various medications are used to treat the symptoms. Physiotherapy can also help those affected. In secondary myopathies, the focus is on treating the underlying disease. Hypothyroidism is treated with thyroid hormone preparations. In hyperthyroidism, thyrostatic drugs are administered. Cushing’s disease is treated with synthetic glucocorticoids. If Cushing’s disease is caused by a tumor, it must of course be removed.Nutritive myopathies require nutrient substitution. Myopathy with cardiac involvement is usually treated additionally with cardiac strengthening drugs and antiarrhythmic drugs.
Outlook and prognosis
Myopathy is unlikely to be cured outright until appropriate advances in genetics occur in the coming years. In some forms of myopathy, a prospect for cure is rather poor, as there are certainly cases with fatal outcomes. This is especially the case in very young children and newborns who are born with congenital myopathy and at the same time with other health disorders. This contrasts with affected individuals with myopathies that have minimal symptoms, with a normal life expectancy. These milder myopathies do not progress and, moreover, can be well controlled with today’s modern treatment methods. Affected children also cope well with some forms of myopathy into adulthood and often well into old age. In particular, the life expectancy and quality of life of patients with congenital and non-congenital myopathy have improved in recent years. Life-threatening symptoms are extremely rare and occur only in isolated cases. The majority of myopathies nowadays show increasing recovery rates and significant improvements in well-being, even if a cure is not always possible. The prognosis of myopathy is therefore extremely variable and individual. Moreover, to date, myopathies can only be treated causally or, depending on the type, only predominantly symptomatically.
Prevention
Primary myopathies are inherited. Prevention is not possible in this case. Secondary myopathies can be prevented by early detection and treatment of the underlying disease. Adequate intake of nutrients and vitamins such as vitamin D or selenium can reliably prevent nutritive myopathies.
Follow-up
In most cases of myopathy, the measures or options for direct follow-up are significantly limited. For this reason, the affected person should ideally see a physician at an early stage to prevent the occurrence of other complaints and complications. As a rule, the condition cannot heal on its own, so treatment by a physician is always necessary. The earlier a doctor is consulted in the case of myopathy, the better is usually the further course of the disease, so that the early diagnosis is in the foreground. As a rule, patients with myopathy are dependent on taking various medications. Attention must be paid to the correct dosage and regular intake. Most sufferers are dependent on regular examinations and checks by a doctor so that further tumors can be detected at an early stage. Eventually, myopathy leads to a reduced life expectancy of the patient, although the further course is very much dependent on the exact manifestation of the disease.
What you can do yourself
In genetic myopathy, treatment can only relieve symptoms and aim to improve quality of life. This includes regular participation in physiotherapy. Especially with water gymnastics very good results could be achieved in the field of muscle building. In general, a balanced diet and a healthy balance of stress and relaxation have a supportive effect. In the case of secondary myopathy, the underlying disease can be treated and thus the muscle weakness remedied. Affected persons should first check their consumption of medications, alcohol and other stimulants. If there is a nutrient deficiency, this can be compensated for by a targeted diet. It may also be possible to start a targeted nutrient therapy. For example, the intake of selenium has been shown to help with this form of muscle weakness. Selenium is also recommended as a supplement to hormone intake in cases of existing hypothyroidism. Especially in the case of an existing autoimmune disease, a healthy lifestyle with sufficient sleep, fluid intake and stress reduction (autogenic training, yoga) is fundamentally important. Since myopathy is mostly inherited and even young children show symptoms, parents of affected children should seek advice at an early stage or seek support themselves in a self-help group or psychological support.The psychological strain on those affected and their parents should not be underestimated. Affected families can also apply for household support from the statutory health insurance funds.
