Corticosteroid-Induced Myopathy WorkupMyopathy is an important side effect of treatment with statins and fibrate drugs used in the treatment of hyperlipidemia. Preston Steroidogenic factor 1 mutation, Barbara E. Myopathies present as pure motor syndromes without any disturbance of sensory or autonomic function. In corticosteroid myopathy emg myopathies, symptoms tend to be bilateral and affect proximal muscles preferentially. Patients usually complain of difficulty rising from chairs, going up and down corticosteroid myopathy emg, or reaching with their arms.
Myopathy - an overview | ScienceDirect Topics
Myopathy is an important side effect of treatment with statins and fibrate drugs used in the treatment of hyperlipidemia. Preston MD, Barbara E.
Myopathies present as pure motor syndromes without any disturbance of sensory or autonomic function. In most myopathies, symptoms tend to be bilateral and affect proximal muscles preferentially. Patients usually complain of difficulty rising from chairs, going up and down stairs, or reaching with their arms. Although most myopathies are symmetric and proximal, there are exceptions to both.
For example, inclusion body myositis IBM and facioscapulohumeral muscular dystrophy may be very asymmetric.
Myotonic dystrophy, distal hereditary myopathy , and IBM may preferentially affect distal more than proximal muscles. In some myopathies, ocular and bulbar muscles may be affected. Deep tendon reflexes are generally preserved or, if reduced, are in proportion to the degree of muscle wasting and weakness. In evaluating a patient with suspected myopathy , it is important to determine whether symptoms are exercise induced.
Such symptoms may manifest as fatigability, exercise-induced muscle cramps, or swelling. Patients who present with exercise-induced muscle cramps see later may develop frank weakness, swelling, and, if severe enough, myoglobulinuria.
These latter symptoms suggest an inherited disorder of muscle energy metabolism. Note that although fatigability is certainly common in myopathies, frank muscle weakness that develops with exercise over a short period of time, if not accompanied by cramps, suggests a disorder of the NMJ rather than a myopathy. Additionally, patients with Lambert—Eaton myasthenic syndrome LEMS and some rare patients with myasthenia gravis MG present with isolated proximal muscle weakness mimicking a myopathy.
In addition, adult onset spinal muscular atrophy, including X-linked bulbospinal muscular atrophy, usually presents with proximal muscle weakness and mimics the typical pattern of a myopathy. Disorders of muscle can be simplified into the following categories: Muscular dystrophies are inherited muscle disorders characterized by a progressive course and often an early onset, usually with a specific clinical and muscle biopsy pattern.
In recent years, the chromosomal abnormality or specific gene product e. The more common muscular dystrophies include myotonic dystrophy, Duchenne muscular dystrophy, Becker muscular dystrophy, Emery—Dreifuss muscular dystrophy, facioscapulohumeral muscular dystrophy, oculopharyngeal muscular dystrophy, and limb girdle muscular dystrophies. Inflammatory myopathies are associated most commonly with a presumed immunologic attack and include polymyositis PM , dermatomyositis DM , and IBM.
Other types of inflammatory myopathy include those caused by muscle infection by parasites, viruses, or bacteria. Endocrine myopathies are often seen in disorders of the thyroid and adrenal glands. In addition, myopathy can accompany some cases of acromegaly and parathyroid disease. Drug-induced and toxic myopathies are becoming increasingly common.
Examples of common drug-induced and toxic myopathies include those caused by steroids, alcohol, colchicine, azidothymidine AZT , clofibrate, and many of the cholesterol-lowering agents. Metabolic myopathies are disorders of muscle resulting from inherited enzyme deficiencies important in intracellular energy production. They may present in one of three ways: In patients with cramps and myoglobinuria, the genetic defect often is found either in the glycogen or lipid metabolism pathways.
These patients may be completely normal at rest but become symptomatic during or after exercise. In patients with disorders along the lipid pathway, symptoms commonly occur after an episode of long or forced exercise e. In patients with disorders along the glycogen pathway, symptoms commonly occur after brief, intense isometric exercise. Muscle aches and fatigue may begin during the exercise, followed by frank myoglobinuria. Headache, nausea, and vomiting may occur.
Muscles become painful and swollen. The creatine kinase CK level often is dramatically elevated into the thousands. The most common of these are caused by a deficiency of carnitine palmitoyltransferase CPT along the lipid pathway and myophosphorylase McArdle's disease along the glycogen pathway.
Patients with defects in mitochondrial metabolism often present with a myopathy , as well as abnormalities involving other systems, including the central nervous system. Short stature, hearing loss, seizures, cardiac abnormalities, learning disabilities, and stroke-like episodes are common. Lastly, some rare defects in metabolism i. Congenital myopathies are a group of myopathies in which each disorder has a fairly specific muscle biopsy finding on histochemical staining e.
Typically, hematoxylin and eosin paraffin staining is normal or nonspecific. Although most patients present in the first few years of life, an occasional patient with a congenital myopathy presents in adulthood with one of these disorders.
The clinical syndromes are nonspecific and tend to be slowly progressive or static. Muscle biopsy usually is needed for definitive diagnosis. Myopathy associated with periodic paralysis occurs in the setting of hypokalemic and hyperkalemic periodic paralysis see Chapter Patients develop proximal weakness in the fifth or sixth decade. Even those patients with hypokalemic periodic paralysis who have never experienced episodic weakness, a common scenario in affected females, invariably will develop a proximal vacuolar myopathy in adulthood.
Which myopathies cause respiratory failure? Myopathies usually cause proximal symmetric weakness, with or without other symptoms. The possibility of respiratory failure is the most serious concern in the management of most patients with myopathies.
Which myopathies are associated with cardiac disease? Ptosis usually without ophthalmoplegia: Chronic progressive external ophthalmoplegia mitochondrial myopathy. Which myopathies are characterized by predominant distal weakness? Early adult-onset distal myopathy type 1 Nonaka , type 2 Miyoshi , and type 3 Laing. Dayalu P, Teener JW: Stiff person syndrome and other anti-GAD-associated neurologic disorders. Curr Opin Neurol Debrancher deficiency, acid-maltase deficiency. References available online at expertconsult.
In Clinical Veterinary Advisor: The Horse , May be hereditary or environmental in origin, acquired, or congenital Disorders of anterior horn cells. Myogenic Inborn errors of metabolism—genetic Disorders of carbohydrate metabolism Polysaccharide storage myopathy in Quarter Horses. Mitochondrial enzyme deficiencies Complex I: Channelopathies, aberrations of ion and electrolyte flux Paramyotonias and myotonias.
Idiopathic chronic exertional rhabdomyolysis may be reclassified as additional diseases are identified. Acquired Traumatic Fibrotic myopathy. Infectious Bacterial Clostridial myonecrosis. Nutritional Vitamin E deficiency; equine motor neuron disease, equine degenerative myelopathy. Nutritional myodegeneration white muscle disease ; vitamin E with and without selenium deficiency.
There are two forms of steroid myopathy. The more common form produces progressive, painless weakness. Typically the myopathy is related to chronic use, but inhaled corticosteroids can cause diaphragmatic weakness within 2 weeks of initial exposure.
Chronic steroid myotoxicity can be prevented in part by exercise, and symptoms improve if the dose is reduced or discontinued. CK is not elevated, and EMG may be normal or show minimal myopathic changes. Muscle biopsy shows type 2 fiber atrophy. It is characterized by acute, severe paralysis that can affect all muscles, including respiratory muscles.
This syndrome has been given many names, including acute quadriplegic myopathy , thick filament myopathy , and critical illness myopathy. EMG may show an acute axonal neuropathy in addition to myopathic changes, which can confound the diagnosis.
Symmetric proximal weakness and atrophy develop over days. The cause of myopathy is extensive loss of thick myofilaments with preservation of thin filaments and Z disks in the atrophic muscle fibers. With supportive care, the prognosis for recovery is variable weeks to 1 year , but there may be considerable mortality. Critical illness polyneuropathy and myopathy. Benefits of intensive insulin therapy on neuromuscular complications in routine daily critical care practice.
Critical Care 13 1 R5, 1—12, Hammans, in Practical Guide to Neurogenetics , This chapter describes genetically determined disorders of skeletal or voluntary muscle. Muscle function can be impaired by disorders of other parts of the nervous system including the anterior horn cell, motor nerve, metabolic factors, or the neuromuscular junction, but this chapter is concerned with primary diseases of muscle.
The diagnostic approach to muscle diseases is very dependent on the clinical assessment. Muscle disease therefore requires careful application of clinical techniques, to minimize unnecessary use of invasive and expensive investigations. Research any investigations into family members even if performed elsewhere with appropriate consent.
Common myopathies diagnosable from clinical assessment include myotonic dystrophy, Duchenne muscular dystrophy, oculopharyngeal muscular dystrophy, and facioscapulohumeral dystrophy. These can sometimes be followed by genetic confirmation without recourse to neurophysiology or biopsy. A creatine kinase CK assay in blood is often a very useful investigation, which may help detect the presence of muscle pathology in subclinical disease.
The CK may also help in specific diagnosis. In the context of a limb girdle syndrome it can help narrow the differential diagnosis.