REFARAT Hipotiroid myopathi
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Myopathy is an abnormality of the skeletal muscle in which striated muscle cells or connective tissue elements are affected. Myopathy can result from abnormalities of skeletal muscle proteins (Duchenne muscular dystrophy), alterations of the sarcolemmal ion channels (hyperkalemic periodic paralysis), mitochondrial alterations (mitochondrial myopathy), or cell-mediated auto-immune mechanisms (polymyositis), to name a few examples. Because of the myriad abnormal mechanisms, treatments vary from one condition to the next. Progress in molecular biology, genetics, and immunology has considerably expanded our understanding of these complicated diseases. Myopathy is a known complication of long-standing hypothyroidism and the incidence of musculoskeletal symptoms varies from 30-80% in different series.456 Kocher' and Debre & Semelaigne 2 described a syndrome of muscular hypertrophy associated with delayed muscle relaxation in two athyreotic cretins. Hoffman 3 in 189 reported an adult who developed stiffness and difficulty in relaxation of muscles with typical myotonic response to contraction, percussion, and electrical stimulation after thyroidectomy. In Hoffman's syndrome, the patients typically complain of cramps, ache and pain in muscles of the shoulder and pelvic girdles. They have enlarged muscles, weakness, slow movements and delayed relaxation of tendon reflexes. Although the Kocher-Debre-Semelaigne syndrome and Hoffman's syndrome were initially described in different age groups, some authors regard them as variants of the same disease process.
CHAPTER IILITERATURE REVIEWS
2.1 DefinitionMyopathy word used for a variety of diseases caused by anatomical and biochemical changes in and around the motor end plate, the muscle fibers, or in the connective tissue of the muscle, and not caused by lesions of the nervous system.12.2 EpidemiologyHereditary myopathy incidence worldwide is about 14%. Of the overall disease, central core disease (16%), nemaline rod (20%), centranuclear numbered (14%), and multicore (10%). Muscular dystrophy higher prevalence in males. In the United States, Duchenne muscular dystrophy and Becker are 1 of 3300 men. Overall incidence of muscular dystrophy is about 63/1 million. The incidence of inflammatory myopathy around the world ranging from 5-10 / 100,000 people. The disorder is more common in women. The incidence and prevalence of endocrine and metabolic myopathy is unknown. Corticosteroid myopathy is most common on the type of myopathy endocrine and endocrine disorders more common in women than men. Metabolic myopathies are rare, but the diagnosis is increasing in the United States.2.3 Etiology1. Primary Myopathy Muscular dystrophy - disorders of the dystrophin: Duchenne muscular dystrophy (DMD) including Becker dystrophy DMD muskuler- most often occur in children with muscular dystrophy (1 in 3,500, or 63 per 1 million children) and Becker (24 per 1 million) Muscular dystrophy Fascioscapulohumeral Limb girdle muscular dystrophy Emery-Dreifuss muscular dystrophy Muscular dystrophy in rare form, among others: Distal muscular dystrophy Muscular dystrophy Oculofaringeal Congenital muscular dystrophy (DMK) - is caused by genetic mutations and autosomal recessive disorders common by (the prevalence is approximately 5 per 100,000): Damage extracellular matrix proteins: Laminin-alpha deficiency 2 Ullrich CMD. Deficiency-integrin alpha7 In Glycosyltransferase: Walker-Warburg syndrome Diseases Muscle-eye-brain (MEB) Fukuyama CMD- generally in Japan (7-12 per 100,000) CMD with deficiency of laminin (2 types) CMD with mental retardation. proteins of the endoplasmic reticulum: Rigid-spine syndrome. Congenital myopathies - rare (incidence unknown) in which genetic damage depends on the location of the muscle protein breakdown: Myopathy "Nemaline rod" Disease "Central core" Myopathy "Centronuclear" Myopathy "Minimulticore" Type 1 muscle fiber predominant. Metabolic myopathies: Disorders hereditary muscle caused by damage to the enzyme (usually caused by disturbances in fetal life that cause damage to the 3 major pathways of metabolism preparation of ATP) and relatively rare (very rare when compared with muscular dystrophy): Glycogen storage disease Disease "Pompe" - maltose acid deficiency (prevalence of 1 / 40,000) Disease "McArdle" - (prevalence of 1 / 100,000) Other forms. Lipid Storage Disease Deficiency Carnitine palmitoyltransferase - (relative deficiency identified approximately 1 out of 150 patients) Myopathy due to carnitine deficiency. Impaired metabolism of purine nucleotides (resulting in ATP release) Impaired Mitochondrial level.
2. Secondary Myopathy Myopathy due to metabolic and endocrine disorders: Thyroid Disease: Miksudema along with myopathy Hyperthyroidism. Parathyroid dysfunction: Hipotiroid- cause tetanus Hipertiroid- cause proximal myopathy Pituitary gland dysfunction (eg, Addison's disease) - myopathy caused by dysfunction of the adrenal or thyroid dysfunction. Corticosteroids: Cushing's disease Eksogen- particularly high-dose steroids (above 25 mg per day). Biochemistry: hypokalaemia and hiperkalemi cause muscle weakness and miotoni Can disebakan by diverse paralysis acute period (genetic) Due to acute gastrointestinal disorders As a result of endocrine disease Renal Disease Prolonged fasting. Diabetes mellitus. Dermatomyositis and polymyositis-an inflammatory myopathy (possibly autoimmune) with weakness, endomysial inflammation and muscle enzyme meniongkatnya: Primary Polymyositis (adult idiopathic) Dermatomyositis (adult idiopathic) Dermatomyositis in children (or myositis with necrotizing vasculitis) Polymyositis associated with connective tissue disorders Polymyositis or dermatomyositis associated with neoplasia. Drug-induced myopathies: Statins Steroids Cocaine Colchicine. Infection: Trikinosis Toxoplasmosis Human immunodeficiency virus (HIV) Coxsackie Virus Influenza Lyme Disease. Polymyalgia rheumatic: Proximal myopathy associated with muscle pain.
2.4 PathophysiologyMost myopathy congenital or hereditary is a chronic disease with a slow progression. Hereditary myopathy caused by mutations in the genetic code for various components of the dystrophin-glycoprotein complex causes muscular dystrophy, a syndrome characterized by progressive muscle weakness. Most bazaar of this form of the disease causing severe disability and ends fatal.Mutations of genes that encode enzymes involved in the metabolism of carbohydrates, fats and proteins into CO2 and H2O in the muscles as well as the formation of ATP, will cause myopathy metabolik. Myotonia is caused by abnormal genes on chromosomes 7,17, or 19, which cause abnormal ion channels Na + or Cl.4
2.5 Symptom and SignsMuscle weakness and fatigability are the most frequent symptoms, and although fatigability is a common complaint in those with muscle diseases, excessive fatigability out of proportion to the degree of weakness should raise suspicion of a neuromuscular junction disorder. Muscle pain, stiffness, spasms, or cramps may occur with varying severity, depend-ing on the nature of injury. Patients should be asked about the color of their urine, which, when dark red, suggests myoglobinuria. Double vision, difficulty swallowing, and shortness of breath may be present. Distribution of weakness may vary among diseases, with some muscles affected more than others. Muscle tone is usually reduced and in infants may result in a floppy infant. In exceptional cases such as those characterized by continuous overactivity of motor units, or dystrophies with early onset of contractures, muscle stiffness is seen. Myotonia is present in specific muscular dystrophies and ion channel disorders (channelopathies). Muscle atrophy is common, but in certain disorders there is pseudohypertrophy (especially of the calf muscles) from connective tissue and fat replacement. In severely weak muscles, tendon reflexes may be diminished or absent. Muscle tenderness may be prominent or absent. Systemic signs and symptoms of endocrine disorders such as thyroid disease may be evident, and a skin rash may offer diagnostic clues. In some congenital myopathies, dysmorphic features and skeletal abnormalities are present.3
2.6 Diagnosis2.6.1 Clinical FindingRoutine and advanced tests used in the evaluation of patients with suspected myositis are detailed in Table 233. Muscle enzymes such as creatine kinase (CK) may be markedly elevated, mildly elevated, or normal. CK is released from the sarcoplasmic reticulum into the serum after muscle injury. When the serum myoglobin level exceeds its renal threshold,with muscle diseases; a normal -glutamyl transpeptidase in this situation makes liver pathology an unlikely culprit. Serum creatinine and electrolytes should be measured, because chronic renal failure and hypokalemia are associated with muscle weakness. Parathyroid hormone levels should be obtained in patients with hypercalcemia. Erythrocyte sedimentation rate is useful when an overlap syndrome is suspected, or in the diagnosis of polymyalgia rheumatica. Elevated serum angiotensin-converting enzyme levels suggest sarcoidosis, and testing for HIV may be warranted. Arterial blood gas measurement may reveal high carbondioxide levels in patients with shortness of breath caused by respiratory muscle involvement, and pulmonary function tests may support this finding. Elevated arterial lactate levels can occur in mitochondrial disorders. Molecular genetic testing for specific mutations may be clinically indicated. In patients with myopathies that involve cardiac muscle, electrocardiography, echocardiography, and Holter monitoring should be performed when clinically indicated.2
Table 233. Laboratory and Diagnostic Studies Used in Evaluation of MyopathyRoutine testsAdvanced tests
Creatine kinase levelUrinalysis and urine myoglobinLiver function testsThyroid function testsRoutine chemistry panel (including calcium, phosphorus, magnesium)Erythrocyte sedimentation rateElectrocardiographyElectromyography
HIV screeningAngiotensin-converting enzyme levelArterial blood gas measurementArterial lactate levelMyositis-specific antibody testingChest radiographyPulmonary function testsTransthoracic echocardiographyHolter monitoringGenetic testingMuscle biopsyMuscle imaging techniques
2.6.2 Imaging StudiesFor routine purposes imaging studies are rarely indicated. In specific situations (eg, muscle infarction), or to help localize the optimal biopsy site, imaging techniques may be useful. Radionuclide scanning using technetium-labeled phosphates, indium-labeled antibodies, and gallium 67 citrate may assess the extent and severity of muscle involvement in inflammatory myopathies and may assist in biopsy site determination. Ultrasound is rapid and may assist in optimizing the biopsy site, especially in younger children. Magnetic resonance imaging (MRI) is useful in evaluating myopathies that cause muscle edema and can be used to assess the response to therapy in inflammatory myopathies.22.6.3 Special TestsElectromyography (EMG) and nerve conduction studies (NCSs) may confirm the presence of a muscle disorder and exclude defects in neuromuscular transmission, neuropathy, or anterior horn cell disease. For the evaluation of myopathy, quantitative EMG should be performed. Classic EMG findings include short-duration, small-amplitude motor unit potentials with early recruitment (so called myopathic features). Spontaneous activity (positive sharp waves, fibrillations) may be present in varying amounts, depending on the etiology. Muscle biopsy is limited by sampling error but remains the gold standard for establishing the diagnosis of a muscle disease. A muscle that is not too severely affected by the disease process is usually selected. Open biopsy is generally performed, but needle biopsy is occasionally preferred in children. The biopsy may include fascia or skin in specific cases. Biopsy of muscles sampled by needle EMG should be delayed by at least 1 month.2
2.7 Differential DiagnosisSome diseases that can cause muscle weakness:- Guillain-Barre syndrome- Lambert-Eaton myasthenic syndrome- Myastenia gravis- Cerebral Palsy- Spinal muscular atrophy2.8 ComplicationsComplications that can occur, among others: Cardiac arrhythmias Hypertension Dysphagia Respiratory disorders Endocrinopathy2.9 TreatmentTreatment of muscle disorders usually involves a multidisciplinary team approach that includes neurologists, physiatrists, cardiologists, pulmonologists, geneticists, rheumatologists and orthopedists. Pharmacotherapy is disease specific; refer to the discussion of individual disorders that follows.32.10 PrognosisThe prognosis depends on the etilogi and specific diagnosis. Death and disability due to myopathy depends on the etiology of the disorder, severity of disease, and the presence of conditions that threaten the endocrine myopathy cases, the prognosis is usually good. Progressive myopathy develops in adulthood better prognosis than that developed during childhood.4
3.1 Endocrine Myopathy Tiroid MyopathyHow thyroid hormone affects the muscle fiber is still a matter of conjecture. Clinical data indicate that thyroxine influences the contractile process in some manner but does not interfere with the transmission of impulses in the peripheral nerve across the myoneural junction or along the sarcolemma. In hyperthyroidism an undefined functional disorder enhances the speed of the contractile process and reduces its duration, the net effect being fatigability weakness, and loss of endurance of muscle action. In hypothyroidism,muscle contraction is slowed, as is relaxation, and its duration is prolonged. The speed of the contractile process is related to the quantity of myosin adenosine triphosphatase(ATPase),which is increased in hyperthyroid muscle and decreased in hypothyroid muscle. The speed of relaxation depends on the rate of release and reaccumulation of calcium in the endoplasmic reticulum. This is slowed in hypothyroidism and increased in hyperthyroidism (Ianuzzo et al) The myopathic effects of hypothyroidism need to be distinguished from those of a neuropathy, which may rarely complicate hypothyroidism.3
Hypothyroid Myopathy1. Symptoms and SignsIn addition to nonspecific constitutional symptoms, including hair loss, thick skin, and mental slowing (which may progress to myxedema coma), muscle weakness and cramping are often present in hypothyroidism. Prolonged or delayed relaxation of deep tendon reflexes is a characteristic finding, and myotonoid features (myotonia is a symptom manifested by the slow relaxation of a group of muscles following contraction) are seen in one quarter of patients. Proximal weakness develops insidiously and may be associated with pain and tenderness. An unusual finding is the presence of muscular enlargement or pseudohypertrophy, which can be seen in children (Debr-Smlaigne syndrome, or infa...