Early detection may happen when patients, family or friends realize there is a reason for these physical limitations. Placing patients into one of these categories based on their risk factors, history, and physical exam findings can help to focus the diagnostic workup on areas most. Neutral lipid storage disease with myopathy genetics. These diseases can be categorized as disorders of lipid metabolism, glycogen and glucose metabolism, or mitochondrial myopathies that impair both lipid and glucose metabolism. Metabolic myopathies are disorders of utilization of carbohydrates or fat in. Pdf metabolic myopathies mm are rare inherited primary muscle disorders that are mainly due to abnormalities of muscle energy. Diagnostic delays are common and clinicians need a high index of suspicion to recognise and differentiate metabolic myopathies from other conditions that present in. Metabolic myopathies are a diverse group of inherited biochemical diseases involving limitation of the use of fuels by skeletal muscle to generate energy. A clinical approach to muscle diseases university of chicago. These problems range from stiffness called myotonia to weakness, with different degrees of severity. Metabolic myopathies are rare diseases, so diagnosis and treatment may be delayed. However, for some, these are the symptoms coming from metabolic myopathy. Impairments in glycolysisglycogenolysis glycogenstorage disease, fatty acid transport and oxidation fatty acid oxidation defects, and the mitochondrial respiratory chain mitochondrial myopathies represent the majority of known defects. The main symptom of most of the metabolic myopathies is difficulty performing some types of exercise, a situation known as exercise intolerance, in which the person becomes tired very easily.
Metabolic myopathies are a diverse group of rare genetic disorders and their associated muscle symptoms may be subtle. Inflammatory myopathies fact sheet national institute of. 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 myopathies may cause symptoms that are normal among healthy people. Metabolic myopathies and the respiratory system clinics in chest. Update 2009 metabolic myopathies are inborn errors of metabolism that result in impaired energy production due to defects in glycogen, lipid, mitochondrial. A patient that presents with muscle weakness can have any of these. The episodic disorders are characterized by acute loss of strength that can return to. Although some experts have considered myoadenylate deaminase deficiency to be part of the group of metabolic myopathies,2,3 it is not directly involved in intermediary metabolism, and its role in causing a metabolic defect in muscle is seriously questioned. Apart from the manual muscle testing for muscle strength, the examination of. More specifically, myopathies are diseases that cause problems with the tone and contraction of skeletal muscles muscles that control voluntary movements. Metabolic myopathies associated with energy defects involve primarily defects in fao, glycogenolysis, glycolysis, oxidative phosphorylation, and mitochondrial disorders. Metabolic myopathies are rare genetic diseases that cause muscle problems.
Links to pubmed are also available for selected references. The metabolic myopathies are a group of muscle disor ders resulting from failed energy production related to defects in glycogen, lipid, or mitochondrial. The goal of treatment is to control symptoms and minimize progression of muscle weakness. Pdf metabolic myopathies comprise a clinically and etiologically diverse group of disorders caused by defects in cellular energy metabolism, including. The most common myopathies seen in the neuromuscular center are inflammatory myopathies, muscular dystrophies, metabolic myopathies, myopathies associated with systemic disorders, and myopathies due to certain medications. People with this condition have muscle weakness myopathy due to the accumulation of fats in muscle tissue. 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. As with peripheral neuropathies and mg, the diagnosis of myopathies requires a neurologic history and. Metabolic myopathies are the most clearly defined and etiologically understood muscle disorders because their fundamental biochemical defects are known through recent developments in molecular biology and biochemistry. Some affected individuals also experience muscle stiffness, aching, or cramps. Diagnostic delays are common and clinicians need a high index of suspicion to recognise and differentiate metabolic myopathies from other conditions that present in a. Introduction the metabolic myopathies are a hetero. This article provides an overview of the most common metabolic myopathies. People with mitochondrial myopathies also may experience muscle weakness in their arms and legs.
Myopathy is a general medical term used to describe a number of conditions affecting the muscles. Pdf the investigation and management of metabolic myopathies. Mitochondrial myopathy fact sheet national institute of. Evaluation of the patient with muscle weakness american. Metabolic myopathies can have symptoms that are similar to those of many other conditions. Neutral lipid storage disease with myopathy is a condition in which fats lipids are stored abnormally in organs and tissues throughout the body. Get a printable copy pdf file of the complete article 1. Inherited metabolic myopathy and hemolysis due to a mutation in aldolase a.
Metabolic myopathies are myopathies that result from defects in biochemical metabolism that primarily affect muscle. We outline key features in the history and examination and discuss some mimics of metabolic myopathies. Myopathies pdf myopathies are classified as either inherited or acquired. We highlight some disorders of glycogen and fatty acid utilisation that present in adulthood and outline current recommendations on management. Myofibrilar myopathy mfm is a neuromuscular disease characterized by slowly progressive muscle weakness that can involve both proximal muscles such as hips and shoulders and distal muscles those further away from the trunk. There are 10 metabolic diseases of muscle myopathies in mdas program. They are generally genetic defects that interfere with muscles ability to create energy. Metabolic myopathies are rare, so diagnosis can be delayed.
Metabolic myopathies renaissance school of medicine. In both glycogen and lipid storage myopathies, quantitative measurement of the deficient enzyme will confirm the diagnosis. Symptoms typically include exertional fatigue, cramping, myalgia and myoglobinuria which usually occur during periods of high energy. Pdf a diagnostic algorithm for metabolic myopathies. The mechanism of exercise intolerance for each of the diseases is discussed in detail elsewhere in this article. Their clinical spectrum is very wide and ranges from infantileonset to adultonset forms and includes fixed myopathies, exercise. Treatments include changes in physical activity and diet, aerobic and anaerobic resistance exercise training, and the use of various vitamins and supplements. The diet, levels of physical activity and dietary supplements recommended for. It is rare for a muscle disease to be responsible for vague 14 table 11 classification of myopathies hereditary. Despite the fact that metabolic myopathies are inherited, treatments can help many people with these diseases live normal lives. Not all people with a metabolic myopathy experience the same symptoms. The metabolic myopathies are a heterogeneous group of disorders that share the common feature of inadequate production of cellular energy in the muscle. Patients may present with indolent myopathic features, exercise intolerance or recurrent rhabdomyolysis. Metabolic myopathies are muscle disorders caused by a biochemical defect of the skeletal muscle energy system, which results in inefficient muscle performance.
The metabolic myopathies result from inborn errors of metabolism affecting intracellular energy production due to defects in glycogen, lipid, adenine nucleotides, and mitochondrial metabolism. Metabolic myopathies are genetic disorders that impair intermediary metabolism in skeletal muscle. There is no specific treatment for many of the metabolic muscle disorders. Metabolic myopathies american college of rheumatology. Dull or burning neck pain some report deltoid weakness emg changes limited to cece ca d to o e rvical mid to lower and upper thoracic spine. The acute nature of energy failure is manifested either by a metabolic crisis with weakness, sometimes associated with respiratory failure, or by myoglobinuria. Metabolic myopathies should be considered in the differential diagnosis of patients with exercise induced muscle symptoms, static or progressive myopathy. 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. At the cellular level, metabolic myopathies lack some kind of enzyme that prevent the chemical reactions necessary to create adenosine triphosphate atp. Metabolic myopathies in spanish espanol download printfriendly pdf. Table 1 includes a nonexhaustive list of more frequently encountered disorders. Full text full text is available as a scanned copy of the original print version. Accordingly, the three main categories of metabolic myopathies are glycogen storage diseases, fatty acid oxidation defects, and mitochondrial disorders due to.
Other symptoms that can be associated with mfm include pain and. The inflammatory myopathies are a group of diseases that involve chronic longstanding muscle inflammation, muscle weakness, and, in some cases, muscle pain. Metabolic muscle diseases that have their onset in infancy tend to be the most severe, and some forms are fatal. Muscular dystrophies and acquired myopathies are inflammatory and non inflammatory. Metabolic myopathies are a clinically and etiologically heterogeneous group of diseases, including muscle glycogenosis, fatty acidrelated myopathies, and mitochondrial respiratory chain defects. A diagnostic algorithm for metabolic myopathies ncbi. However, pain is usually not common in most muscle diseases and is more likely to be due to orthopedic or rheumatological disorders kincaid, 1997.
Metabolic myopathies treatments vary according to the patients particular myopathy. 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 pdf myopathies pdf myopathies pdf download. Metabolic myopathies are disorders of utilization of carbohydrates or fat in muscles. They are sometimes misdiagnosed as muscular dystrophies or inflammatory myopathies. Metabolic myopathies muscular dystrophy association. Myopathy itself is divided into 3 categoriesmyositic, intrinsic, and toxicwhich reflect the condition, or medication, that brought on the muscle damage table 2 2,415. Facts about metabolic diseases of muscle muscular dystrophy. The symptoms, signs, and laboratory abnormalities resulting from a metabolic myopathy vary with the underlying defect. Living with metabolic myopathies everyone has run out of energy, become tired when doing physical activities, or experienced muscle pains and cramps after exercising. Metabolic myopathies are a clinically and genetically heterogeneous group of disorders caused by defects in cellular muscle metabolism resulting in muscle weakness, recurrent myoglobinuria, and exercise intolerance.
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