Muscle Diseases
Terms
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- What is a myopathy?
- Is a motor dysfxn due to a disease of the muscle.
- What can cause myopathies?
- Muscle membrane abnormalities, cytoskeletal protein abnormalities, metabolism errors, inflammatory destruction, toxins
- What are things to look out for clinically in regards to myopathy?
- muscle bulk, palpation, and percussion. Also reflexes and weakness.
- What is important about weakness, muscle bulk, palpation, percussion, and reflexes?
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The distribution (proximal and symmetric).
Preserved or enlarged. Palpation induarated or tender (unreliable).
Diminished muscle contraction.
Parallel degree of muscle strength. - What clinical fx's may suggest that weakness is not due to myopathy?
- If it is distal, fasciculations occur, tremors are present, sensory signs, fatigue, and abscence of reflexes occur.
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What do the following things indicate:
1) distal weakness, 2)fasciculations, 3) tremor, 4) sensory signs, & 5) pathologic fatigue -
1) neuropathy
2) ant. horn cell syndrome
3) per. neuropathy, ant. horn cell disease, or central process
4) per. neuropathy or central process
5) NMJ disorder - What dose MERRF stand for and what are its symptoms?
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Myoclonic epilepsy and ragged red fibers
Myoclonus, gen. seizures, ataxia, dementia, hearing loss, optic atrophy, & muscle weakness - What does MELAS stand for and what are its symptoms?
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Mitochondrial lactic acidosis and strokes
Encephalopathy, high lactic acid levels in serum/CSF, and stroke-like episodes - What are fx's of KEARNS-SAYRES syndrome?
- Ophthalmoplegia, retinitis pigmentosa, abnormal cardiac conduction, & myopathy
- What is a dynamic glycogen metabolism disorder?
- It relates to exercise intolerance (cramps, pain, myoglobinuria)
- What is the one fx of static glycogen metabolism disorders?
- Fixed weakness
- Mitochondrial myopathies are classified by defects in what things?
- tranport, substrate utilization, Kreb's cycle, oxidation/phosphorylation, or coupling
- Most mitochondrial proteins are encoded by what?
- Nuclear DNA
- What fx of cell division causes some mitochondria DNA to have no mutants, some mutants, or be predominantly mutants?
- Segregation
- Why is the nervous system more susceptible to mitochondrial disorders?
- It requires a constant supply of energy
- Why do most mitochondrial myopathies have a maternal pattern of transmission and affect males & females equally?
- Mitochondria are inherited from the mother
- What does a classic muscle biopsy demonstrate in reference to mitochondrial disorders?
- ragged red fibers, and abnormalities in oxidative enzymes stains (NADH, succinyl dehydrogenase, & cytochrome oxidase)
- What clinical fx's suggest weakness is not due to myopathy?
- distal weakness, fasciculations, tremor, sensory signs, pathologic fatigue & early absence of reflexes
- What do distal weakness and fasciculations suggest?
- Neuropathy and ant. horn cell syndrome.
- What does a tremor suggest?
- Peripheral neuropathy, ant. horn cell disease, or central process
- What do sensory signs (symptoms) and pathologic fatigue suggest?
- Peripheral neuropathy, and a NMJ disorder