pattismith
Senior Member
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A PATTERN RECOGNITION APPROACH TO THE PATIENT WITH A SUSPECTED MYOPATHY
Abstract
Myopathies are a heterogeneous group of disorders that can be challenging to diagnose. The purpose of this review is to provide a diagnostic approach based predominantly upon the clinical history and neurologic examination. Laboratory testing that can be subsequently used to confirm the suspected diagnosis based upon this pattern recognition approach will also be discussed. Over the past decade, there have been numerous discoveries allowing clinicians to diagnose myopathies with genetic testing. Unfortunately, some of the testing, particularly molecular genetics, is extremely expensive and frequently not covered by insurance. Careful consideration of the distribution of muscle weakness and attention to common patterns of involvement in the context of other aspects of the neurologic examination and laboratory evaluation should assist the clinician in making a timely and accurate diagnosis, and sometimes can minimize the expense of further testing
(the full article is available)
a few extracts:
...
BOX 2
SYMPTOMS ASSOCIATED WITH MYOPATHIES
“Negative”:
Exercise Intolerance
Fatigue
Muscle atrophy
Weakness
“Positive”:
Cramps
Contractures
Muscle Hypertrophy
Myalgias
Myoglobinuria
Stiffness
...
BOX 3
MUSCLE DISEASES ASSOCIATED WITH MYALGIAS
Toxic/drug-induced myopathies (statins and others)
Eosinophilia-myalgia syndrome
Hypothyroid myopathy
Inflammatory myopathies (dermatomyositis, polymyositis)
Myotonic disorders
Mitochondrial myopathies
Tubular aggregate myopathy
Muscular dystrophies, examples:
X-linked myalgia and cramps/Becker’s dystrophy variant
Infectious myositis (especially viral)
Myoadenylate deaminase deficiency (controversial)
BOX 4
MYOPATHIES ASSOCIATED WITH MUSCLE CONTRACTURES
Brody’s Disease
Glycolytic/glycogenolytic enzyme defects
Myophosphorylase deficiency (McArdle’s disease)
Phosphofructokinase deficiency
Phosphoglycerate kinase deficiency
Phosphoglycerate mutase deficiency
Lactate dehydrogenase deficiency
Debrancher enzyme deficiency
Hypothyroid myopathy
Rippling muscle disease
BOX 5
MYOPATHIES ASSOCIATED WITH MUSCLE STIFFNESS
Hypothyroid myopathy
Myotonia congenita
Paramyotonia congenita
Myotonic dystrophy type 1
Proximal myotonic myopathy (myotonic dystrophy type 2)
Hyperkalemic periodic paralysis
Myopathies Presenting in Adulthood
Centronuclar myopathy
Distal myopathies
Endocrine myopathies – thyroid, parathyroid, adrenal, pituitary disorders
Inflammatory myopathies - polymyositis, dermatomyositis, inclusion body myositis, viral (HIV)
Metabolic myopathies – acid maltase deficiency, lipid storage diseases, debrancher
deficiency, phosphorylase b kinase deficiency
Mitochondrial myopathies
Muscular dystrophies – Limb-girdle, Facioscapulohumeral, Becker, Emery-Dreifuss
Myotonic dystrophy
Nemaline myopathy
Toxic myopathies – alcohol, corticosteroids, local injections of narcotics, colchicine,
chloroquine
BOX 9
DRUGS THAT CAN CAUSE TOXIC MYOPATHIES
Inflammatory:
Abstract
Myopathies are a heterogeneous group of disorders that can be challenging to diagnose. The purpose of this review is to provide a diagnostic approach based predominantly upon the clinical history and neurologic examination. Laboratory testing that can be subsequently used to confirm the suspected diagnosis based upon this pattern recognition approach will also be discussed. Over the past decade, there have been numerous discoveries allowing clinicians to diagnose myopathies with genetic testing. Unfortunately, some of the testing, particularly molecular genetics, is extremely expensive and frequently not covered by insurance. Careful consideration of the distribution of muscle weakness and attention to common patterns of involvement in the context of other aspects of the neurologic examination and laboratory evaluation should assist the clinician in making a timely and accurate diagnosis, and sometimes can minimize the expense of further testing
(the full article is available)
a few extracts:
...
BOX 2
SYMPTOMS ASSOCIATED WITH MYOPATHIES
“Negative”:
Exercise Intolerance
Fatigue
Muscle atrophy
Weakness
“Positive”:
Cramps
Contractures
Muscle Hypertrophy
Myalgias
Myoglobinuria
Stiffness
...
BOX 3
MUSCLE DISEASES ASSOCIATED WITH MYALGIAS
Toxic/drug-induced myopathies (statins and others)
Eosinophilia-myalgia syndrome
Hypothyroid myopathy
Inflammatory myopathies (dermatomyositis, polymyositis)
Myotonic disorders
Mitochondrial myopathies
Tubular aggregate myopathy
Muscular dystrophies, examples:
X-linked myalgia and cramps/Becker’s dystrophy variant
Infectious myositis (especially viral)
Myoadenylate deaminase deficiency (controversial)
BOX 4
MYOPATHIES ASSOCIATED WITH MUSCLE CONTRACTURES
Brody’s Disease
Glycolytic/glycogenolytic enzyme defects
Myophosphorylase deficiency (McArdle’s disease)
Phosphofructokinase deficiency
Phosphoglycerate kinase deficiency
Phosphoglycerate mutase deficiency
Lactate dehydrogenase deficiency
Debrancher enzyme deficiency
Hypothyroid myopathy
Rippling muscle disease
BOX 5
MYOPATHIES ASSOCIATED WITH MUSCLE STIFFNESS
Hypothyroid myopathy
Myotonia congenita
Paramyotonia congenita
Myotonic dystrophy type 1
Proximal myotonic myopathy (myotonic dystrophy type 2)
Hyperkalemic periodic paralysis
Myopathies Presenting in Adulthood
Centronuclar myopathy
Distal myopathies
Endocrine myopathies – thyroid, parathyroid, adrenal, pituitary disorders
Inflammatory myopathies - polymyositis, dermatomyositis, inclusion body myositis, viral (HIV)
Metabolic myopathies – acid maltase deficiency, lipid storage diseases, debrancher
deficiency, phosphorylase b kinase deficiency
Mitochondrial myopathies
Muscular dystrophies – Limb-girdle, Facioscapulohumeral, Becker, Emery-Dreifuss
Myotonic dystrophy
Nemaline myopathy
Toxic myopathies – alcohol, corticosteroids, local injections of narcotics, colchicine,
chloroquine
BOX 9
DRUGS THAT CAN CAUSE TOXIC MYOPATHIES
Inflammatory:
- Cimetidine
- D-penicillamine
- Procainamide
- L-tryptophan
- L-dopa
- Alcohol
- Amphetamine
- Cholesterol lowering drugs
- Cocaine
- Heroin
- Toluene
- ε-aminocaproic acid
- Alcohol
- Cholesterol lowering agents
- Chloroquine
- Colchicine
- Cyclosporine and tacrolimus
- Emetine
- ε-aminocaproic acid
- Isoretinoic acid (vitamin A analogue)
- Labetalol
- Vincristine
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