Myotubular myopathy, also known as centronuclear myopathy, is a slowly progressive disease that causes drooping of the eyelids, foot drop, facial weakness, and other muscle weakness. Energy supplements to improve exercise tolerance in metabolic. To diagnose you may require clinical examination, graded exercise tests, and a muscle biopsy. In medicine, myopathy is a disease of the muscle in which the muscle fibers do not function properly. Oct 19, 2016 metabolic myopathies presenting with exercise intolerance, cramps, and myoglobinuria cramps and myalgia may occur after brief exercise or after prolonged physical activity. Patients with metabolic myopathies have underlying deficiencies of energy production in muscle due to a wide variety of defects.
This fact sheet will cover 10 of the more common metabolic diseases of muscle. Education of the patient regarding intervention is critical for understanding the problems associated with metabolic diseases of musculature. Metabolic refers to chemical reactions that provide necessary energy and nutrients for healthy muscle growth. Pdf mcardle disease and exercise physiology researchgate. Energy supplements to improve exercise tolerance in metabolic myopathies the safety and scientific validity of this study is the responsibility of the study sponsor and investigators. These disorders may include defects in glucose metabolism, lipid metabolism, or defects in oxidative phosphorylation. The genedx metabolic myopathy panel includes genes causing glycogen storage disorders, fatty acid oxidation disorders and other wellestablished metabolic myopathies. Metabolic myopathies by classification can be primary or secondary 5, 6. There are 10 metabolic diseases of muscle myopathies in mdas program. The first has onset in infancy, does not progress past adolescence, and is not incapacitating. Pdf mcardle disease glycogen storage disease type v. Accordingly, the three main categories of metabolic myopathies are glycogen storage diseases, fatty acid oxidation defects, and mitochondrial disorders due to. The presentation of metabolic myopathy is variable.
Energy supplements to improve exercise tolerance in. Prenatal diagnosis for known familial mutation s in atrisk pregnancies. The inflammatory process leads to destruction of muscle tissue, and is accompanied by weakness and sometimes pain. A number of other metabolic myelopathies, also frequently associated with other neurological dysfunction, have been characterized and should be considered in the diagnosis of patients with subacute or chronic myelopathies. Patients experience muscle weakness due to a dysfunction of the muscle fibers. These disorders usually present during periods of increased metabolic energy demand i. These include defects in lipid, glycogen, glucose, adenine nucleotide, and mitochondrial metabolism 1. Metabolic myopathies comprise a clinically and etiologically diverse group of disorders caused by defects in cellular energy metabolism, including the breakdown of carbohydrates and fatty acids to. Metabolic myopathies presenting with exercise intolerance, cramps, and myoglobinuria cramps and myalgia may occur after brief exercise or after prolonged physical activity. Avoiding rhabdomyolysis and myoglobinuria when overexertion triggers acute muscle breakdown rhabdomyolysis, muscle proteins are released into the blood and ultimately appear as rustcolored urine myoglobinuria.
Most patients with a metabolic myopathy eg, glycogen storage diseases, carnitine palmitoyltransferase deficiency have dynamic rather than static symptoms, and therefore usually complain of exercise intolerance or muscle pain. Among complex i gene defects, three have been found thus far in sporadic patients with myopathy. Pdf a diagnostic algorithm for metabolic myopathies. Some myopathies are genetic and can be passed from parent to child. The first five chapters describe the clinical approach to the patients who are suspected of having a metabolic myopathy, and summarize the role and the range of findings that may be seen with electromyography, muscle biopsy and magnetic resonance spectroscopy, and the. Integrative data mining highlights candidate genes for monogenic myopathies article pdf available in plos one 910. Metabolic myopathies stony brook school of medicine. These abnormalities can be detected and monitored via serum biomarkers. Metabolic myopathies muscular dystrophy association.
In some cases, the pathology extends to involve cardiac muscle fibers, resulting in a hypertrophic or dilated cardiomyopathy. Get a printable copy pdf file of the complete article 1. A myopathy is a muscle disease, and inflammation is a response to cell damage. The cpt codes provided are based on ama guidelines and are for informational purposes only. Metabolic syndrome is a progressive condition that encompasses a wide array of disorders with specific metabolic abnormalities presenting at different times.
Metabolic myopathies may present in different stages of life and can be difficult to diagnose. Pdf the investigation and management of metabolic myopathies. These metabolic diseases cause problems with the energy levels associated with activity. Cpt coding is the sole responsibility of the billing party. Metabolic refers to chemical reactions that provide energy, nutrients and substances necessary for health and growth.
You may require intravenous fluids to avoid kidney failure. The genetic causes for rhabdomyolysis include metabolic myopathy, disorders of intramuscular calcium release, mitochondrial disorders and muscular dystrophies. Some people with a metabolic myopathy muscle disease develop weakness. Metabolic myopathy definition of metabolic myopathy by. Myopathy refers to a clinical disorder of the skeletal muscles. It usually presents with episodic cramps, weakness or myoglobinuria after exertion or prolonged exercise. When benign entities are ruled out and metabolic myopathy is suspected, the first diagnostic step is to perform an electromyogram.
Metabolic myopathies mm are rare inherited primary muscle disorders that are mainly due to abnormalities of muscle energy metabolism resulting in skeletal muscle dysfunction. Disorders of muscle can be simplified into the following categories. Myopathy rhabdomyolysis panel by massively parallel sequencing bcmmitomengs sm. This meaning implies that the primary defect is within the muscle, as opposed to the nerves neuropathies or neurogenic disorders or elsewhere e. Pdf integrative data mining highlights candidate genes. Metabolic myopathies are a clinically and etiologically heterogeneous group of disorders due to defects in muscular energy metabolism. The patient then exercises that arm for 1 minute, after which repeat serum lactate and blood ammonia levels are measured. Myopathy is a general term referring to any disease that affects the muscles that control voluntary movement in the body. Metabolic myopathies should be considered in the differential diagnosis of exercise intolerance, and a detailed clinical approach will help determine which of the three main disorders glycogenoses, lipidrelated disorders, or mitochondrial diseases is the underlying cause. Although the use of highdose intravenous corticosteroids can result in druginduced myopathies adam mor, m. Myopathy, any skeletal muscle disorder that directly affects the muscle fibres and does not arise secondarily from disorders of the nervous system. Myopathies related to glycogen metabolism disorders europe pmc. A traditional test used in the evaluation of a suspected metabolic myopathy is the ischemic forearm test.
Over time, there can be loss of muscle bulk atrophy. This condition can cause severe kidney damage, and should be dealt with as an emergency see below. Listing a study does not mean it has been evaluated by the u. A metabolic myopathy due to absence of muscle phosphorylase. Metabolic myopathy a metabolic muscle disease or metabolic myopathy is established when the compromised functioning or weakening of muscles is caused by problems in metabolic functions such as the inability to process the energy resources of the body. Approach to patients with neuromuscular disease aaem.
Myopathies can be distinguished from other disorders of the motor unit, including the neuromuscular junction, peripheral nerve, or motor neuron, by characteristic clinical and laboratory features. Not all people with a metabolic myopathy experience the same symptoms. Those that begin in childhood or adulthood tend to be less severe, and changes in diet and lifestyle can help most people with the milder forms adjust. Myopathies are disorders affecting either the channel, structure or metabolism of skeletal muscle. What diet and exercise is best with metabolic myopathy. Mitochondrial myopathylactic acidosisdeafness is a type of metabolic myopathy described only in two sisters to date, presenting during childhood, and characterized clinically by growth failure, severe muscle weakness, and moderate sensorineural deafness and biochemically by metabolic acidosis, elevated serum pyruvate concentration. Lipid storage diseases are due to abnormal fat processing. The most common defect in sugar metabolism is mcardles disease. Others are acquired later in life and can be due to autoimmune disease, known. Most patients with a metabolic myopathy eg, glycogen storage diseases, carnitine palmitoyltransferase deficiency have dynamic rather than.
The symptoms, signs, and laboratory abnormalities resulting from a metabolic myopathy vary with the underlying defect. This topic will briefly describe fatty acid oxidation disorders faods, which are inborn errors of metabolism resulting in failure of. However, recurrent rhabdomyolysis is often genetic in nature. Those who do not develop a form of a metabolic myopathy until they are in their young adult or adult life tend to have more treatable symptoms that can be helped with a change in diet and exercise. Accordingly, the three main categories of metabolic myopathies are glycogen. Metabolic myopathies have varying levels of symptoms, being most severe when developed during infancy. Metabolic myopathies are genetic diseases, usually inherited, that affect the bodys muscles. When these symptoms are associated with physical exertion, a metabolic myopathy should be suspected although inflammatory myopathies may present with similar features, such a pattern should prompt a thorough evaluation for an underlying metabolic myopathy. Primary metabolic myopathy as a type of congenital myopathies was first described by mcardle in 1951. Accordingly, the three main categories of metabolic myopathies are glycogen storage diseases, fatty. A spontaneous mouse model of xlinked myopathy with excessive autophagy 4 introduction a myopathy is a muscular disease in which the muscle fibers do not function resulting in muscular weakness. The metabolic myopathies are a heterogeneous group of genetically determined conditions that may present at any age box 1.
Nemaline myopathy, also known as rod body disease, develops from birth. A diagnostic algorithm for metabolic myopathies springerlink. May 19, 2015 energy supplements to improve exercise tolerance in metabolic myopathies the safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Mitochondrial myopathiesin this condition, the mitochondria of the cells are affected. All may result in fatigue and functional limitations such as impaired exercise capacity. Myopathies are marked by muscular degeneration and weakness and may have a genetic or nongenetic basis. This is performed by obtaining baseline serum ammonia and lactate levels taken from the forearm. Here you can read posts from all over the web from people who wrote about metabolic myopathy and rhabdomyolysis, and check the relations between metabolic myopathy and rhabdomyolysis. Medical genetics test details baylor genetics laboratories. Full text full text is available as a scanned copy of the original print version. Please direct any questions regarding coding to the payer being billed.
Some of these disorders share a common pathogenetic mechanism and similar pathological findings with the myelopathy of vitamin b12 deficiency and. However, some patients of metabolic myopathies present with fixed or slowly progressive wecikness. Metabolic muscle diseases that have their onset in infancy tend to be the most severe, and some forms are fatal. Confirmation of a clinical diagnosis can help direct treatment and medical management.
Metabolic myopathies are rare genetic diseases that cause muscle problems. The name of each metabolic myopathy is based on which pathway doesnt have enough enzymes. Metabolic myopathies american college of rheumatology. Facts about metabolic diseases of muscle md australia. Metabolic myopathies are genetic disorders of energy metabolism due to defects in the pathways of carbohydrate and fatty acid catabolism, and the subsequent energy production through mitochondrial oxidative phosphorylation. The next step would be to perform an ischemic exercise test.
Metabolic myopathies comprise a clinically and etiologically diverse group of disorders caused by defects in cellular energy metabolism, including the breakdown of carbohydrates and fatty acids to generate adenosine triphosphate, predominantly through mitochondrial oxidative phosphorylation. Abnormalities of muscle cell structure and metabolism lead to various patterns of weakness and dysfunction. Links to pubmed are also available for selected references. Mitochondrial myopathies 148and only patients with mutations in cox genes showed predictably coxnegative rrf as well as nonrrf, thus contradicting the fourth dogma. The degree of exercise intolerance in the metabolic myopathies varies greatly between disorders and even from one individual to the next within a disorder.
Metabolic myopathy an overview sciencedirect topics. This is a defect in the metabolic pathway and can interfere with atp energy production causing pain and cramping in muscles and joints and easy fatigue after and during exercise. However, metabolic myopathies may predispose to statininduced myopathy or may be unmasked as a result of increased creatine kinase testing in patients on statins. For example, diseases caused by a defect in sugar metabolism are called glycogen storage diseases. Mitochondrial myopathy with lactic acidosis genetic and. The typical manifestations of a metabolic myopathy are exerciseinduced myalgias, exercise intolerance, and cramps. They include glycogen storage diseases, fatty acid oxidation defects, and mitochondrial disorders. Fusionner pdf, fusionner des fichiers pdf, diviser des fichiers pdf. Metabolic myopathy refers to a group of disorders that limit production of adenosine triphosphate atp 105. Metabolic myopathies are a group of genetic muscular diseases resulting from defective metabolism affecting primarily muscles. However, the term mitochondrial dna depletion syndrome. Mitochondria are the energygenerating part of the human cells.
The most common druginduced myopathies seen by rheumatologists are probably caused by corticosteroids. These include defects in lipid, glycogen, glucose, adenine nucleotide, and mitochondrial metabolism. This chapter book comes from a respected multidisciplinary group of myologists who are affiliated with oxford university. They are characterised by defects in the biochemical pathways of storage, mobilisation and utilisation of the substrates of muscle energy generation. Also, for metabolic myopathy a test called forearm ischemia exercise test can be done. Glycogen is the main source of energy during brief exercise, while free fatty acids are the most important source of fuel during prolonged exercise. Metabolic myopathies are rare, genetic disorders that cause muscle problems. This condition is known by different names such as kearnssayre syndrome and leighs syndrome. Glycogen storage disease is a disease caused by genetic mutations involved in glycogen. This messures the levels of lactic acid and ammonia in the blood before and after exercise to see if the muscles are able to use glucose and fats as their energy source. Md is a metabolic myopathy caused by a deficiency in muscle glycogen phosphorylase.
The first five chapters describe the clinical approach to the patients who are suspected of having a metabolic myopathy, and summarize the role and the range of findings that may be seen with electromyography, muscle biopsy and magnetic resonance spectroscopy, and the normal response of skeletal muscle during exercise. Recommendations for energy, diet, and exercise are difficult because diagnosis is sometimes missed. Metabolic myopathies are genetic disorders that impair intermediary metabolism in skeletal muscle. Another alarming trend is the increased incidence of metabolic syndrome in young people. For instance, some people may run into trouble only when jogging, while others may have trouble after mild exertion such as walking across a parking lot or even blowdrying their hair. Metabolic myopathies are inherited and tend to run in families. Hyperthyroid myopathy does have a genetic predisposition like most other autoimmune diseases. A diagnostic algorithm for metabolic myopathies ncbi. May 01, 2014 mitochondrial myopathy lactic acidosisdeafness is a type of metabolic myopathy described only in two sisters to date, presenting during childhood, and characterized clinically by growth failure, severe muscle weakness, and moderate sensorineural deafness and biochemically by metabolic acidosis, elevated serum pyruvate concentration. Mar 12, 2018 patients with metabolic myopathies have underlying deficiencies of energy production in muscle due to a wide variety of defects.
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