Pseudohypertrophy
False enlargement of muscle due to infiltration of fat or other tissue / From Wikipedia, the free encyclopedia
Pseudohypertrophy, or false enlargement, is an increase in the size of an organ due to infiltration of a tissue not normally found in that organ.[1] It is commonly applied to enlargement of a muscle due to infiltration of fat or connective tissue,[2] famously in Duchenne muscular dystrophy. This is in contrast with typical muscle hypertrophy, in which the muscle tissue itself increases in size.[2] Because pseudohypertrophy is not a result of increased muscle tissue, the muscles look bigger but are actually atrophied and thus weaker.[2][3] Pseudohypertrophy is typically the result of a disease, which can be a disease of muscle or a disease of the nerve supplying the muscle.[2]
Pseudohypertrophy | |
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Other names | false enlargement |
Drawing of seven-year-old boy with Duchenne muscular dystrophy. There is pseudohypertrophy of the lower limbs. | |
Symptoms | Weakness |
Causes | muscle disease, nerve disease |
Causes of pseudohypertrophy include muscle diseases: dystrophinopathies, limb-girdle muscular dystrophies, metabolic myopathy, Dystrophic myotonias, Non-dystrophic myotonias, endocrine disorders, parasitic muscle conditions, amyloid and sarcoid myopathy, and granulomatous myositis.[2]
Neurological causes include radiculopathy, poliomyelitis, Charcot-Marie-Tooth disease, spinal muscular atrophy.[2]
In pseudohypertrophy where the atrophied muscle tissue has been infiltrated by fat tissue, upon palpitation the seemingly large muscles feel doughy.[3]
Not all muscles infiltrated by fat or other tissue are pseudohypertrophic. In muscular steatosis, sometimes the muscles may appear a normal or a slender size, even though the atrophied muscle has been infiltrated with fat tissue, such as the calf muscles in Bethlem myopathy 1.[4][5][6][7][8] In myosclerosis, the muscle is infiltrated with connective tissue and fibrosis, having a firm, "woody" feel upon palpitation, with the muscles appearing slender.[9][10]