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44 Cards in this Set
- Front
- Back
causes of sensory neuropathy
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rare: toxins (B6/pyridoxine), anti-Hu (ANNA-1) abs due to paraneoplastic syndrome associated with small cell lung carcinoma, Sjogren's
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EMG denervation signs
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Motor unit APs are larger and longer, but fewer MUs present because of renervation using the few remaining LMN due to sprouting; also see fibrillation (small AP of single fiber)
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ALS
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common (increases with age); progressive loss of motor neurons (both LMN and UMN) w/o sensory involvement; begins in bulbar muscles (speech, chewing, swallowing), arms, or legs; usually idiopathic (10% inherited)
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SMA
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progressive loss of motor neurons w/o sensory involvement; caused by loss of SMN1 gene (replaced by SMN2); severity depends on type but is genetic so affects children from birth (SMA 1) to after 1 yr (SMA3) and adults after 30 yr (SMA 4 only)
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SMN1/2 gene
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SMN protein needed to prevent motor neuron loss; SMN1 gene produces stable full length protein while 90% SMN2 produces truncated protein; in SMA SMN2 replaced by SMN1 and thus instead of 110% of SMN protein we get 20%
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radiculopathies most common causes
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very common, usually due to compression of nerve root by herniated disks, boney overgrowth, or mass; most common in cervical (C5-8 and most common C7) and lumbosacral (L4-S1 and most common L5)
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PMP22
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duplication (i.e. 3 copies) leads to Charcot-Marie-Tooth disease (CMT1A) and deletion (i.e. 1 copy) leads to herid neuropathy with liability to pressure palsies (HNPP) -> these two diseases are thos emost common inherited demyelinating neuropathies, and in this case caused by too little or too much PMP22 in the myelin sheath
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presynaptic NMJ diseases
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Lambert-Eaton, botulusm
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postsynaptic NMJ diseases
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myasthenia gravis
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repetitive stimulation used to diagnose what?
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NMJ disorders -> presynaptic defects will see increased CMAP amplitude with repetitive stimulus (small at rest, rises as more ACh enters cleft); postsynaptic defects will see decreased CMAP amplitude with repetitive stimulus (normal at rest, drops as axon terminal runs low on AcH); normal will see no change in amplitude because of large safety factor
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congenital myopathies vs muscular dystrophies
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congenital myopathies have no active muscle breakdown and regeneration -> may show improvement or stable course rather than decline seen in MD
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classic congenital myopathies (4)
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nemaline myopathy, centronuclear/myotubular myopathy, central core disease, multi/minicore myopathy -> each describes a histological finding, not a cause (each disease is genetically heterogeneous)
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nemaline myopathy
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disease of thin filaments (often nemalin or actin mutations), cause nemaline rods composed of Z-line material in sarcoplasm regions of interrupted sarcomere structure (looks like red rods on trichrome)
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muscular dystrophy histology (3)
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degeneration, regeneration, connective and fatty tissue infiltration
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Duchenne muscular dystrophy: time course (3), symptoms (3), complications (3)
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onset 2-4 yrs (not floppy baby) and wheelchair in under 12 yrs, can live until 30s; proximal progressive weakness, pseudohypertrophy, elevated CK; complications: cardiomyopathy, respiratory insufficiency, scoliosis
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Gower's maneuver
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child on back can't get up immediately because of proximal muscle weakness -> must roll over and walk forward on hands to stand
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Trendelenburg sign
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hip abductor weakness due to proximal muscle weakness brought out by climbing stairs -> excessive hip swing
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Becker muscular dystrophy: demographics, time course (4), lab values (1), complication (1)
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10x less common than DMD (1:30,000 in Becker vs 1: 3500 in DMD); variable onset with wheelchair in more than 15 yrs and severity and lifespan variable; CK elevated; complication: cardiomyopathy, even while still ambulant -> usually looks similar to DMD in proximal progressive weakness and pseudohypertrophy b/c it's a MD after all!
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muscular dystrophy causes
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mutations in dystrophin (v. large protein that is important in binding proteins on sarcolemma); 65-70% mutations are deletions of exons (majority around exon 45-53) and 30% mutations de nova (common because large?); deletions that lead to disruption of reading frame (more common) leads to DMD (worse prognosis) while preservation of reading frame leads to BMD (less common, better prognosis) -> poss tx of forcing exon 51 skipping in DMD to lead to frame restoration and BMD
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"girls with DMD" have what?
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sarcoglycanopathy (limb-girdle MD due to mutation of sarcoglycan, a protein in complex with dystrophin) -> AR disease
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sarcoglycanopathy
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AR disease (aka both sexes!) that looks like DMD -> limb-girdle MD due to mutation of sarcoglycan, a protein in complex with dystrophin
|
|
facioscapulohumeral dystophy (FSHD): demographics, inheritance, onset, symptoms, cause
|
3rd most common dystrophy (after DMD and myotonic -> 1-5:100,000); AD or de nova (30%); onset variable but usually young adult (depends on deletion size); asymmetric weakness in face, scapula, biceps, distal leg (foot drop); caused by loss of repeat elements (DUX4) on the A version of 4qter (more deletions = more severe/earlier onset disease but lose all = no disease) -> this is because deletions allow the chromatin structure to relax and DUX4 to be polyadenylated (pLAM only on A 4q) and thus expressed = toxic
|
|
causes of sensory neuropathy
|
rare: toxins (B6/pyridoxine), anti-Hu (ANNA-1) abs due to paraneoplastic syndrome associated with small cell lung carcinoma, Sjogren's
|
|
EMG denervation signs
|
Motor unit APs are larger and longer, but fewer MUs present because of renervation using the few remaining LMN due to sprouting; also see fibrillation (small AP of single fiber)
|
|
ALS
|
common (increases with age); progressive loss of motor neurons (both LMN and UMN) w/o sensory involvement; begins in bulbar muscles (speech, chewing, swallowing), arms, or legs; usually idiopathic (10% inherited)
|
|
SMA
|
progressive loss of motor neurons w/o sensory involvement; caused by loss of SMN1 gene (replaced by SMN2); severity depends on type but is genetic so affects children from birth (SMA 1) to after 1 yr (SMA3) and adults after 30 yr (SMA 4 only)
|
|
SMN1/2 gene
|
SMN protein needed to prevent motor neuron loss; SMN1 gene produces stable full length protein while 90% SMN2 produces truncated protein; in SMA SMN2 replaced by SMN1 and thus instead of 110% of SMN protein we get 20%
|
|
radiculopathies most common causes
|
very common, usually due to compression of nerve root by herniated disks, boney overgrowth, or mass; most common in cervical (C5-8 and most common C7) and lumbosacral (L4-S1 and most common L5)
|
|
PMP22
|
duplication (i.e. 3 copies) leads to Charcot-Marie-Tooth disease (CMT1A) and deletion (i.e. 1 copy) leads to herid neuropathy with liability to pressure palsies (HNPP) -> these two diseases are thos emost common inherited demyelinating neuropathies, and in this case caused by too little or too much PMP22 in the myelin sheath
|
|
presynaptic NMJ diseases
|
Lambert-Eaton, botulusm
|
|
postsynaptic NMJ diseases
|
myasthenia gravis
|
|
repetitive stimulation used to diagnose what?
|
NMJ disorders -> presynaptic defects will see increased CMAP amplitude with repetitive stimulus (small at rest, rises as more ACh enters cleft); postsynaptic defects will see decreased CMAP amplitude with repetitive stimulus (normal at rest, drops as axon terminal runs low on AcH); normal will see no change in amplitude because of large safety factor
|
|
congenital myopathies vs muscular dystrophies
|
congenital myopathies have no active muscle breakdown and regeneration -> may show improvement or stable course rather than decline seen in MD
|
|
classic congenital myopathies (4)
|
nemaline myopathy, centronuclear/myotubular myopathy, central core disease, multi/minicore myopathy -> each describes a histological finding, not a cause (each disease is genetically heterogeneous)
|
|
nemaline myopathy
|
disease of thin filaments (often nemalin or actin mutations), cause nemaline rods composed of Z-line material in sarcoplasm regions of interrupted sarcomere structure (looks like red rods on trichrome)
|
|
muscular dystrophy histology (3)
|
degeneration, regeneration, connective and fatty tissue infiltration
|
|
Duchenne muscular dystrophy: time course (3), symptoms (3), complications (3)
|
onset 2-4 yrs (not floppy baby) and wheelchair in under 12 yrs, can live until 30s; proximal progressive weakness, pseudohypertrophy, elevated CK; complications: cardiomyopathy, respiratory insufficiency, scoliosis
|
|
Gower's maneuver
|
child on back can't get up immediately because of proximal muscle weakness -> must roll over and walk forward on hands to stand
|
|
Trendelenburg sign
|
hip abductor weakness due to proximal muscle weakness brought out by climbing stairs -> excessive hip swing
|
|
Becker muscular dystrophy: demographics, time course (4), lab values (1), complication (1)
|
10x less common than DMD (1:30,000 in Becker vs 1: 3500 in DMD); variable onset with wheelchair in more than 15 yrs and severity and lifespan variable; CK elevated; complication: cardiomyopathy, even while still ambulant -> usually looks similar to DMD in proximal progressive weakness and pseudohypertrophy b/c it's a MD after all!
|
|
muscular dystrophy causes
|
mutations in dystrophin (v. large protein that is important in binding proteins on sarcolemma); 65-70% mutations are deletions of exons (majority around exon 45-53) and 30% mutations de nova (common because large?); deletions that lead to disruption of reading frame (more common) leads to DMD (worse prognosis) while preservation of reading frame leads to BMD (less common, better prognosis) -> poss tx of forcing exon 51 skipping in DMD to lead to frame restoration and BMD
|
|
"girls with DMD" have what?
|
sarcoglycanopathy (limb-girdle MD due to mutation of sarcoglycan, a protein in complex with dystrophin) -> AR disease
|
|
sarcoglycanopathy
|
AR disease (aka both sexes!) that looks like DMD -> limb-girdle MD due to mutation of sarcoglycan, a protein in complex with dystrophin
|
|
facioscapulohumeral dystophy (FSHD): demographics, inheritance, onset, symptoms, cause
|
3rd most common dystrophy (after DMD and myotonic -> 1-5:100,000); AD or de nova (30%); onset variable but usually young adult (depends on deletion size); asymmetric weakness in face, scapula, biceps, distal leg (foot drop); caused by loss of repeat elements (DUX4) on the A version of 4qter (more deletions = more severe/earlier onset disease but lose all = no disease) -> this is because deletions allow the chromatin structure to relax and DUX4 to be polyadenylated (pLAM only on A 4q) and thus expressed = toxic
|